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The use of echolocation as an aid in mobility for blind persons Boehm, Richard George 1985

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THE USE OF ECHOLOCATION AS AN AID IN MOBILITY FOR BLIND PERSONS by RICHARD G. BOEHM B.A., Universi ty of Saskatchewan, Canada, 1973 B.Ed., Univers i ty of Saskatchewan, Canada, 1976 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS in THE FACULTY OF GRADUATE STUDIES College of Education Department of Educational Psychology and Special Education We accept th is thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA May 1985 ®Richard G. Boehm, 1985 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by h i s or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of The University of B r i t i s h Columbia 1956 Main Mall ' Vancouver, Canada V6T 1Y3 DE-6 (3/81) i i DEDICATION To the subjects, thesis committee members and research assistants who encouraged and lent direct assistance with this investigation from commencement to fruition. i i i ABSTRACT This invest igat ion studied the degree of spat ia l data that could be perceived by subjects, through the use of echolocation, who were led through an indoor environment and verbal ly reported the i r spat ia l perceptions. The experimental group was composed of 5 t o t a l l y b l ind and severely v i sua l l y impaired subjects and the control group had 11 sighted subjects who were under b l i nd fo l d . Each subject was led through the space, using the sighted guide technique, and the subject would c l i c k a c l i c ke r and attempt to perceive spat ia l data through echolocation. The space had 25 preselected reference points in i t , and the experimental subjects averaged 20.2 correct responses and the control subjects 7.727 for an overal l mean of 11.3125. i v TABLE OF CONTENTS Page DEDICATION i i ABSTRACT . . . i i i TABLE OF CONTENTS iv LIST OF TABLES . . v LIST OF FIGURES v i i CHAPTER ONE: INTRODUCTION AND STATEMENT OF THE PROBLEM . . . . 1 CHAPTER TWO: BACKGROUND OF THE PROBLEM AND LITERATURE REVIEW . 9 CHAPTER THREE: METHODOLOGY . . . . 21 Subjects 29 C l i cker 40 B l indfo ld 42 Data Co l lec t ion and Analysis 42 CHAPTER FOUR: RESULTS 46 Questionnaire Interview Responses 98 CHAPTER FIVE: DISCUSSION, IMPLICATIONS AND RECOMMENDATIONS FOR FUTURE RESEARCH 101 Discussion 101 Implications and Recommendations 113 REFERENCES 118 V LIST OF TABLES Table Page 3.1 Ages of the control subjects 33 3.2 Ages of the experimental subjects 34 4.1 Responses at each reference point for subject 1 . . . 47 4.2 Responses at each reference point for subject 2 . . . 49 4.3 Responses at each reference point for subject 3 . . . 52 4.4 Responses at each reference point for subject 4 . . . 56 4.5 Responses at each reference point for subject 5 . . . 58 4.6 Responses at each reference point for subject 6 . . . 61 4.7 Responses at each reference point for subject 7 . . . 63 4.8 Responses at each reference point for subject 8 . . . 65 4.9 Responses at each reference point for subject 9 . . . 67 4.10 Responses at each reference point fo r subject 10 . . . 69 4.11 Responses at each reference point for subject 11 . . . . 71 4.12 Responses at each reference point for subject 12 . . . 73 4.13 Responses at each reference point for subject 13 . . . 75 4.14 Responses at each reference point for subject 14 . . . 78 4.15 Responses at each reference point for subject 15 . . . 79 4.16 Responses at each reference point for subject 16 . . . 81 4.17 Subjects' response at reference point 1 82 4.18 Subjects' response at reference point 2 83 4.19 Subjects' response at reference point 3 83 4.20 Subjects' response at reference point 4 84 4.21 Subjects' response at reference point 5 84 4.22 Subjects' response at reference point 6 85 4.23 Subjects' response at reference point 7 85 vi Table Page 4.24 Subjects' response at reference point 8 86 4.25 Subjects' response at reference point 9 86 4.26 Subjects' response at reference point 10 87 4.27 Subjects' response at reference point 11 87 4.28 Subjects' response at reference point 12 88 4.29 Subjects' response at reference point 13 88 4.30 Subjects' response at reference point 14 89 4.31 Subjects' response at reference point 15 89 4.32 Subjects' response at reference point 16 90 4.33 Subjects' response at reference point 17 90 4.34 Subjects' response at reference point 18 91 4.35 Subjects' response at reference point 19 91 4.36 Subjects' response at reference point 20 92 4.37 Subjects' response at reference point 21 92 4.38 Subjects' response at reference point 22 93 4.39 Subjects' response at reference point 23 93 4.40 Subjects' response at reference point 24 94 4.41 Subjects' response at reference point 25 94 4.42 Errors made between two reference points 95 4.43 Overall performance of a l l subjects 96 4.44 Walking and c l i c k i n g counts fo r a l l subjects . . . . 97 vi i LIST OF FIGURES Figure Page 3A Ground f l oo r plan - Faculty of Education 22 3B C l i cker 24 3C Testing area with 25 reference points 26 1 CHAPTER ONE INTRODUCTION AND STATEMENT OF THE PROBLEM For severely v i sua l l y impaired or t o t a l l y b l ind persons to move conf ident ly and competently within a spat ia l environment, basic o r i en ta -t ion and.mobility s k i l l s should be present to reduce s i g n i f i c a n t l y p e r i l -inducing and/or injury-causing instances. These s k i l l s would increase the wi l l ingness of a t rave ler to seek information concerning the spat ia l arrangement and to attempt to become mobile within i t . The t rave ler must develop a high level of t rust for the or ientat ion and mobi l i ty i ns t ruc to r ' s s k i l l s , in order to overcome anxiety connected with movement in d i f f e r i ng spat ia l conf igurat ions, by demonstrating safe, reassuring methods of seeking information concerning the environmental space and being mobile. Very elementary s k i l l s , such as wall t r a i l i n g or the use of the sighted guide technique, could be employed with persons whose or ientat ion and mobi l i ty s k i l l s are at a low level of development. Through procedures l i k e these of sensory enhancement, the t rave le r ' s desire for information and the rate of movement should increase markedly. By i l l u s t r a t i n g the pleasure derived from movement, by showing that movement can be a safe process, and that movement within spat ia l environments can resu l t in the t rave ler a r r i v ing at locations of i n te res t , the requis i te cu r ios i t y should be stimulated for the t rave ler to seek out methods for obtaining informa-t ion concerning the space and the most benef ic ia l route for moving from one locat ion to another. An elementary mode for the f a c i l i t a t i o n of movement within a spat ia l environment i s wall t r a i l i n g . In th is technique, the t rave ler moves within a space by maintaining hand contact with a wall by which means informational 2 cues are monitored. Such a method of movement does not require the assistance of another person, making i t possible to encourage movement from one locat ion to another, however other more e f f i c i e n t travel modes are ava i lab le as the level of independent movement increases. Due to the placement of furn i ture or other objects next to wa l l s , wall t r a i l i n g often i s not a very successful pract ice in most rooms. For th is reason, alternate s k i l l s for walking through spat ia l environments without t r a i l i n g along a wall should be taught as soon as the t rave ler can manifest that more e f f i c i e n t locomotion means ex is t than by moving from one locat ion to another by t r a i l i n g along a wa l l . Such independent means as the long cane or the use of various u l t rasonic devices can provide a severely v i sua l l y impaired or t o t a l l y b l ind person with a safe means of moving within a spat ia l environment. Advanced warnings can be transmitted to the t rave le r , through the cane s t r i k i ng the object or the ul t rasonic beam encountering the object and changing the pitch of the sound heard through the earphones or the degree of v ibrat ion produced by the device, to indicate the presence of an obstruction near to , or along-s ide , the course that is being walked. The long cane or the u l t rasonic devices make i t possible for more rapid locomotion to occur with p e r i l -or injury-inducing obstacles being perceived at more than an arm's length distance. The most d i rec t path from one locat ion to another in a spat ia l environment can be used by detecting potential blockages of the course to be walked and traversing the space without having to maintain contact with a wal1. At present many severely v i sua l l y impaired or t o t a l l y b l ind persons are employing dogs as guides through the environment. This form of travel necessitates a high degree of dependence upon the dog and, should any 3 misfortune befa l l i t , there must always be a ready or ientat ion and mobi l i ty system avai lable to prevent serious l im i ta t ions to mobi l i ty to occur. Although there i s a necessary level of dependence upon the dog as a guide, the ultimate decisions during travel s t i l l reside with the dog user. The dog provides warnings of curbs or unsafe areas for travel and the t rave ler must decide how to deal with the received information. Las t l y , and occurring from the commencement of t ra in ing and continu-ing long a f ter i t has ceased, i s the sighted guide technique for locomo-t i o n . In th is technique, the severely v i sua l l y impaired or t o t a l l y b l ind person is led by another person by holding on to the back of the leader 's arm jus t above the elbow. This form of walking dictates depen-dence upon the person doing the leading, however i t is often the most convenient and safest mode for b l ind and sighted persons to walk with one another. As or ientat ion and mobi l i ty s k i l l s develop, the severely v i sua l l y impaired or t o t a l l y b l ind person can become more comfortable and competent in walking through spat ia l conf igurat ions. The development of s k i l l s permits a heightened enjoyment of the pleasure of moving f ree ly through a space and a lowering of concern for the d i rec t wel l-being, on a second to second bas is , while moving through that space. More e f for ts can therefore be concentrated on noting the var iety of sounds, smel ls , and var iat ions in textured surfaces throughout the environment. A large emphasis would be placed upon auditory d i f f e r en t i a t i on between sounds in the spat ia l environment, where the t rave ler would be required to d is t inguish between sounds occurring natural ly in that space or whether the sounds are man-made. Natural ly occurring sounds in the environment that the t rave ler should be aware of could be caused by the wind blowing 4 through the leaves of a t ree , birds s ing ing, or the barking of a dog; whereas, man-made sounds in nature to be discerned could be the flow of t r a f f i c along a roadway, sounds from a construction s i t e , or the sounds of people's shoes as they walk along the s t reet . By concentrating awareness upon these sounds in the environment could focus a higher level of interest in the t rave le r ' s surroundings and could take on addit ional spat ia l cues concerning that person's pos i t i on , at any given moment, within the space. The major drawback to the awareness of audi -tory events, for travelers using u l t rasonic devices l i k e the sonicguide, would be the potential for interference between the sounds heard by the t rave ler from the mobi l i ty device and the second set of sounds occurring in that space. The double set of informational cues could lead to misinterpretat ions or sensory overloading that could impair ser iously the t rave le r ' s a b i l i t y to react to the received information (Shingledecker, 1978; Shingledecker and Foulke, 1978). Once the severely v i sua l l y impaired or t o t a l l y b l ind person is focusing outwards upon sounds in the environment, special e f for ts would have to be made to have the t rave ler d is t inguish between sounds that could be used to locate spec i f i c locations or centres of a c t i v i t y such as playgrounds, highways or a photocopier through the sound locat ion system; or using sound produced by a human or environmental source by which stat ionary cars , open doorways, or a wooden fence could be detected through echolocation. Should th is level of employing environmental sounds be achieved, then i t i s possible for the t o t a l l y b l ind and the severely v i sua l l y impaired to use these auditory environmental cues as a means for receiving continuous or ientat ion information from the environment while navigating through i t . Obstacles could be detected by the t rave le r , thus 5 l i m i t i n g or e l iminat ing the number of unwanted c o l l i s i o n s with the per-ceived obstacles. Both confidence and competence could then augment the t rave le r ' s or ientat ion and mobi l i ty s k i l l s . Echolocation i s based upon a system of echoes which i s established between the person or object creating the i n i t i a l sound and a second object off which the sound is bounced to create the echo (Amnions, Worchel and Dallenbach, 1953; Kel logg, 1962; Rice, Feinstein and Schusterman, 1965; Rice, 1967; Rice, 1969; Juurmaa, 1970a and b; and Rice, 1976). The i n i t i a l sound source could be caused by an event in the environment: a hammer s t r i k i ng a n a i l , a barking dog, or l i gh t t r a f f i c along a roadway, which would produce an echo-producing sound that would be bounced of f of obstacles in the near vac in i t y . A lack of obstacles in the space would also be perceivable by the absence of echoes resu l t ing from the sound created by the or ig ina l sound source. Should the i n i t i a l sound source be too loud in volume or be too long in durat ion, the perception of environ-mental obstacles could be l imi ted by the ob l i t e ra t ion of the returning echo causing environmental confusion to the t rave ler attempting to i n t e r -pret such informational cues. While i t may be d i f f i c u l t for a t rave ler to ant ic ipate the types of spat ia l environmental cues that may be avai lable in unfamil iar se t t ings , th is consideration could be dealt with quite successful ly through echo-locat ion to receive a l l necessary spat ia l data pertaining to the presence, or absence, of obstacles. These echoes could be established through de l iberate ly produced sounds by the t rave ler and bounced of f of objects in the d i rec t l i n e , or o f f to the s ide , of the course to be walked. This system could also be used while standing s t i l l as a means to explore the t rave le r ' s surroundings in deciding which route has the least obstructional 6 impediments. The ultimate distance range of the echolocation system is dependent upon the loudness or quietness of the i n i t i a l sound source. Whereas the u l t rasonic mobi l i ty devices are l imi ted to a maximum range of approxi -mately 6 metres (Kay, 1974), the distance range for echolocation produced by a human or a natural environmental sound source has not been documented (Ammons, Worchel and Dallenbach, 1953; Kel logg, 1962; and Rice, Feinstein and Schusterman, 1965). The maximum range, however, for detecting a large bui ld ing through echolocational cues produced and interpreted by humans would be fa r beyond the 6 metre distance. Very near obstacles also could be detected by th is system, but the qua l i t a t i ve and textural differences between various surfaces were d i f fe rent ia ted more c l ea r l y (Juurmaa, 1970b) by u l t rasonic mobi l i ty devices by human or natura l ly produced environmental sound sources. In order to establ ish maximal conditions in which echolocation can take place, the i n i t i a l sound source must have su f f i c i en t volume and be of short durat ion. These conditions would allow the sound to travel toward the object, or throughout the environment, and return bearing the required information in the form of an echo. The frequency of echo-producing sounds may vary according to the complexity of the environment, with few sounds being produced when l i t t l e information is being sought and many sounds being produced in a highly complex conf igurat ion, however so long as information i s required for or ientat ion and mobi l i ty within that space the echolocational system would have to be used to ensure the reception of information. The degree of concentration required to process that spat ia l information would vary from indiv idual to indiv idual accord-ing to the degree of information that i s sought, the interference of 7 a l ternat ive competing sounds with the i n i t i a l echolocational sound source creating confusions, and the overal l experience in d is t inguish ing between competing sounds and echoes to arr ive at a true interpretat ion of the confusing spat ia l s igna ls . The motivational factor a f fect ing the use of echolocation could provide the t rave ler with a greater comprehension of the spat ia l configuration resul t ing in an increased awareness of obstacles and the knowledge d ic ta t ing the safest route through that space. Where visual cues are ava i lable for constant or ientat ion and mobi l i ty reference, there is no need for employing echolocation. Where continual visual referencing capab i l i t i e s are diminished ser iously or eliminated altogether, a replacement system such as echolocation often i s found for cur ious, highly motivated persons who wish to be well informed about the i r spat ia l environment. This i s not only the case for .severe ly v i sua l l y impaired, t o t a l l y b l i n d , or bl indfolded sighted persons (Amnions, Worchel and Dallenbach, 1953; Kel logg, 1962; Rice, Feinstein and Schusterman, 1965; Rice, 1967; Rice, 1969; Juurmaa, 1970a and b; and Rice, 1976), but also for b i rds , animals and f i sh operating in darkness (Rosenzweig, Ri ley and Krech, 1955; G r i f f i n , 1958; G r i f f i n , 1959; and Kel logg, 1961). The echolocational system can be used in conjunction with the long cane or the dog guide. It also can be used as a mobi l i ty a i d , in very f ami l i a r se t t ings , separate from the long cane or dog guide. Its most serious d e f i c i t i s that no information i s received regarding drop-offs in the environment which could pose a hazard for travelers who do not combine echolocation with another mobi l i ty a i d , such as a long cane or dog guide. 8 The pr inc ipa l hypothesis to be investigated w i l l be: The a b i l i t y , through echolocation, to make correct verbal reports of an indoor space between bl ind and bl indfolded sighted subjects. Subhypotheses to be pursued w i l l be: 1. The expression of anxiety of subjects par t i c ipa t ing in the experiment. 2. The da i l y reported use of echolocation by b l ind persons during t r a ve l . In th is study, the phrase severely v i sua l l y impaired refers to those persons who have l i g h t perception, or addit ional v i s i o n , but whose v i s ion is not useful beyond very l imi ted or ientat ion and mobi l i ty cues. 9 CHAPTER TWO BACKGROUND OF THE PROBLEM AND LITERATURE REVIEW Obstacle detect ion, through the use of echolocation, has often been reported as ex is t ing for t o t a l l y b l ind or severely v i sua l l y impaired persons throughout h is tory . Such h i s to r i c a l reports have treated human echolocation reverent ia l l y as i f i t were a special g i f t that the t o t a l l y b l ind or the severely v i sua l l y impaired were granted, in l i eu of v i s i o n , s imi la r to an ins t inctua l a r t i s t i c or mathematical a b i l i t y (Ammons, Worchel and Dallenbach, 1953). It was not unt i l the f i f t h decade of th is century that researchers at Cornell Univers i ty (Supa, Cotzin and Dallenbach, 1944) were able to resolve the dilemma regarding the basis of obstacle detect ion. Pr ior to the i r f i nd ings , obstacle detection by the t o t a l l y b l ind and the severely v i sua l l y impaired had been a highly contentious controversy concerning the locus of perception. The Facial Vis ion theor ists contended that there were unspecified points on the face which were u t i l i z e d in the detection of obstacles. The face, being the most anter ior portion of the head, was very useful in detecting sunlight, or currents of a i r , so that i f these and other environmental cues were perceivable the s igni f icance of auditory perception could be relegated to an unimportant locat ion in the hierarchy of relevant obstacle detection senses. A contrast ing obstacle detection viewpoint was held by the Hearing theor i s t s , supported by the f indings of the Cornell group, who demonstrated that echolocation was dependent upon the a b i l i t y to hear normally. Although the face i s important in detecting certa in environmental cues, persons lacking normal auditory acuity can not usefu l ly u t i l i z e echolocation 10 as an or ientat ion and mobi l i ty strategy (Juurmaa, 1970a). Notable var iat ions in obstacle detection have been observed between t o t a l l y b l ind and severely v i sua l l y impaired persons who re ly heavily on auditory cues while t r ave l ing . The Hearing theor ists would describe th is demonstrable difference in mobi l i ty s k i l l s to : - a dif ference in auditory acu i ty , - a mis interpretat ion of auditory cues, or - an undeveloped obstacle detection sense in which echolocation has not been learned. The most basic consideration for obstacle detection resides with a normal sense of hearing, without which a l l further perceptual p o s s i b i l i t i e s are untenable. Where normal auditory acuity e x i s t s , however, the returning echo from the obstacle i s not being interpreted to the advantage of the t rave ler due to confusion in the perceived s igna l s ; or th is t rave ler has never been taught, or has not developed, a system of echoes to aid move-ment in the environment. To reduce s i g n i f i c a n t l y major confusions over information contained in employing echolocation for the purpose of obstacle, or informing t o t a l l y b l ind or severely impaired persons of the usefulness of echo-loca t i on , would be a pos i t ive step in improving overal l mobi l i ty performance. The detection of targets in a laboratory set t ing has been demonstrated with human subjects, pr imar i ly in a s t a t i c , seated pos i t ion (Kel logg, 1962; Rice, Feinstein and Schusterman, 1965; Rice, 1967; Rice, 1969; Rice, 1976; Juurmaa, 1970b), can perceive when a target i s being presented to them; and, when present, whether i t moves toward or away from them. These perceptions were not merely speculations on the part of the subject, but were based on a systematic use of an echo-producing 11 sound—either u l t rasonic or nonultrasonic--which would provide the requ is i te information. Echo-producing sounds may be caused in numerous fashions by a person seeking information related to the environment. In u t i l i z i n g nonultra-sonic , human-produced, echo-producing sounds the subject may produce such sounds with sharp, d i s t i n c t s i b i l a n t or vocal productions, or with the throat , tongue, l i p s , hands or feet . Whist l ing, throat c lear ings , tongue c l i c k s , l i p smackings, hand clappings or f inger snappings, the scraping or the stamping of feet can a l l provide important information to a t o t a l l y b l ind or severely v i sua l l y impaired person. Other nonhuman echolocational cues can be produced by tapping a long cane harder than necessary on a sidewalk, u t i l i z i n g a c l i c ke r held in the hand, the barking of a dog, or l i gh t vehicular t r a f f i c along a roadway. These, and many other s im i l a r methods, can be u t i l i z e d by a t o t a l l y b l ind or severely v i sua l l y impaired t rave ler in order to move safely and conf ident ly in the environment. U l t rason ica l l y produced sounds are beyond the auditory capacity of the human ear. The aural capacity of the human ear ranges from 20-20,000 cycles per second, and the u l t rasonic beams produced by the Sonicguide (Kay, 1974), the Mowat Sensor, the Lazar Cane, and other devices, range between 45,000-90,000 cps, far beyond the interpretable levels of the human ear. Although an early example of one of these devices was employed in one series of experiments (Juurmaa, 1970b), they did not appear in any other echolocational works. In a s t a t i c , seated posi t ion in a laboratory se t t i ng , the nonultra-sonic echo-producing human sounds would have to be produced so as to return the echo at the level of the ears. The hands, l i p s , tongue, wh i s t l i ng , or sharp s i b i l a n t or vocal sounds, rather than any type of sound produced by 12 the fee t , would most l i k e l y create the most sa t i s fac tory echoes at ear level (Kel logg, 1962; Rice, Feinstein and Schusterman, 1965; Rice, 1967; Rice, 1969; Rice, 1976; Juurmaa, 1970a and b) . For a t o t a l l y b l ind or a severely v i sua l l y impaired t rave ler in a mobile condit ion in the environment, the range of echo-producing sounds are multitudinous in scope and the information received may be much more diverse, complex or confusing than the information received and i n t e r -preted in a laboratory se t t i ng . The sounds de l iberate ly produced by the feet or the long cane may have to be much louder and harsher than normal, however the sounds created at th is severe angle below the level of the ears do not necessari ly have to be excluded from the arsenal of poss ib i -l i t i e s for obtaining information related to the spat ia l layout of the t rave le r ' s environment (Ammons, Worchel and Dallenbach, 1953). If moving in the environment i s more complex or confusing for a t rave ler employing echolocation techniques, at least i t permits a greater d i ve rs i t y of echo-producing p o s s i b i l i t i e s to be ca l led upon for or ientat ion and mobi l i ty , ass istance. In the l i t e r a tu re there are several studies done using animals as subjects (Rosenzweig, R i ley and Krech, 1955; G r i f f i n , 1958; G r i f f i n , 1959; and Kel logg, 1961), and the a b i l i t i e s of bats, nocturnal b i rds , sea ls , seal ions, porpoises, dolphins, and several types of whales have been documented as having highly adapted echolocational sensory systems. These creatures were able to detect the presence of the i r prey, establ ish v i t a l information concerning i t s s ize and rate of motion, pursue i t , and capture i t through the use of echolocation. This heightened development of sensory awareness is c ruc ia l to these creatures and can spel l the d i f f e r -ence between a successful hunter, or one whose l i f e cycle i s foreshortened 13 due to inadequate sensory development. The human subject, espec ia l ly those who are t o t a l l y b l ind or severely v i sua l l y impaired, have not developed the i r obstacle detection through echolocation to a comparable degree. The c i ted creatures are f a r more capable of employing echolocation than are humans; yet , though i t s use appears myst ica l , humans can u t i l i z e i t in a more general sense to indicate when an obstacle is present or absent. Overa l l , th is more generalized sensory development may not appear comparably acutely developed, however i t can d i f f e ren t i a te sharply between a t rave ler who is able to negotiate successful ly the spat ia l configurat ion of the environ-ment and one who can not avoid making regular contact with obstacles in the environment. Unless a t o t a l l y b l ind or a severely v i sua l l y impaired person is de l iberate ly creating an echolocational sound to detect the presence or absence of an obstacle, i t may not be obvious to the subject why the detection of an open door leading from a hallway into a room or , in other cases, the detection of a barr ie r placed at random in a corr idor can occur. The sound caused by shoes s t r i k i ng a hard walking surface, or such s im i l a r events, can produce echoes in the environment of which a subject may be unaware t o t a l l y without special emphasis being placed upon the echo-producing st imulus, and un l e ss . i t is brought to the subject 's attent ion the event w i l l contain no meaning. Having made the subject aware of the type of stimulus that creates an information seeking echo, the subject can be taught to use echolocation as an addit ional or ientat ion and mobi l i ty aid to supplement the methods for discovering pertinent spat ia l information. With the demonstrated usefulness of echolocation as an integral portion of or ientat ion and mobi l i ty t r a i n i ng , the subject has 14 the luxury of deciding whether th is strategy i s one that can exercise note-worthy improvements in spat ia l awareness and mobi l i t y , or produces unwanted environmental interferences while t r ave l ing . The subject w i l l become aware of another means of coping with f ami l i a r or unfamil iar spat ia l configurations and locat ing obstacles that e i ther should be avoided or must be located as the f i na l dest inat ion of a walk, e .g. locat ing a mailbox. Having established the auditory centers in the ears of human subjects in the 1940s, the amount of l i t e r a tu re in th is area declined sharply. Other than several important works in the 1960s (Kel logg, 1962; Rice, Feinstein and Schusterman, 1965; Rice, 1967; and Rice, 1969) and in the 1970s (Juurmaa, 1970a and b; and Rice, 1976) research regarding the t o t a l l y b l ind and the severely v i sua l l y impaired has taken other paths away from the area of echolocation as an aid for those persons who do not use visual s t imul i as an addit ional resource while t r ave l ing . These studies sought addit ional evidence that echolocation could be f i ne l y honed to d is t ingu ish not only the presence of a target , but the difference in s ize of paired targets , the difference in distance from the subject of the targets , and the difference in material from which each target was constructed. These research projects were carr ied out in laboratory conditions where the subjects were stat ionary , divorced from r e a l i t y , with l imi ted head move-ments being permitted. In 1953, Ammons, Worchel and Dallenbach conducted an experiment in which univers i ty students were a l ternate ly bl indfolded and bl indfolded while wearing earplugs to demonstrate the role that visual and auditory cues ass isted in or ient ing and guiding those persons who re l i ed heavi ly , or exc lus i ve l y , on these sensory systems. This study had subjects walking along a sidewalk, while v is ion or v i s ion and hearing were impaired 15 de l ibera te l y , and attempting to perceive a target placed on the sidewalk without c o l l i d i n g with i t . Their f indings were not followed up, and the l i t e r a tu re t r ad i t i on turned toward the s t a t i c subject in an iso lated laboratory condi t ion. At the conclusion of the 1950s and the commencement of the 1960s Kellogg (1961), l i k e several other researchers, had completed experimental research on nonhuman l i f e and recognized that l i t t l e work had been done with human subjects for whom visual cues did not contribute to the i r under-standing of the environment. As a consequence, in 1962 he conducted a series of experiments in which 4 subjects, 2 advent i t iously b l ind and 2 bl indfolded sighted subjects, were presented with pairs of targets followed by questions concerning the comparative sizes of the targets , the i r com-parative distance from the subject (were they both a s im i l a r distance or was one nearer?), and the materials from which the targets were constructed. The targets were presented at 7 preestablished distances, they appeared in a var iety of s i z e s , and they were constructed from 6 d i f f e r i ng mater ia ls . Kellogg permitted these subjects to use whatever echolocational sounds that they wished—varying from s ing ing , wh i s t l i ng , c l i c k i n g the tongue, snapping the f ingers , or using harsh vocal sounds--to detect the targets. The f indings showed that the subjects could d is t inguish between 86-99.5 percent of the time, p i s equal to or less than .01 , between most materials except glass and painted or unpainted wood which were f r a c t i ona l l y above or below the pure chance l e v e l . Subjects could d is t inguish a 4 i n . d i f f e r -ence between the targets at the 24 i n . distance, demonstrating that minute distance var iat ions were perceivable. For nearly each target , there was a 100 percent perception, p i s equal to or less than .01, between the presence or absence of a target . Kellogg was certa in that echolocation 16 for humans, with the necessary t ra in ing to d is t inguish qua l i t a t i ve differences between objects rather than merely concentrating on the i r detect ion, could develop systems equivalent to bats or porpoises. Rice, Feinstein and Schusterman (1965) wished to conduct a series of experiments s im i l a r to those performed by Kel logg. I n i t i a l l y , a pretest was conducted to determine whether the subject could d is t inguish between a present or an absent target ; then, further tests were performed to determine 90-100 percent accuracy for 5 6-in. distances between 24-48 i n . and 3 distances at 67 i n . , 87 i n . , and 108 i n . at which the smallest targets could be detected. Once the smallest target at each distance was confirmed 4 smaller targets , successively 60 percent smal ler, with which to test the subject 's perception even more, were presented. To ensure that obstacle detection was not occurring without emitting echolocational sounds—the subjects were unable to detect the presence or absence of a target--thus, demonstrating the s igni f icance of echo-producing sounds in th is experiment. In th is experiment there were 5 advent i t iously b l ind subjects between 23-30 years of age: 2 had l i gh t perception and the remaining 3 did not. Their scores tended to remain constant over the series of experiments resu l t ing in a mean score of .78, p is equal to or less than .01. It was hoped to discover the maximum distance at which targets could be perceived; t h i s , however, was not possible due to the l imi ted labora-tory space which permitted a maximum distance of 108 i n . Rice et a l . (1965) did determine that the smallness of the target s ize detectable at greater distances was larger than at less distant locat ions . The sound required at greater distances had to be successively more d i s t i n c t than for comparably nearer distances. 17 In F in land, Juurmaa (1970) was conducting s im i l a r experiments to those of Kellogg (1962) and Rice, Feinstein and Schusterman (1965) but was unaware of the i r work due to slowness in t r ans l a t ion . His experiments u t i l i z e d a double pronged look at obstacle detection through echolocation by d iv id ing his subjects into 2 groups with the Control group having 4 subjects and the Experimental group containing 3 subjects (1970b). The Experimental group was permitted to employ an u l t rasonic a i d , while the Control group was to re ly upon nonultrasonic echolocational sounds. The Control group had a s im i l a r mean score to that achieved by the group in the Rice, Feinstein and Schusterman (1965) f ind ings , with the Experimental group scoring approximately 10 percent higher. The subjects, in the f i r s t experiment, had to discern when the target reached several predetermined distances from them and stop i t at that point . In the second series of experiments, the subjects had to determine when a stat ionary target began to move toward or away from them. Over-ly ing these experiments was the consideration that the targets were con-structed of d i f fe rent materials which had to be d i f f e ren t i a ted . The Experimental group received i t s greatest advantage in overal l scoring by d is t inguish ing much better between the target mater ia ls . A f i na l series of experiments were run in which the largest and smallest targets perceiv-able were paired and s i z e , distance, and material a l l had to be compared simultaneously by the subjects. Throughout the fol lowing decade, Rice conducted several experiments to compare the scanning a b i l i t y of the t o t a l l y . b l i n d and severely v i sua l l y impaired of a target surface with human-produced and speaker-produced sounds (1967), and the difference in perceiving of small targets and com-paring re l a t i ve movements by these targets between congenital ly b l i n d , 18 advent i t ious ly b l i n d , and bl indfolded sighted subjects (1969 and 1976). He attempted to determine the auditory angles at which a subject, with l im i ta t ions placed on the degree of head ro ta t ion , could d is t inguish the s ize of a target through human-produced sounds and hiss ing played through a mechanical speaker near the subject 's head. There were 4 b l ind subjects and they were tested with small targets , and found that the sounds which they produced created more qua l i t a t i v e l y d i s t i n c t results than those produced by the cont inual ly h iss ing speaker. In 1969, Rice looked at the sensory enhancement of 6 congenita l ly b l ind subjects and compared them with 8 advent i t iously b l ind and 8 b l i n d -folded sighted subjects. He compared these groups in several spat ia l awareness experiments and found that the congenita l ly b l ind were superior in detecting targets and could point the i r noses more accurately at the center of each target , but they did less well in other awareness exercises causing a resu l t of no superior sensory enhancement to be proved. This experiment was rediscussed in 1976 where Rice manifested that the con-gen i ta l l y b l ind group could detect targets more readi ly than the other groups and were able to detect target movement more read i l y . Although the detection experiments conducted in a s t a t i c , laboratory set t ing are important, experiments requir ing the subjects to be mobile in an out-of-doors set t ing would be more d i f f i c u l t to perform. Outdoor condi t ions, however, more c lose ly approximate much of the t rave l ing that i s required by a t o t a l l y b l ind or severely v i sua l l y impaired t rave le r . The Ammons, Worchel and Dallenbach (1953) study looked at dupl icat ing the Supa, Cotzin and Dallenbach (1944) Cornell study, except that i t would be done out-of-doors. 19 Twenty bl indfolded sighted univers i ty students were divided into two groups: group A and group B. Eight persons in group A had normal hearing and 7 in group B had normal hearing, working from the assumption that any subject with normal hearing could learn to detect obstacles through echo-loca t i on , so that the normal hearing subjects should be capable of achieving c r i t e r i o n learning in th is obstacle detection task. C r i t e r ion learning meant that there had to be at least 25 successes in 30 t r i a l s . The subjects were required to be e i ther bl indfolded or bl indfolded and deafened. They would walk along a sidewalk, raise the i r r ight arm when they f i r s t detected the obstacle—which was 58 i n . high, 48 i n . wide, and stood on a 24 i n . base—approach the obstacle and, without c o l l i d i n g with i t , ra ise the i r l e f t arm when they were within reaching distance of the obstacle. A l l 8 of the normally hearing subjects in group A achieved c r i t e r i on task mastery, while 6 of the normally hearing subjects in group B performed equally as w e l l . No group coef f i c i en ts were given for the experiment, but the standard deviations for each subject in group B were much greater than for group A. At the end of the f i r s t experiment, the roles were reversed and the experiment was reconducted. Each subject, by th is time, had developed a strategy for mastering the task so that the major d i f f i c u l t i e s in achieving c r i t e r i on performance did not emerge. There were d i f f i c u l t i e s with the experiment in that the obstacle gave of f an odor while standing in the sun, the heat from the sun could be detected from the obstacle, and the wind pressure or the in tens i ty from the heat of the sun could be affected by the posit ioning of the obstacle along the sidewalk. 20 Nevertheless, th is experiment i s of great pract ica l use due to i t s locat ion in an environment where meteorological condit ions, ambient noise, and several senses were combined to produce var iable perceptual conditions for learn ing. The speed of learning did not develop as quickly as in the Cornell experiments and the experimenters were not prepared for the add i -t ional cues by which the obstacle was detected by the subjects. For research f indings to have more d i rec t da i l y app l i ca t ions , they should be conducted in locations and circumstances that would not be res t r i c ted from, nor be beyond, the general experience of a member of the target population. Bl indfolded sighted subjects have shown (Ammons, Worchel and Dallenbach, 1953) that they can successful ly develop obstacle detection capab i l i t i e s through echolocation. Should the s i tua t ion ar ise that the b l ind subjects have not, or for many years have never, used echolocation techniques as an addit ional set of or ientat ion and mobi l i ty cues, i t would appear very l i k e l y that the i r scores should be very s im i l a r to those of bl indfolded sighted subjects that are exposed to echolocational exper i -ments for the f i r s t time. If a b l ind subject, however, has used echo-locat ion successful ly in the past and has maintained i t in the reper to i re , that score should be higher than those of b l ind and bl indfolded sighted subjects who have never used i t as a strategy for seeking information related to the space through which they are moving. 21 CHAPTER THREE METHODOLOGY The experimental portion of the thesis was conducted inside the Education Bui lding on the campus of the Univers i ty of B r i t i s h Columbia in Vancouver. The lobby area of th is bui ld ing runs in a north-south d i rec t ion and connects 2 east-west wings into an H configurat ion (see Figure 3A). The lobby area i s further divided into a hallway, which takes up the eastern half of th is area, while the western portion consists of a lounge containing f ixed benches and movable coffee tables . The lounge and corr idor areas are connected by 3 wide openings with a f l i g h t of 3 steps leading from the lounge level to the higher corr idor e levat ion ; otherwise, a wall i s interposed between these lobby halves. Along with the 3 interconnecting openings between these areas of the lobby, each ha l f also has d i s t i n c t entry or ex i t doorways. The hallway segment of the lobby was chosen as the environment in which the experiment would take place. This s i t e was chosen as the area through which the subjects would be led due to i t s length and width, i t i s 160 f t . long and 20 f t . wide, and contains a large var iety of environmental data. Sections of th is hallway are closed on e i ther side by walls and give the perception of being very confined, whereas other segments of th i s space are open on e i ther side producing a perception of vast openness. The areas perceived as confining are at e i ther end of the hallway, with the more open perceptions coming in the central portions of the environment. The width, var iety of spat ia l information, and the openness of the central segment of th is space a l l combine to create the impression of walking in an environment s im i l a r to Figure 3A. Ground Floor Plan - Faculty of Education Scale : \" - 30' ''Note: A l l doors are usually closed except the one marked. r o IN3 23 conditions out-of-doors. Throughout the school day the hallway and lounge areas of th is bui ld ing have periodsof high pedestrian t r a f f i c occurring before or a f te r c lasses , and most espec ia l ly between 11:30-1:30, with low periods of pedestrian t r a f f i c in the early morning and evening. The sounds of people ta lk ing or the sounds of the i r shoes as they walk could resu l t in the production of addit ional echolocational sounds leading to a confusion of echo-laden information. Groups of stat ionary persons standing in the hallway or s i t t i n g in the lounge also could create confused environmental conditions for a t rave ler by becoming potential obstructions or o b l i t e r a t -ing spat ia l cues through loud conversation. -Occasionally, portions of th is space may be used for special displays with tables p a r t i a l l y , or completely, blocking the hallway. For a severely v i sua l l y impaired or t o t a l l y b l ind person to cope with the hubbub of loud conversation from both areas of the lobby, to know when groups of people are walking slowly or are completely s tat ionary , or to maneuver around temporary d isp lays , can present an overload of environmental data creating d i so r i en ta t ion . Other than the high t r a f f i c conditions during the lunch hour, i t is d i f f i c u l t to predict how many persons w i l l be in the lobby areas and the volume of the i r d i s t rac t ing sound production. A walking course through th is co r r idor , containing 25 reference points , was designed to test the echolocation a b i l i t i e s of the subjects that would be led through i t . The i n i t i a l sound production source would be a hand-held c l i c k e r (see Figure 3B) which the subject would hold in the r ight hand, to make possible the detection of the reference points . The spec ia l l y modified J103E Craig cassette machine was used to monitor the subject 's verbal comments while walking through the experiment. Every Figure 3B. C l i cker 25 correct response was noted by a depression of the tone index button, located on the top of the machine, causing an audible beep to be recorded on the cassette. Following each subject 's walk through the experimental area, these audible tone indexed beeps could be counted when the cassette machine was in the fast forward or rewind mode or when l i s t en ing to the recording of the walk with headphones. The tone indexing system allowed an accurate summary to be kept of incorrect responses as no audible tone would be present for such a response. The recording of each subject 's walk through the experiment created a permanent record of the conditions ex is t ing at that moment and permitted immediate comparison capab i l i t i e s for the researcher. When l i s t en ing to the recorded information on head-phones, i t was possible to hear a l l the environmental sounds along with the inser t ion of the tone indexed sounds which provided a back-up checking procedure for the f i na l tota l of reference points detected by each subject. This back-up system resulted in minor adjustments, e i ther higher or lower, of very few f i na l detection tota l scores. Figure 3C shows the arrangement of the f ixed reference points along the course of the experimental walk. To enhance the fee l ing of confidence and safety of each subject, they were a l l led along the hallway using the sighted guide technique whereby the subject would hold on to the leader 's arm jus t above the elbow. This del iberate guiding procedure avoided unnecessary c o l l i s i o n s with tables and cha i r s , which were purposely moved out of the walking course, or with persons standing or walking in that space. Every subject began the walking course at the south end of the hallway and was led down the r ight side to the north end, across the width of the fa r end, and returned along the r ight side back to the south end. The subject would be walking between 3-4 f t . from the wall at a l l Figure 3C. Testing Area with 25 Reference Points 27 times with no stoppages being permitted during the course of the e x p e r i -ment. The subject would be very busy during the experiment: c l i c k i n g the c l i c k e r with one hand and holding on to the research a s s i s t a n t ' s arm with the other hand, l i s t e n i n g and attempting to i n t e r p r e t the echoloca-t i o n a l sounds, and r e p o r t i n g v e r b a l l y on the perceived s p a t i a l environ-ment. To increase the complexity of the experiment f o r the c o n t r o l group, they were under b l i n d f o l d e d c o n d i t i o n s to e l i m i n a t e any v i s u a l cues which would be a v a i l a b l e to them o r d i n a r i l y . The consequent emphasis, with the e l i m i n a t i o n of v i s u a l cues, then would f a l l upon a l t e r n a t e senses, such as o l f a c t o r y or a u d i t o r y , with the more dominant a u d i t o r y sense i n t h i s case t a k i n g precedence f o r these m o b i l i t y requirements. The most uneventful a r c h i t e c t u r a l segment of the walking course occurs, f o r a considerable d i s t a n c e , from the outset with a continuous wall with 3 small p i l l a r s j u t t i n g out from i t . Rather than have each subject t r y to detect every p i l l a r en route, i t was decided that the f i r s t 2 reference pointswould be e s t a b l i s h e d along t h i s wall without g i v i n g them pr e c i s e l o c a t i o n s . So long as the subjects i n d i c a t e d that there was a w a l l and that i t continued f o r a considerable length of the walking course, they would r e c e i v e c r e d i t f o r reference points 1 and 2. Where the verbal comments did not commence q u i c k l y enough, or the comment was i n c o r r e c t , no c r e d i t would be given f o r reference p o i n t 1. I f the comments d i d not continue on the existence of the wall on the r i g h t , or i n c o r r e c t s p a t i a l information was reported, then no c r e d i t f o r reference point 2 would be granted. The b l i n d experimental group had very c l e a r and accurate reports of t h i s w alled segment. Each subject was able to detect the p i l l a r s along t h i s s e c t i o n of the course, along with the subsequent recessed portions between the p i l l a r s . 28 below: A complete l i s t of the remaining detectable reference points follows i / : rp3--wide opening on the r i g h t ; (leading to a lecture ha l l ) rp4--wall on the r i g h t ; (information booth) rp5--wide opening on the r i g h t ; (leading to a lecture ha l l ) rp6--wall on the r i g h t ; rp7--closer wall on the r i gh t ; ( c i r cu l a r information p i l l a r ) rp8—wall on the r i g h t ; rp9--wall s t ra ight ahead; (end of hallway) rplO—small opening to the r i g h t ; (doorway) rp l l--wal l s t ra ight ahead; (other side of the far end of the hallway) rpl2--near wall on the r i g h t ; (movable blackboard) rpl3--wide opening to the r i g h t ; rpl4--small p i l l a r to the r i g h t ; rpl5--wide opening to the r i g h t ; rpl6--wall to the r i gh t ; rpl7--wide opening to the r i g h t ; rpl8--small p i l l a r to the r i g h t ; rpl9—wide opening to the r i gh t ; rp20--wall to the r i g h t ; rp21--wide opening to the r i g h t ; rp22--small p i l l a r to the r i g h t ; rp23—wide opening to the r i g h t ; rp24--wall to the r i g h t ; leading to the lounge) d iv id ing the opening) leading to the lounge) leading to the lounge) d iv id ing the opening) leading to the lounge) leading to the lounge) d iv id ing the opening) leading to the lounge) rp25—wall s t ra ight ahead; (closed doors at the south s tar t ing-f i n i sh ing end of the hallway). 29 The research ass istant was required to carry the cassette machine with which to record the subject 's detection comments, to carry a map of the environment with the reference points marked c l ea r l y on i t , to depress the tone index button every time a reference point was reported co r rec t l y , as well as safely guiding the subject through the space. The research ass istant and subject had precise tasks to fol low which kept them highly occupied during the experiment. The number of persons present in the lobby areas, and the volume of sounds they created, varied considerably from subject to subject. For most subjects, the pedestrian t r a f f i c was l i gh t with a consequent low level of sound production but, for a few of them, the pedestrian t r a f f i c level was heavier with a resultant increased volume of sound. Four of the subjects part ic ipated in the experiment in the mid morning with the remainder par t i c ipa t ing early or in the middle of the afternoon. The heaviest pedestrian t r a f f i c times of the day were avoided for echolocational test ing purposes. Subjects There were 2 groups of subjects in the echolocation project : a con-t ro l group of 11 bl indfolded sighted persons and 5 severely v i sua l l y impaired and t o t a l l y b l ind persons in the experimental group. One subject (subject 3) from the experimental group had the a b i l i t y to perceive l i gh t which necessitated b l indfo ld ing her as w e l l . A l l but one subject in the experimental group (subject 4) are presently, or were, students at the Univers i ty of B r i t i s h Columbia. The control subjects were recruited as volunteers from two U.B.C. c lasses . Six came from an introductory class dealing with Special Education, 30 and 5 came from the Diploma Program for the Education of the V isua l l y Impaired. The introductory Special Education class is designed for under-graduates with class s izes generally varying between 15-30, and the class sections are taught by a number of professors throughout the academic year. The Diploma Program for the Education of the V isua l l y Impaired, on the other hand, is a graduate program honing the teaching s k i l l s of students to teach the v i sua l l y impaired and multihandicapped. It i s a one-year academic program with a current enrollment of 12 students. This i s the only fu l l- t ime univers i ty program in Canada and at t racts students from many provinces throughout the country. Each control subject, being f ami l i a r with the layout of the campus, would meet the author and research ass istant at a predetermined o f f i ce where the subjects would be b l indfo lded. The c l i c ke r would be presented to them and, i f necessary, i t s proper usage would be demonstrated. A very br ie f preliminary demonstration of echolocation would be carr ied out i n -side the o f f i c e and in the hallway outside i t . Each subject would be led to an accessible wall in the o f f i c e and would be to ld to l i s t e n to the changes in the echoes as the wall was approached. Then, the subject would be led out of the o f f i ce into the hallway and diagonally along i t unt i l a wall was encountered some distance along i t . Retracing the i r steps, the subject would be led back along the hallway and would be asked to detect the open door leading into the o f f i c e . This preliminary warm-up period generally would take from 3-5 minutes. By introducing echolocation through th is warm-up period pr io r to the commencement of the experiment, i t was hoped that every subject would have a c lear idea of what d i s t i n c -t ions they should be l i s t en ing for to d is t inguish between d i f fe rent types of spat ia l data, and to reduce the degree of guessing that otherwise would 31 occur i n the course of the verbal r e p o r t s . Proper, continuous c l i c k e r usage a l s o was sought by which the s p a t i a l information heard could lead to a d e f i n i t e i n t e r p r e t a t i o n . Most subjects had to be requested to c l i c k much o f t e n e r , approximately once per second, during the warm-up to ensure that a l l s p a t i a l data were det e c t a b l e . The subject and the research a s s i s t a n t would become accustomed to walking with one another with proper sig h t e d guiding being demonstrated. The students from the Diploma Program, who had a minimum of 12 hours under supervised b l i n d f o l d e d c o n d i t i o n s , i n s i s t e d upon a great deal of information being relayed to them as they walked through the warm-up area, over to the Education b u i l d i n g , and through the experimental hallway. In t h e i r o r i e n t a t i o n and m o b i l i t y c l a s s e s they had been made aware of what information they would be required to pass along to a b l i n d t r a v e l e r and, f o r that reason, they required s i m i l a r amounts of information to be passed along to them. The research a s s i s t a n t , whose a b i l i t y to employ the sighted guide technique was not we l l developed, found the Diploma students to be h i g h l y r e s i s t a n t to being l e d through unknown areas without r e c e i v i n g adequate s p a t i a l data. He was very t i r e d a f t e r l e a d i n g a l l 5 Diploma students through the experimental s i t e on the same afternoon. The students from the i n t r o d u c t o r y Special Education c l a s s , who were unaware of the demands which they could make regarding s p a t i a l data, were often much more w i l l i n g to place t h e i r t r u s t i n the research a s s i s t a n t ' s guiding a b i l i t i e s . Although t h e i r a n x i e t y l e v e l s were judged to be as high as the Diploma students under b l i n d f o l d e d c o n d i t i o n s , at l e a s t 2 of them (subjects 7 and 9) developed a high l e v e l of t r u s t f o r the research a s s i s t a n t ' s guiding a b i l i t i e s and allowed themselves to be l e d very u n r e s i s t i n g l y . 32 The bui ld ing containing the o f f i ce and hallway, in which the p r e l im i -nary warm-up tasks were carr ied out under bl indfolded condit ions, i s not connected with the Education bu i ld ing . Therefore, i t was necessary to guide each subject from the bui ld ing in which they were met to the Educa-t ion bu i ld ing . Every control subject was aware of the spat ia l arrangement of the campus bui ldings and, by putting them under bl indfolded conditions and leading them through an outside environment, these measures should be p a r t i a l l y successful in d isor ient ing them in the i r new spat ia l l oca t ion . Many of these subjects afterward declared that they had thought they were in the Education bui ld ing but were not certa in of i t . Only subject 13 stated that she was aware f u l l y of the bui ld ing that was used and the precise area into which she had been l ed . She i s a Diploma student and had a great deal of experience under b l indfo ld but, despite her declared awareness, her v isual memory did not ass i s t the echolocation performance in the experiment. The walk between the two bui ldings took approximately one minute and the subjects were encouraged to pract ice the i r echoloca-t ional s k i l l s during the walk. The Diploma students part ic ipated in the experiment during a s ingle afternoon convenient to everyone.- It took each student approximately 15-20 minutes to accomplish a l l the tasks required for th is project . Due to the i r lack of information about echolocation, and the unfami l i a r i t y of being under bl indfolded condi t ions, each student from the introductory Special Education class required approximately 20-25 minutes to f i n i s h a l l of the necessary tasks. Every student would be returned to the o f f i c e in which the warm-ups had been performed, at the conclusion of the experiment. 33 When the subjects were met at the o f f i c e , pr ior to the commencement of the preliminary tasks, they were asked to complete a consent form containing the i r name, address, telephone number and date of b i r t h . As these subjects were daytime students, they e i ther l i ved on campus or in the metropolitan Vancouver area. Seven of the 11 subjects in the control group had moved s p e c i f i c a l l y to the Greater Vancouver area, from other provinces or within B r i t i s h Columbia, in order to attend classes at U.B.C. Due to the var iety of areas of the country from which these subjects come, a much wider national representation i s in ef fect created. The ages of the control subjects are shown below in Table 3.1. Table 3.1 Ages of the Control Subjects Subject Number Age 6 27 years, 10 months 7 22 years, 2 months 8 21 years, 4 months 9 21 years, 5 months 10 29 years, 10 months 11 23 years, 10 months 12 23 years, 11 months 13 22 years, 2 months 14 35 years, 4 months 15 24 years, 2 months 16 34 years, 8 months Average: (26.63 years) There are 6 subjects under 24, 3 are 29 or more, and the remainder are between 24 and 29. The 2 subjects in the i r mid 30s (subjects 14 and 16) pul l the average age up s i g n i f i c a n t l y . Had those subjects not been 34 included in the ca l cu la t ions , the average age would have declined by nearly 2 years to 24.77 years. The Diploma students a l l part ic ipated in the experiment on the same afternoon, while the introductory Special Education students had times scheduled over a 10-day period of time. Two of the Special Education students part ic ipated in the mid morning (subjects 6 and 7) and a l l remaining subjects were scheduled during the middle of the afternoon. The subjects in the experimental group were e i ther severely v i sua l l y impaired or t o t a l l y b l i n d . Subject 3 had l i g h t perception and, consequently, had to be bl indfolded to prevent her from obtaining visual mobi l i ty cues from the l i gh ts in the hallway. A l l other subjects in th is group were t o t a l l y b l ind and did not require b l i nd fo lds . The ages of the 5 part ic ipants in the experimental group are shown below in Table 3.2. Table 3.2 Ages of the Experimental Subjects Subject Number Age 3 4 5 2 1 29 years, 11 months 40 years, 7 months 34 years, 2 months 22 years, 1 month 33 years, 2 months Average: (27.58 years) This puts the average age for th is group .95 years higher than that of the control group. The age range is fa r greater than the control group, covering a range of 19 years and 6 months for the experimental group and 35 13 years for the control subjects, with one subject (subject 4) keeping the average age level considerably lower than i t would have been without his inc lus ion (22.1 years) . Of the 4 remaining subjects, 3 were between 29 and 35, and one was at the top end at 40. The age group under invest igat ion is between 18-60. Due to the low level of total blindness or severe visual impairment in th is age group, i t was quite d i f f i c u l t to locate persons who would f a l l into th is c l a s s i -f i c a t i on for th is project . Subjects were obtained through the Charles Crane Memorial L ibrary , a special l i b r a r y for v i sua l l y impaired students on the U.B.C. campus. It has b r a i l l e d , recorded, and large pr in t materials for v i sua l l y impaired students on campus or , on loan, for students at other un i ve r s i t i e s . Two students (subjects 1 and 3) were recruited from among those that are presently in attendance there; one subject (subject 5) had been a student there who had been served by th is l i b r a r y ; one subject (subject 2) i s a l i b r a r i an who works for the University L ibrary system at th is par t i cu la r l i b r a r y ; and one subject (subject 4) was recruited from the Sons of Norway ski club which i s organized through the Canadian National Inst i tute for the Bl ind and provides v i sua l l y impaired persons with the opportunity to. go cross-country s k i i n g . The author and th is subject are members of th is sk i ing group. Subject 4 has never been a student at th is un ivers i t y . A l l of the experimental group subjects were met by the author at the Charles Crane Memorial L ibrary and were taken across campus fo r a walk of approximately 15 minutes to the bui ld ing where the preliminary warm-up tasks would be carr ied out. The research assistant assisted with the completion of the consent form, and each subject was introduced to the c l i c k e r . A l l of them had used echolocation to varying degrees and 36 required very l i t t l e pract ice time to become accustomed,to i t s use. To make certa in that each subject in th is group was f ami l i a r with echolocation, they were a l l taken through the warm-up pract ice period to ensure that every subject received s imi la r test preparation. Not one of these subjects had ever been in the bui ld ing in which the preliminary tasks were carr ied out and only 2 subjects (subjects 1 and 2) had ever been in the Education bui ld ing previously. Subject 1 had been in that bui ld ing 12 months ea r l i e r and subject 2 had l as t been there approximately 24 months e a r l i e r . Subjects 1 and 2 were very accomplished travelers and enjoyed t rave l ing a great deal on the i r own. Subjects 3, 4 and 5 were less successful t ravelers than subjects 1 and 2 but by necessity these subjects (subjects 3, 4 and 5) were required to travel and could, with some assistance, generally ar r ive at the i r dest inat ion. Subjects 3, 4 and 5 often became disoriented within a small space and found mobi l i ty to be a d i f f i c u l t task. They were not as w i l l i n g to travel as were subjects 1 and 2. Due to the differences in travel s k i l l s , i t was suspected that subjects 1 and 2 would perform very well in the experimental hallway but that subjects 3, 4 and 5 would be far behind these 2 in the i r overal l detection a b i l i t i e s . This was not the case f o r , although subjects 3, 4 and 5 did less w e l l , the i r performances were not that much less successful than the top subjects. By having the research ass istant lead them through the hallway, any d i so r i en ta -t ion that may have occurred was not permitted to take place and the i r performances ref lected the i r echolocational capab i l i t i e s to be less successful ly adapted than subjects 1 and 2, but far better than any of the subjects in the control group. Following the warm-up period, which took approximately one minute, they were led over to the Education bui ld ing and performed the echolocation 37 t es t . At the conclusion, of the test they were taken back to the o f f i ce where the members of th is group were asked a series of questions re la t ing to the use of echolocation in the i r da i l y l i v e s : 1. Have you ever used echolocation pr ior to today? If yes, at what age did you s ta r t to use i t and in what circumstances? 2. In what walking conditions do you think that echolocation could improve mobi l i ty for v i sua l l y impaired persons? 3. In what walking conditions would echolocation not improve mobi l i ty for v i sua l l y impaired persons? 4. Do you think that echolocation could, or should, be taught during or ientat ion and mobi l i ty t ra in ing for v i sua l l y impaired persons? The f i na l questions of the interview related to the aeteology of the i r visual impairment and the age of i t s onset. This ent i re interview was recorded with the Craig cassette tape recorder. The primary mobi l i ty a id employed by subjects 1, 2, 3 and 4 was the long white cane. Only one subject (subject 5) used a dog guide as her primary mobi l i ty a i d . Not one of the experimental subjects used any type of u l t rasonic mobi l i ty device to ass i s t the i r mobi l i ty in the environment. Following the completion of the questionnaire segment of the project with the experimental group, each subject was led back to the Charles Crane Memorial L ibrary . The subjects were thus reoriented to the campus and could proceed on the i r own from that point . Every subject came to the project knowing that echolocation s k i l l s would be tested in a s p e c i f i c , unrevealed environment. It was hoped that by b l indfo ld ing the control group and leading the experimental group to an 38 unfamil iar portion of the campus, su f f i c i en t spat ia l d isor ientat ion would occur in walking through the outside environment and entering the Education bui ld ing through a seldom used entrance. Of a l l the subjects only one (subject 13) declared that she had known which bui ld ing had been entered and in which portion of the bui ld ing the test ing took place. A few others, pr imar i ly from the control group, suspected that they were walking through the Education bui ld ing but were not certain of the i r precise locat ion within i t . As each subject walked from the bui ld ing containing the o f f i ce and hallway wherein the preliminary tasks had been performed, c l i c k e r use was encouraged to reinforce the pr inc ip les behind echolocation through l i s t en ing to the echoes as they bounced of f a small structure to the l e f t and o f f of the Education bui ld ing as i t was approached. The space to the r ight was mainly free of detectable objects, other than some short shrubs, with l i t t l e usable environmental information returning to the subject. The experimental subjects commented upon the strength of the returning echoes from the Education bui ld ing as i t was approached whereas, in every instance, the control subjects had to be spec ia l l y instructed to l i s t en to the echoes rebounding from the walls of the Education bu i ld ing . In entering the bui ld ing from the south end, i t was necessary to lead the subjects through two sets of closed doors. When the experimental hallway was reached, the author would halt the subject and give the fol lowing ins t ruc t ions : As you walk through th is area, you w i l l be 3-4 f t . from the nearest wall but you w i l l not be allowed to reach out and touch i t . Please c l i c k the c l i c ke r as often as you think necessary, about once per second, and give verbal reports of your perceptions of th is space. The research ass istant i s carrying a cassette machine and w i l l record a l l of 39 your comments. Make your reports as c lear and complete as poss ib le . There are no s ta i r s or special hazards that you should be concerning yourself about, and you w i l l be guided around any person or object in th is area. In your reports about what you perceive about th is space, concentrate your reports mainly on the areas to your r ight and st ra ight ahead. If you notice something of importance to your l e f t mention i t as w e l l , but pay more attent ion to the areas ahead and to the r ight of you. The major events in th is space that you should be reporting on are the presence of a wall or an opening. In each case, say whether i t i s large or smal l . I w i l l meet you at the end of the walk. Are there any questions about these instruct ions? Most questions related to the reporting of the perceived space and, espec ia l ly for a few control subjects, anxiety with the b l ind fo ld was expressed through the requirement of addit ional reassurance concerning unexpected hazards or undulations in the walking surface. Several sub-j e c t s , again from the control group, wished to receive immediate feed-back re la t ing to the i r perceptions by reaching out and touching the area through which they were walking but th is was not permitted. As the reports began, special requests had to be made that the perceptions be reported as statements rather than in an interrogat ive tone. Every subject held the c l i c ke r in the r ight hand and held on to the research ass i s tan t ' s arm sighted guide fashion with the l e f t hand. The research ass istant was holding the cassette machine and the spec ia l l y marked map to ensure that no reference point would be overlooked for scoring purposes. The cassette machine would be put into a recording mode pr io r to the instruct ions being read to the subject and would remain on record un t i l the experimental area was ex i ted . A permanent t ranscr ip t was 40 thereby created. Whereas the control subjects took on an average approximately 20 minutes to complete the ent i re experiment and the experimental group, with the inc lus ion of the walk to and from the Charles Crane Memorial L ibrary and the addit ional questionnaire interview segment, took between 45-60 minutes. An audiometric hearing test was given to every subject in the project . Both ears were tested separately with progressively decreasing beeps that had to be designated as being heard by the ra i s ing of a hand. A l l but one subject in the experimental group (subject 5) had normal hearing a b i l i t i e s . Subject 5 had los t much of the hearing in the l e f t ear during childhood and compensated for th is loss by turning the r ight ear toward the person or sound. This adaptation provided her with the capacity to use auditory spat ia l cues but caused, in many instances, spat ia l d isor ienta t ion through the degree of aural-auditory compensation. Two of the control subjects (subjects 7 and 14) had par t ia l hearing loss in one ear. Subject 7 had a hearing loss in the low reg is ter range, and subject 14 had a loss in the high reg is ter range. Every other subject had normal hearing l e ve l s . C l i cker The c l i c ke r used was beetle-shaped in design with two longitudinal red str ipes running from the head to the t a i l . The main body of the c l i c ke r was 3-3/16 i n . in length and 1-5/8 in width at i t s widest port ion. •The ent i re structure was formed from a th in meta l l i c substance with a small tongue-like s t ructure , which produced the c l i c k i n g sound being 1-1/4 i n . long and 1 i n . wide, emerging on i t s underside. To create the 41 c l i c k i n g sound, th is tongue-like structure has to be pressed by one of the subject 's f ingers . This c l i c k i n g structure produces a c l i c k when i t i s squeezed and a second one when i t i s released. This produces, in e f f e c t , two c l i cks with the squeezing and releasing motions. The second c l i c k i s unavoidable once the f i r s t one has been created. When subjects were to ld to c l i c k the c l i c k e r at least once per second, th i s meant that the tongue-like structure had to be squeezed that frequently. Therefore, when c l i c k i n g tota ls are shown, the amount shown refers to the number of occasions that the c l i c k i ng structure was squeezed. The t ru l y accurate t o t a l s , i f the count were done considering both c l i c k s , otherwise would appear double those which are actua l ly shown. Each separate c l i c k produces a sharp, d i s t i n c t sound that creates an echo by which spat ia l data could be co l l ec ted . With the suggestion that the c l i c k e r be c l i cked at least once per second, the rate would s t i l l vary according to the information which was sought. For those subjects who were seeking prec ise, or t ry ing to sort out confusing, spat ia l configurations the frequency of c l i c k s would often increase. Where the environment was unvarying or the subject was unable to interpret the received information, the c l i c k i n g frequency ei ther remained constant or decreased. The c l i c k e r was not well constructed and often the tongue-like structure would s l i p out of the small area which held i t in place. When the c l i c k i n g structure sl ipped out of i t s holder, usual ly i t could be repaired by pushing i t back in place. On occasion, however, the tongue-l i k e structure would gradually a l t e r i t s shape af ter being used and repaired several times and the c l i c k i ng volume would be reduced. At that point , the c l i c k e r would be eliminated from further use in the project . 42 Three c l i ckers were deleted during the course of the experiment. B l indfo ld Each subject in the control group, and one in the experimental group, wore a b l ind fo ld while walking through the test ing area. The b l ind fo ld was worn during the preliminary warm-up period, throughout the experiment, and was not removed unt i l the experiment was concluded and the subject was returned to the o f f i ce area where a l l preparations had begun. The b l ind fo ld was a Canadian Pac i f i c A i r l i n e s Nightshade which passengers can wear to blot out impinging l i g h t . It i s black in color and consists of several layers of nylon material which are shaped in such a manner as to f i t over the eyes and nose area to el iminate any in te r fe r ing l i gh t from enter ing. The layered material i s held in place by two adjust -able straps at the back to permit addit ional comfort for the wearer regard-less of head s i z e . When the straps have been adjusted for the comfort of the wearer and the b l ind fo ld i s in place, a subject with normal visual acuity could par t ic ipate on an equal basis with t o t a l l y b l ind subjects. Data Co l lec t ion and Analysis A l l subjects were led through the experimental hallway beginning at the right-hand side of the south end and walking to the north end, across the width of the north end, and returning along the r ight side of the hallway to the south end. The subject would hold the c l i c k e r in the r ight hand and would hold on to the research ass i s tan t ' s arm sighted guide fashion with the l e f t hand. The c l i c k e r would be c l i cked approximately once per second, producing the echolocational sound source, and the 43 returning echoes would provide the subject with information re la t ing to the environment. As indicated in the inst ruct iona l segment for every subject, verbal reports would be given by the subject concerning the presence of walls or openings in the near vac in i t y . The subject would be led through the hallway by the research ass istant to ensure that c o l l i s i o n s with persons or objects would be avoided. The research ass istant carr ied a J103E spec ia l l y modified Craig cassette machine on which would be recorded the subject 's verbal reports , along with a map of the space with c l ea r l y marked reference points . As the subject was led through the space, a l l of the subject 's correct responses would be indicated through the depression of the tone index button on the cassette machine producing a d i s t i n c t beep tone on the recording that does not inter fere with the qual i ty of the recording as i t is being made. Afterward, these beeps could be counted when the cassette machine is in the fas t forward or rewind mode, or when l i s t en ing to the recording on regular speed with headphones. No tone indexed beeps were used to indicate e i ther an incorrect response or no response indicat ing the missing of a feature during the walk. Having made a preliminary tota l of correct responses fo r every subject through the counting of tone indexed beeps, the accuracy of these tone indexed beeps would have to be checked by l i s t en ing to the recordings with headphones. Minor a l terat ions to the correct response to ta ls were made by th i s means, and to ta ls could be worked out for the incorrect responses and no responses categories by th is same means. Tables present-ing the tota l scores for every subject, in these categories, were made up. For every reference point a table was prepared at which the performance of each subject i s indicated. In a few cases, incorrect verbal reports 44 were given by subjects between spec i f i c reference points which necessitated an addit ional table showing these addit ional er rors . By set t ing up these correct , incorrect and no response categories, to gauge qua l i t a t i v e l y the detection capab i l i t i e s of each subject and quant i ta t ive ly the amount of accurate reports of spat ia l data to a maximum tota l of 25 reference points. Descriptions of every subject 's walk through the experiment w i l l be given to i l l u s t r a t e the types of perceptions that were revealed through the verbal reporting procedure.„ Environmental data such as the level of pedestrian t r a f f i c and the consequent sound production a l l w i l l be com-mented upon. Data ex is t for the walking time for each subject through th is space and the rate of c l i c ke r use per second during the walk. Descript ive data w i l l be presented from the questionnaire conducted with every member of the experimental group. This information was obtained a f ter the echolocational test had been completed. These data were col lected on cassette tape, as was the walk through the experimental hallway, by which means a permanent record could be kept. Observational data w i l l re late to the ease with which the research ass istant was able to lead every subject through the experimental hallway. Certain subjects adapted well to being led in the sighted guide fashion, whereas others were highly res is tant due to the lack of necessary spat ia l data which would increase the i r confidence in being l ed . The frequency of c l i c k e r usage varied highly throughout the walk. When the information was e i ther confusing or complex the frequency would often increase or , when the environment was unvarying and interpretable , i t would remain constant or decrease. Observations also w i l l be given for the confidence with which subjects reported the i r spat ia l perceptions. Some subjects were very ce r t a in , some 45 wished to make the i r reports in interrogat ive tones and had to be to ld to state the perceptions in statement formats, while others had to be coaxed for the i r perceptions. The qua l i ty and spat ia l correctness of the reports varied widely. Experimental r e l i a b i l i t y and v a l i d i t y w i l l be shown. R e l i a b i l i t y w i l l re late to the consecutive nature of the echolocational test ing for each subject and the re l a t i ve s i m i l a r i t y of accurate perceptions for the subjects in e i ther group. Va l i d i t y w i l l show how echolocation was the primary means by which spat ia l information was perceived by each subject. By e l iminat ing a l l visual cues of the environment, the only remaining p o s s i b i l i t i e s of sensory perception were through o l factory or auditory cues. No other sensing means were avai lable for obtaining spat ia l data by any subject . in the experiment. Due to the nonrandomness of the subject population, no s t a t i s t i c a l summation w i l l be shown. A l l essential data w i l l appear in the descr ipt ive tab les , comments upon the verbal descr ip t ions , and observations. The resul ts w i l l be shown with the subjects divided into control and experimental groups with the differences in detection a b i l i t i e s , confidence of verbal reports re la t ing to the spat ia l environment, walking times through the space, and the data gathering techniques through the overal l frequency of c l i c k e r usage during the walk. 46 CHAPTER FOUR RESULTS Summaries w i l l fol low showing the overal l performances of each sub-jec t going through the experiment, how these performances compared to the group mean, and the mean of a l l the par t i c ipants . Descriptions w i l l be given of the walk through the experimental area and the types of comments that were made by the subject re la t ing to the environmental information received through echolocation. Subject 1 performed very w e l l , second best in overal l correct scores, with 21 correct responses, 1 incorrect response, and 4 reference points were not commented upon (see Tables 4.1 and 4.43). His correct scores were s l i g h t l y above the group mean and nearly double the overal l mean, his incorrect score was just below the group mean and a th i rd of the overal l mean. This subject did not comment upon information received from 4 reference points which was higher than the group mean but substan-t i a l l y lower than the overal l score for a l l subjects. He completed the course faster than a l l other subjects, completing the course 50 seconds faster than the group mean and 47 seconds faster than the overal l mean (see Table 4.44). Very few persons walked through the hallway as th is subject was led through the experiment. When he part ic ipated in the experiment in the early afternoon, there was a continuous hubbub of voices coming from the lounge which was loud enough to cause potential d i s t r a c -t ions for th is subject. His competence in using echolocation was demon-strated through a constant c l i c k e r use that did not a l t e r in order to discern par t i cu la r landmarks along the route. His c l i c k i ng count was s i gn i f i c an t l y below the group and overal l levels as was his per second Table 4.1 Responses at Each Reference Point for Subject 1, L is ted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 11-12 10 2 14 3 18 4 22 5 6 7 8 9 11 12 13 15 16 17 19 20 21 23 24 25 21 .1 4 48 frequency of c l i c k s . At the beginning of the f i r s t section of the walk, he was able to detect the p i l l a r s along the r ight hand wall and the subsequent recesses which they produced. No d i f f i c u l t y was encountered in the area of the information booth and the c i r cu l a r information pole was observed on the r i gh t , at very close quarters, which very few others were able to detect and in te rpre t . To conclude the f i r s t part of the walk, the side and end walls of the hallway were detected. In traversing the width of the h a l l -way, he commented upon the wall in front of him but did not observe the open doorway to the r i gh t . The angle caused by the blackboard standing somewhat away from the side wall gave him the i l l u s i o n of a doorway producing his one incorrect response. With every successive opening into the lounge, he would comment upon the wide openness of these openings but, in each case, the small p i l l a r d iv id ing the opening into two parts was not detected. The walls between the openings, and at the end of the hallway, caused him no interpretat ion d i f f i c u l t i e s . Subject 2's walk through the experimental hallway occurred approxi -mately 30 minutes a f te r subject 1 had completed the course. She received the highest number of correct responses at 22, with no incorrect responses, and 3 missed reference points (see Tables 4.2 and 4.43). The correct response count was above the group mean and nearly double the overal l mean, the incorrect response level was below the group and overal l means, and the no response count was s l i g h t l y below the group mean and a th i rd of the overal l mean. Her walking time was nearly 25 seconds slower than the group mean and nearly 28.5 seconds slower than the overal l mean (see Table 4.44). Her frequency of c l i c k s during the experiment was nearly 31 higher than the group mean and almost 53 higher than the overal l mean. Table 4.2 Responses at Each Reference Point for S u b j e c t s , L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 7 2 14 3 22 4 5 6 8 9 10 11 12 13 15 16 17 18 19 20 21 23 24 25 Totals 22 0 3 50 Her use of the c l i c ke r proved to be very e f fec t i ve . She adopted a constant rapid frequency of c l i c k i ng which, when she became puzzled or confused by environmental transformations, she would increase to a much more frequent l e v e l . Her comparatively slow walking time and the high frequency of c l i cks provided her with a great deal of spat ia l information. While walking through the hallway, a l l of the p i l l a r s projecting inward from the wall and the consequent recesses caused by them were a l l detected. Other than the c i r cu l a r information pole, which she did not report , the remainder of the f i r s t side of the hallway gave her no d i f f i c u l t i e s . As she and the research ass istant approached the end of the hallway, she asked him i f i t might not be time to turn due to the presence of the wall ahead of them. They crossed the width of the hallway, with no detection problems, and she noticed the lack of straightness in the placement of the blackboard which jut ted out from the wa l l . The large s ize of the openings leading to the lounge were observed but, in only one instance, did she detect the p i l l a r d iv id ing the opening into two d i s t i n c t parts. The walls separating the openings gave her the sense of not being s t r a igh t , and the area of the hallway at the f i na l opening to the lounge had the most open appearance to her. She declared that the ends of the hallway seemed to be very closed i n , while the central portions were much more wide open. The conditions for th is subject to go through the test were nearly perfect : Very few persons were walking through the area at that moment and the sound of voices coming from the lounge was a low murmur. Although she did not detect the c i r cu l a r information pole and two of the p i l l a r s d iv id ing the openings to the lounge, she did extremely well and was the only subject to detect that par t i cu la r p i l l a r , r p l 8 , and only one other subject (subject 4) was able to detect any of these p i l l a r s d iv id ing the 51 openings. Subjects 1 and 2 were very confident of the i r perceptions. Their reports were c lear with no encouragement being necessary to comprehend the i r in terpreta t ions . On account of the i r t ravel s k i l l s , i t was a n t i -cipated that the i r overal l correct scores would be high and the level of incorrect scores would be minimal. Subject 3 had the lowest number of correct responses of a l l the experimental subjects at 18, with one incorrect response, and 6 missed reference points . These tota ls placed her well below the group mean •• for correct responses but well ahead of any subject in the control group and 7 above the overal l mean, below the group mean for incorrect responses and a th i rd of the overal l mean, and nearly double the group mean for no responses but well below the overal l mean (see Tables 4.3 and 4.43). Her walking time was nearly 11 seconds slower than the group mean, and almost 14 seconds slower than the overal l mean of subjects (see Table 4.44). The amount of c l i c k s during the walk was over 59 less than the group mean and over 39 less than the overal l mean, while her level of c l i cks per second was lowest of all the experimental subjects and 0.22 below the overal l mean. Her c l i c k e r use was quite d i f fe rent from other subjects in the experimental group in that she would c l i c k frequently to receive an impression of the environment and then she would slow the rate to allow hersel f time to interpret the information. On a few occasions when the c l i c k i ng slowed to a complete ha l t , she had to be encouraged to resume c l i c k i n g to receive new spat ia l data. Subject 3 walked through the hallway portion of the lobby area in the mid morning. This was the f i r s t , occasion on which she had walked through th is bu i ld ing . It was necessary to b l ind fo ld th is subject, the Table 4.3 Responses at Each Reference Point for Subject 3, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 9 4 2 8 3 10 5 14 6 18 7 22 11 12 13 15 16 17 19 20 21 23 24 25 Totals 18 1 6 53 only one.inthe experimental group, due to her a b i l i t y to perceive l i g h t . The b l ind fo ld placed her on an equivalent standing with a l l other persons par t i c ipa t ing in the experiment. Two or three persons walked through the hallway during the course of the experiment; however, a consideration which may have affected her performance was the presence of several persons s i t t i n g in the lounge who were ta lk ing loudly as she was tested. The peripheral sounds, although th is subject gave no indicat ion of being distracted by these persons in the lounge area, may have caused a degree of confusion for her echoloca-t ional s k i l l s as her detection capab i l i t i e s were the poorest of th is group. It i s possible that she r e l i e s upon her l i gh t perception to a greater extent for mobi l i t y . Her travel s k i l l s are not well developed but she i s very s k i l l e d at asking for d i rect ions and by fol lowing them, or having someone guide her personal ly, she can generally ar r ive at her desired dest inat ion . In the early section of the walk, she was able to detect one of the p i l l a r s j u t t i ng out from the wall but she had to be encouraged to make verbal reports during th is portion of the hallway. Just pr io r to rp3, she claimed to detect a non-existent radiator along the wall at about knee height. She detected the ha l l s leading to the lecture hal l but, rather than noting the s o l i d i t y of the walls of the information booth, she must have detected the p i l l a r projecting from i t s centre and described i t as being l i k e a flowering plant . This detect ion, a f ter much de l ibe ra -t i o n , was assigned to the no response category due to i t s inappropriate-ness as being e i ther a wall or an opening and she did not detect the wall on e i ther side of the central p i l l a r . She noted the wall at rp6 and also the central information p i l l a r , which caused a degree of confusion, but 54 she noted that something was very near on the r ight without being able to describe i t . She noted a curve to her l e f t , which must have been coming from the blackboard area, but she did not perceive the wall on her r ight nor the end wall which she declared to be an open doorway. In crossing the hallway, she did not respond at the doorway but did perceive the wall at the fa r s ide . She noted the blackboard on the r ight as being a t a l l w a l l . She perceived rpsl3 and 15 as being wide open, but missed the d iv id ing p i l l a r . She detected a l l of the openings to the lounge in a s im i l a r vain and the walled separations between the openings. The wall at rpl6 she perceived as being curved and the wall at rp20 was perceived as being constructed l i k e a bookshelf. The wa l l s , making up rps24 and 25, were perceived as being very s o l i d . Her correct responses may have been less than any other subject in the experimental group, however th is score was fa r better than any of the control subjects. She showed much more imagination in describing her interpretat ions than other members of the experimental group, but these descript ions did cause comprehension d i f f i c u l t i e s concerning the environ-mental information. She did not verbal ize any anxiety or discomfort caused by the b l i n d f o l d . She did not give her verbal reports with the authority of a t rave ler conf ident ly interpret ing the environment. Her reports required f lesh ing out which was not assisted by her c l i c ke r use. When she was near the openings to the lounge, she would cease c l i c k i n g and would miss the p i l l a r s by defaul t . Subject 4 t ied with subject 5 for the th i rd highest number of correct responses with 20, 1 incorrect response, and 5 missed reference points. This placed him just under the group mean for correct responses, s l i g h t l y 55 under the group mean for incorrect responses, and he missed more reference points than the mean of other group members (see Tables 4.4 and 4.43). His correct responses were nearly 3 times the control group mean, 1/3 of the overal l incorrect level and nearly 1/4 of the control mean, and less than hal f of the overal l no response count and approximately 40 percent of the control group's mean. He used a very constant c l i c k i ng level throughout the walk. His overal l number of c l i c k s was nearly 20 below the group mean but nearly r ight on the mean of c l i c k s for a l l par t i c ipants . The frequency of c l i cks per second was above the group and overal l means, and was the second highest mean count in the experimental group. His walking time through the experiment was the second fastest of th is group being nearly 36 seconds fas ter than the group mean and almost 33 seconds fas ter than the overal l mean (see Table 4.44). This subject had never been a univers i ty student and had not previously walked in the Education bu i ld ing . Like subject 3, he walked through the experimental hallway in the mid morning, with conditions for echolocation being almost perfect with very few persons walking along the hallway and re la t i ve s i lence ex is t ing in the lounge. He detected the three p i l l a r s along the f i r s t portion of the walk and the recessed areas between them. The openings leading to the lecture ha l l and the information booth were discerned, but he did not report rps6 and 7. He noted the walls to the r ight and ahead at the end of the hallway, and missed reporting the doorway to the r ight in crossing the far end. He detected the wall ahead of him before turning to walk along the second side and observed a change in the wall where the blackboard was located. At the fa r end of the blackboard he reported an opening, Table 4.4 Responses at Each Reference Point for Subject.4, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 12-13 6 2 7 3 10 4 18 5 22 8 9 11 12 13 14 15 16 17 19 20 21 23 24 25 Totals 20 1 5 57 which was his one incorrect response, where i t curved out from the wa l l . He commented upon the wide open space "which seemed to go on forever" with a p i l l a r in the middle of i t . The report of the p i l l a r , r p l 4 , was the only report for that reference point and, along with subject 2, he was the only other subject to detect a d iv id ing p i l l a r . Without detecting any further p i l l a r s , his comments about the openings to the lounge were the same each time. He noted the walls separating the openings and thought that the hal l seemed to become narrow toward i t s end. The walls making up rps24 and 25 were detected eas i l y . His reports were made with confidence and c l a r i t y . In describing the openings to the lounge area "as seeming to go on forever" he provided a c lear picture of the wideness of the openings as perceived through echolocation from the c l i c k e r . There was very l i t t l e d i s t rac t ion to him from the environment and th is gave him ample opportunity to receive unencumbered cues re la t ing to the spat ia l conf igurat ion. Subject 5 was the f i na l member of the experimental group to be tested and she t ied with subject 4 for th i rd highest number of correct responses overal l and jus t below the mean of the group with 20, 3 i n -correct responses which was nearly 3 times higher than the group mean but equal to the overal l mean, and 3 missed reference points which was below the group mean and a th i rd of the overal l mean (see Tables 4.5 and 4.43). Her walking time was the slowest of the experimental subjects and over 40 seconds slower than the group mean and over 43 seconds slower than the overal l mean (see Table 4.44). Her c l i c k e r use was very interest ing in that she would c l i c k in bursts to receive spat ia l informa-t i o n , then would slow the frequency as she interpreted the data, and would then increase the rate again. She would not slow to a ha l t , but confusing Table 4.5 Responses at Each Reference Point for Subject 5, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 14 18 22 Totals 1 1-2 2 7 3 9 4 5 6 8 10 11 12 13 15 16 17 19 20 21 23 24 25 20 3 59 data would cause a very rapid series of c l i cks to be emitted. She had the highest number of c l i c k s of a l l the subjects in her group, being over 110 c l i c k s above the group mean and over 132 above the overal l mean. She had the highest mean of c l i cks per second in the experimental group and the th i rd highest frequency of a l l tested subjects. She part ic ipated in the experiment in the middle of the afternoon. Echolocational conditions for her were rather adverse with many persons standing or walking through the hallway at that moment and a loud level of confusing background noise coming from both the lounge and hallway areas. Due to the number of persons in the hallway i t was necessary fo r the research ass istant to walk more slowly with her, and she had to c l i c k more often to receive c lear echoes from the environment so that she could understand i t more read i l y . She had been a univers i ty student several years ago, but had not been in the Education bui ld ing previously so that no memory of th is space would ex is t for her. She detected the unevenness of the f i r s t part of the course and, a f ter noting the presence of the w a l l , said that there was an opening in i t by which she must have been describing one of the recessed areas be-tween the p i l l a r s . She observed other p i l l a r s in th is area but was con-fused by them and could not describe them. She detected the f i r s t h a l l -way leading to the lecture ha l l and the information booth and, at the next opening, she was able to d is t inguish the opening as being d i s t i n c t from several persons who were standing at the mouth of the opening. Other than not reporting the c i r c u l a r information p i l l a r , which she described as being an opening, she detected the walls on e i ther side of i t . She described the end wa-11 as being an opening l i k e a doorway. She noted the 2 reference points in crossing the hallway and reported the 60 echoing nature in the openings leading to the lounge every time that one was passed. She did not report the p i l l a r s in the openings, but detected a l l other reference points along the second side of the cor r idor . She described the end of the hallway as seeming to become smal ler , and she detected a table located along the wall near the end of the walk. Considering the number of persons in the hallway and the high noise, she coped extremely well with the confusion and the environmental sounds through which she received environmental data. Pa r t i cu l a r l y when she had to d is t ingu ish between spat ia l circumstances and persons s i t t i n g or standing in the hallway, her a b i l i t y to d is t inguish between permanent and temporary hallway features was astonishing. She was not f lustered or i r r i t a t e d by these addit ional confusing factors in the environment and dealt with them as well as she was able. The conditions for her test ing may have been the most adverse for any of the subjects in the experiment. Despite the d i f f i c u l t i e s associated with her t e s t , subject 5's reports were frequent, c lear and stated conf ident ly . No encouragement was necessary to maintain the reporting or c l i c k i ng levels to ensure that the environment was being understood. Subject 6 was the f i r s t representative of the control group. Her scores were 9 in the correct response category which was higher than the control group mean but below the overal l mean, 6 incorrect responses which were nearly double the group mean and exactly double the overal l mean, and the 10 unreported reference points were below the group mean and s l i g h t l y below the overal l mean (see Tables 4.6 and 4.43). Her walking time through the hallway was the second slowest time in th is group and the th i rd slowest of a l l subjects. Her walking time was almost 42 seconds slower than the group mean and nearly 40 seconds slower than the overal l Table 4.6 Responses at Each Reference Point fo r Subject 6, L is ted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 4 2 3 5 6 8 16 7 9 19 10 11 20 12 13 23 14 15 18 17 22 21 24 25 Totals 9 6 10 mean^see Table 4.44). Her c l i c ke r use was very steady and there was very l i t t l e var ia t ion in the frequency as she was being led through the t e s t . In overal l c l i c k s she was nearly 24 above the group mean and over 15 above the overal l c l i c k i ng mean. The frequency of c l i cks per second was below the group mean and overal l mean resu l t ing in a decreased opportunity to receive a great deal of spat ia l information through the re l a t i ve slow walking time and the low level of c l i c k s per second. She part ic ipated in the test during the mid morning when a few persons were s i t t i n g in the lounge creating a low murmur of voices. Only one or two persons walked through the hallway during the test and no addit ional obstructions were caused by persons s i t t i n g or standing in the hallway. 62 Subject 6 wished to val idate her perceptions through reaching out and checking whether a wall or an opening existed in her vac in i t y , but th is was not permitted. She noted the wall to her r ight at the beginning and appeared to detect the unevenness in th is sect ion , but her comments were too br ie f for a correct score for the second reference point . She detected the f i r s t opening leading to the lecture h a l l , but misinterpreted rps4 and 5. She did not report rps6 and 7 but was able to detect the walls making up rps8 and 9. Rather than s ta t ing , in many cases, whether there was a wall or an opening she would state that there was something near or fa r away. In crossing the hallway, she did not observe the door-way and detected the wall ahead of her. She did not report the presence of the blackboard but did note the "big space" leading to the lounge. At th is point she feared that there were steps going downward ahead of her which, ac tua l l y , were beside her not ahead of her. She misinterpreted the wall separating the openings, but reported correc t ly the f i r s t portion of each "big space" leading to the lounge. Her reports on the second long side of the hallway were more spasmodic and less accurate despite the encouragement to provide more complete verbal reports. Near the end of the hallway, which was enclosed by walls on 3 s ides , she reported as a "big space." She was very tentat ive and anxious concerning her safety during the walk r es i s t i ng strongly as she was l ed . Her reports were made in an interrogat ive tone that did not r e f l e c t confidence in her detection a b i l i t i e s . Despite the lack of confidence in her echolocation a b i l i t i e s , she did perform better than the group mean. She commented that she could feel currents of a i r from the a i r condit ioning system in the bui ld ing but could not decide how these currents could ass i s t her. She did not know 63 where she had been walking, therefore no visual memory cues influenced her performance. Subject 7 also part ic ipated in the test during the mid morning. Her correct response count of 13 was the highest of th is group and was above the overal l mean, she was below the group mean and overal l mean for incorrect responses, and was below the group mean but above the overal l mean in the no response category (see Tables 4.7 and 4.43). She used a very slow, but steady, c l i c k i n g rate which was the lowest of a l l the subjects to create the echolocational sounds by which she was expected to interpret the environment (see Table 4.44). Her frequency of c l i c k s per second was also the lowest of a l l the subjects at less than 0.5 per second. Her walking time, however, was almost even with the group mean and the overal l mean. A few more persons walked through the test ing area than for subject 6 but the sound level was very quiet pro-ducing excel lent echolocational conditions for the t e s t . Table 4.7 Responses at Each Reference Point for Subject 7, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 2 3 5 7 11 12 13 16 19 20 21 24 1-2 9 4 6 8 10 14 15 17 18 22 23 25 Totals 13 2 11 64 Af ter being encouraged to make af f i rmat ive statements upon beginning the walk, she detected the wall to the r ight but thought that there was an opening in i t s central sect ion. It was necessary to encourage her to be more spec i f i c in her comments which were very b r i e f . Her reports were extremely b r ie f and did not go beyond reporting in any deta i l the walls or openings along the walk. She observed the opening leading to the lecture hal l but missed detecting the information booth. She was one of the few subjects who was able to detect the c i r cu l a r information ... p i l l a r , but she did not report the wall on e i ther side of i t and thought that the end wall was an opening. In crossing the hallway, she missed reporting upon the doorway but did detect the wall d i r e c t l y ahead of her. She detected the blackboard on the r ight and the f i r s t portion of the opening to the lounge. She noted the two separating walls between the openings leading to the lounge and the second portion of the l a s t lounge opening. She commented upon the pipe or c igar smoke coming from the seating area into the hallway at th i s point . She reported on the wall to the r ight near the end of the hallway, making up rp24, but did not observe the end w a l l . It was astonishing how much information she could receive through her l imi ted c l i c k i n g as she was 39 c l i c k s below the second lowest subject (subject 9) in the t es t . She walked f ree ly and had no fear of c o l l i s i o n s with obstruct ions. This subject did not recognize the bu i ld ing . Subject 8 part ic ipated in the experiment in the middle of the a f t e r -noon with a substantial murmur of voices coming from the lounge area and several persons were walking through the test ing area. She found the sound level to be d i s t rac t ing to the degree that her a b i l i t y to use echolocation probably was ser iously a f fected. She had 7 correct responses 65 which was s l i g h t l y below the group mean and below the overal l mean, she had nearly double the group mean of incorrect responses and more than double the overal l mean, and she was below the group mean but s l i g h t l y above the overal l mean for no responses,(see Tables 4.8 and 4.43). Her walking time was below the group and overal l means, and the overal l amount of c l i c k s was more than 3 below the group mean and 12 below the overal l mean (see Table 4.44). The frequency of c l i c k s per second was nearly equal to the group mean but below the overal l mean. Her c l i c k i n g rate was very steady during the walk. Table 4.8 Responses at Each Reference Point for Subject 8, L is ted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 4 3 2 9 5 7 12 6 8 16 10 11 21 13 17 24 14 19 25 15 ' 18 20 22 23 Totals 7 7 11 66 She was able to d is t inguish the wall to her r i gh t , which went on for a considerable length, for the f i r s t 2 reference points but she did not cor rec t ly report another reference point un t i l she arr ived at the c i r cu l a r information p i l l a r . She kept noting the clearness of space ahead of her and the voices to the l e f t , otherwise, she missed interpret ing the reference point at the information booth. She noted the wall to the r ight at rp8 but thought that the end wall was an opening. In traversing the hallway, she did not detect the doorway but reported the wall ahead of her. On the return walk she detected only the openness of. the middle opening leading to the lounge, but the comments concerning the blackboard, the walled section at rp l6 , rp21, and the f i na l 2 reference points were a l l incorrect . She did not comment on other reference points . Her tentativeness while walking through the test ing area was ref lected in the many comments concerning the openness ahead of her and the voices coming, at least i n i t i a l l y , from the l e f t . There was a great deal of resistance to being led and the confusion caused by the persons in the lounge area did not improve her confidence l e v e l . She said that she had suspected that she had been led into the Education bui ld ing and had been walking in the lobby sect ion , pr imar i ly due to the sound of the voices from the l e f t as she began the t es t . Her comments concerning the environment during the walk were very b r ie f and undescript ive. When subject 9 walked through the test ing area in the middle of the afternoon the conditions for using echolocation were s imi la r to those for subject 8. Fewer persons walked through the test ing area, but the sound of voices coming from the lounge area was considerable. Her 10 correct responses were above the group mean and below the overal l mean and t i ed her for the second best performance of the test in the control 67 group with subject 10, the one incorrect response was below the group and overal l means, and her no responses level was well above the group and overal l means (see Tables 4.9 and 4.43). Her walking time through the test was well below the group and overal l means, being more than 35 seconds under these levels (see Table 4.44). Her c l i c k i n g rate was quite slow, being the second lowest frequency of a l l subjects, but i t did increase in frequency when she sought addit ional environmental data. The c l i c k i ng count was 86 below the group mean and 95 below the overal l mean. The mean of c l i c k s per second, due to the fast walking time, was jus t over 0.8 per second which put her below the group and overal l means. Table 4.9 Responses at Each Reference Point for Subject 9, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 12 2 3 4 5 6 9 7 11 8 13 10 17 14 21 15 24 16 25 18 19 20 22 23 Totals 10 1 14 68 She had to be encouraged to commence her verbal reporting and she commented upon the wall to the r ight for rp l but, due to her lack of observations, she did not receive any c red i t for rp2. She did state that there were many people speaking quite near to where she was walking but i t did not appear to cause her much concern. She detected the two openings leading to the lecture ha l l and the end w a l l , however a l l other points were not commented upon along the f i r s t portion of the hallway. In crossing the hallway she observed the wall ahead of her, but missed detecting the doorway. At rpl2 she reported an opening, for her only incorrect response, and was able to interpret the f i r s t portion of the openings leading to the lounge but the lack of commentary in each case caused her to lose further credi t for these observations. She reported the wall to the r ight at rp24 and did not comment upon a l l other features of the walk. It is l i k e l y that the lack of commentary kept down the number of incorrect responses. Her confidence level in being led through the test was high and she walked very f r e e l y . Despite the low number of c l i c k s , she was able to receive and interpret a great deal of information con-cerning the space. Spatial memory did not inter fere with her a b i l i t i e s as she was unaware of which bui ld ing she had been walking through. Subject 10's walk through the experimental environment took place in the middle of the afternoon when there was very l i t t l e confusing noise coming from the lounge area. Only a few people were ta lk ing through the hallway. With these favourable low levels of d i s t rac t ing sound subject 10's resul ts were ident ica l to those of subject 9. Her correct response level of 10 put her above the group mean but below the overal l mean, the one incorrect response was below both the group and 69 overal l means, and the 14 missed reference points were above the group and overal l means (see Tables 4.10 and 4.43). Her walking time through the test ing area was nearly 49 seconds below the group mean and nearly 50 seconds faster than the overal l mean (see Table 4.44). The overal l frequency of c l i c k s was almost 64 above the group mean and nearly 55 above the overal l mean. The frequency of c l i c k s per second was the highest of a l l the subjects at more than 1.5 per second. The c l i c k i n g level was constant and rapid with l i t t l e var ia t ion throughout the course. Table 4.10 Responses at Each Reference Point for Subject 10, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 24 4 2 6 3 7 5 10 8 11 9 12 13 14 16 15 20 17 25 18 19 21 22 23 Totals 10 1 14 70 It was necessary to urge her to comment throughout the ent i re walk. She detected the f i r s t 3 reference points , missed detecting the informa-t ion booth, and reported the second hallway leading to the lecture h a l l . She missed interpret ing rps6 and 7, but reported the wall on the r ight for rp8 and the end wall of the hallway. Both reference points were not discerned when crossing the hallway, but she observed the f i r s t portion of the f i r s t opening leading to the lounge. The two walls separating the openings to the lounge at rpsl6 and 20 were observed along with the wall on the r ight at rp24, but a l l other reference points were not reported. Near the l as t opening leading to the lounge she reported that there was something very near in f ront of her which, in r e a l i t y , there was not. This subject was insecure throughout the t e s t i ng . Although she had the highest c l i c k i ng mean per second rate , i t did not t ranslate into a high rate of information regarding the spat ia l conf igurat ion. Her verbal reports were not del ivered in a confident manner. She had no idea con-cerning through which bui ld ing she had been led so that no interference from residual visual memory would e x i s t . Subject 11 walked through the experimental hallway in the middle of the afternoon when echolocational conditions were very favourable with a low murmur of voices coming from the lounge and very few persons walked through the test ing area. She had 6 correct responses which was below the group mean and approximately hal f of the overal l mean l e v e l , there were 3 incorrect responses which was close to the group mean and equal to the overal l mean, and the number of no response s i tuat ions was well above both the group and overal l means.(see Tables 4.11 and 4.43). Her walking time through the test was over 39 seconds above the group mean 71 Table 4.11 Responses at Each Reference Point for Subject 11, L is ted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 6 5 2 12 7 3 13 8 4 9 17 10 24 11 14 15 16 18 19 20 21 22 23 _25 Totals 6 3 16 and more than 40 seconds above the overal l mean (see Table 4.44). Her overal l c l i c k i ng count was the th i rd lowest of a l l the subjects but, when combined with the r e l a t i v e l y quick walking pace, the frequency per second worked out to the second highest rate of a l l subjects behind only subject 10. The c l i c k i ng rate was rapid and unvarying throughout the t es t . She had to be encouraged to give verbal reports during the walk and she was not confident about stat ing her perceptions. She was able to detect the f i r s t 4 reference points , incor rec t l y reported rp6 to be an 72 opening, and did not make any further reports for the remainder of th i s - side of the hallway. She did not; report upon the 2 reference points in crossing the hallway and incorrect ly reported rpsl2 and 13 as, f i r s t l y , an opening and, secondly, a wa l l . She detected rpsl7 and 24, but did not report on any other reference points during the remainder of the walk. The reports , espec ia l l y toward the end, became more sporadic and she often stated that she was not certa in about the echoes she was rece iv ing. She was not confused or anxious about the ambient sounds in the test ing area coming from the lounge. She showed t rus t in the research ass i s tant ' s leading a b i l i t i e s by being led eas i l y without much resistance. She had no idea concerning which bui ld ing she had been led i n t o , nor which portion of that bui ld ing was being used for the experiment. Subject 12 part ic ipated in the experiment in the early afternoon. There was a high level of d i s t rac t ing sound coming from the lounge area, but few persons were walking through the hallway. She was quite d i s -oriented by the level of sound and had much d i f f i c u l t y interpret ing the echolocational qua l i t i e s produced by the c l i c k e r . She was the lowest of a l l the subjects in scoring correct responses, her incorrect responses were s l i g h t l y higher than the group and overal l means, and her 21 no responses were second highest of a l l the subjects in the experiment (see Tables 4.12 and 4.43). Her walking time through the hallway was by far the slowest of a l l the subjects being over 2 minutes above the group and overal l means. Due to the length of the walk, the overal l c l i c k i n g count was substant ia l l y above the group and overal l means; yet , the frequency of c l i c k s per second was below the group and overal l means (see Table 4.44). Her c l i c k i n g rate varied w i ld l y throughout the walk from very rapid to Table 4.12 Responses at Each Reference Point for Subject 12, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 2-3 1 3 2 8 4 12 5 6 7 9 11 13 14 15 16 17 18 19 20 21 22 23 24 25 Totals 1 4 21 74 complete ha l t s . The var ia t ion in the c l i c k i n g rate appeared to be unrelated to the complexity of the environment. The only reference point that she cor rec t ly reported on was rplO, the doorway at the fa r end of the hallway, which many others did not detect. Otherwise, she reported a stairway on the r ight along the f i r s t long walled sect ion. She reported more of an echo at rp3, "which could have been more s t a i r s , " and in the area of rps6 and 7 she reported less of an echo. At rp8 she reported a doorway "as there was more of an echo there. " She reported the differences in sounds as she was led through the hallway, but she would not attempt to interpret the var iat ions in the echoes. She thought there was an opening at r p l 2 , the l as t reference point at which she would commit herse l f , and the remainder of the walk had no c lear spat ia l i den t i f i c a t i ons by th is subject other than stat ing that there were differences in sound in the area of the openings in front of the lounge and near the wa l l s . This subject was also insecure in moving through the t es t . Her con-fidence level was not improved by the d i s t rac t ing level of ambient sound in the environment. Even her c l i c k e r use was unpredictable with frequent unexpected f luctuat ions in rate . The f rus t ra t ion f ac to r , pa r t i cu l a r l y returning along the second long side of the hallway, was demonstrated by the gradual reduction in the given verbal commentary. She had no idea concerning which bui ld ing she had been led i n to , nor which segment of that bui ld ing was being used for test ing purposes. Subject 13 walked through the test ing area in the early afternoon when there was a high rate of pedestrian t r a f f i c but the noise level was not beyond a low murmur. The pedestrian t r a f f i c did not seem to cause any expressed d i f f i c u l t i e s during the walk. Her correct response level 75 of 7 was nearly equal to the group mean but below the overal l mean, her incorrect score was nearly t r i p l e the group and overal l means, and the no response score was below the group mean and nearly equal to the overal l mean0(see Tables 4.13 and 4.43). Her walking time was almost 35 seconds higher than the group mean and 34 seconds higher than the overal l mean (see Table 4.44). The overal l c l i c k i ng count was nearly 52 higher than the group mean and nearly 43 higher than the overal l mean. The frequency of c l i c k s per second was higher than both the group and overal l means. She would c l i c k quite s teadi ly for a time and then, rather unexpectedly, would cease altogether while she interpreted the information. Table 4.13 Responses at Each Reference Point for Subject 13, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response •1 2 3 6 4 5 8 7 9 10 12 11 21 13 14 24 15 18 25 16 19 17 20 22 23 Totals 7 8 10 76 She was encouraged to give more frequent reports , however long periods of s i lence continued to occur between these reports. She detected the f i r s t reference point , but incorrect ly reported rp2 as an open, space and rp4 as a doorway. She reported the walls at rps6 and 8, but incor rec t l y reported rp7 as a doorway. She commented upon the doorway to the r ight while crossing the hallway, and only was able to report the f i r s t portion of the f i na l opening (rp21) leading to the lounge and the f i na l 2 reference points on the second long side of the hallway as correct responses. Rpl2 was described as an opening, rpsl3 and 15 were reported as being a w a l l , rpl6 was an opening and rpl7 was a w a l l . Her c l i c k e r rate appeared to increase dramatical ly for the crossing of the hallway and up to the f i r s t opening leading to the lounge. She claimed to know exactly which hallway was being used for the t e s t , and she attempted to use her visual memory to ass i s t her performance. Once the end of the hallway was reached, i t appeared as though there were discrepancies between the visual memory and her posi t ion in that space for which she attempted to compensate through an increased c l i c k i n g frequency. A high level of t rus t in being led did not develop. Her i n i t i a l reports , though intermit tent , were made with confidence but by the f a r end of the hallway a degree of doubt was expressed, through tonal q u a l i t i e s , in her reports. Subject 14 part ic ipated in the experiment in the middle of the afternoon. The echolocational conditions for him were very good with only a low murmur of voices coming from the lounge and very few persons walked through the hallway. He was the second lowest subject overal l in making correct responses with 2, he made only one incorrect response which was below the group and overal l means, but his no response score of 22 was 77 the highest of a l l subjects (see Tables 4.14 and 4.43). His walking time was over 36 seconds faster than the group mean and 37 seconds faster than the overal l mean (see Table 4.44). His overal l c l i c k i n g rate was below the group and overal1 means, and the frequency per second was higher than the group and overal l means. The c l i c k i n g rate was constant and was not subject to change due to var iat ions in the environment. His reports were neg l i g ib l e , despite encouragement to comment, to the point that only 3 reference points were attempted during the walk. His comments did not begin un t i l near the end of the walled portion of the hallway where he detected rps2 and 3. He noted a difference in the clicker-produced sound at the far end of the hallway, and reported an open space at rp l2 . The only comments on the second long side of the hallway were that he could not ident i fy spec i f i c environmental features en route. It was d i f f i c u l t to gauge th is subject 's reactions as his comments re la t ing to the space were so b r i e f . He was attempting to concentrate so much on hearing the differences in the echoes that , in hes i tat ing before he would commit himself concerning an environmental feature, i t would be by-passed and another feature would replace i t . He res isted strongly while being l ed , as he was accustomed to being given spat ia l information, and the reports he gave were given in a very unconfident manner. He stated that he suspected that he had been led into the Education bu i ld ing , but he could not reinforce his fee l ing from any environmental features that he was asked to ident i fy during the walk. Subject 15 walked through the experimental hallway in the middle of the afternoon when echolocational conditions were nearly perfect with very l i t t l e noise coming from the lounge and only 1 or 2 persons walked Table 4.14 Responses at Each Reference Point for Subject 14, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 2 12 1 3 4 5 6 7 8 9 10 11 13 14 15 16 17 18 19 20 21 22 23 24 25 Totals 2 1 22 79 through the hallway. Her 9 correct responses were above the group mean and below the overal l mean, the 4 incorrect responses were above the group and overal l means, and the 12 missed reference points were below the group mean but above the overal l mean (see^Tables 4.15 and 4.43). Her c l i c k i n g rate varied between quite slow and moderately fas t with no d iscern ib le environmental reason being ref lected in the va r i a t i on . Table 4.15 Responses at Each Reference Point for Subject 15, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 3 " 2 5 9 4 6 12 7 10 13 8 16 11 19 14 20 15 24 17 25 18 21 22 23 Totals 9 4 12 Her reports , despite encouragement, were br ie f and without e laborat ion. She reported cor rec t l y concerning r p l , reported a wall at rp3, and detected the open space at rp5. Rp6 was reported co r rec t l y , but the fa r end wall was described as a doorway. In crossing the hallway, the doorway was reported. Rpl2 was reported as an opening and rpl3 was described as a w a l l . Rpsl6, 19, 20, 24 and 25 were a l l reported co r rec t l y . She thought that 80 there was a doorway close at hand stra ight in front of her when she was near the f i na l opening leading to the lounge. Her reports , toward the end of the walking course, were even less elaborate in deta i l and number than those at the commencement of the walk. She showed l i t t l e t rus t in being led through the course and res isted f a i r l y s trongly . She, l i k e subject 14, was attempting to be so accurate with her perceptions that she would miss reporting an environmental feature when there was some doubt concerning i t . Her reports were not made in a confident manner, and she was uncertain about the bui ld ing and the space in which the test ing was done. Subject 16 walked through the experimental area in the middle of the afternoon with rather var iable echolocational condit ions. For the most part , there was very l i t t l e ambient sound coming from the lounge and few persons walked through the area, but when he reached the fa r end of the hallway several persons exited the bui ld ing through rp8 jus t pr ior to the subject crossing the width of the hallway necessitat ing a momen-tary hal t in the walk. He had 6 correct responses which were below both the group and overal l means, his 5 incorrect responses were above the group and overal l means, and the 14 no responses were above the group and overal l means (see Tables 4.16 and 4.43). His walking time was over 11 seconds faster than the group mean and over 12 seconds faster than the overal l mean (see Table 4.44). The overal l c l i c k i n g count was over 67 above the group mean and 58 more than the overal l mean. The frequency of c l i c k s per second was below both the group and overal l means. The c l i c k -ing rate was quite steady regardless of the complexity of the environment. When he commenced the walk he reported a wall to the r ight and, due to the s i m i l a r i t y of condit ions, he reported the continuation of the wall Table 4.16 Responses at Each.Reference Point fo r Subject 16, L isted by Reference Number and Type of Response Correct Response Incorrect Response No Response 1 . 7 3 2 15 4 9 16 5 10 20 6 12 24 8 25 11 13 14 17 18 19 21 22 _23 Totals 6 5 14 resu l t ing in a correct score for rps l and 2. From that point he could not hear any var ia t ion in the echoes un t i l a r r i v ing at rp7, which he described "as being more open," which was not t rue. A difference was detected in front of him which he stated must be a w a l l , producing a correct score for rp9. The timing of the walk stopped as he waited to be led across the width of the fa r end of the hallway, as a group of persons walked from rplO to rp8 and exited through the doors, at which point the timing recommenced. This delay lasted fo r approximately 10 seconds. He detected the doorway at rplO and the blackboard at r p l 2 . Rpl5 was described as a wall and rpl6 was described as being more wide open, which were both incorrect reports. He also described the walls 82 at rps20 and 24 as being more open. In approaching rp25, he reported that i t sounded l i k e he was coming up to something. He did not show a high degree of. t rus t in being led through the environment. His reports, in the central portions of e i ther side of the hallway, were mainly to the ef fect that he could not d is t inguish what features were present in the environment but he did attempt more descr ip -t ions than subjects 11, 12 and 14. Almost a l l of the reports were given in a very unconfident manner. He did not recognize to which bui ld ing he had been led or in which portion of that bui ld ing the test ing was carr ied out. The fol lowing tab les , Tables 4.17 to 4.41, display the breakdown of subjects ' performances at each spec i f i c reference point . Table 4.42 shows the errors which were made between spec i f i c reference points along the walk. Table 4.17 Subjects' Response at Reference Point 1, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 12 2 14 3 4 5 6 7 8 9 10 11 13 15 16 Totals 14 0 2 Table 4.18 Subjects' Response at Reference Point 2, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response Totals 1 13 6 2 9 3 12 4 15 5 7 8 10 11 14 16 11 1 4 Table 4.19 Subjects' Response at Reference Point 3, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 12 8 2 15 13 3 16 4 5 6 7 9 10 11 14 Totals 11 Table 4.20 Subjects' Response at Reference Point 4, L isted by Subject Number and Type of Response Correct Response . Incorrect Response No Response 1 6 3 2 8 7 4 13 9 5 10 11 12 14 15 16 5 3 8 Table 4.21 Subjects' Response at Reference Point 5, L is ted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 6 8 2 11 3 12 4 13 5 14 7 16 9 10 15 Totals 9 1 6 Table 4.22 Subjects' Response at Reference Point 6, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 11 4 2 6 3 7 5 8 13 9 15 10 12 14 _16 Totals 6 1 9 Table 4.23 Subjects' Response at Reference Point 7, Listed by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 5 2 3 13 4 7 16 6 8 9 10 11 12 14 15 Totals 4 3 9 Table 4.24 Subjects' Response at Reference Point 8, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 12 .3 2 7 4 9 5 11 6 14 8 15 10 16 13  Totals 8 1 7 Table 4.25 Subjects' Response at Reference Point 9, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 3 11 2 5 12 4 7 13 6 8 14 9 15 10 16 7 5 4 Table 4.26 Subjects' Response at Reference Point 10, L is ted by Subject Number and Type of Response Correct Response Incorrect Response No Response Totals 2 1 5 3 12 4 13 6 15 7 16 8 9 10 11 14 6 0 10 Table 4.27 Subjects' Response at Reference Point 11, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 10 2 11 3 12 4 13 5 14 6 15 7 16 CO 9 9 0 7 Table 4.28 Subjects' Response at Reference Point 12, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 6 10 Totals 1 2 9 3 11 4 12 5 13 7 14 16 15 7 7 Table 4.29 Subjects' Response at Reference Point 13, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 11 8 2 13 12 3 15 14 4 16 5 6 7 9 10  Totals 9 3 4 89 Table 4.30 Subjects' Response at Reference Point 14, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 4 1 2 3 5 6 7 8 9 10 11 12 13 14 15 J J 6 Totals 1 0 15 Table 4.31 Subjects' Response at Reference Point 15, L is ted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 . 1 3 7 2 16 8 3 9 4 10 5 11 6 12 14 _15 Totals 6 2 8 Table 4.32 Subjects' Response at Reference Point 16, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response Totals 1 6 9 2 8 11 3 13 12 4 16 14 5 7 10 15 8 4 4 Table 4.33 Subjects' Response at Reference Point 17, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response Totals 1 13 7 CXI 10 3 12 4 14 5 15 6 16 CO 9 11 9 1 6 91 Table 4.34 Subjects' Response at Reference Point 18, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 2 1 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Totals 1 0 15 Table 4.35 Subjects' Response at Reference Point 19, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 6 9 2 10 3 11 4 12 5 13 7 14 8 16 _15 _ Totals 8 1 7 Table 4.36 Subjects' Response at Reference Point 20, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 6 8 2 16 9 3 11 4 12 5 13 7 14 10 15  Totals 8 2 6 Table 4.37 Subjects' Response at Reference Point 21, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 8 7 2 10 3 11 4 12 5 14 6 15 9 16 13  Totals 8 1 7 Table 4.38 Subjects' Response at Reference Point 22, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 JL6 Totals 0 0 16 Table 4.39 Subjects' Response at Reference Point 23, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response 1 6 7 2 8 3 9 4 10 5 11 12 13 14 15 16 Totals 5 1 10 Table 4.40 Subjects' Response at Reference Point 24, L isted by Subject Number and Type of Response Correct Response Incorrect Response No Response Totals 1 8 6 2 10 12 3 16 14 4 5 7 9 11 13 15 10 3 3 Table 4.41 Subjects' Response at Reference Point 25, L isted by Subject Number and Type o f Response Correct Response Incorrect Response No Response Totals 1 8 6 2 7 3 11 4 12 5 14 9 10 13 15 16 10 1 5 95 Table 4.42 Errors Made Between Two Reference Points , L isted by Subject Number Between Points Subject Number 11- 12 1 12- 13 4 1-2 5 1- 2 7 2- 3 12 Totals 5 5 Table 4.43 Overall Performance of A l l Subjects Subject Correct Response(s) Incorrect Response(s) No Response 1 21 1 4 2 22 0 3 3 18 1 6 4 20 1 5 5 20 3 3 Mean for subjects 1 to 5 20.2 1.2 4.2 6 9 6 10 7 13 2 11 8 7 7 11 9 10 1 14 10 10 1 14 11 6 3 16 12 1 4 20 13 7 8 10 14 2 1 22 15 9 4 12 16 6 5 14 Mean for subjects 6 to 16 7.727 3.818 13.909 Mean for a l l 16 subjects . 11.3125 3 10.8125 97 Table 4.44 Walking and Clicking Counts for A l l Subjects Subject Walking Time • Number of Clicks Clicks per Second 1 3 mins. 32 sec. 205 0.9669 2 4 " 38 " 303 1.0899 3 4 " 24 " 211 0.7992 4 3 " 37 " 251 1.1566 5 4 i. 53 " 383 1.3071 Mean for subjects 1 to 5 4 mins. 12.8 sec. 270. 6 1.06394 6 4 " 50 " 266 0.9172 7 4 " 7 " 116 0.4696 8 4 " 2 „ 238 0.9834 9 3 " 13 " 155 0.8031 10 3 " 19 11 305 1.5326 11 3 " 29 " 199 1.4306 12 6 " 14 " 314 0.8395 13 4 " 43 11 293 1.0353 14 3 " 32 " 230 1.0849 15 4 " 4 " 232 0.9508 16 3 " 57 " 309 0.9169 Mean for subjects 6 to 16 4 mins. 8.181 sec. 241. 545 0.9967181 , Mean for a l 1 16 subjects 4 mins. 9.63 sec. 250. 625 1.017725 98 Questionnaire Interview Responses At the conclusion of the walk through the test ing area, every exper i -mental subject was led back to the o f f i ce where they would be asked questions re la t ing to the i r experiences with echolocation in the past, present and future . Each subject 's responses are shown below. Subject 1 had los t a l l of his v is ion due to re t ina l blastoma within the f i r s t 10 months of l i f e . He used echolocation cont inual ly through the day and has done so for as long as he can remember. He e i ther produces an environmental cue by tapping his cane with more than necessary force , or sounds from other sources are used, to traverse open areas l i k e a parking l o t in a fashion by which or ientat ion can be maintained. The best echolocational conditions for travel require dryness and quietness in uncrowded surroundings. Poor acoustical areas, or where a space may be larger than 40-50 metres, would prove to be problematic as the echoes would provide only confusing messages or there would be no structures of f which sound could be bounced. He thought that i f echolocation could be taught i t should be taught as a part of the or ientat ion and mobi l i ty t ra in ing program. He was not certain how echolocation could be taught, as he had developed his techn i -ques on his own, but he thought that i t was quite poss ib le . Subject 2 had los t her v i s ion by the time she was a year of age due to congenital glaucoma. This subject uses echolocation constantly as w e l l , and started using i t when she was approximately 3 years of age. Her mother had made her pay addit ional attent ion to the environment by l i s t en ing to sounds rather than by locat ing objects with her hands. This subject had t r i ed 99 out th i s method and found i t e f fec t ive as a means of loca t ing , or avoiding, objects. Hard leather shoes can ass i s t echolocation through producing a sound that can resu l t in echoes. It i s easier to locate an object or bui ld ing when walking toward i t , rather than walking through an empty space with hopes of locat ing an object. Echolocation did not aid mobi l i ty when echoes would be bounced of f of the c e i l i n g creating " fa l se wa l l " - l i k e acoustical impressions. It does not work well in noisy conditions l i k e near construction s i t e s . It does not ass i s t at a l l in areas with drop-o f f s . She thought that echolocation should de f i n i t e l y be taught as a part of or ientat ion and mobi l i ty t ra in ing s tar t ing as soon as poss ib le . She creates a sound source by c l i c k i ng her tongue or tapping her foo t . Subject 3 had los t nearly a l l of her v is ion by 18 months of age due to ret ro lenta l f i b r o p l a s i a . She uses echolocation da i l y as an aid for her mobi l i t y . She would feel self-conscious about de l iberate ly producing the sound herse l f , instead she uses the sounds created by others in the environment. She started using th is system when she was 4-5 years of age by clapping her hands. Echolocation works well in quiet , uncrowded condit ions. This system would not work well in conditions of extreme r a i n , wind, snow or noisy conditions l i k e loud music. She thought that echolocation should be taught as a part of the or ientat ion and mobi l i ty curriculum. It would be espec ia l ly valuable for those who had not l o s t the i r v i s ion at a very young age. Such persons might not develop th is system as readi ly as those who had los t the i r 100 vision very early in l i f e . Subject 4 lost a l l of his vision through retrolental fibroplasia at. birth. He uses echolocation quite often and produces the sound by tapping his cane more forcefully than usual. He has used this system since he was about 4 years of age. He thought that echolocation would work well in finding buildings or doorways in a building. It would not work well in the rain, snow or wind. He thought that echolocation should be taught as an orientation and mobility aid, but the user should be aware of using i t in a socially acceptable circumstance. Subject 5 has been blind since birth due to retrolental fibroplasia. She is not aware of using echolocation very frequently but when she uses i t the sound is produced by finger snapping. She began using i t at approximately 3-4 years of age. She is the only dog guide user in this group of subjects. This system would work well in quiet, uncrowded conditions. It would not work well in areas that were crowded, and had a great deal of noisy t r a f f i c or loud music. She thought that long cane users would pay more attention to sounds in the environment than would dog guide users as the tapping of the cane would create more usable echolocational sounds to which the traveler could listen. She used this system much more as a long cane traveler than as a dog guide user. For persons who were unaware of echolocation for locating or avoiding objects, this system should be taught as a part of orientation and mobility training. Well motivated persons would most likely develop this system on their own but, for those who did not, its teaching would greatly assist them. 101 CHAPTER FIVE DISCUSSION, IMPLICATIONS AND RECOMMENDATIONS FOR FUTURE RESEARCH Discussion The conditions of the experiment were consistent for each subject. All visual cues were eliminated, either due to total blindness or by the wearing of a blindfold, requiring the acquisition of spatial knowledge through other sensory means. Each subject was led through the hallway by the research assistant at an average distance of 3-4 feet from the wall without deliberate pauses to enhance comprehension of the environment. The sound source for the investigation was uniform, through the use of the clicker; therefore, other than any ambient sound created by persons in or near the environment, which would then be available for the subject to interpret, the primary sound source for all subjects was created by the clicker. The monitoring of the subjects, for the purpose of scoring their perceptions during the walk, was facilitated by the tape recording of their verbal responses,identifying spatial features in the environment. All these controlled factors in the testing area are the dependent varia-bles for this experiment. Additional dependent variables, outside the testing area, included conditions which created deliberate spatial disorientation for all subjects. For the experimental group, this was carried out by leading them to an area of the university campus where none of them had usable knowledge of the layout. Of the two subjects who had any spatial knowledge of the Education building from this group, spatial confusion was created through entering the building through a seldomly used entrance. 102 For the control subjects, as they had spat ia l information related to the i r posi t ion on campus, i t was hoped that the walk under b l ind fo ld through the outside environment would create su f f i c i en t spat ia l d i s -or ientat ion to el iminate residual visual memory from ass i s t ing the i r test performance. For the subject who was certa in of her posi t ioning in space at a l l times, although th is certa inty was not matched with as much certa inty in her reports and correct scores, there i s evidence that the b l indfo ld ing and the walk through the outside environment did create more spat ia l d isor ientat ion than th is subject would recognize. Other control subjects suspected that they had been walking in the Education bu i l d i ng , while others were unaware of the i r spat ia l l oca t ion . An invest igat ion of th is type, in nonlaboratory condit ions, can be influenced by several independent variables beyond the experimenter's con t ro l . The two major independent variables would be: 1. the number of persons in the test ing area, and 2. the amount of ambient sound created by persons in the lounge or hallway. The f i r s t independent variable could be p a r t i a l l y control led by e l iminat ing testing, from the bus iest ,por t ion of the day, which existed during the lunch hour. There were other busy pedestrian t r a f f i c periods during the day, pr imar i ly associated with class changes, but careful scheduling could avoid these interferences. Unfortunately, i t was not possible for a l l subjects to be tested in i d e a l , quiet and uncrowded condit ions. The second major independent var iable concerned the noise factor and could not be predicted at a l l . Other than de l iberate ly scheduling the test ing for early mornings, evenings, or weekends, i t may have been possible to control the ambient sound l e v e l ; but, in a nonlaboratory se t t i ng , the existence of potent ia l l y confusing ambient sound levels in 103 highly used areas cannot be adequately el iminated. This var iable w i l l complicate invest igat ions of th is type due to i t s uncon t ro l l ab i l i t y and unpred ic tab i l i t y for researchers in the future . Another independent var iable related to potential confusions caused by persons standing or s i t t i n g in the test ing area that could be i n t e r -preted as a permanent obstacle, or could transform the perception of an opening or an object. One subject (subject 5) was able to d is t inguish the difference between a group of persons standing in an opening from the opening i t s e l f . For a less experienced echolocation user, th is type of d iscr iminat ion would not readi ly be avai lable and environmental con-fusion could r e su l t . In laboratory sett ings (Kel logg, 1962; Rice, Feinstein and Schusterman, 1965; Rice, 1967; Rice, 1969; Juurmaa, 1970b; and Rice, 1976), the ef fect of the independent variables can be control led s u f f i c i e n t l y through spec ia l l y adapted environments away from possible confusing factors such as standing or s i t t i n g persons who are not concerned with the resul ts of subjects par t i c ipa t ing in a research project , or who may be involved in a v i t a l discussion that interferes with the sound source employed by a subject. The environment and the independent variables were highly con-t r o l l e d in these s tud ies ; however, in nonlaboratory condit ions, the subject i s exposed to da i l y conditions in the test ing environment and, regardless of the care taken to reduce the ef fect of certa in complicating fac tors , i t would be very d i f f i c u l t to el iminate a l l of them. The Ammons, Worchel and Dallenbach study (1953) was done with univers i ty students, hal f of whom were bl indfolded and the remainder were bl indfolded and deafened. The study was done in an outside environ-ment with the subjects having to pred ic t , through the use of echolocation, 104 when they were approaching an obstacle and, as w e l l , when they were within an arm's length of i t . One arm would be raised when the obstacle was f i r s t perceived, and the other arm would be raised when the subject per-ceived the obstacle to be within an arm's length. The subjects whose hearing was not occluded were able to develop obstacle detection c a p a b i l i -t i e s , while those whose hearing was impaired for the study were able to develop other sensory means for detecting the obstacle. At certa in times of the day, the sun's rays or the wind would be blocked. At times, when the obstacle was located in the hot sunshine, the wood would produce a d i s t i n c t odour. That invest igat ion was a transposit ion of the 1944 Supa, Cotzin and Dallenbach study, demonstrating the importance of the ears as the centre for obstacle detection rather than unspecified centres on the face, as held by the f a c i a l theor i s t s , from an indoor to an outdoor se t t ing . These possible sensory means of detecting the obstacle were not predicted by the invest igators and ser iously question the experimental v a l i d i t y of that study. The experimental v a l i d i t y in th is invest igat ion concerned potent ia l l y confusing nonvisual mobi l i ty cues. Two of the subjects mentioned possible nonauditory cues which might ass i s t the mobi l i ty of a t rave le r : c igar smoke and a i r currents produced by the a i r condit ioning system in the bu i ld ing . The c igar smoke that the subject mentioned would not be a r e l i ab l e cue due to the unpred ic tab i l i t y of when i t would be present in the environment, and the d r i f t i n g qua l i ty of the smoke in the environment would reduce i t s dependability as w e l l . Only one subject mentioned the presence of the a i r current in the test ing area. At rplO, the open doorway at the fa r end of the hallway, a i r flowed from one portion of the bui ld ing to another depending upon 105 which doors were open in the basement. Due to only one subject mentioning the presence of th is a i r current, and i t s d i r e c t i ona l i t y being dependent upon doors on another level of the bu i l d ing , the v a l i d i t y of the dependa-b i l i t y of the a i r current i s un l ike ly to be a usable mobi l i ty cue. The regular i ty of the f l oo r plan, with the closed in areas at e i ther end of the hallway and the more open areas in the central area, would not provide a subject with a d i s t i n c t usable mobi l i ty cue as, pa r t i cu l a r l y in the area of the information booth on the f i r s t long side of the hallway and at the openings leading to the lounge on the returning s ide , there i s a sudden requirement for the subject to make immediate spat ia l detections and relay them verbal ly without wasting valuable time in e i ther process and missing the next reference point . The experimental subjects were able to detect the small p i l l a r s projecting into the hallway at the s ta r t of the walk but, in the openings leading to the lounge, only two subjects were able to detect one p i l l a r each in the open spaces. In the 1953 Ammons, Worchel and Dallenbach study, a subject could take several steps and declare that the obstacle had been perceived, more by predict ion than by echolocation. Due to the structure of the area, the subjects could predict that somewhere along th is route the obstacle would be placed awaiting the i r detect ion. In the present study, the regular i ty of the hallway would very quickly change with several d i s t i n c t spat ia l features replacing the formerly uniform se t t i ng . The texture of the f l oo r is constant, other than the mats in f ront of the doors at the fa r end, on which the subjects were not permitted to walk. By e l iminat ing the doormats from considerat ion, the sound and the feel of the f l o o r would be unvarying throughout i t s length and breadth. 106 Should conditions be very uncrowded and quiet , the humming of the f luorescent l i gh t s might be heard by the subject. This possible mobi l i ty cue might give some spat ia l data to the subject, but i t i s more l i k e l y to cause confusions as the humming would be coming from several s imul ta -neous d i rect ions causing the information to be intermingled rather than c lear and d i s t i n c t . Every subject, without exception, did not experience such quiet , uncrowded condit ions. Beyond these fac to rs , other experimental v a l i d i t y variables would concern auditory mobi l i ty cues: e i ther echolocation or sound l o c a l i z a -t i o n . Echolocation i s based upon the production of a sound which pro-duces information related to the environment by bouncing of f objects in the area, or d iss ipat ing in unoccupied space, and thereby sounds of d i f fe rent in tens i ty can return as echoes bearing varying amounts of spat ia l information. Sound l o ca l i z a t i on i s a system based on the concept of the sound source being the primary goal or dest inat ion of importance in the environment. In th is experiment the sound source producing the eventual echo was the c l i c k e r ; whereas, sound l o ca l i z a t i on would be demonstrated by the experimenter c l i c k i n g the c l i c k e r and the subject walking d i r e c t l y to i t . Sound l o ca l i z a t i on in th is inves t iga t ion , had the subjects known s p e c i f i c a l l y which space they were walking through, might have used i t to know that the lounge was to the l e f t , at the beginning of the walk, and that the entry-exit doors near the f a r end, which were treated as a wall when they were c losed, could be located when persons were walking through them or when the doors banged shut. Otherwise, lacking th i s pr io r informa-t i o n , these sound l o ca l i z a t i on features could complicate the understanding of th is environment. Other instances in which sound l o ca l i z a t i on could have influenced the performance of a subject would be when s i t t i n g or standing 107 persons i n , or near, the environment were speaking with one another. Their voices could a t t rac t the attention of the subject to become the overr iding stimulus sound in the environment, thus l im i t i ng or e l iminat -ing any other informational source. As i t was not the wish of the experimenter to vary the day-to-day conditions in the Education bu i l d ing , evacuating th is area or i n s i s t i ng upon quietness was beyond the scope and capacity of th is invest igat ion . The Ammons, Worchel and Dallenbach (1953) study was carr ied out in conditions with a great deal of ambient sound, which could have distracted the subjects, but these invest igators wished to discover whether echo-locat ion could be conducted under these circumstances. The equivalent d i f f i c u l t i e s with echolocation were ant ic ipated for th i s current i n v e s t i -gat ion, caused by stat ionary or ambulatory persons, but i t was hoped that the instances of sound l o ca l i z a t i on would not detract from the subjects ' performances. Cer ta in ly , i t proved to be neither a d i s t rac t ion nor a detracter from the overal l performances of the experimental group in th i s invest igat ion with an overal l mean of 20.2 out of a possible 25 reference points . In the case of the control group, however, none of them had pr io r experience of using echolocation in locat ing objects and some subjects, most pa r t i cu l a r l y subject 12, found the ambient sound l o ca l i z a t i on sounds to be very d i s t r a c t i ng . For subjects without previous use of echolocation, substantial ambient sound could challenge the v a l i d i t y of the i r perfor -mance. The presence or absence of ambient sound l o ca l i z a t i on i s further complicated by the lack of experience in comprehending echolocational properties so that the par t ia l i n v a l i d i t y caused by the ambient sound loca l i za t ions for these subjects is n o t . s t r i c t l y related to the ambient sounds. 108 The subjects in the invest igat ion were not d i r e c t l y requested to wear soft soled shoes, but none wore hard leather shoes which would produce loud reverberations. Addit ional echolocation was not.produced by the subject or research ass is tant by sounds created by shoes. Various persons, however, walking through the test ing area were wearing hard leather shoes and these could cause sounds that could be c l a s s i f i e d as f a l l i n g in both echolocational and ambient sound l o ca l i z a t i on categories. Those subjects comprehending echolocation received addit ional echoes from these persons' shoes, thus aiding the i r performance, and for subjects without th is understanding th is sound would be an added confusing d i s t rac t ion to the i r performance. With the e l iminat ion of a l ternat ive systems for receiving mobi l i ty cues from the environment, the sole remaining auditory system would be echolocation. Alternate o l factory or auditory cues would have no r o l e , as shown through th is inves t iga t ion , in the detection of open or walled spaces. Experimental r e l i a b i l i t y can be manifested by the consistency of the preparation of each subject p r io r to the t e s t , the re la t i ve group consis -tency as each subject was tested, the consistency of the hearing t e s t , and the questionnaire resul ts from the experimental subjects fol lowing the t es t . The challenge of visual memory interferences a f fect ing the test resul ts can be discounted as only one subject in the control group claimed to have precise knowledge of the space, a f ter the route had been walked, but the resul ts demonstrate that the appl icat ion of her visual memory to the test conditions did not transfer very well with actual spat ia l d isor ienta t ion occurring early in the walk from which th is subject did not recover s u f f i c i e n t l y to match her environmental perceptions to the degree of accuracy which was intended. Several others in the control group 109 suspected that they were walking in the Education bui ld ing but, in the i r cases, the influence of visual memory was not an overr iding factor in the i r spat ia l comprehension. The degree of certa inty was not s im i l a r and, i t may be in fe r red , had i t been s im i l a r the spat ia l misconceptions would also have increased the i r environmental confusions. Two of the experimental subjects had previous experience walking through th is space, but so much time had elapsed that any cognit ive map which they retained did not contribute to the i r understanding of the area. Guessing, hereafter referred to as."devination," may have been practiced by several of the control subjects who did not have experience in using echolocat ion; but, i t is c lear that devination was not employed by the experimental subjects. The subjects were not to ld how many reference points were contained within the test ing area, pr ior to or fol lowing the walk, thus negating the p o s s i b i l i t y for a subject to feel that a minimum score of 50 percent of the reference points had to be achieved. The d i f f i c u l t i e s of the scoring procedure, through the arch i tectura l design of the test ing area, was that the reference points were mainly grouped in c lus te r s . Spatial uniformity would suddenly be replaced by rapid d i v e r s i t y . Devination or predict ion could not account for the placement of detectable information along th is hallway. A d i rec t pol icy of discouraging devination was implemented by which subjects were encouraged to make the i r verbal reports using af f i rmat ive statements instead of interrogat ive formats. The subject was thereby no t i f i ed that the accuracy of the verbal reports would be dependent upon the i r a b i l i t y to perceive differences in the echo qua l i ty of various environmental areas rather than having the subject re ly upon safe spat ia l estimations. The subjects, regardless of the i r overal l correct response 110 score, paid very close attent ion to the echolocational information which they produced from the c l i c ke r and attempted, to the best of the i r a b i l i t i e s , to ident i f y correct ly the space through which they were walking. A l l the subjects, whether they were under bl indfolded conditions or not, underwent s im i l a r f am i l i a r i z a t i on with the c l i c ke r and how i t created usable echoes in the environment. They were encouraged to use the c l i c ke r in the o f f i c e , and in the hallway outside of i t , and were subsequently led over to the Education bui ld ing fol lowing the exact course. Experience with the c l i c k e r and the use of the sighted guide technique were performed pr io r to the commencement of the walk in the test ing area. The r e l i a b i l i t y of the subjects ' correct response scores can be shown in the context of the groups' s t a t i s t i c a l means,(see Table 4.43). Four of the f i ve experimental subjects have very even correct response scores ranging between 20 and 22. The poorest performing subject in th i s group did very well achieving a score of 18. This produced a mean of 20.2 out of a maximum of 25 reference points . A high degree of consistency appears through the s i m i l a r i t y of these correct response scores and re f l ec ts the high rate of cer ta inty with which th i s group was able to report upon th is par t i cu la r spat ia l layout. The control subjects, who did not have previous echolocational experience, were able to achieve a mean of 7.727 (see Table 4.43) with a top score of 13 and the lowest score of 1. Even i f these subjects had re l i ed upon devination as the means by which to describe the environment, only one.subject was able to surpass the 50 percent ba r r i e r . Other than the two subjects who scored 10 correct responses and the two lowest subjects, the remainder were very close to the mean score. Thus, with the experimental group achieving a correct response rate almost three I l l times greater than the control group, r e l i a b i l i t y of these correct scores i s demonstrated and the pr inc ipal hypothesis of th is invest igat ion is accepted. Performance consistency can also be demonstrated in the re la t i ve uniformity of the walking times through-the test ing area. With one major exception, a l l subjects completed the walking course in a time between just over 3 minutes and s l i g h t l y under 5 minutes. As requested, most subjects followed the recommended c l i c k i ng frequency regardless of the walking time of approximately one c l i c k per second. There were minimal differences above and below th is rate , but the mean of the experimental group was s l i g h t l y above th is level and the control group was s l i g h t l y below i t . The expressed anxiety level for the control subjects under b l ind fo ld revealed i t s e l f in several ways. Only one subject f e l t that she was in actual physical danger, thinking that there were s ta i r s in front of her, that would have to be ascended or descended. Except for two subjects, who f e l t comfortable so long as they maintained contact with the research ass i s tant ' s arm, a l l others expressed anxiety through d i rec t resistance in being led through an undescribed environment and by the unconfident vocal fashions in which the verbal reports were given. As 9 of the 11 control subjects expressed anxiety in a var iety of ways while walking through the test ing area, subhypothesis 1 i s accepted. With the exception of the subject in the experimental group who had a severe hearing loss in one ear and the two control subjects who had a degree of hearing l oss , a l l other subjects had normal hearing l e ve l s . Of the three subjects who had some hearing loss the experimental subjects t ied for the th i rd highest number of correct responses, one control 112 subject had the highest score for that group and the other control subject had the second lowest score of a l l subjects. The overal l correct response mean was s l i g h t l y above 11 with the high experimental subjects ' scores being pulled below the 50 percent level by the results of the control subjects. A l l subjects, with or without normal hearing l e ve l s , were expected to cope with the information del ivered by echolocation and the experimental subjects demonstrated that they could interpret the informa-t ion to a high degree and the control subjects were much less successfu l . The responses given by the experimental subjects to the questionnaire r e f l e c t a high degree of comprehension for the pr inc ip les of echolocation. They have a l l used i t , and they understand the conditions where i t works well and where no assistance i s gained by i t s use. Their responses are very nearly carbon copies of one another. The consistency of echoloca-t ional use, both past and present, by th is group supports the acceptance of subhypothesis 2. No d i rec t references to l i t e r a tu re can be made in the area of com-paring the r e l i a b i l i t y of scores as the laboratory studies (Kel logg, 1962; Rice, Feinstein and Schusterman, 1965; Rice, 1967; Rice, 1969; Juurmaa, 1970a and b;„and Rice, 1976) investigated the existence of echolocation with human-produced, loud speaker-produced and ultrasonica'Ny-produced sounds to detect targets of various s i z e s , shapes and texture at various distances. The Ammons, Worchel and Dallenbach (1953) study tested echolocation in an outside environment where one target had to be detected. These sett ings bear no resemblance to the test ing area used in th is inves t iga t ion . The r e l i a b i l i t y of th i s experiment pr ior to , during, and a f ter the test ing of these subjects has been demonstrated. By i l l u s t r a t i n g the 113 consistency of group scores, as each subject sought spat ia l information through echolocation produced by the c l i c k e r , the r e l i a b i l i t y and v a l i d i t y strengths of th is invest igat ion are shown. Implications and Recommendations The impl icat ions of th is research indicate that for v i sua l l y impaired persons, who have learned the use of echolocation independently or have been taught i t s use, the echolocational system can lead to an immediate and accurate comprehension of a spat ia l s e t t i ng . The openness of the space, the,placement and re la t i ve distances of objects, the locat ion of an open doorway, and the avoidance of c o l l i s i o n s with objects are a l l made possible through the use of echolocation. The p r a c t i c a l i t y of th is system can not be overstated. The subjects in the experimental group, a l l of whom had experience in using echolocation, were able to walk through the hallway of the Education bui ld ing and make correct verbal reports on more than 80 percent of the preselected reference points in that space. The correct response scores ranged from 18 out of 25 (72 percent) to 22 put of 25 (88 percent). Not only were they able to detect the changes in the environment, but the i n t e rp r e t ab i l i t y of the spat ia l information created comprehension out of a s i tua t ion that potent ia l l y could have been very confusing. An open, or deeply recessed, doorway along a hallway can be located through th is system without necessitat ing wall t r a i l i n g with a hand or long cane or being guided by another person. Regardless of the i n i t i a l sound source which sets the echolocational system in motion, the human-produced form of th is system is always avai lable to a t rave ler that can create a sound and can hear the resultant echo from i t . The tools employed in the 114 production, hearing, and interpretat ion of th is system can never be mis-placed or forgotten by the t rave le r . The development and use of u l t rasonic mobi l i ty devices in th is area for the v i sua l l y impaired raises the p o s s i b i l i t i e s for re f in ing the d i s -criminations between textures to a much greater extent. At no time in th is invest igat ion was there ever any consideration given to the question of having subjects ident i fy the textural components of reported structures. Glass, cement, wood, metals, and other materials are contained within th is space and, had the detection of objects been combined with the tex-tural descr ipt ion of the i r construct ion, the subjects would have been required to perform a much more d i f f i c u l t test ing task. It would be . highly probable that a t rave ler with an u l t rasonic mobi l i ty device could f a c i l i t a t e the detection and discr iminat ion of textural differences be-tween such objects. Should the detection of an object in space be paramount to knowing i t s physical s t ructure , then human-produced echo-locat ion would be su f f i c i en t to cope with the environment. The cause, a f te r a l l , for using echolocation i s the comprehension of spat ia l con-f igurat ions and to move within that space as confidently and independently as poss ib le . Too much deta i led information in too confined an area could lead to a spat ia l processing overload for the t rave ler . Such a circum-stance could, very ea s i l y , resu l t in spat ia l d i so r i en ta t ion . The human-produced version of th is system could avoid much of the processing over-load by relaying less detai led and less confusing information to the t rave ler for processing. For experienced echolocation users, the informa-t ion received using a human-produced sound source would be adequate for most travel needs. The u l t rasonic device would de f i n i t e l y ass i s t with the detection of objects, l i k e tables and cha i rs , of a l imi ted height which 115 are d i f f i c u l t to detect with human-produced echolocation. The greatest area of concern for echolocation, regardless of i t s production, is the disadvantage of not detecting drop-offs in the environment. Steps, curbs, and other steep d e c l i v i t i e s can not be detected by the t rave ler which could lead to potent ia l l y serious accidents. Other than th is major exception, however, the advantages of detecting objects and comprehending the environment make th is system relevant for nearly a l l v i sua l l y impaired t rave lers . The d i f f i c u l t y of detecting drop-offs in the environment i s dealt with by coupling the echolocational system with another mobi l i ty device, such as a dog guide or long cane, which would detect th is otherwise undetectable environmental feature. In certa in circumstances, i t may be necessary to i l l u s t r a t e to the t rave ler how to use echolocation in a soc i a l l y acceptable manner. I f , for instance, hand clapping or loud f inger snapping was inappropriate in a se t t i ng , a surrept i t ious tongue c l i c k or forceful cane tapping might accomplish s im i l a r r esu l t s . The t rave ler must be made aware that , on occasions, echolocational sound source production may be viewed by members of society without comprehension as being inappropriate behaviour. The r e l a t i v i t y of such an observation ignores completely the spa t i a l l y s i g n i -f i can t purpose behind th is system. Special or ientat ion and mobi l i ty cur r i cu la should be developed to teach the use of echolocation to v i sua l l y impaired persons who have not developed i t independently. This t ra in ing program probably would be most e f f e c t i ve , as was shown through the responses of the experimental group subjects, with young ch i ld ren . Lessons concentrating on the t ra in ing of young chi ldren to move d i r e c t l y toward sound sources, using sound l o c a l i -za t ion , could be the manner in which these lessons could commence and 116 bu i ld toward the development and use of echolocation. By teaching th is system to those who did not develop i t independently and to give d i rec t ion to those who have developed i t , the most important factor of having v i sua l l y impaired chi ldren express early cu r ios i t y concerning spat ia l environments and to develop safe, independent locomotion within that space could be great ly st imulated. Due to the paucity of l i t e r a tu re in the area of echolocation, numerous recommendations related to future research can be suggested. This study could be repl icated in a s im i l a r indoor space or , to i n v e s t i -gate out-of-doors t r a v e l , i t could be conducted in an outside environment. The adult population of th is study could be replaced with a population of chi ldren or , to compare populations of d i f fe rent ages, a group of chi ldren could be matched with a group of adul ts . The var iable of t ra in ing could be tested in a series of experiments. For example, the present study could be repl icated with the control group undergoing special t ra in ing in the use of echolocation in which case the i r i n i t i a l performance could be compared with the i r second performance a f ter receiving spec i f i c t r a i n ing . A l so , i t would have been interest ing to have the experimental group from the present study walk through the test ing area for a second time to discover whether the i r correct response scores would improve beyond the i r present l e v e l . Would the i r perceptions be s imi la r to those of the f i r s t t e s t , or what va r i a -t ions might be discovered? Direct comparisons between human-produced and ul t rasonic mobi l i ty device-produced echolocation very de f i n i t e l y should be conducted in a nonlaboratory set t ing s im i l a r to the Juurmaa (1970a and b) study i n v e s t i -gating object detect ion, textural d i sc r iminat ion , maximum distance 117 detect ions, and other pertinent considerations. Human-produced and ultrasonical ly-produced echolocation could be conducted with populations of s im i l a r age groups or populations of d i f fe rent age groups could be compared. As important as laboratory sett ings are for doing i n i t i a l echo-locat ional s tudies , i t i s hoped that in the future many more non-laboratory studies w i l l be carr ied out in spat ia l sett ings with moderate or heavy pedestrian t r a f f i c . The exposure of echolocational test ing in nonlaboratory conditions ul t imate ly should manifest i t s s ign i f icance with v i sua l l y impaired persons comprehending spat ia l layouts and moving safely and independently within them. 118 REFERENCES Ammons, C.H. , Worchel, P. and Dallenbach, K.M. 1953. Facial v i s i on : the perception of obstacles out-of-doors by b l inded, bl indfolded and deafened subjects. American Journal of Psychology, 66(4), 519-534. G r i f f i n , D.R. 1958. L istening in the dark. New Haven: Yale University Press. G r i f f i n , D.R. 1959. Echoes of bats and men. Garden C i t y , New York: Doubleday. Juurmaa, J . 1970a. On the accuracy of obstacle detection by the b l i nd : Part 1. New Outlook for the B l i nd , 64(3), 65-72. Juurmaa, J . 1970b. On the accuracy of obstacle detection by the b l i nd : Part 2. New Outlook for the B l i nd , 64(4), 104-118. Kay, L. 1974. A sonar aid to enhance spat ia l perceptions of the b l i n d : engineering design and evaluat ion. Radio and Electronic Engineer, 44(11), 605-627. Kel logg, W.N. 1961. Porpoises and sonar. Chicago: Chicago University Press. Kel logg, W.N. 1962. Sonar system of the b l i nd : new research measures the i r accuracy in detecting the texture, s i z e , and distance of objects by ear. Science, 137(3528), 399-404. Rice, C.E. , Fe ins te in , S.H. and Schusterman, R.J. 1965. Echo detection a b i l i t y of the b l i nd : s ize and distance fac tors . Experimental  Psychology, 70(3), 246-251. Rice, C.E. 1967. Human echo perception: behavioral measures are being made of human echo a b i l i t y to detect objects by use of echoes. Science, 155(3763), 656-664. Rice, C.E. 1969. Perceptual enhancement in the early b l i nd . Psychological  Record, 19(1), 1-14. Rice, C.E. 1976. The effects of blindness and other impairments on ear ly development, pp. 51-59. In: Zofja S. Jastrzembska (ed. ) , New York; American Foundation for the~Blind. Rosenzweig, M.R., R i l ey , D.A. and Krech, D. 1955. Evidence for echoloca-t ion in the ra t . Science, 121, 600. Shingledecker, C A . 1978. The effects of ant ic ipat ion on'performance and processing load in b l ind mobi l i t y . Ergonomics, 2(5), 355-371. 119 Shingledecker, C A . and Foulke, E.A. 1978. A human factors approach to the assessment of the mobi l i ty of b l ind pedestrians.. Human Factors, 20(3), 273-286. Supa, M., Cotz in , M. and Dallenbach, K.M. 1944. Facial v i s i o n : the perception of obstacles by the b l i nd . American Journal of  Psychology, 57, 133-183. 

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