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Feedback of stutterers’ electromyographic activity Hanna, Richmond 1975

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FEEDBACK OF STUTTERERS1 ELECTROMYOGRAPHIC ACTIVITY RICHMOND CHARLES HANNA M.A., Un i v e r s i t y of Alb e r t a , 1971 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department of Psychology We accept t h i s thesis ad coj/f Qr'jnin-g' to the required standard THE UNIVJ&SlTY- OF BRITISH ^ COLUI^fJIA September 1975 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Psychology The University of British Columbia Vancouver 8. Canada D a t e September ? S J i i Professor P.O. Davidson, Research Supervisor Abstract Five studies were performed to explore the f e a s i b i l i t y of tre a t i n g severe chronic s t u t t e r i n g with EMG feedback. EMG spiking from the throat was found to c o r r e l a t e with s t u t t e r i n g , and to d i f f e r e n t i a t e between s t u t t e r i n g and fluent speech. EMG spiking tended to disappear when s t u t t e r i n g was reduced by metronome-paced speech and by speech therapy. Likewise, when EMG spiking was reduced by feedback t r a i n i n g , s t u t t e r i n g was concurrently reduced. Presentation of the feedback tone without i n s t r u c t i o n s or i n f o r -mation produced no reduction i n s t u t t e r i n g or EMG spiking. Pseudofeedback was also generally i n e f f e c t i v e . I t was concluded that the feedback effect i s apparently not an a r t i f a c t of i n s t r u c t i o n s , masking, d i s t r a c t i o n , adap-t a t i o n , slowing of speech, or of a stutter-contingent aversive tone, nor i s i t a Hawthorne or placebo e f f e c t . Implications of the r e s u l t s are discussed. TABLE OF CONTENTS ABSTRACT LIST OF TABLES LIST OF FIGURES ACKNOWLEDGEMENTS Chapter I. INTRODUCTION 1 Stuttering 1 Biofeedback- 10 I I . GENERAL METHODOLOGY 17-Subjects 17 Dependent Variables 18 Stuttering 18 EMG Spiking 20 Speech Rate 20 Observer Agreement 21 Design 23 I I I . STUTTERING AND LARYNGEAL HYPERTENSION 29 Laryngeal Involvement i n Stu t t e r i n g 29 Study 1 31 Method 33 Results 35 Study 2 35 Method 35 Results 37 Discussion of Studies 1 and 2 37 IV. FEEDBACK OF ELECTROMYOGRAPHIC ACTIVITY 42 P i l o t f o r Study 3 42 Method ' 42 Results and Discussion 44 Study 3 47 Method 47 Results 48 Discussion 53 Page l i V y l v i i i v Chapter Page V. FEEDBACK WITHOUT INSTRUCTIONS 55 Study 4 55 Method 56 Results 56 Discussion 60 VI. FALSE FEEDBACK 62 P i l o t to Study 5 63 Method 63 Results and Discussion 63 Study 5 66 Method 66 Results 67 Discussion 71 VII. CONCLUSION 74 V I H l i ADDENDUM 81 REFERENCE NOTES 84 REFERENCES 85 APPENDICES 93 A. Assignment of Subjects to Studies 93 B. Inter-Rater R e l i a b i l i t y Check 94 C. Minimum Pen Deflections Defining an EMG Spike 95 D. Instructions f o r Studies 3 and 5 96 E. Questions Used to Investigate Awareness of Feedback Condition 9.7 LIST OF TABLES Table 1. Designs Used i n the Present Series of Studies 2. Reduction i n Stuttering as a Function of Rate Control Therapy" 3. Reduction i n EMG Spiking as a Function of Rate Control Therapy 4. Co r r e l a t i o n Between Percent S y l l a b l e s Stuttered and EMG Spikes per 100 S y l l a b l e s i n Study 1 And 5. C o r r e l a t i o n Between Percent S y l l a b l e s Stuttered and EMG Spikes per 100 S y l l a b l e s i n Study 2 6. Suppression of Stuttering and EMG Spiking by Metronome Treatment 7. E f f e c t s of EMG Feedback: P i l o t Study 8. E f f e c t of EMG Feedback on Stuttering and Spiking 9. E f f e c t of EMG Feedback on Speech Rate 10. E f f e c t of Feedback Without Instructions on Stuttering and EMG Spiking 11. E f f e c t of Feedback Without Instructions dn Speech-Rate 12. E f f e c t s of Genuine and False Feedback: P i l o t Study 13. E f f e c t of Genuine and False Feedback on Stuttering and EMG Spiking 14. E f f e c t of Genuine and False Feedback on Speech Rate 1 15. ^Changes i n Muscle Action P o t e n t i a l (MAP) Levels and Stuttering Frequency v i LIST OF FIGURES Figure Page 1. Sample EMG Recordings 32 2. E f f e c t of Metronome on Stu t t e r i n g ; David 38 3. E f f e c t of Metronome on EMG Spiking: David 39. 4. EMG Feedback System 43 5. E f f e c t of EMG Feedback on S t u t t e r i n g : John 45 6. E f f e c t of EMG Feedback on S t u t t e r i n g : Don 49 7. E f f e c t of Feedback on EMG Spiking: Don 50 8. E f f e c t of EMG Feedback on S t u t t e r i n g : Ruth 52 9. E f f e c t of Feedback Without Instructions on St u t t e r i n g : Rick 57 10. E f f e c t of Feedback Without Instructions on EMG Spiking: Rick 58 11. E f f e c t of Genuine and False Feedback on Stu t t e r i n g : John 65 12. Sample EMG Recordings From Study 5 68 13. E f f e c t of Genuine and False Feedback on Stu t t e r i n g : Doug 69 y i i ACKNOWLEDGEMENTS The author wishes to thank Robert D. Hare, Ph.D. f o r the use of his laboratory, Brent McNeill f o r constructing the b i o -feedback equipment, and N e v i l l e Owen, Ph.D. f o r hi,s p a r t i c i p a t i o n i n the i n t e r - r a t e r r e l i a b i l i t y check. Special thanks are due; to the G.F. Strong R e h a b i l i t a t i o n Centre f o r providing the subjects fo r t h i s research. 1 CHAPTER 1 INTRODUCTION Stuttering Stuttering i s one of the most thoroughly researched topics i n psycho^ pathology, with over 2000 references i n the psychological, medical ? and speech-l i t e r a t u r e since 1900. Despite t h i s vast amount of research-and the apparent s i m p l i c i t y of the disorder, there i s as yet no generally accepted theory or treatment for s t u t t e r i n g , nor even a standard d e f i n i t i o n . S tuttering appears to be an u n i v e r s a l phenomenon, unrelated to i n -t e l l i g e n c e and socio-economic status. S l i g h t differences i n incidence figures within and across cultures probably r e f l e c t the lack of a standard d e f i n i t i o n of s t u t t e r i n g , plus the p o s s i b i l i t y that i t i s continuous with normal d i s -fluency. Whether i t arises out of normal childhood disfluency i s not known. At any rate, nearly a l l s t u t t e r i n g has i t s onset between the ages of two and seven (Van Riper, 1971). Male stu t t e r e r s outnumber females by about three to one, f o r unknown reasons. The prognosis f o r c h i l d s t u t t e r e r s i s good: about 80% remit spontaneously (Sheehan & Martyn, .1966).. The prognosis f o r adult st u t t e r e r s i s r e l a t i v e l y poor (Beech. & F r a n s e l l a , 1968)_. It i s common to speak of a genetic p r e d i s p o s i t i o n to s t u t t e r i n g , but t h i s hypothetical mechanism has not been i d e n t i f i e d and thus has no explanatory value. Genetic research on s t u t t e r i n g i s scanty, but i t has been established that a c h i l d w i l l have a disproportionately high r i s k of becoming a s t u t t e r e r i f he has r e l a t i v e s who s t u t t e r (Andrews & H a r r i s , 1964). The possible model-l i n g e f f e c t of contact with such r e l a t i v e s has usually not been c o n t r o l l e d . Adequate modern studies of concordance are lacking. 2 Stuttering usually- consists mainly of s y l l a b l e r e p e t i t i o n s and k e s i ^ t a t i o n s , plus obvious tension and diverse motor behaviors- (e.g., b l i n k i n g , head j e r k i n g , f i s t clenching) which-are often considered to be superstitious, operants. Stuttering can take -many forms- across individuals-, and wit h i n i n ^ dividuals over time. Van Riper Q971). reviewed 63 noso l o g i c a l studies of t h i s disorder and concluded that d e f i n i t e subgroups have not yet Keen defined. Nevertheless,, the p o s s i b i l i t y that there are d i s t i n c t types of st u t t e r e r s re-r-mains an en t i c i n g one, f o r i t would help account f o r the many-inconclusive and contradictory results- i n the huge s t u t t e r i n g l i t e r a t u r e . Stutterers can predict with: considerable accuracy the words on which they w i l l s t u t t e r (Bloodstein, 1972). Stuttering occurs most" frequently at points where a normal speaker i s l i k e l y to h e s i t a t e or pause, e.g., between phrases. It i s not related to word length, grammatical form, or i n i t i a l sound, but i t i s p o s i t i v e l y r e l a t e d to the p r o p o s i t i o n a l i t y (meaningfulness): of the message being communicated and to the perceived status of the l i s t e n e r . Stuttering tends to occur during manding, a state i n which the speaker i s experiencing deprivation or other aversive stimulation (Skinner, J957)_. It Is- well-established that s t u t t e r i n g tends to decrease "spontaneously" over time i n a r e l a t i v e l y constant stimulus s i t u a t i o n (Beech & F r a n s e l l a , 1968). This-phenomenon i s commonly c a l l e d the adaptation e f f e c t . It has been a t t r i ^ buted to e x t i n c t i o n due to anxiety reduction (Johnson, .1959), although, there are some differences between e x t i n c t i o n and adaptation curves (Wingate, 1966)_. Gray and Brutten (1965) found adaptation occurred without a decline In palmar sweating, an index of anxiety, and concluded that adaptation is-due to the accumulation of reactive i n h i b i t i o n . This- i n t e r p r e t a t i o n is: consistent w i t H 3 the f a c t that a f t e r adaptation and a short r e s t - p e r i o d , during which time rea c t i v e i n h i b i t i o n could d i s s i p a t e , .stuttering tends: to return to i t s base-r l i n e l e v e l . Another p o s s i b i l i t y is* that adaptation i s simply a s p e c i a l case of stimulus habituation (Van Riper, 19.71).. The adaptation phenomenon is-.not •• u t i l i z e d i n therapy, since i t i s very- transient and does not:transfer to e x t r a - c l i n i c a l s i t u a t i o n s . Instead, i t is- considered a nuisance v a r i a b l e which must be c o n t r o l l e d , l e s t i t r a i s e f a l s e hopes i n the naive researcher. Adaptation and spontaneous, recovery- can largely- be eliminated ..by-- the simple expedient of changing speech s t i m u l i rather than exposing the'subject repeatedly-to the same material, and by-using continuous speech, rather than allowing breaks.. A minority of adult stutterers-<over,come t h e i r handicap without, speech-therapy. For those who do not-remit spontaneously-, the c l i n i c a l p i c t u r e re-r mains r e l a t i v e l y - b l e a k i n s p i t e of a vast amount of research; Stutterers, haye been treated with almost every- conceivable variety- of' psychotherapy- and he-r-havior therapy, medicated with almost everything from ataractics.- to ampKeta-mines, and even treated with surgery-, ECT and acupuncture. A number of speech, therapies which have no counterparts i n psychology-or-medicine haye also been developed s p e c i f i c a l l y f o r s t u t t e r e r s . The various therapies: have been thoroughly reviewed by Van Riper Q973), the undisputed dean of s t u t t e r i n g research, and therapy, who a f t e r 40 years i n the f i e l d remains a s t u t t e r e r himself. Van Riper is. p e s s i m i s t i c about the l i k e l i h o o d of a "cure" f o r ' s t u t t e r i n g , p r e f e r -ring instead to desensitize the s t u t t e r e r to h i s problem so that, he may learn to l i v e with i t . For Van Riper and h i s numerous followers, successful therapy involves turning a tense, anxious s t u t t e r e r into a more relaxed, " f l u e n t " 4 s t u t t e r e r who no longer avoids the., s i t u a t i o n a l and phonemic cues which pre-cede s t u t t e r i n g . Three of four recently developed therapies appear to have considerable p o t e n t i a l , however. One of these i s r a t e - c o n t r o l therapy (e.g., Perkins, Note . 1) i n which behavioral techniques are used to t r a i n the s t u t t e r e r to.speak at a slow rate. Nearly a l l s t u t t e r e r s can be made fl u e n t t h i s way, but main-tenance of fluency involves continuing ,to speak abnormally slowly at times. In a six-month follow-up study, Perkins found that 92% of h i s s t u t t e r e r s had retained some improvement and 53% maintained "normal" fluency, although speech rate data were not given. . Adequate independent follow-up studies of rate control therapy remain to be done. It has been known f o r centuries that s t u t t e r i n g i s reduced dramati-c a l l y when the s t u t t e r e r paces his words or s y l l a b l e s with an i t e r a t e d stimulus, e.g., a metronome. Th i s e e f f e c t i s not due to a deficiency i n the perception or production of rhythm on the s t u t t e r e r ' s part (Rotter, 1955). Rhythm per se i s not an e s s e n t i a l property of the stimulus.: rhythmic and arhythmic beats of equal p r e d i c t a b i l i t y are equally e f f e c t i v e i n suppressing s t u t t e r i n g CBrady, 1969). Nor i s . t h e metronome e f f e c t merely a variant of rate control therapy, f o r i t s e f f e c t has been found to be independent of speech rate (Hanna & Morris, Note 2). Van Riper Q.97.1) suggested that the metronome acts as a timing device to integrate the motor patterning of speech, but i t i s not known how t h i s occurs. Unfortunately, the metronome e f f e c t i s apparatus-rbound: i t wears off i n a matter of minutes. S t i l l , i t . may have therapeutic p o t e n t i a l . A great deal of s t u t t e r i n g research and therapy has been based on the assumption that s t u t t e r i n g i s symptomatic of neurosis. The extreme state-5 ment of this, p o s i t i o n is: the orthodox psychoanalytic view (Jeniehel, 19.45)_, wherein s t u t t e r i n g i s a symptom of a preg e n i t a l conversion neurosis which.: involves a symbolic upward displacement of the anal sphincter. S t u t t e r i n g . thus allows the.speaker to smear h i s l i s t e n e r with!symbolic feces. Other psychodynamic inter p r e t a t i o n s are less entertaining but equally unconstrained by data. Although psychotherapy remains one of the most' common treatments for s t u t t e r i n g , i t s value r-afiiis§ to be demonstrated (Perkins, .1973; Van Riper, 1973). Moreover, reviewers of the personality l i t e r a t u r e have con s i s t e n t l y concluded, sometimes to t h e i r own su r p r i s e , that the case f o r s t u t t e r i n g as a neurosis has not been made. There i s l i t t l e unequivocal evidence that s t u t -terers as a group are more neurotic.or maladjusted than nonstutterers (Beech & F r a n s e l l a , 1968; Sheehan, 1970). According to,Van Riper, "most of our s t u t -terers have been pretty normal i n d i v i d u a l s — except when they- had to say something" .(1971, p. 2721. In the r e l a t i v e l y few. cases where-neurotic symp-toms are present, they probably represent the outcome of years of communica-t i v e f r u s t r a t i o n and s o c i a l p e n a l t i e s . The popular stereotype portrays the stutterersas aeneuroticnlntroyert, as exemplified by P-P-Porky P-Pig. While some st u t t e r e r s undoubtedly f i t t h i s d e s c r i p t i o n , as a whole they do not. There i s no evidence to suggest that the s t u t t e r e r has a p a r t i c u l a r personality p r o f i l e or group of t r a i t s that d i f f e r e n t i a t e s him or her from the nonstutterer. The bulk of a huge body of research has f a i l e d to demonstrate, that s t u t t e r e r s as a group have b a s i c a l l y d i f f e r e n t p e r s o n a l i t i e s from normal speakers, even a f t e r years of s t u t t e r i n g (Beech & F r a n s e l l a , 1968; Van Riper, 19711. Much of the recent psychological research on s t u t t e r i n g has been concerned with the p o s s i b i l i t y that i t i s e s s e n t i a l l y a learned behavior. 6 Brutten and Shoemaker (1967) have proposed an elegant two-rfactor theory of s t u t t e r i n g . Stress is- known to cause fluency f a i l u r e i n normal speakers. Through repeated exposure to s t r e s s , negative emotion may" become c l a s s i c a l l y conditioned to c e r t a i n s t i m u l i , e.g., speaking to an authority f i g u r e . The pattern of autonomic a c t i v i t y which- defines negative emotion causes d i s i n t e r gration of the precisely-timed motor behavior of speech. > Thus the h e s i t a t i o n s , r e p e t i t i o n s , breathing abnormalities etc. which, c o n s t i t u t e the core behaviors of s t u t t e r i n g are thought to be respondents. In the second stage of the de^ velopment of s t u t t e r i n g , secondary symptoms are acquired by some i n d i v i d u a l s through escape and avoidance conditioning, e.g., head-jerking that occurs during s t u t t e r i n g may be reinforced by eventual fluent utterance and by: the termination of self-generated and listener-generated aversiye st a t e s . Of course, the f a c t that such-operants are reinforced intermittently-makes them highly r e s i s t a n t to e x t i n c t i o n . Van Riper (1973). developed such gross head-j e r k i n g behavior that h i s s t u t t e r i n g was once mistaken f o r an e p i l e p t i c seizure. As therapy, Brutten and Shoemaker prescribe r e c i p r o c a l i n h i b i t i o n therapy to weaken the core of c l a s s i c a l l y conditioned negative emotion, plus the optional treatment of secondary symptoms through, unreinforced massed per-formance. Although some e a r l y reports of r e c i p r o c a l i n h i b i t i o n therapy for s t u t t e r e r s were not encouraging (e.g., Lazarus,-1963;'Wblpe,'.19.61)1, there have been some p o s i t i v e r e s u l t s r e c e n t l y (Adams, 1971; Webster, 19-70)1. Lanyon (1969) and Tyre, Maisto, and Companik .'(19.73)1 reported a decrease i n both., s t u t -t e r i n g and state anxiety a f t e r r e c i p r o c a l i n h i b i t i o n therapy, but' Gray and England (1972) found that these occurred at d i f f e r e n t times. Stuttering was reduced early i n treatment when anxiety, measured i n terms of s k i n conductance 7 scores, was high. Anxiety seems to have been a l l e v i a t e d a few. sessions a f t e r s t u t t e r i n g had decreased. This is; inconsistent with, the two-factor theory. The two-factor theory predicts: that the core behaviors of s t u t t e r i n g would be increased by punishment, .through the production of d i s r u p t i v e autono^ mic a c t i v i t y . There are reports that random punishment does indeed increase s t u t t e r i n g (Siegel & Martin, 1965 ; Brookshire & Eveslage, .19691, although, t h i s e f f e c t was not found by Biggs and Sheehan (19691. Contingent punishment, however, has usually been found to increase s t u t t e r i n g . Such contingent aver^ s i v e s t i m u l i have included verbal reprimand CQuist & Martin, 19671, very loud noise (Flanagan, Goldiamond & Az.rin, 1958; Siegel & Martin, 1965) , e l e c t r i c shock (Daly & Cooper, 19671, and even the b l i n d i n g f l a s h , of a photographer's 100-candihepower gun (Brady, 1968),. On balance, the bulk, of recent research on punishment supports a purely operant view of s t u t t e r i n g , as opposed to the two-factor theory. Stuttering has other operant properties as. w e l l . I t has been tem-p o r a r i l y i nstated i n normal speakers through- p o s i t i v e and negative reinforce-^-ment (Van Riper, 1973; Flanagan, Goldiamond, & A z r i n , 19581. Reinforcement of fluency reduces s t u t t e r i n g (Van Riper, 1973; Perkins , Note J)., as do re s -ponse cost (Halvorson, 1971) and stutters-contingent time-out from speaking (Haroldson, Martin & Starr, 1968). Once established, a st u t t e r e r ' s fluent speech can be brought under stimulus control (Martin & S i e g e l , .19661. I f s t u t t e r i n g i s an operant, i t s a c q u i s i t i o n and maintenance schedules are not f u l l y understood (Sander, 1975). Many operant researchers assume that normal speech includes s t u t t e r s , but at such a low frequency that no problem i s apparent (Goldiamond, 1965).,In some c h i l d r e n , r e p e t i t i o n s and other d i s -8 fluencies that occur during mandingmay- he -unintentionally^reinforced by. parents and other l i s t e n e r s : through, attention and-noninterruption. Furthermore, repetitions, and h e s i t a t i o n s may serve to postpone the aversive consequences of s t u t t e r i n g (Shames & Sherrick, 1963)_. However, self-generated and l i s -tener-generated punishment probably occur p r i o r to reinforcement ( i . e . , f l u e n t utterance), and thus i t i s d i f f i c u l t to understand how s t u t t e r i n g i s main-r tained. Halvorson Q973) has suggested that s t u t t e r i n g and I t s punishment may be the i n i t i a l components of a behavior chain terminating with r e i n f o r c e -ment f o r fluency. At any rate, the value of the operant approach Is i l l u s . t r a ^ ted by therapies which have s u c c e s s f u l l y u t i l i z e d shaping (Perkins, Note 1), stimulus control (Azrin, Jones, & F l y e , 19681, self-recording_ (LaCroix, J.9.73V., time out (James' & Ingham, 1974)., s o c i a l reinforcement f o r fluency and punish.-^ ment f o r s t u t t e r i n g (Ryan, 1971; Quist & Martin, 1967), and even token econo? mi-€s (Ingham & Andrews, J973b)_. Although most researchers probably would agree that many of the sym-^  ptoms of s t u t t e r i n g are learned, some suspect that the e s s e n t i a l cause of the disorder i s a disturbance of auditory feedback. " A r t i f i c i a l s t u t t e r i n g " may be induced i n a large proportion of normal speakers be feeding back t h e i r tape-recorded speech at a delay of about .20 seconds (Lee, 1951). Apparently t h i s delayed auditory feedback (DAF) disrupts the p r e c i s e timing required fo r the simultaneous and successive contractions of the dozens of antagonistic muscles involved i n speech. However, DAF has a paradoxical e f f e c t on many s t u t t e r e r s : i t makes them " a r t i f i c i a l l y f l u e n t " . DAF i s not a v i a b l e t r e a t s ment at t h i s time because there i s l i t t l e carry-over of fluency- from lab to l i f e , but i t has spawned several i n t r i g u i n g models-of s t u t t e r i n g as a feedback 9 disturbance ( e . g . , Gruber , 1965; Mysak, 1960; S k l a r , 19691. Speech, i s a f i n e l y -integrated motor a c t i v i t y which presumably Involves at l e a s t three kinds of feedback: 1. ) a irborne auditory feedback 2. ) bone-conducted and t i s s u e ^ o n d u c t e d a u d i t o r y feedback, and 3.1 somesthetic (1.e., t a c t i l e , k i n e s t h e t i c , and p r o p r i o c e p t i v e ) , feedback from the speech, musculature. Left-Bright feedback asynchrony, a p o s s i b l e source of i n s t a b i l i t y * has been found i n some s t u t t e r e r s (Stromsta, Note 3 ) . Another source of feedback dis-r t o r t i o n might be temporal d i f f e r e n c e s between competing channels., and indeed t h i s has been demonstrated f o r channels I and 2 (Stromsta, -1962)1.. In other words, some s t u t t e r e r s may have an organic DAF system. Stress presumably causes t h i s unstable feedback system to f a i l , e . g . , Timmons and-Boudreau 0.9.721 hypothesized that anxiety- produces changes i n the contour of the o r a l cavity-, which lead to f u r t h e r feedback, d i s t o r t i o n , greater anxiety-, and SQ on. The s t u t t e r e r c a r r i e s h i s own s t r e s s e r s with, him, i n the form of negative emotion condi t ioned to s i t u a t i o n a l and phonemic cues. Each, f a i l u r e to be f l u e n t presumably adds to future s t r e s s ; ' DAF must u s u a l l y be at l e a s t as loud as the speaker 's .own speech to be e f f e c t i v e , and i t i s most d i s r u p t i v e when loud enough to mask bone conduc-t i o n , i . e . , greater than 50 dB above threshold (Butler-& Galloway, 19.57). Yates (1963) hypothesized that nonstut terers whose speech i s - n o t d i s r u p t e d by DAF a c t u a l l y monitor t h e i r speech, v i a channel 2 and/or 3. Indeed, Goldia-^ mond, Atkinson and B i l g e r 1(1962)1 found that nonstut terers can become r e l a t i v e l y r e s i s t a n t to DAF when i n s t r u c t e d not to l i s t e n to i t . 10 The defective feedback theory is. supported by another phenomenon as well:, many- stu t t e r e r s become a r t i f i c i a l l y - fluent when l i s t e n i n g to white noise at a loudness of approximately 90 dB above threshold (Cherry & Sayers, 1 9 5 6 L . Speech therapists c a l l ; t h i s treatment "masking noise" because i t minimizes; or eliminates the stutterer's, hearing of h i s 1 speech, v i a channels 1 and 2 . Like DAF, masking noise generally has no lo n g - l a s t i n g therapeutic e f f e c t but i t i s of considerable t h e o r e t i c a l i n t e r e s t because.it apparently- forces the s t u t t e r e r to monitor his speech through, channel 3 . The therapeutic implications of the feedback,model of .stuttering : are c l e a r : I f channels 1 and 2 are somehow defec t i v e , therapy should involve teaching the s t u t t e r e r to r e l y on channel 3 (Mysak, 1 9 6 0 ; Gruber, 1 9 6 5 ) . This could be achieved through masking chanrieilsifi oand'.^ 2"cb'.yjhap"plying 'loud _ wha-lre-bnoWse^ie^• CSklar, 1 9 6 9 ) . An a l t e r n a t i v e strategy, which i s the essence of t h i s d i s s e r t a t i o n , involves enhancing proprioceptive information by feeding i t through the airborne auditory feedback channel. Biofeedback Biofeedback t r a i n i n g i s based on the fundamental learning p r i n c i p l e that we can learn to make a given response when we receive<iinformation that we have made that response, or an approximation to i t (Lazarus, 1975 ) . Im-mediate feedback i s the most e f f e c t i v e , e.g., feedback from the eyes f a c i l i -tates control of the s t r i a t e muscles involved i n w r i t i n g a sentence. Under ordinary conditions, we do not receive much feedback about c e r t a i n p h y s i o l o g i -c a l processes, e.g., the f i n e a c t i v i t y of the po s t e r i o r cricoarytenoid muscle i n the larynx, but biofeedback can make th i s information more s a l i e n t . 11 In the past decade, bipfeedback has been shown to• have important t h e o r e t i c a l ramifications as we l l as p o t e n t i a l f or the treatment of a host of disorders. According to Budzynski . Q-973) : "An accumulating body of c l i n i c a l and research, evidence suggests that biofeedback represents a r e l a t i v e l y e f -f e c t i v e technique for the shaping of s e l f - c o n t r o l over c e r t a i n p h y s i o l o g i c a l events. These events are u s u a l l y autonomous In that they tend to occur automatically and below the l e v e l of awareness. When these, i n t e r n a l events f a l l outside the normalrrange of functioning, they con-s t i t u t e maladaptive behaviors that can lead to fe e l i n g s of anxiety,, or the - appearance of such, stres s — r e l a t e d ' disorders as migraine and tension headaches, c e r t a i n cardiovascular problems, and sleep-onset insomnia, to name a few. Through feedback t r a i n i n g , patients learn to maintain t h e i r physiology within a normal range of functioning." (p. 546).. In view of the p o s s i b i l i t y that s t u t t e r i n g i s the r e s u l t of defective feed-back, an i n v e s t i g a t i o n of the e f f e c t s of feedback t r a i n i n g on s t u t t e r i n g seems warranted. Some of the e a r l i e s t and most important biofeedback research, from a t h e o r e t i c a l point of view, involved operant conditioning of autonomic r e s -ponses. These included reward and avoidance conditioning of smooth..muscle responses such as heart rate ( M i l l e r & DiCara, 1967), and vasomotor behavior' (Snyder & Noble, 1968); and of glandular responses such, as s a l i v a t i o n ( M i l l e r & Carmona, 1967) and GSR (Snyder & Noble, .1968).. M i l l e r , DiCara and colleagues curarized and a r t i f i c i a l l y respirated t h e i r animal subjects i n order to control f o r the p o s s i b i l i t y that the autonomic responses were a c t u a l l y mediated by s k e l e t a l muscles under voluntary c o n t r o l . Under these conditions t h e i r sub-j e c t s were able to increase and decrease t h e i r heart rate' and blood pressure, produce l o c a l i z e d Blood flow i n one ear without producing such, a change In the other ear, modify t h e i r stomach and i n t e s t i n a l contractions, and vary 12 t h e i r rate of urine secretions. Results l i k e these,if they can be r e p l i c a t e d , provide the basis f o r a r e i n t e r p r e t a t i o n of psychosomatic symptoms.in humans, v i . z . , operant conditioning of autonomic responses. Another e a r l y l i n e of biofeedback research, has involved attempts to teach human subjects to produce or suppress alpha waves (Kamlya, J.9.69.).. ' F a c i l i t a t i o n of alpha was i n i t i a l l y touted as a roya l road to al t e r e d states of consciousness and other i l l - d e f i n e d experiences. I t now appears that alpha a c t i v i t y i s experienced only as normal re l a x a t i o n . Moreover, i t appears that f a c i l i t a t i o n and blocking of alpha did not involve operant conditioning at a l l , as o r i g i n a l l y claimed. Alpha can be r e a d i l y blocked by eye movement and f a c i l i t a t e d by lack.of eye movement. Thus what was f i r s t thought to be evidence of operant conditioning of EEG a c t i v i t y now. appears to be an ar t i - ^ fact of responses which were already i n the r e p e r t o i r e , v i z . ^oculomotor ac-r t i v i t y . Moreover, the magnitude of EEG changes did not exceed the l i m i t s of baseline f l u c t u a t i o n s (Peper & Mulholland, 1970),. In s p i t e of the f a c t that some e a r l y r e s u l t s have not,been substan-t i a t e d , biofeedback does appear to have considerable c l i n i c a l p o t e n t i a l . Auditory feedback of GSR has been used i n the treatment of agoraphobia (Lader & Wing, 1966) and generalized phobia (Lader & Mathews, JL968)_, Sargent ? Green and Walters (1973) taught t h e i r subjects to co n t r o l the d i f f e r e n c e i n skin temperature between the forehead and the r i g h t index f i n g e r . This study has implications f or the treatment of migraine headaches, since skin tempera-ture i s d i r e c t l y related to blood flow. Elder, Ruiz, Deabler and D i l l e n k o f f e r (1973) taught e s s e n t i a l hypertension patients how to reduce t h e i r d i a s t o l i c blood pressure by attending to a v i s u a l s i g n a l . Rosen Q.9.73J. used a s i m i l a r .13 s i g n a l , v i z . , a red l i g h t to inform h i s subjects when they had excessive penile tumescence. This study has p o t e n t i a l f o r the treatment of psychogenic impotence, f e t i s h i s m and other sexual disorders. Lovibond and Caddy (1971) used feedback of blood alcohol l e v e l to teach a l c o h o l i c s to drink without becoming profoundly intoxicated. Other disorders c u r r e n t l y being treated with: biofeedback include epilepsy, premature v e n t r i c u l a r contractions, car-diac arhythmias, stomach a c i d i t y , and excessive p e r s p i r a t i o n ( M i l l e r , Barber, DiCara, Kamiya, Shapiro & Stoyva, 1974). Feedback of electromyographic a c t i v i t y (EMG). i s p a r t i c u l a r l y promising. S e l f - c o n t r o l of EMG responses can be achieved r e l a t i v e l y e a s i l y (Green, Green & Walters, 1971), presumably because i t involves s t r i a t e muscle func-tions. Using indwelling electrodes, Basamajian (1963) has demonstrated that humans can make f i n e adjustments of s i n g l e motor units i n the thumb muscles. Surface EMG has been used to treat several disorders which involve excessive muscle tension. Hardyck, P e t r i n o v i t c h and Ellsworth..'0-9.66). eliminated sub-^ v o c a l i z a t i o n i n students with reading problems by providing them with auditory feedback of laryngeal muscle a c t i v i t y . Jacobs and Felton 0969). used v i s u a l EMG feedback to induce r e l a x a t i o n i n neck-injured patients. Auditory feed-back of f r o n t a l i s muscle a c t i v i t y has been used to t r e a t tension headaches (Budzynski, Stoyva, Adler & Mullaney, 1973) and chronic anxiety and insomnia (Raskin, Johnson & Rondestvedt, 1973). N e t s e l l and Cleeland O9.73). reduced l i p hypertonia i n a Parkinsonian patient by means of EMG feedback and Cleeland (1973) also applied t h i s paradigm to the modification of spasmodic t o r t i c o l l i s . A general review of the current state of EMG feedback: i s provided by Basmajian 0972). •14 Biofeedback i s a remarkable form of behavior therapy i n that subjects often achieve strong p o s i t i v e r e s u l t s i n a single session, e s p e c i a l l y when the s t r i a t e d musculature i s involved. This learning can be achieved without reinforcement other than knowledge of the r e s u l t s , i.e.", the feedback i t s e l f . Curiously, subjects u s u a l l y are unable to v e r b a l i z e how they exerted control over a given p h y s i o l o g i c a l response, any more than one could describe how to move a f i n g e r . In order to apply the promising biofeedback paradigm to s t u t t e r i n g , i t was necessary to s e l e c t a psychophysiological c o r r e l a t e of t h i s disorder. Several such correlates have been investigated, although the amount of research i n t h i s area i s perhaps less than one might expect from the immense volume of the s t u t t e r i n g l i t e r a t u r e i n general. Severe s t u t t e r i n g i s often accom-panied by a host of obvious bodily movements, e.g., eyeblinks, gasping, swal-lowing, head nodding, l i p tremors and gross movements of the limbs. There may also be increases i n palmar sweating (Brutten,--19-63)1, increases i n GSR (Kline, 1959), abnormal EEG a c t i v i t y (Knott, C o r r e l l & Shepherd, -19591, and p u p i l d i l a t i o n (Luchsinger & Arnold, 19651. Williams Q955)_ monitored mas-seter EMG and found that action p o t e n t i a l s from t h i s s i t e were s i g n i f i c a n t l y higher during s t u t t e r i n g than during fluency. Spikes appeared on the EMG record during s t u t t e r i n g , but disappeared when s t u t t e r e r s d e l i b e r a t e l y made r e l a t i v e l y relaxed r e p e t i t i o n s of s y l l a b l e s . Moreover, when normal speakers faked s t u t t e r i n g , spiking was produced. Williams concluded that s t u t t e r i n g i s accompanied by excessive tension i n the jaw muscles. Sheehan and Voas (1954) found that masseter tension peaked before s t u t t e r i n g . Shrum (Note 4)_ f a i l e d to r e p l i c a t e t h i s f i n d i n g but did f i n d more tension i n the neck, chest 15 Land jaw during s t u t t e r i n g than /.during ...fluency. EMG appeared t o b e the most rea c t i v e p h y s i o l o g i c a l parameter during s t u t t e r i n g and thus was a promising modality f o r feedback, t r a i n i n g . I t was assumed that EMG would probably discriminate s t u t t e r i n g from fluency i n a large proportion of subjects, although, i t was also r e a l i z e d that each, s t u t ^ terer has his own p r o f i l e of responses. A f t e r some p i l o t research, the masseter s i t e was rejected i n favour of electrode placement near the larynx, f o r several reasons: F i r s t , since the majority of st u t t e r e r s are male, the masseter s i t e i s often covered with sideburn h a i r . Second, movement a r t i f a c t s are common at the masseter s i t e but less common near the larynx. More spiking was recorded from the layrngeal s i t e than from the masseters i n p i l o t research. And f i n a l l y , there i s evidence that the larynx may be a locus of the s t u t t e r i n g block (Schwartz, 1974). Thus I decided to in v e s t i g a t e the e f f e c t of feeding back stu t t e r e r ' s EMG a c t i v i t y from a s i t e near the larynx. Stuttering research and biofeedback research are both notable f o r i n i t i a l l y p o s i t i v e r e s u l t s that tend not to be substantiated l a t e r (Van Riper, 1973; Blanchard & Young, 1973). Green, Green and Walters (1971) touted feedback t r a i n i n g as a cure f o r everything from warts to cancer. Budzynski (1973) warned against such high, expectations and urged that care-f u l l y c o n t r o l l e d laboratory studies be done before c l i n i c a l studies are a t ^ tempted. In stepwise research, demonstration of a treatment e f f e c t precedes the evaluation of that treatment. The intent of the present research, was not to devise a new speech therapy at t h i s time, but rather to observe the e f f e c t of EMG feedback i n a con t r o l l e d l a b o r a t o r y s i t u a t i o n . If i t were 16 shown that biofeedback did suppress stuttering, then biofeedback would have potential as speech, therapy. However, the development of an effective therapeutic program was- not within the scope of the present research. 17 CHAPTER IT GENERAL METHODOLOGY Sub j ects-Severe chronic s t u t t e r i n g Is r e l a t i v e l y rare i n adults. The i n c i > dence of s t u t t e r i n g i n the general population i s less- than 1% (Beech- & F r a n s e l l a , 1968), but even t h i s f i g u r e may lead one to underestimate the difT -f i c u l t y of procuring subjects f o r research. The prevalence of s t u t t e r i n g i s undoubtedly much lower than the incidence, because 1)1. the rate of spontaneous remission In young st u t t e r e r s i s about 80% CSheehan & Martyn, 1970)1, and 2) even i n adults, s t u t t e r i n g i s . o f t e n an Intermittent disorder which may disappear f o r days or weeks and then recur. Probably the prevalence of severe chronic s t u t t e r i n g i n adults i s a small f r a c t i o n of .1%', Stuttering research has always been hampered by small sample s i z e s . The median sample s i z e i n 70 a r t i c l e s on s t u t t e r i n g published i n the Journal  of Speech and Hearing Disorders and the Journal of Speech and Hearing Research from 1970 through 1974 was 14. Some researchers cope with t h i s problem by having fluent subjects simulate s t u t t e r i n g (e.g., Williams, 1955; Freeman & Ushijima, Note 5). A more v a l i d s o l u t i o n to the problemtuof subject s c a r c i t y i s the use of single-subject designs (e.g., Martin, 1968). A t o t a l of 14 adult s t u t t e r e r s (11 males and three females, whicfu approximates the usual sex ratio), p a r t i c i p a t e d i n various phases of the present series of studies. This sample was very heterogeneous-with.regard to socio-economic status, e t h n i c i t y , education and age (range 17^-49-years-;, mean age 27.3). A l l had received speech, therapy-or psy-chotherapy f o r t h e i r s t u t t e r i n g , without much success, and were on a waiting l i s t f o r r a t e - c o n t r o l .18 therapy. Most reported that t h e i r s t u t t e r i n g was a severe s o c i a l and oc-cupational handicap. In general, these subjects seemed to be underachievers r e l a t i v e to t h e i r l e v e l of education (e.g., a 36-year^old PhD i n physics was employed as a sawmill l a b o r e r ) . Most seemed d e f i c i e n t i n s o c i a l s k i l l s . Five subjects p a r t i c i p a t e d i n a s i n g l e study, eight i n two studies, and two i n three studies. The exact assignment of subjects to studies i s given i n Appendix A. There were :3Q single-subject studies of s t u t t e r i n g , fit'studies of EMG and .23 studies of speech rate i n the present research. S t a t i s t i c a l analysis was based on the number of observations per subject rather than on the number of subjects. Dependent Variables S t u t t e r i n g . Is s t u t t e r i n g i n the ear of the beholder, or i s i t suf-f i c i e n t l y d i s t i n c t from fluency that i t can be defined and measured r e l i a b l y ? In a lengthy review of t h i s issue, Van Riper (1971) argued: Just because s t u t t e r i n g i s occasionally d i f f i c u l t to d i s t i n g u i s h from normal disfluency i n i t s e a r l y or minor forms (and we must remember that s t u t t e r e r s also have normal d i s f l u e n c i e s ) we need not deny that s t u t -t e r i n g e x i s t s as an ;entity. (p. 15) Van Riper concluded by defining s t u t t e r i n g as "a word improperly patterned i n time and the speaker's reactions thereto" (p. 15). While Van Riper's d e f i n i t i o n i s c e r t a i n l y c o r r e c t , i t i s not s u f f i c i -ently s p e c i f i c . For the purpose of the present research, s t u t t e r i n g was defined as i n c l u d i n g : 1. Sound or s y l l a b l e r e p e t i t i o n s . These comprise the largest proportion ,:t r p f .^stutters foremost j sub jieets^ r-"Kuhl-kun^Kuh^^ counted as -• one.stutter. ,19 2. Abnormal prolongations of sounds. ''Abnormal" would Se. i n the order of about one second at the beginning of a word, or l e s s than one second i f the prolongation occurred within a word. 3. Abnormal h e s i t a t i o n s . These are accompanied by- the strange h i s s i n g noises c a l l e d "vocal f r y " (Moser, 1942), or By other indications' of excessive tension and r e s p i r a t o r y abnormalities, and are thus- d i s t i n -guishable from normal hesi t a t i o n s that r e s u l t from not knowing what to say. Thompson (1971) used a s i m i l a r d e f i n i t i o n of s t u t t e r i n g ("hesitations, prolongations, part-word r e p e t i t i o n s , undue pauses") and achieved a r e l i -a b i l i t y c o e f f i c i e n t of _r = .87 when two raters who had been trained to use t h i s d e f i n i t i o n scored tapes for s t u t t e r i n g . Martin (1968), also scoring tapes, reported an i n t e r - r a t e r r e l i a b i l i t y of _r =.98. MacDonald and Martin (1973) used untrained students to count s t u t t e r s and other d i s f l u e n c i e s from videotapes, without giving them any a p r i o r i d e f i n i t i o n s of. these two res-ponse categories. Nevertheless, they found high i n t r a - and i n t e r ^ r a t e r r e l i a b i l i t y , i n terms of percent agreement, and concluded that s t u t t e r i n g i s an unambiguous and r e l i a b l e response class even to untrained judges. A z r i n , Jones and Flye (1968) measured s t u t t e r i n g i n terms of percent of words stuttered. This measure i s s a t i s f a c t o r y i f a l l subjects use the same words (e.g. , i n a reading task) but i t i s c l e a r that i f two subjects have the same percentage sco<re?tTth\eTS;ub#ect<^ words w i l l a c t u a l l y be more f l u e n t . For t h i s reason James and Ingham (1974) advocate percent s y l l a b l e s stuttered. Although t h i s i s not a d i r e c t measure of the duration of each s t u t t e r , judgements of the s e v e r i t y of s t u t t e r i n g 20 are h i g h l y correlated with: frequency-of s t u t t e r i n g and with, speech, rate (Young, 1961; Sander, 1961), Percent s y l l a b l e s stuttered i s a measure of frequency, and controls for differences i n speech rate, e.g,, between ad-jacent one-minute segments of speech. According to Ingham and Andrews (1973a).: ... changes i n the s e v e r i t y of the disorder may be s u i t a b l y assessed from frequency counts of moments of s t u t t e r i n g and possibly from measures of the rate of speaking. These two indices can also Be measured "on l i n e " with high r e l i a b i l i t y - (Ingham and Andrews, 1971b), thereby providing useful indices of a subject's: speech behavior. (p. 407). EMG spiking. Since the auditory feedback- tone used i n t h i s research-was activated By the same e l e c t r i c a l a c t i v i t y - w h i c h produced spikes and other pen d e f l e c t i o n s i n the EMG record, a count of EMG spikes was chosen as an appropriate measure of the ef fec't'f of cf eedbaekd'trainlng''onr EMG'activity. Because of differences i n basal l e v e l s , the threshold at which the feedback tone was activated was determined i n d i v i d u a l l y f o r each subject during the baseline period (Appendix C). Depending on the subject's own pattern of EMG a c t i v i t y and on the s e n s i t i v i t y l e v e l at which the polygraph was set, f l u e n t speech produced pen d e f l e c t i o n s representing not more than .20 mV. S t u t t e r s , on thee other hand, were often (but not i n e v i t a b l y ) accom-panied by conspicuous spikes representing up to .50 mV, Signals a t t r i b u t a b l e to yawning, swallowing and movement a r t i f a c t s were r e a d i l y distinguishable from s t u t t e r spikes and were hofctcounted, Spikes, l i k e s t u t t e r s , were expressed r e l a t i v e to speech, rate. Thus the degree of spiking was expressed as the number of spikes per 100 s y l l a b l e s for each minute of speech. Speech rate. When normal speakers are required to speak abnormally 2 1 fast,' they become d i s f l u e n t . Stutterers tend to speak, f a s t e r than normals, and can become more fl u e n t by slowing down (Van Riper, 1971, 19.73). This trade-off between rate and f l u e n c y is- the essence of r a t e - c o n t r o l therapy and may be involved i n other therapies as w e l l . In order to determine that a biofeedback e f f e c t was independent of rate c o n t r o l , i t was necessary to monitor speech rate, which i s u s u a l l y expressed i n s y l l a b l e s per minute CSPM). It should be noted that even i f a biofeedback e f f e c t were accompanied by or even produced by a retarded speech rate, this, would not n e c e s s a r i l y detract from i t s effectiveness. It i s important to note that SPM i s only an estimate of true a r t i c u -l a t o r y rate, since i t does not take into account pauses between moments of speech. It i s a conceivable paradox, although not a l i k e l y one, that an i n -crease i n SPM could be produced by a retarded a r t i c u l a t o r y rate i f slower speech were accompanied by a decrease i n time—consuming pauses, hesi t a t i o n s and r e p e t i t i o n s . That i s , s y l l a b l e prolongation could o c c a s i o n a l l y be more than o f f s e t by a decrease i n the time occupied by stutters-. A true measure of a r t i c u l a t o r y rate would include speech only, and eliminate a l l pauses. In p r a c t i c e , i t would be so d i f f i c u l t to c a l c u l a t e a true a r t i c u l a t o r y rate that SPM i s v i r t u a l l y always used instead. SPM i s an adequate estimate of a r t i c u l a t o r y rate for our purposes, and the possibility-: that i t could occa-s i o n a l l y be misleading i s outweighed by the p r o b a b i l i t y - t h a t i t would not be misleading i n several replications:. Observer Agreement on the Dependent Variables One subject was selected at random from eacIL of the f i y e studies i n t h i s d i s s e r t a t i o n , and a lO^minute sample of speech.was- randomly selected' 22 from each_.of these subjects. Stuttering and speech rate data were calculated from tape recordings, and EMG spikes were counted from the corresponding polygraph, records. These data were t a l l i e d on hand counters by myself and a p r a c t i c i n g speech therapist who was unaware of the experimental hypotheses. Stuttering was defined according to the : d e f i n i t i o n described e a r l i e r i n t h i s chapter. An EMG spike was defined as a sharp downward deflection' of the EMG pen trace, which exceeded a c e r t a i n cutoff ( v i z . , the feedback threshold).. S y l l a b l e s that were repeated during s t u t t e r i n g were only counted once. Before scoring the data, both; raters practiced on an a d d i t i o n a l speech, sample, i n order to ensure that the d e f i n i t i o n s of the dependent va r i a b l e s were f u l l y understood. Inter- r a t e r r e l i a b i l i t y data are given i n Appendix B., Mean i n t e r -rater r e l i a b i l i t i e s of .89, .93, and ,9.5 were achieved f o r s t u t t e r i n g , spiking, and speech rate, r e s p e c t i v e l y , using Fisher's Z-^transformation. A l l r e l i a b i -l i t y c o e f f i c i e n t s were s i g n i f i c a n t at the .01 l e v e l ( c r i t i c a l value of r_C8)_= , 77)_. However, a high degree of r e l i a b i l i t y does not n e c e s s a r i l y imply agreement on s p e c i f i c instances, so an a d d i t i o n a l analysis was performed, Agreement between raters was calculated according to the formula no. of agreements , n n a, ^ • x 100 % agreement = •—•=-• ——: ;— — — - — no. of agreements & disagreements Using t h i s more conservative measure, mean agreements of 80%, 9.2% and 97% were found for s t u t t e r i n g , spiking, and speech rate, r e s p e c t i v e l y (Appendix B l . A l e s s e r degree of agreement was consistently found f o r s t u t t e r i n g and spiking than f o r speech rate. This Is i n part due to the f a c t that the former variables were expressed r e l a t i v e to a denominator of 100. s y l l a b l e s , 23 and thus included the error variance of the speech rate measure. Less agreement was found f o r s t u t t e r i n g than f o r spiking, probably because the. low base rate of the former (e.g., 2%-20% s y l l a b l e s stuttered) minimized observer agreement due to chance alone. Moreover, the d i s t i n c t i o n between s t u t t e r i n g and fluency i s sometimes a subtle one.. The high degree of agreement between the.two raters indicates, that the data are not s e r i o u s l y contaminated by random error and experi-menter bias , i . e . , nonrandom error which i s confounded with the treatment e f f e c t . This tends to i n s p i r e confidence i n the r e s u l t s of the .studies that follow. Design Design Time serie s methodology has been used for decades i n the experi-mental analysis of behavior, and recently has gained increasing acceptance i n other areas of behavioral research CSidman, 1960; Chassan,.1967; Leitenberg, 1973). Campbell and Stanley (1970) define a time-series design as 0 . 0 0 1 0 . 0 0 . where each 0 represents a regular observation of the dependent v a r i a b l e and I represents the experimental intervention. A c t u a l l y the basic design used i n the present series of studies i s better i l l u s t r a t e d as-0 0 0 10 10 LO because the intervention continues-throughout the ; treatment period. A sum-mary of designs used i n .the present research i s given i n Table I. Time-series designs appear to-be p a r t i c u l a r l y appropriate i n psychophysiology (Johnson & Lubin, 1972) and s t u t t e r i n g research (Martin, 1968).. 24 Table 1 Designs Used i n the Present Series of Studies Study Schematic Intervention 1 °1 T l °2 T^=rate control; therapy 2 Ca). Cb) °i 02---°i5 T2°ie h°ir"h°3o-i 2o 1 I 2 O 2 . . . I 2 O 1 5 o 1 6 o i r..o 3 0 T.2 = me t r onome paced speech 3 ( p i l o t ) . . . Og /break/ I^O^Q ^ ^ l l ' ' ' ^ 3°18 8l9 ° 2 0 , , , 0 2 7 13°28 I3°29**' 13°36 °37 038--'°45 1^ = feedback 3 °i °2---°i5 V i e Wn — h^o 4 Ca) °1 • 02"'- 015.- I4 Oi6. r4 017.v r4 0 3 0 . I,= feedback without 4 . i n s t r u c t i o n s Cb). V l I4 02--- I4°15 °16 °17-"°30 5 ( p i l o t ) °1 02"-°9 / b T e a k / h010T30ll'''13018 I^ = feedback °19 0 2 0 , , , 0 2 7 I5°28 I5°29"'" I5°36 r3°37 1,. = f a l s e feedback I 3 ° 3 8 ' * , , I 3°'45 5 Ca) °1 02---°15 T3016 I 3 ° 1 7 - - - I 3 0 3 0 / b r e a k / °31 °32--°45 E5 Q46 I5°47' ' ' r5°60 Cb). °1 0 2 " - ° 1 5 X5°16 Vn-'-VsO / b r e a k / °31 ° 3 2 " , 0 4 5 I3°46 I3°47*' " ^ ^ O 25 A time^series analysis i s an.economical and e f f i c i e n t way to begin resear-ching a new area, such as i n the present instance, because i t can be used with_ a s i n g l e subject. Where subjects are rare, t h i s method i s almost i n -evit a b l e . The power of a time—series analysis i s a function of the number of data points rather than the number of subjects. Another advantage of thi s approach i s i t s f l e x i b i l i t y . Tn stepwise research., early r e s u l t s can be used to determine the course of subsequent studies without s e r i o u s l y depleting a small sample of rare subjects. ' (This i s i l l u s t r a t e d by the way i n which Studies 3 and 5 d i f f e r from t h e i r p i l o t studies.1 A r e l a t e d advantage of single^subject designs i s that they permit r e p l i c a t i o n with a minimum of subjects. Inter-subject r e p l i c a t i o n may be more valuable than inter-group r e p l i c a t i o n where the r e l i a b i l i t y and genera-l i t y of a treatment e f f e c t are of i n t e r e s t . In group des i g n s , . r e p l i c a t i o n • of changes i n c e n t r a l tendency requires r e l a t i v e l y large samples, and may obscure within-group differences- (Sidman, I960). Within^group differences are p a r t i c u l a r l y common i n d s t u t t e r i n g (yan.Riper, 1971) and psychophysiology (Lacey, 1967). I once.had a c l i e n t who stuttered on 77% of h i s s y l l a b l e s . Consider the e f f e c t of grouping t h i s subject with f i v e others who each stuttered severely on 5% of t h e i r s y l l a b l e s : a strong biofeedback e f f e c t on the l a t t e r f i v e subjects could be obscured p a r t i a l l y or completely by a weak e f f e c t on the former subject, and vice-versa. In exploratory investigations l i k e the present research, i n d i v i d u a l differences need to be s c r u t i n i z e d c l o s e l y rather than ascribed to error variance. I t makes; a great deal of sense to use eacL subject as his own co n t r o l . An untreated control group i s an unattainable luxury where 26 subjects are scarce, and seems p a r t i c u l a r l y Inappropriate i n the present research where a l l subjects have been s t u t t e r i n g severely-, for 15-^45 years.. (However, i n Study 5 each, subject p a r t i c i p a t e d i n a pseudotreatment c o n t r o l condition as. w e l l as serving as-hisr. own control.)_ Another unique advantage of the time-^series design i s i t s longitu-r d i n a l perspective. Tlme^serles research, involves continuous measurement rather than only pre- and post-^treatment measures, thus, permitting process as .well as outcome research. The time series i l l u s t r a t e s the immediacy-and duration of treatment effects:, plus changes i n treatment e f f e c t s oyer time. This kind of information i s c l e a r l y of great i n t e r e s t i n biofeedback and therapy research. Of course, the time-series design has c e r t a i n p o t e n t i a l disadvantages') as w e l l . One.of these i s h i s t o r i c a l i n v a l i d i t y , where a variable, other than the treatment may account for any e f f e c t Cor lack of effect)! that occurs a f t e r the point of intervention (Campbell & Stanley, .19.70.).. H i s t o r i c a l inT-v a l i d i t y i s a major problem i n ex post facto analyses, e.g. , i n v e s t i g a t i o n s of a r c h i v a l data. In the present planned time ser i e s analyses i t i s not a relevant.problem, because the i n t e r v a l between pretreatment and posttreatr-ment observations i s only 60 seconds. Repl i c a t i o n i s a recognized defense against h i s t o r i c a l i n v a l i d i t y . Another p o t e n t i a l problem is; regression to the mean.(Glass, K i l l s o n , & Gottman, 1972). This is. of major concern i n true c l i n i c a l research.wh.ere subjects come for-treatment during a personal c r i s i s . . Any-spontaneous change back toward baseline would appear to be an e f f e c t .of therapy-. In s t u t t e r i n g research a regression a r t i f a c t could occur i f the treatment coincided with. 27 a l a r g e spontaneous f l u c t u a t i o n In s t u t t e r i n g i n e i t h e r d i r e c t i o n . A subset-quent decrease i n v a r i a n c e would tend to : l o o k s i g n i f i c a n t , . e y e n i n the ah-?-sence of a change i n l e v e l or s lope of tlie time series;.- This; could be con^ t r o l l e d s t a t i s t i c a l l y - through the use of an i n t e g r a t e d moying ayerage, so that no extreme value occurred at the end of the b a s e l i n e p e r i o d . - Replica-r-t i o n would be an a d d i t i o n a l precaut ion ; Where two or more treatments are a p p l i e d during a s i n g l e t i m e - s e r i e s experiment, there i s a r i s k of m u l t i p l e treatment i n t e r f e r e n c e (Campbell & Stanley , 1970). This p o s s i b i l i t y can be c o n t r o l l e d by counterbalancing , by appropriate s t a t i s t i c a l a n a l y s i s , and by a res t p e r i o d between treatments ( e . g . , Study 5) . i U n t i l r e c e n t l y , the t i m e - s e r i e s design has been used without b e n e f i t of s t a t i s t i c a l a n a l y s i s . Few would argue that the experimental a n a l y s i s of behavior has been h e l d back because of a d is regard of s t a t i s t i c s ; neverthe-r l e s s , mere v i s u a l i n s p e c t i o n of the data can markedly- increase the r i s k of inappropr ia te inferences (Gottman, 1973). Chassan (1967) suggested that a standard t - t e s t could be a p p l i e d to p r e - and p o s t - i n t e r v e n t i o n data . Others have used a n a l y s i s of v a r i a n c e . I t i s not d i f f i c u l t to imagine instances where such analyses might be misp-l e a d i n g , e . g . , a strong adaptation e f f e c t would tend to produce a s p u r i o u s l y s i g n i f i c a n t d i f f e r e n c e i n p r e - and p o s t - i n t e r v e n t i o n means. . Moreover, s t u t -t e r i n g data (and most t i m e - s e r i e s data , f o r that m a t t e r l are dependent and thus, v i o l a t e a b a s i c assumption of._t_-tests a n d . a n a l y s i s of v a r i a n c e , v i z . , that errors associated w i t h observations must be independent. Although the time s e r i e s i s - b a s i c a l l y an extension of the pretest-r-posttest d e s i g n , i t 28 raises unique s t a t i s t i c a l problems. Fortunately, techniques-have r e c e n t l y been developed which permit v a l i d s t a t i s t i c a l inference from the time-^series- data (Glass, Willson & Gottman, 1972). . The analysis-used i n the present research^is Eased on a program developed by Maguire and Glass. Q.967)_. I t uses an integrated moving average model with deterministic d r i f t to transform the pre^- and post—in-r tervention data and test f o r s i g n i f i c a n c e between them. This model can accomodate some i n s t a b i l i t y i n the baseline data. The least^squares e s t i -mate of the l e v e l of the time series has a t d i s t r i b u t i o n w i t h N^3 degrees of freedom when divided by i t s * standard error, where N equals the number of observations i n the,time s e r i e s . An abrupt s h i f t i n the l e v e l of the s e r i e s at the point of i n t e r v e n t i o n implies a treatment e f f e c t . A delayed t r e a t -ment e f f e c t would be r e l a t i v e l y u n l i k e l y to reach s t a t i s t i c a l s i g n i f i c a n c e . Abrupt or delayed changes i n the d r a f t and variance of the time ser i e s are not analyzed, but fortunately they are of l i t t l e i n t e r e s t here. Since m u l t i v a r i a t e s t a t i s t i c s f o r time series analysis have not yet been perfected, each dependent v a r i a b l e must be analyzed separately. 29 CHAPTER I I I STUTTERING AND LARYNGEAL HYPERTENSION Laryngeal Involvement i n Stuttering As mentioned previously, a p h y s i o l o g i c a l c o r r e l a t e of s t u t t e r i n g i s a necessary p r e r e q u i s i t e to a biofeedback treatment. Laryngeal EMG was selected because of accumulating evidence of. laryngeal involvement i n the st u t t e r i n g block. I t has long been known that s t u t t e r i n g i s accompanied by abnormalities i n r e s p i r a t i o n (VantiRiper, 197.1). Since a i r - f l o w (usually exhalation) i s a necessary condition f o r phonation, some>speech pathologists are of the opinion that what the .stutterer c a l l s a "block" i s indeed a p h y s i o l o g i c a l block, i . e . , a temporary occlusionviof the airway. According to Van Riper (1971), such a block could occur at one or more of four l o c i : at the l i p s , at.the front or rear of the tongue, or at the larynx. Van Riper suggested that the s i t e of the s t u t t e r i n g block need not be the same f o r a l l s t u t t e r e r s . S u r p r i s i n g l y , the ro l e of the larynx i n s t u t t e r i n g has l a r g e l y escaped scrutiny u n t i l recently. Laryngeal involvement i n airway blockage i s cer-t a i n l y p l a u s i b l e , f o r the g l o t t i s i s the smallest-aperture along the airway. Freeman and Ushijima (Note/S) used depth electrodes to take EMG recordings from four i n t r i n s i c laryngeal muscles during the speech, of a si n g l e s t u t t e r e r and a normal speaker who faked s t u t t e r i n g . I t was found that fluent speech, was accompanied by a precise r e c i p r o c a l i n t e g r a t i o n of adductor and abductor muscles, but that t h i s r e c i p r o c i t y was not present during stuttered speech. In other words, s t u t t e r i n g i s l i t e r a l l y - a d i s i n t e g r a t i o n of speech." These researchers also found generally Higher l e v e l s of laryngeal-muscle a c t i v i t y 30 during s t u t t e r i n g than during fluency, presumably because s t u t t e r i n g involves simultaneous antagonsitic adductor-abductor a c t i v i t y . Schwartz (1974) provided the d e f i n i t i v e statement of the.position that s t u t t e r i n g i s a disorder of laryngeal hypertension. During normal r e s p i r a t i o n the vocal f o l d s abduct s l i g h t l y with i n h a l a t i o n and adduct s l i g h t l y with exhalation. This abduction and adduction is~ presumably due to the contraction or i n h i b i t i o n of the p o s t e r i o r cricoarytenoid (PCA)_, one of the strongest i n t r i n s i c muscles of the larynx. Uninhibited contraction of the. PCA would probably prevent phonation by blocking or c o n s t r i c t i n g the airway. Schwartz argued that the normal supramedullary control of the PCA i s dis-r rupted during psychological stress.' Stress produces abnormalities of r e s r p i r a t i o n and the PCA responds to these with, a vigorous, inappropriate ab-ductiye response. An i n d i v i d u a l could attempt to overcome t h i s response i n several ways, e.g., f o r c e f u l contraction'of other laryngeal muscles or of the l i p s , tongue and jaw. Unfortunately, these responses produce a i r pressures which only perpetuate the excitation.of the PCA. Eventually, however, the i n d i v i d u a l does manage to speak. The consequent reduction i n stress i s thought to r e i n f o r c e the maladaptive struggle Fehaviors. While the above hypotheses about laryngeal involvement i n s t u t t e r i n g are p l a u s i b l e , they are based on insufficietnt data at t h i s time. Further research i s required to demonstrate that laryngeal hypertension i s indeed intimately r e l a t e d to the s t u t t e r i n g block. During p i l o t research I noted that s t u t t e r s were often accompanied by EMG spiking from the larynx, whereas fluency was accompanied by an absence of spiking. Similar r e s u l t s were found by Williams (1955), who placed electrodes on the masseters. I o r i g i -31 nally. attempted to investigate the temporal relationship between spikes and stutters by recording laryngeal EMG on one polygraph channel, and using the adjacent channel to record speech. Any noise at the approximate frequency of human speech caused pen deflection away from a silent baseline. Unfor-tunately, sounds other than human speech caused artifacts' which were not readily distinguishable from speech. Moreover, stuttering was often charac-terized by silent hesitations and thus was not always accompanied by pen deflections. In short, the speech, channel did not permit discrimination between fluency and stuttering, or even between speech and silence. As an alternative a tape recorder was- synchronised with, the EMG record so that the temporal relationship between stuttering and spiking could.be investiga-ted with an accuracy of a fraction of a second. The results were striking. T found that often hesitations, repeti-tions, and prolongations which, were counted as stutters were not accompanied by spiking, but most pen deflections not attributable to artifacts (e.g., yawning, swallowing) did occur during moments of stuttering. Depending on i t s severity, a single stutter may be accompanied by no spiking, by a single spike, or by more than 100 spikes. Some illustrations of the stutter-spiking relationship are given in Figure 1. These pilot data were highly encouraging. Subsequently, 'two related studies were performed to explore the relationship between stuttering and EMG spiking. Study 1 Stuttering can be reduced dramatically by rate control therapy, at Figure 1. Sample EMG recordings, a) Don ; , : .' ; Baseline, Study 3 j i i .5 SEG. i ! i 1 rr A ... ! L 32-• T'"lo"Vv~^~~T';'^-yv ^SILENCE ^ ' \ \ " 1" | ! \ \ 1 • ' \ i ; ' 1 i \ i • i • 1 '. * . 1 y \ '• : • \ \ \ A .\ "G-G-GOAL" \ ^ ' . > '. V6" SWALLOW \ ', !. \ 1 \ b) Don Biofeedback condition. Studyj3 ^ FEEDBACK THRESHOLD !.Q5 mV ' • - \ \ \\\ FLUENT SPEECH SWALLOW"'. c) Ruth, I FeedbackTwi,thout-ihstru:ctiLons (condition; Study'4 i • • i i • -i • 1 i ! FEEDBACK THRESHOLD . .025 mV: SILENCE ,1; • "M4M0THER" "F-FUTILE" i \ \ d) Rufh ,' .' ; ; ; ; ; • •' ,: J /• Metronome condition, Study 2 I 1 FLUENT SPEECH , 33 l e a s t temporarily .(Perkins, Note i>l. It was predicted that i f s t u t t e r i n g and spiking are' indeed intimately r e l a t e d , suppression of s t u t t e r i n g would be accompanied by a s i m i l a r reduction i n spiking. Method Three subjects p a r t i c i p a t e d i n t h i s study. Each received an intensive course of speech therapy from myself and four other.therapists. Five two-hour therapy sessions were held d a i l y f o r three weeks (excluding week-ends). The therapy.emphasized rate c o n t r o l , which was achieved by c a l c u l a t i n g speech rate and percent s y l l a b l e stuttered and feeding t h i s information back to the subject at the end of every f i v e minute period of speech. Increases i n fluency were rewarded monetarily, e.g., one d o l l a r f or every 10% reduction intthe percentage of s y l l a b l e s stuttered. Stutters were punished by means of a loud, aversive tone. Transfer and maintenance of fluency were emphasized during the t h i r d week of treatment, e.g., the subjects were required to move out of the c l i n i c and engage strangers i n conversation while recording t h e i r own d i s f l u e n c i e s covertly on golf counters. No attempt was made to induce the subjects to relax t h e i r speech muscles or any other muscles. Measures of disfluency and laryngeal tension were taken at the be-ginning and end of the three-week treatment. Two surface EMG electrodes were attached 2 cm b i l a t e r a l to the body ^ejafcey-jL^e^ approximately 1 cm above the thyroid prominence. A ground electrode was attached to the l e f t w r i s t . The subjects sat i n a padded armchair i n a sound-proof room, while I recorded integrated EMG data on a Beckman R411 polygraph i n an adjacent room. Head movement did not appear to produce EMG a r t i f a c t s . Cards from the Thematic Apperception Test (TAT) were used as s t i m u l i 34 Table 2 Reduction i n Stuttering as a Function of Rate Control Therapy-Subject Percent s y l l a b l e s s tuttered Pre Post i-ramc Frank 12.04 0 Rick 14.65 3.12 John 17.91 2.80 Table 3 Reduction i n EMS Spiking as a Function of Rate Control Therapy Subject EMG spikes per 100 s y l l a b l e s Pre Post Frank 50.07 3.56 Rick 71.18 5.19 John 131.54 . 0.97 35 for speech.. The subject's, task was: to speak for three minutes about the s i t u a t i o n portrayed on each card. Each subject was- exposed to f i v e randomly-^ selected cards. The same procedure was repeated at the end of the three-week treatment , except that d i f f e r e n t cards were used. No attempt was made to i n t e r p r e t the TAT responses, as- these&do not d i f f e r e n t i a t e s t u t t e r e r s from normal speakers CSheehan, 197.0.).', Results Stuttering and spiking data are presented i n Tables 2 and 3 respec-t i v e l y . Time-series analysis was not used i n t h i s study because the three-week i n t e r v a l between the pre- and post^-treatment measures allowed for h i s -t o r i c a l confounding. Instead, a one^tailed _t-test f o r re l a t e d measures was used, y i e l d i n g £(2). = 11. 52 , p_ <. 005 , f o r s t u t t e r i n g and t_C2L = 3.19, p_, <. 05, f o r spiking. Stuttering and spiking were p o s i t i v e l y correlated f o r a l l three subjects (Table 4). The mean c o r r e l a t i o n , using Fisher's. Z-rtransformation, was _r(28) = .72, p_ <.01. Study 2 Stuttering can be almost t o t a l l y suppressed by the simple expedient of i n s t r u c t i n g the subject to speak i n time with a metronome beat (Brady, 1969.; Hanna and Morris, Note 2). The r a t i o n a l e behind t h i s study was s i m i l a r to the previous one: i f s t u t t e r i n g and EMG spiking are r e l a t e d , they should covary. Method The subject (David), performed the TAT task f o r 30 minutes while l a r y n -geal EMG was recorded as i n Study 1, During the l a s t 15 minutes- the subject Table 4 Corr e l a t i o n Between Percent S y l l a b l e s Stuttered and EMG Spikes-per 100 Sy l l a b l e s In Study! J. Subject " r_ Frank .79*. Rick .78* John .52* * p_ ,<;.0.1 • Table 5 Corr e l a t i o n Between Percent S y l l a b i es Stuttered and EMG Spikes-per 100 Sy l l a b l e s i n Study- 2 Subj ect • r David .15 Ruth- ,37* Don .85** Ray .33 *p_ <,05 p_ <,01 37 spoke i n time with: a metronome set at 120:jieats: per -minute. . This study was r e p l i c a t e d with another subject (Ruth) ; then two other stutterers: (Don and Ray) performed the speech tasks- i n reverse order. This balancing strategy was used to o f f s e t the adaptation e f f e c t . Results Stutters and EMG spikes were calculated from tape recordings and polygraph records for each minute of speech. David's data are presented g r a p h i c a l l y i n Figures 2 and 3, Data f o r a l l four subjects are summarized i n Table 6. Speech rate data were not analyzed i n t h e i r own: r i g h t , because the metronome s e t t i n g of .120 beats per minute c l e a r l y produced a slowing of speech. Stuttering and spiking were s i g n i f i c a n t l y c orrelated f o r two of the subjects .'([Table 5). The mean c o r r e l a t i o n , using Fisher ^ s Z - r t r ans format ion, was £(28) = .49, p_<.01. Discussion of Studies 1 and 2 Two major conclusions can be drawn from these data. F i r s t , the rate control and metronome treatments were d r a m a t i c a l l y - e f f e c t i v e i n the short run. (An informal threes-month follow-up of the three rate control subjects revealed that one had relapsed completely, another hadrretained some improvement, and the t h i r d retained s u b s t a n t i a l improvement. The metro-nome e f f e c t , which hadbbeen even more s t r i k i n g , wore o f f within minutes.). Second, and more to the point, s t u t t e r i n g and EMG spiking appear to be p o s i t i v e l y correlated. The r e l a t i o n s h i p i s close f o r some subjects, moderate f o r others, and n e g l i g i b l e f o r two subjects, but on the whole i t i s s i g n i f i c a n t . Possibly the c o r r e l a t i o n would have been higher except f o r the f a c t that the number of spikes i s r e l a t e d to the duration of a s t u t t e r , which 38 BASELINE METRONOME w H H !=> H co CO w I J OO EH W U w C H 25 20 15 TO rv~\ 20 25 5 10 15 MINUTES Figure 2. E f f e c t of metronome on s t u t t e r i n g : David (p_<s.005), 30 39 BASELINE METRONOME 5 10 15 20 25 30 MINUTES Figure 3. E f f e c t of metronome on EMG spiki n g : David (p_< .005).. Table & Suppression of Stuttering and EMG Spiking By- Metronome Treatment Subject t(27)_ f o r change i n Percent s y l l a b l e s stuttered per l e v e l EMG spikes-100 s y l l a b l e s A A A A David 5.93 2.86 A A A A Ruth 2.85 2.18 Don .88 .79 Ray * 2.59 1.17 p_<.05 A A p_ <.005 41 i s h ighly v a r i a b l e within subjects. At any rate, the., correlation,b.etween s t u t t e r i n g and EMG spiking i s consistent with_ the laryngeal hypertension model. Laryngeal hypertension i s not n e c e s s a r i l y a cause of s t u t t e r i n g , although t h i s would make t h e o r e t i c a l sense. I t could j u s t as w e l l be an e f f e c t of the stress of Being a s t u t t e r e r . C o r r e l a t i o n a l data i s not suf-f i c i e n t to demonstrate c a u s a l i t y ; nevertheless, the degree of concomitant v a r i a t i o n I have found was s u f f i c i e n t to j u s t i f y further research, i n t h i s vein. The next step was an attempt to demonstrate the converse of what had Been achieved here, v i z . , to reduce EMG spiking i n the hope that s t u t t e r i n g would be concurrently reduced. 42 CHAPTER IV . FEEDBACK OF ELECTROMYOGRAPHIC ACTIVITY At l e a s t three independent l i n e s of research suggest that i t may be possible to reduce s t u t t e r i n g with biofeedback. The f i r s t of these, which was the most i n f l u e n t i a l i n i n i t i a t i n g the present seri e s of studies, i s simply that EMG feedback has already been applied s u c c e s s f u l l y to a host of s t r e s s - r e l a t e d disorders (e.g., Raskin, Johnson & Rondestvedt, 1973). Ad d i t i o n a l impetus and d i r e c t i o n was provided by the laryngeal hypertension model (Schwartz, .1974). F i n a l l y , the p o s s i b i l i t y that s t u t t e r i n g involves defective feedback (Mysak, .1960) implies that enhanced proprioceptive feed-back might suppress s t u t t e r i n g . - ;Tt xwaS anticipate*-- aiat i f biofeedback were e f • ;-a greater (more di r e c t ) e t t e c t on spiking than on s r u c i -P i l o t f o r Study 3 Method A s i n g l e subject (John) p a r t i c i p a t e d i n t h i s study. EMG was recorded from the throat as described i n Study 1, while the subject performed the TAT task. After a baseline period of nine minutes of speech, auditory feed-back was presented through a speaker at the subject's si d e . The feedback consisted of a tone whose frequency va r i e d i n proportion to the amplitude of the EMG s i g n a l . The feedback apparatus i s i l l u s t r a t e d i n Figure 4. The subject was t o l d that the feedback tone r e f l e c t e d tension i n h i s speech muscles: the greater the tension, the higher the p i t c h . o f the tone. His task was to produce a low frequency tone as often as p o s s i b l e , j u s t as 43 A C PRE-AMPLIFIER LOW PASS FILTER 5 Hz HIGH PASS FILTER 10 Hz AMPLIFIER EMG PRINTOUT <-L J. j BECKMAN R411 POLYGRAPH Experimenter INTERCOM Subject AUDIO . FREQUENCY MODULATOR SPEAKER TAT TAPE RECORDER SOUNDPROOF CHAMBER Figure 4. EMG feedback system. 44 one learns to control the amount of pressure exerted .on an automobile ac-celerator by l i s t e n i n g to the sound of the motor. The subject was not t o l d how to relax his- speech, muscles; he was-merely instruc t e d to t r y to do so. Stuttering /was not mentioned e x p l i c i t l y . The biofeedback e f f e c t was demonstrated by having the subject swallow several times. He p r a c t i c e d tensing and.relaxing h i s throat, without .speaking for about a minute and: a half,, u n t i l he was able to vary the p i t c h of the'. . tone at w i l l . , Then the .subject practiced saying his. name, address, etc, several times, .noting changes i n the pitch, of ;the tone as he blocked on these words.. Within, two and a h a l f minutes, he was able to chat without s t u t t e r i n g severely.and without greatly i n c r e a s i n g the frequency of the tone. A f t e r , this b r i e f p r a c t i c e period the ^subject resumed the TAT task as before, with., the -tone on. He was t o l d that the feedback .would-be turned on and off,.inter-,. m i t t e n t l y while he .spoke. A complete ,on--off cycle comprised :six- cards . (18 minutes) ., .The session was concluded\after the subject had. completed speaking about .the f i f t e e n t h card. Results and Discussion . Stuttering data are i l l u s t r a t e d t i i n Figure 5, and s t a t i s t i c a l analyses for a l l three dependent v a r i a b l e s are summarized i n Table 7. The f i r s t com-z parison, v i z . , the f i r s t baseline vs. the f i r s t feedback period, i s a t y p i c a l i n that a four minute i n t e r v a l occurred between these conditions. Fortunately, the r i s k of h i s t o r i c i l confounding during such. a.brief i n t e r v a l is. s l i g h t , . The second comparison must also, be interpreted .cautiously because of the p o s s i b i l i t y of carryover of the biofeedback, e f f e c t from the f i r s t feedback. . period into the .second baseline period. If t h i s occurred i t would tend to 45 BASELINE 1 PRACTICE FEEDBACK 1 5 10 15 20 MINUTES BASELINE 2 FEEDBACK 2 BASELINE 3 -i 1 1 1 r-25 30 35 40 MINUTES Figure 5. E f f e c t of EMG feedback on s t u t t e r i n g : John (From Hanna et a l . , 1975). 46 Table 7 Effects, of EMG Feedback.; P i l o t Study t_Q5). f o r change i n l e v e l Percent EMG spikes. Speech, rate. Comparison s y l l a b l e s stuttered per J.00 s y l l a b l e s (SPM)_. Baseline .1 vs. Feedback! 4.66** 2.31* 1.86* Baseline 2 vs. Feedback 2 1.80* . 1.14 .43 * p_<; .05 **£P_< .0005 47 obs cure the re v e r s a l e f f e c t , and thus the time s e r i e s s t a t i s t i c may be con-servative. In s p i t e of these q u a l i f i c a t i o n s , i t appears that the feedback treatment was accompanied by a s i g n i f i c a n t decrease i n s t u t t e r i n g both, times. EMG spiking was s i g n i f i c a n t l y reduced the f i r s t time, but not the second.. The subject's speech, rate appeared to increasev^the f i r s t time, but did not increase during the second a p p l i c a t i o n of feedback. I t can be concluded t e n t a t i v e l y that the feedback e f f e c t was not dependent on slowing of speech. Other time s e r i e s comparisons- of l e s s e r i n t e r e s t , e.g,, the second feedback period vs. the t h i r d baseline, were not analyzed s t a t i s t i c a l l y be-cause of the problems inherent In using the t_ d i s t r i b u t i o n to make multiple comp a r i s ons. among/me ans; Study 3 The re s u l t s of the p i l o t study were s u f f i c i e n t l y - encouraging that an attempt was made to r e p l i c a t e these findings several times. The rever s a l design used i n the p i l o t study was abandoned because of the d i f f i c u l t y of in t e r p r e t i n g carryover e f f e c t s . The pr a c t i c e I n t e r v a l between the baseline and feedback periods was also eliminated. Each-period was lengthened to 15 minutes i n order to increase the power of> the time s e r i e s , , s t a t i s t i c . Method The general procedure was s i m i l a r to that used i n the p i l o t study. The subject (Don) was ito&d that a f t e r a baseline period of 15 minutes, of speech, an auditory feedback tone would be presented through, a speaker at his side. Again, the feedback tone increased In frequency-Tn proportion to the amplitude of the EMG s i g n a l . This was accomplished by> using the ampll^-48 f i e d EMG s i g n a l to power a tone generator. Below a c e r t a i n amplitude, the tone shut o f f e n t i r e l y . I t was explained to the subject that the tone r e f -lected tension In h i s speech muscles: the greater the tension, the higher the p i t c h of the tone. The subject's task was to t r y to turn the tone o f f , or at l e a s t to produce a low-r-pitched tone sas often as p o s s i b l e . These i n -st r u c t i o n s had to be given at the beginning of the experiment, rather than at the end of the baseline period, because the time—series design did not permit an Interruption between baseline and treatment periods. (Verbatim i n s t r u c t i o n s are given i n Appendix D.)_ Laryngeal EMG was recorded as i n the previous studies while the subject performed the TAT task. The study took 30 minutes: 15 minutes of baseline speech, followed immediately by a J.5 minute period during which the feedback was i n operation. This study was* r e p l i c a t e d with four other subjects. Results Data f o r the f i r s t subject (Don), are i l l u s t r a t e d g r a p h i c a l l y i n F i -gures 6 and 7. Biofeedback resulted i n a s i g n i f i c a n t reduction i n s t u t t e r i n g , but not i n EMG spiking, f o r t h i s subject. The c o v a r i a t i o n i n s t u t t e r i n g and spiking i s noteworthy nevertheless. S t a t i s t i c a l analyses of the stut^-ter l n g and spiking data for a l l f i v e subjects are summarized i n Table 8 . Ruth's s t u t t e r i n g data (Figure - 8 ) . i l l u s t r a t e the value of t e s t i n g the s i g s -n i f i c a n c e of time ser i e s data. The treatment e f f e c t appears highly s i g n i f i -cant because there was no s t u t t e r i n g at a l l i n the biofeedback period. However, closer inspection reveals that there was a high degree of spontaneous f l u c t u a t i o n i n the baseline data, and that seven of the 15 baseline observa-tions were zero. In short, biofeedback did not reduce RuttL's s t u t t e r i n g 49 BASELINE FEEDBACK 5 10 15 20 25 30 MINUTES Figure 6. E f f e c t of EMG feedback on s t u t t e r i n g : Don (p_•<, .05).. 50 BASELINE FEEDBACK MINUTES F i g u r e 7. E f f e c t of feedback on EMG s p i k i n g : Don CNot s i g n i f i c a n t ) . 51 Table 8 E f f e c t of EMG Feedback on Stuttering and Spiking tp.1) f o r change i n l e v e l Subj ect Percent s y l l a b l e s stuttered EMG spikes per .100 s y l l a b l e s Don * 2.24 .91 A ** David 2.61 2.97 Ray .86 .30 ** Ruth .63 3.37 ** Larry 1.27 6.32 £ <-05 p <.005 5 2 Figure 8. E f f e c t of EMG feedback on s t u t t e r i n g : Ruth (Not s i g n i f i c a n t ) . 53 s i g n i f i c a n t l y . Nevertheless-, s t u t t e r i n g was- s i g n i f i c a n t l y - reduced b.y- Biofeedback i n two out of f i v e cases-. Spiking was reduced i n three cases. Speech rate data are given i n Table 9.. One of the f i y e subjects showed a s i g n i f i c a n t reduction i n speech, rate* during the. feedback, condition. Discussion • The biofeedback e f f e c t appears to Be a promising one: four out of s i x subjects (including the p i l o t s u b j e c t ! achieved reductions i n spiking i n a s i n g l e session and three achieved reductions In stuttering..- ' This?- e f f e c t i s p a r t i c u l a r l y s u r p r i s i n g i n view'of the f a c t that a l l s i x suEjects were chronic s t u t t e r e r s who haddheen treated-unsuccessfully in- the past. Moreover, the l a s t f i v e subjects did not have the advantage of a p r a c t i c e i n t e r v a l between the baseline and feedback periods, yet three of them .showed an abrupt treatment e f f e c t . This learning e f f e c t was achieved without reinforcement other ithaft knowledge of the r e s u l t s . Only one subject appeared to slow his.speech during -the feedback treatment. This may have been a response to the novelty.of the feedback task. I t can be concluded t e n t a t i v e l y that, the feedback, e f f e c t was, not an a r t i f a c t of rate control. , F u r t h e r . r e p l i c a t i o n s of the feedback e f f e c t may- be found i n Study 5 . Table 9 E f f e c t of EMG Feedback on Speech Rate Subject tC27). f o r change i n l e v e l Speech rate (SPM) Don .1.09 * David 1.80 Ray- .39 Ruth. .73 Larry .66 p_ <.05 •55 CHAPTER V FEEDBACK WITHOUT INSTRUCTIONS Study 4 It appears that feedback t r a i n i n g can be used e f f e c t i v e l y to modify a given p h y s i o l o g i c a l response, even when the subject has not been informed which response he i s supposed to modify. Beatty Q972) reported that merely i n s t r u c t i n g his subjects to increase the loudness of a tone (which was r e -l a t e d to EEC a c t i v i t y ) resulted i n s i g n i f i c a n t changes-in the proportion of alpha and beta a c t i v i t y , although the subjects- were not informed that EEC was- the dependent v a r i a b l e of i n t e r e s t . Ascough, and S i p p r e l l e 0-968! and others have reported s i m i l a r r e s u l t s w i t h heart rate conditioning. I t would be of r e l a t i v e l y l i t t l e i n t e r e s t to r e p l i c a t e t h i s "feedback without i n s -formation" e f f e c t i n the present s e r i e s of studies. However, a r e l a t e d and unexplored problem concerns the e f f e c t of i n s t r u c t i o n s (to reduce the p i t c h of the tone) as d i s t i n c t from information (that the.tone i s r e l a t e d to mus-cle tension). Instructions are presumably a necessary component of the feedback e f f e c t reported i n Study 3, i f i t i s indeed authentic, feedback without i n s t r u c t i o n s should not he accompanied by a reduction i n s t u t t e r i n g and EMG spiking. If i t were, we should have to conclude that the "hiofeed-s-back" e f f e c t was an a r t i f a c t of the presentation of the tone I t s e l f , rather than being due to enhanced information about laryngeal muscle a c t i v i t y . I t has been reported that s t u t t e r i n g can be reduced by presentation' of a loud averslve tone (Barr & Cannel, 1969; Biggs & Sheehah, .1969; Flanagan, Goldiamond & A z r i n , 19581. However, the f a c t that t h i s e f f e c t occurs whether 56 the tone i s presented at random or contingent upon s t u t t e r i n g suggests that i t may be an a r t i f a c t of masking. Masking i s not a f e a s i b l e explanation of the present biofeedback e f f e c t , because the EMG feedback tone i s too• .high-pitched and i n s u f f i c i e n t l y loud to mask the frequencies of speech. Method The subject (Rick) performed the TAT task f o r 30 minutes, while EMG and s t u t t e r i n g data were recorded as usual. At the end of the 15T minute baseline period, I announced: "From now on you w i l l hear an Intermittent high-pitched tone while you are speaking. Continue t a l k i n g about the p i c -tures as before." When 30 minutes of speech had been recorded, the subject was questionedd to see i f he had perceived the function of the tone (see Appendix E). F i n a l l y the subject was debriefed about the true purpose of the experiment. This procedure was repeated i n two more single-subject studies. (The subjects were Frank and Ruth. .One week l a t e r , Ruth p a r t i c i p a t e d i n Study 3). Three other subjects (Teresa, Doug, Ron) received the feedback-without-i n s t r u c t i o n s treatment f i r s t , followed by a .15 minute period without feed-back. (This precaution against the adaptation e f f e c t may- have' been unneces-sary, i n view of the f a c t that the.ttime-series s t a t i s t i c does attempt to accomodate trends i n the data. Results Stuttering and spiking data for the f i r s t subject.(Rick): are giyen i n Figures 9 and 10 respectively-. Data for a l l s i x subjects-are summarized i n Table 10. Results were s i g r i i f l e a n t f o r two subjects: Frank showed an i n -crease i n s t u t t e r i n g and spiking during the feedback condition and Teresa 57 10 15 20 25 30 MINUTES Figure 9. E f f e c t of feedback without i n s t r u c t i o n s on s t u t t e r i n g : Rick CNot signifi c a n t ) . . 58 Figure 10. E f f e c t of feedback without i n s t r u c t i o n s on EMG s p i k i n g : Rick CNot s i g n i f i c a n t ) . Table 10 E f f e c t of Feedback Without Instructions on Stuttering and EMG Spiking _tC27) f o r change i n l e v e l Percent s y l l a b l e s EMG spikes Subject y , stuttered • per 100 s y l l a b l e s Rick .83 .45 * Frank 1.78 . 2.01 . Ruth .06 .52 * Teresa 1.23 1.83 Doug .66 .19.. . Ron .66 .88 p <.05 60 showed an increase i n spiking;.. The i n s i g n i f i c a n t r e s u l t s f o r the other fi v e , subjects" were, i n Both d i r e c t i o n s : there were two increases :and three decreases i n s t u t t e r i n g during the feedback condition,, and three increases . , and, one .decrease i n spiking., Speech rate data are given i n Table ,11,. Feedback without i n s t r u c -tions, produced no s i g n i f i c a n t change- In speech, rate for" any of the. s i x sub-j ects'. None of the subjects-were aware that, the tone.reflected laryngeal muscle tension. One subject (Ru'th). commented, " I t squeaks when.I swallow.". None.of the subjects reported that the tone made any d i f f e r e n c e to their,' speech. Discussion . Instructions, appear to be a necessary component of the feedback, e f f e c t reported i n Study 3. Feedback without i n s t r u c t i o n s did hot. produce . a reduction.in spiking,and s t u t t e r i n g , i n f a c t , i t apparently-tended;to.in-crease them. This may have been due.to the alarming nature of the tone.per se-,'. or to the f a c t that i t s function was, not explained, , I f the former hy-r pothesis i s correct, feedback by means, of a v i s u a l s i g n a l might be l e s s , alarming and more e f f e c t i v e than auditory feedback. At any:.rate, the feedback e f f e c t appears not to be an a r t i f a c t of masking or of the presentation of a loud-, aversive tone. The findings that - feedback, without instructions.- produced no\ s i g n i f i-?. cant changes i n speech rate, regardless of i t s effeet,on s t u t t e r i n g and • spiking, supports - a similar, f i n d i n g i n Study 3. We have concluded that i n s t r u c t i o n s are necessary. The f i n a l study i n t h i s series'addresses i t s e l f to the question: "Are i n s t r u c t i o n s s u f f i c i e n t ? 61 Table 11 E f f e c t of Feedback Without Instructions on, Speech Rate t_G27l f o r change i n l e v e l Subject Speech rate (SPM) Rick .47 Frank 1.19 Ruth .25 Teresa .59-Doug .64 Ron .52 62 CHAPTER VI FALSE FEEDBACK The r e l a t i v e ease with which, s t u t t e r i n g can be manipulated i n the laboratory has given r i s e to numerous f a l s e leads i n the search.: for' an e f -f e c t i v e treatment (Van Riper, 19731. Martin and Siegel (1966) demonstrated ; that merely i n s t r u c t i n g t h e i r subjects -to• MRead;.more c a r e f u l l y " and-.to "say-each word f l u e n t l y " r e s u l t e d . i n a reduction i n s t u t t e r i n g . Likewise, simply• c a l l i n g a s t u t t e r e r ' s attention to his d i s f l u e n c y w i l l sometimes decrease i t temporarily (Wingate, 1959).. s .Thus the e f f e c t of instructlonsr.needed to be investigated i n the present s e r i e s of experiments. Likewise, the placebo effect-had to be c o n t r o l l e d . The i n i t i a l "success"-of several questionable treatments used i n the past:suggests that the attention given and hope aroused during any novel:treatment f o r s t u t - , ter i n g may w e l l haVe an e f f e c t on fluency. A r e l a t e d problem -concerns the Hawthorne e f f e c t , i . e . , the p o s s i b i l i t y that changes In s t u t t e r i n g and/or spiking.may be due to the subject's awareness: of the experimentation rather than to the s p e c i f i c nature.of the,treatment. The aim of the present research, was, to e s t a b l i s h a p o t e n t i a l l y permanent psychophysiological e f f e c t rather than a transient, purely p s y c h o l o g i c a l - e f f e c t . The s t u t t e r e r ' s fund of'hope i s too small to be wasted. In s t r u c t i o n , placebo and Hawthorne e f f e c t s could a l l be "ruled out i f pseudofeedback were found to be ineffective'. 63 P i l o t f o r Study 5 . Method. The subject i n - t h i s .study (John), had had previous experience i n feedback-training, i . e . , he had p a r t i c i p a t e d i n the p i l o t f o r Study 3 a week e a r l i e r . Stuttering and spiking.data were recorded as usual while the subject performed the TAT task. • Af t e r a nine minute baseline and a b r i e f s p r a c t i c e period, genuine feedback was-given : f o r nine minutes, s This was fol4-lowed by a second nine minute baseline, then nine minutes of f a l s e feedback and f i n a l l y nine more minutes of genuine feedback. False feedback was ac^r complished simply by recording EMG f rom'-another subject i n an.adjacent room and presenting.this person's feedback to John, ostensibly- as.his own. Results and Discussion . S t a t i s t i c a l analyses for a l l three dependent v a r i a b l e s are summarized i n Table 12. .Changes i n the frequency of John ?s s t u t t e r i n g are i l l u s t r a t e d i n Figure 11. . I t appears that s t u t t e r i n g was reduced to about 50% of base-l i n e during the f i r s t feedback period.' "Spiking was concurrently reduced. .. False feedback reduced s t u t t e r i n g and - s p i k i n g ' s l i g h t l y , but,not s i g n i f i c a n t l y . This s l i g h t reduction may have been due to the f a c t that the s u b j e c t j who • had already had some exposure to feedback t r a i n i n g i n the p i l o t .for Study: 3, < was e s s e n t i a l l y receiving random signals to relax h i s throat muscles during the f a l s e feedback condition. Moreover, he kept complaining during the l a t -ter period that " t h i s thing i s n ' t ;adjusted •right1.', which suggests that he had indeed acquired some degree of awareness of his. laryngeal muscle a c t i v i t y . The subject appeared to increase his speech rate during the f i r s t genuine feedback period, but not/during the f a l s e feedback, period., This i s Table 12 E f f e c t s of Genuine"and False Feedback: P i l o t Study-; £p-5)„ f o r change i n l e v e l Percent EMG. spikes.. Speech, rate Comparison s y l l a b l e s s t u t t e r e d , per 100 s y l l a b l e s (S?M)_. Baseline .1 vs, Feedback! . 2.86** 1.91* 3.96* BaBaseMne. .2svs. False Feedback 1.30 1.59. .'1.04 * _p_,^  .05 ** p_ < .01 65 BASELINE 1 PRACTICE GENUINE FEEDBACK 1 T I 1 ' I 5 10 15 20, 25 MINUTES Figure 1 1 . E f f e c t of genuine and f a l s e feedh.ack. on s t u t t e r i n g : John CFrom Hanna et a l . , 1975)_. 66 consistent with e a r l i e r findings that feedback-induced fluency i s not accom-panied by a reduction i n speech rate. These conclusions- are subject to the q u a l i f i c a t i o n s , discussed i n the p i l o t f o r Study 3. Study- 5 The re s u l t s of the p i l o t study were encouraging but inconclusive, . so I attemptedtto r e p l i c a t e these findings several times, w i t h methodological refinements. Method' EMG and s t u t t e r i n g were recorded as usual while the subject (Eric), performed the TAT task. A 15 minute baseline was followed immediately by 15 minutes of genuine feedback. (No p r a c t i c e i n t e r v a l occurred between these periods, as i n the p i l o t study-. 1 'Following a J-0>minute_bTreak, there was a. second baseline period followed by J.5 minutes of f a l s e feedback. The -10 minute break was given i n order to reduce the p o s s i b i l i t y of multiple treatment interference, 1.e., carryover of fluency from the genuine feedback session into the f a l s e feedback session. vThe subjectTreeemved exactly the same i n s t r u c t i o n s f o r f a l s e feedback as f o r genuine feedback (Appendix Di, 'False feedback was achieved By. presenting each- subject with, feedback of h i s own EMG a c t i v i t y , but with, a delay of 30 seconds.. This was r e a d i l y accomplished manually: I simply copied each subject's EMG record on a second channel of the polygraph, at a lag of 30 seconds, By manipulating the "centre" control. Deflections of the pen on this- a r t i f i c i a l EMG channel powered the tone generator. The f i d e l i t y with-which- the f a l s e EMG record resembled the 67 genuine record i s . i l l u s t r a t e d i n Figure 12. The auditory, s i m i l a r i t y was even more s t r i k i n g . While l i s t e n i n g to':tapes of this; e x p e r i m e n t I found i t d i f f i c u l t to d i f f e r e n t i a t e Between genuine and f a l s e feedback.conditions on the .Basis ,of sound alone. , This: type of f a l s e feedBack was superior to that used.in the p i l o t study i n t h a t , i t .resembled genuine feedBack jnore closely, and did not require a confederate suBj.ect. The suBject was questioned a f t e r t h i s study i n order to ascertain his degree of awareness of the experimental manipulation (Appendix E), and then was, deBriefed aBout the true nature.of the experiment. The procedure . was repeated i n the .same order for two other suBjects (Teresa and Doug)., and .then r e p l i c a t e d three more times ( J e f f , Ron and Susan! i n counterBalanced . order, i . e . , f a l s e feedBack preceded genuine feedBack. Results The e f f e c t s of genuine and f a l s e feedBack were tested f o r signi-r ficance against t h e i r respective Baselines rather than against each, other, , Because of the p o s s i B i l i t y of h i s t o r i c a l i n v a l i d i t y - and multiple-rtreatment interference. The 10 minute Break at half.time appears ,to have Been s u f f i -cient to allowtstuteteringnand^spi^^ Baseline (e.g., Figure 13). Doug reduced Both, this s t u t t e r i n g and spiking with., genuine feedBack (TaBle J.3).. The reduction i n o E r i c ' s. EMG spiking during genuine feedBack f e l l short of s i g n i f i c a n c e : t_(28)l =^T.64, xp_ <.06. Genuine feedBack was sometimes e f f e c t i v e when i t preceded f a l s e feedBack, But never when i t followed f a l s e feedBack. False feedBack was remarkaBly i n e f f e c t i v e : i t reduced .spiking only-once In s i x cases, and did not reduce.stuttering . at a l l . -6.8 Figure 12. Sample EMG recordings from Study 5. a) J e f f / Baseline •,'.'!•'' /e;5 S E C . ' ; ' ' • FLUENT SPEECH. ! '! ''".'.!•' b) J e f f : i •'!'!' . True EMG record .during false' feedback; condition , ! I I i I r . . ........f c) J e f f /.....•/.. Manually pperateci false; feedback ; - / j I FEEDBACK THRESHOLD .05 mV dl Jeff,: •';'//•/• / Genuine feedback condition^ I • j FEEDBACK. THRESHOLD .05 mV; 1 . I n t h i s i T l u s t r a t i o n the •feedback tone was activated only once, i . e . , when the pen deflection.exceeded the threshold. 69 BASELINE 1 GENUINE FEEDBACK t — i r1 1 1 r-5 .10 15 20 25 30 MINUTES 3 w H H 1= H c n co W iJ sa >> CO H W u w BASELINE 2 FALSE FEEDBACK 20-10-40 — i — 45 50 —r 55 60 65 70 MINUTES Figure 13. E f f e c t of genuine and f a l s e feedback on s t u t t e r i n g : Doug (p_^.005 f o r genuine feedback; f a l s e feedback not s i g n i f i c a n t ) . 70 Table 13 E f f e c t of Genuine and Ealse Feedback on Stuttering and EMG Spiking _t(27) f o r change i n l e v e l Order of Percent s y l l a b l e s EMG spikes Subject treatments stuttered per 100 s y l l a b l e s E r i c genuine J .21 1.64 f.'aMee • 1.05 .77 genuine .04 .45 Teresa f a l s e .06 .04 genuine ** 3.32 1.75! Doug f a l s e .70 1.35 f a l s e 1.26 2.27' J e f f genuine .95 .88 f a l s e .39 .20. Ron genuine genuine .93 .77 f a l s e 1.31 .39 Susan genuine .70 .32 71 Speech rate data are given i n Table 14. Only two of the 12 com- . . parisons were s i g n i f i c a n t : E r i c ' s speech, rate decreased under f a l s e feedr-, back, while Ron's increased under genuine feedback. Generally, neither type of :feedback had a consistent e f f e c t on speech.,rate. Two subjects CDoug and Eric), detected a diffe r e n c e between genuine and f a l s e feedback. Doug stated, "Even whenT was relaxed the second time, that thing s t i l l squeaked ... I couldn't control i t as w e l l the second time." E r i c claimed that i t was equally d i f f i c u l t to co n t r o l the genuine and f a l s e feedback tones. The other four subjects reported that the tones made no . difference to t h e i r speech, which-was generally true. Susan claimed that, she was able to control the tone, which, was not true. , The subject who was able .to .control the genuine feedback tone s u c c e s s f u l l y was, unable to a r t i -culate how he did so, except i n vague terms, e.g., "L j u s t concentrated on i t and t r i e d to r e l a x " T@ou'gl;.' Discussion This study (and i t s p i l o t ) , demonstrated that a b r i e f period of genuine feedback t r a i n i n g was sometimes e f f e c t i v e i n reducing s t u t t e r i n g and EMG spiking. And i f any more evidence were needed, the feedback e f f e c t appeared independent of speech, rate. These conclusions are consistent with, those of . Study 3. False feedback was generally i n e f f e c t i v e . Moreover, genuine feed^ back was i n e f f e c t i v e i n the three cases i n which, i t was preceded by f a l s e feedback. This suggests that f a l s e feedback may have i n t e r f e r e d with subse-quent genuine feedback t r a i n i n g , because of negative t r a n s f e r . Unfortunately-, the data are not s u f f i c i e n t l y strong to support t h i s l i n e of speculation. 72 Table 14-E f f e c t of Genuine and False Feedback on Speech. Rate _tC27) for change i n l e v e l Speech rate ($ml Speech, rate (STM). Subject under genuine feedback under f a l s e feedback E r i c .29 ** 2.87 Teresa 1.29 .55 Doug .35 1.53 J e f f .30 .63 , Ron * 1.83 . 1.19L Susan .04 .03 ' _p_<.05 £ <.005 73 The f a l s e feedback- control condition allows, us to discount the pos-s i b i l i t y that any changes i n s t u t t e r i n g or spiking were due to concentra-t i o n on the task of c o n t r o l l i n g the tone, or to d i s t r a c t i o n of the subject's attention away from his speech. Although d i s t r a c t i o n has often.been i n -voked as an "explanation" of treatment e f f e c t s i n the s t u t t e r i n g l i t e r a -ture, i t has r a r e l y been defined .operationally. Moreover, Thompson (1971) demonstrated i n a se r i e s of unpublished studies':that d i s t r a c t i n g tasks do not reeuce s t u t t e r i n g s i g n i f i c a n t l y . In summary, the f a l s e feedback control condition allows us to con-clude that the biofeedback e f f e c t was. not a t t r i b u t a b l e to a placebo dr Hawthorne e f f e c t , nor was i t an a r t i f a c t of i n s t r u c t i o n s , masking d i s t r a c -t i o n or rate control. 74 CHAPTER VII CONCLUSION In retrospect, i t may Be seen that there were several i n d i c a t i o n s that feedBack of EMG act i v i t y ; should have worked as w e l l as i t did. EMG feedBack has already Been applied e f f e c t i v e l y to several other s t r e s s - r e l a -ted disorders, e.g. , insomnia, tension headaches and chronic anxiety, More-over, one of the leading theories of s t u t t e r i n g suggests that s t u t t e r e r s s u f f e r from defective feedBack about t h e i r own speech-, and thus enhanced feedBack of laryngeal muscle a c t i v i t y would seem to Be an appropriate remedy. F i n a l l y , the fledging model of s t u t t e r i n g as a disorder of excessive l a r y n -geal muscle tension c e r t a i n l y Implies that feedBack-induced r e l a x a t i o n might Be therapeutic. The r e s u l t s of t h i s s e r i e s of studies support the laryngeal hyper-tension model i n tplprticular. EMG spiking from the throat, which- d i f f e r e n -t i a t e d Between s t u t t e r i n g and fluency, was found to co r r e l a t e p o s i t i v e l y with s t u t t e r i n g ( S t u d i e s ! and 2)_, Suppression of s t u t t e r i n g as a r e s u l t of rate-co n t r o l therapy and metronome-paced speech resulted i n a p a r a l l e l sup-pression of EMG spiking (Studies 1 and 2)_. The d i f f e r e n c e i n s t u t t e r e r s ' EMG a c t i v i t y Before and a f t e r these treatments was- s t r i k i n g ; the post-treatment EMG records (e.g.. Figure l ( d ) X are i n d i s t i n g u i s h a B l e from those of f l u e n t speakers. Suppression of EMG spiking witb_BiofeedB.ack- resulted i n concurrent reductions i n s t u t t e r i n g (Studies 3 and 5). These data certainly-implicated the larynx as a locus of the s t u t t e r i n g Block, although not neces-s a r i l y the only locus: . a i r f l o w Blockage could also occur.at the l i p s or at .the front or Back of the tongue (Van Riper, 1971)-. 75 The present r e s u l t s are also consistent with the feedback model of s t u t t e r i n g : several subjects did become more fluen t when t h e i r somesthetic feedback was enhanced. Moreover, t h i s e f f e c t can be interpreted w i t h i n an operant framework, e.g., the proportion of low amplitude EMG signals was increased through negative reinforcement, v i z . , termination of an aversive auditory stimulus. The spontaneous: comments of some subjects: leave l i t t l e doubt that the tone was aversive f o r them. A t o t a l of twelve subjects received feedback t r a i n i n g i n Studies 3 and,5. Four subjects achieved s i g n i f i c a n t reductions i n s t u t t e r i n g , and f i v e reduced t h e i r EMG spiking s i g n i f i c a n t l y . The feedback e f f e c t was also r e p l i -cated twice within one subject, w i t h p o s i t i v e r e s u l t s . These re s u l t s may be conservative, because the timer-series s t a t i s t i c i s s e n s i t i v e to immediate changes only, i . e . , changes occuring i n the f i r s t minutes of feedback t r a i n i n g . Indeed, the strongest e f f e c t was achieved by the p i l o t subject, who was al^-lowed to p r a c t i c e manipulating the feedback:tone f o r a few minutes between baseline and feedback periods. Nevertheless, some subjects attained p o s i t i v e r e s u l t s r a p i d l y without t h i s advantage. There are a d d i t i o n a l reasons why these results, may be conservative. For one thing, the length of each EMG spike was not taken i n t o account. In theory, a subject could have reduced.the amplitude of h i s EMG spikes by 50% during the feedback treatment, yet t h i s would not n e c e s s a r i l y be r e f l e c t e d i n the frequency of spikes which exceeded the feedback threshold. I t would be a tedious task to measure the lengths of about ten thousand spikes, so t h i s hypothesis has not been tested. However, v i s u a l inspection of the EMG re-r cords of some subjects-does not discourage t h i s l i n e of speculation. '<.. 76 The strength of the feedback e f f e c t may also have been l i m i t e d by the f a c t that the subjects were drawn from a waiting l i s t f o r a therapy about which they.had high expectations.' This might have.tended to l i m i t t h e i r enthusiasm f o r the biofeedback treatment. Moreover\ the subjects, were a l l chronic and severe s t u t t e r e r s who had h i s t o r i e s of unsuccessful speech therapy. Laryngeal hypertension during s t u t t e r i n g must be a very minute and grossly overlearned response, yet nearly h a l f of the subjects were apparently.able to make f i n e adjustments of t h e i r speech, musculature on the basis of a mere 15 minutes of auditory feedback. This i s indeed a promising trestment e f f e c t . It i s not immediately apparent why some subjects were able to master the biofeedback task while others were not. There are no well-estab-l i s h e d prognostic i n d i c a t o r s i n the biofeedback l i t e r a t u r e . Perhaps the most l i k e l y explanation i s that the 15 minute feedback period was simply too b r i e f f o r some subjects. The EMG feSdbaekheffeet appears to be an authentic.one, rather than an a r t i f a c t of some other condition that reduced s t u t t e r i n g . The importance of monitoring speech rate during any treatment f o r s t u t t e r i n g has been stressed by Perkins (1975). i n Studies 3 through.4, 27 tests of s i g n i f i c a n c e f o r change i n speech rate were.performed. Two subjects were found to increase t h e i r speech rate, while two others decreased t h e i r s . . I t can be concluded that feedback e f f e c t i s not generally accompanied by, much less a r e s u l t of, slowing of speech. Information that the feedback tone i s rela t e d to laryngeal muscle tension, plus i n s t r u c t i o n s to reduce the p i t c h of the tone, appear to be necessary (Study 4), but not s u f f i c i e n t (Study 5). Thus the feedback e f f e c t 77 i s not a t t r i b u t a b l e to i n s t r u c t i o n s alone, nor i s i t merely a case of reduc-t i o n of s t u t t e r i n g by means of a contingent aversive tone. False feedback did not reduce s t u t t e r i n g for any of the seven subjects who received i t , nor did i t reduce EMG spiking i n s i x out of seven cases, i t can be con-r eluded, then, that the feedback e f f e c t i s not a placebo oriHawthorne e f f e c t , nor i s i t an a r t i f a c t of d i s t r a c t i o n or masking (Study 5L. The r e l a t i v e l y high degree of observer agreement on the dependent measures i n s p i r e s some confidence i n these r e s u l t s . Moreover, the s t a t i s -t i c a l tests which support the above conclusions were not based on the sma!ibnumber'.of esubjeegsyinoeachastudy^.-but rather ono the 30-60 data points in-eachdtime-series .reLTihis is;.an, exSmp-leijoif3:the?cWayi on.which a small number of r e l a t i v e l y rare subjects can be used e f f i c i e n t l y . I disagree with- the opinion of Johnson and Lubin 0-9721 that we need not use s i g n i f i c a n c e tests i n single-subject psychophysiological experiments. The ease with, which, errors of inference could a r i s e from v i s u a l inspection of the data i s i l l u s -trated i n Figures 7 and 8. At t h i s point, biofeedback can be said to have joined several other treatments which reduce s t u t t e r i n g . Similar laboratory e f f e c t s have been demonstrated for masking noise (Cherry & Sayers, 1956), delayed auditory feedback (Goldiamond, .1965) and metronome-paced speech. (Fransella &.Beech, 1965). Unfortunately, none of the l a t t e r treatments have much carryover from laboratory to l i f e , and thus they have not f u l f i l l e d t h e i r therapeutic pro^-mise. The prospects for biofeedback as speech therapy appear more encoura-r ging. Probably the feedback e f f e c t could be made stronger and more durable. 78 Shaping (i.e..', varying the EMG amplitude at which, the feedback, tone i s ac-ti v a t e d or becomes high-pitched), could be used to make feedback t r a i n i n g easy at f i r s t , then progressively more challenging. As feedback was faded out, the s t u t t e r e r would presumably be forced to r e l y i n c r e a s i n g l y on somes-r th e t i c cues. Manipulation of the volume and frequency range of the feedback tone might also enhance feedback t r a i n i n g . Non-auditory-modalities (e.g., a v i s u a l display of red, green, and amber l i g h t s ) might be used instead of, or i n conjunction with., the auditory tone. Indeed, there Is a s l i g h t I ndica-t i o n that the aversive feedback tone i t s e l f may have tended to disrupt the speech of some subjects (Study 4)1. Back-rup reinforcers- could be used to make the feedback task more rewarding. And of course, feedback of several para-meters (e.g. , GSR, r e s p i r a t i o n , heart rate), could be used to teach, the s t u t t e r e r to moderate h i s general arousal l e v e l . Biofeedback, t r a i n i n g could also be used i n conjunction with: other treatments f o r s t u t t e r i n g , e.g., rate c o n t r o l therapy, or with flooding or systematic d e s e n s i t l z a t i o n to feared s i t u a t i o n a l and phonemic cues-. The laboratory- s i t u a t i o n could be. made more r e a l i s t i c by having subjects converse spontaneously- with. each, other, or with a videotaped speaker. EMG might prove u s e f u l i n the diagnosis of i n c i p i e n t s t u t t e r i n g , i f EMG spiking were found to discriminate true s t u t t e r i n g from normalechildhood disfluency. Young st u t t e r e r s could perhaps, be given p r e v e n t i t i v e feedback t r a i n i n g . Now that a treatment e f f e c t has been established, the next step i n t h i s l i n e of research might involve a comparison of the effectiveness of biofeedback against the best e x i s t i n g therapy, v i z . , rate^-control therapy. If a s u f f i c i e n t number of matched subjects could Fe found, a group design 79 would be appropriate f o r t h i s purpose. Otherwise, time-series analysis could be used p r o f i t a b l y , e.g., each data point might represent the mean frequency of s t u t t e r i n g during a one-hour weekly treatment session. Subjects could be followed up c o v e r t l y a f t e r the therapy had been completed, e.g., they could be telephoned on some p l a u s i b l e pretext by an accomplice of the experimenter. The use of nonreactive measures and n a t u r a l i s t i c observation i n the evaluation of s t u t t e r i n g therapy has' been advocated by. Andrews and Ingham.(1972). It might be possible to construct a miniature EMG feedback, u n i t (consisting of a p o c k e t s - s i z e d a m p l i f i e r plus electrodes and an earplug)_ which could be worn as a pro s t h e t i c . Similar devices are already being de-r-. veloped. Brady (1972) has patented a miniature metronome which, can be worn l i k e a hearing a i d , But unfortunately i t Imparts a staccato q u a l i t y - t o the wearer's speech which i s as conspicuous as a severe s t u t t e r , A portable masking noise generator i s a v a i l a b l e (Trotter & Lesch, .1967).but i t produces fluency i n the wearer at the cost of temporarily deafening him, and thus. is. d i f f i c u l t to use i n conversational s i t u a t i o n s . Portable delayed auditory-feedback units have been constructed but are not s u i t a b l e f o r c l i n i c a l use at t h i s time (Van Riper, 1973),. B a i l e y (Note 6),, following the lead of Hanna et a l . (1975), i s ; presently testing a take-home.feedback, unit f o r s t u t t e r e r s . The advantage of a takes-home feedback unit are obvious-: the s t u t t e r e r could learn control of h i s laryngeal muscles i n l h i s own time and at his own!place, rather than during r e g u l a r - v i s i t s to the clinician''s o f f i c e . A take^hbme device could also Be u s e f u l i n a c r i s i s s i t u a t i o n when access to the c l i n i c would be im-80 possible. The cost and q u a l i t y . o f portable EMG feedback, equipment i s becoming more a t t r a c t i v e (Paskewitz,. 1975). The success of sucli a device r e l i e s on the p o s s i b i l i t y that the biofeedback e f f e c t i s not apparatus-abound, but w i l l t ransfer to r e a l l i f e speaking s i t u a t i o n s . Biofeedback as a treatment f o r s t u t t e r i n g deserves to be i n v e s t i -gated i n the context of an intensive treatment program emphasizing transfer and maintenance of:fluency. Although t h i s treatment requires r e l a t i v e l y sophisticated instrumentation i t i s conceivable that -.after:'.sufficient train--ningj a s t u t t e r e r could learn to attend to proprioceptive.cues of laryngeal tension i n the absence of Biofeedback equipment. I n d e e d , t h i s has been demonstrated i n other biofeedback ^ a pplications .'• Biofeedback may -be the technique that will'prevent or eliminate the core disruptions of the •motor sequences that perhaps comprise the heart of the '(stuttering), problem" (Van Riper, 1973, p. 203).. ' 81 CHAPTER VIII ADDENDUM Guitar (Note 7). has independently performed a s e r i e s of experiments which resemble Study 3. Guitar trained three s t u t t e r e r s to reduce t h e i r muscle action p o t e n t i a l s (MAPs) at four s i t e s : 1) over the o b i c u l a r i s o r i s superior ( l i p 1 , 2) over the anterior b e l l y of the d i g a s t r i c Cchinl, 3) j u s t above the thyroid c a r t i l e g e ( l a r y n x ) , . 4) over the f r o n t a l i s muscle (forehead). EMG feedback consisted of a tone which increased i n frequency i n proportion to the voltage of the EMG s i g n a l . Guitar's and Ilanna's EMG feedback were apparently very s i m i l a r , because both were based on the electrode s i t e and feedback apparatus-used by Hardyck, Petrinovich and Ellsworth (1966). Following a baseline period, feedback t r a i n i n g focused on one muscle group at a time. Shaping was used to f a c i l i t a t e feedback t r a i n i n g . Results are presented i n Table 15. Although s i g n i f i c a n c e levels: are not given, a l l three subjects appeared to show s u b s t a n t i a l improvement with feedback from the laryngeal s i t e . Guitar also found that subjects 1 and 3 showed improvement with feedback from the l i p as w e l l , and concluded that the s t u t t e r i n g b l o c k may not be l o c a l i z e d at the larynx alone f o r a l l s t u t t e r e r s . The degree of change shown i n Table 15 may be an overestimate because of the p o s s i b i l i t y of a strong adaptation e f f e c t during repeated reading of l i s t s of stimulus words. Indeed, the decrease i n s t u t t e r i n g during feedback from the f r o n t a l i s s i t e probably r e f l e c t s some degree of adaptation^ as; w e l l as-general head relaxation. -82 Table.15 Changes i n Muscle Action P o t e n t i a l CMAP) Levels and Stuttering Frequency (From Guitar, Note.7) Percent decrease Percent decrease Subject S i t e i n MAP l e v e l l h s t u t t e r i n g f r o n t a l i s 19 18 l i p 76 . 89 1 chin 24 1 larynx 51 • 44 f r o n t a l i s 52 0 l i p 39 6 2 chin 13 2 larynx 56 25 f r o n t a l i s 41 28 3 l i p 87 57 chin 73 32 . • larynx 37 55 83 Guitar claimed that two of his three subjects achieved " p a r t i a l " and "considerable" generalization of fluency outside the laboratory, but presented no data to t h i s e f f e c t . Subsequently, EMG feedback from the chin was used as therapy for a fourth, subject. Stuttering was reduced to a n e g l i g i b l e l e v e l a f t e r only.three sessions of feedback during conversational speech. Five weeks l a t e r the subject reported that he was " s a t i s f a c t o r i l y fluent i n a l l s i t u a t i o n s " , and did not s t u t t e r during a videotaped conversa-t i o n with a stranger. At a nine-^month: follow-up, the subject was reported to be speaking f l u e n t l y at a normal rate. The s i m i l a r i t y between the r e s u l t s of Guitar's research and Study 3 i s encouraging, as i s Guitar's exploratory treatment study. 84 REFERENCE. NOTES 1. Perkins, W.H. Behavioral management of s t u t t e r i n g . F i n a l report, S o c i a l and R e h a b i l i t a t i o n Service research grant 14-P----55281. Washington, D.C.: Department of Health, Education, and Welfare, 1973.. 2. Hanna, R., & Morris, S. Speech, rate and the metronome effect.. Manu-s c r i p t submitted f o r p u b l i c a t i o n , 1975. 3. Stromsta, C. Average evoked responses of s t u t t e r s and nonstutters as a function of i n t e r n a l time r e l a t i o n s h i p s . Technical report. 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APPENDIX A Assignment of Subjects to Studies Subject 1 . 2 3 4 5 Rick X X Frank X X John X X X David X X Don X X Ray- X X Ruth X .. X X Larry X Teresa X X Doug X X Ron X X E r i c X • J e f f X Susan X N =14. 3 • 4 6 6 7 94 APPENDIX B Dependent Vari a b l e s : Inter-Rater R e l i a b i l i t y and Percent Agreement Dependent v a r i a b l e Percent EMS spikes Speech; rate Study Subject syllables- stuttered per .100 syllables; (SPM) 1 Frank .87 .90. .9,4 81% 92% 9.6% 2 . David .84 .92 . . .90 76% 90% 94% 3 Ray .89 .94 .9-7 85% 93% 98% 4 Ruth .93. T95 .96 77% 90% .,97% 5 Doug .89. .92 .94 83% 94% 98% 95 APPENDIX C Minimum Pen Deflections. Defining an EMG Spike Polygraph, s e n s i t i v i t y Feedback a c t i v a t i o n Subject (mV/cm). threshold (mVl David .05 .025 Don .10 .05 Ray .05 .05 Ruth .05 .025 John ( p i l o t studies). .10 .10. (Study 1) .20 .20: Rick .10 .05 Frank .10 .05 Larry .10 .05 Teresa .05 .075 Doug .05 .075 Ron .05 .05 E r i c .05 .025 J e f f .05 .0.5 Susan .02 .02 , 96 * . APPENDIX D Instructions- f o r Studies 3 and 5 (Before baseline, a f t e r TAT i n s t r u c t i o n s ) When you nave spoken about the cards f o r 15 minutes, you w i l l hear a high^ pitched tone coming from the speaker at your side. The tone indicates, the tension i n your speech muscles. The higher the p i t c h of the tone, the more tense you are. When you are speaking i n a relaxed way, the tone w i l l shut of f completely. Your job i s to t r y to shut i t o f f , or at l e a s t to keep the p i t c h of the tone as low as possi b l e . I can't explain how you could do t h i s , any more than I c o u l d . t e l l you how to l i f t your arm. Just t r y anything you can to prevent the tone from coming on, or being highr-pitched, while you speak about the cards. Do you understand? (At the end of the baseline period) The tone w i l l be i n operation from now on. Do anything you can to prevent the tone from coming on, or from being high-pitched, while you speak. Take a new card and continue speaking. 97 APPENDIX E Questions Used to Investigate Awareness of Feedback Conditions Study 4 CFeedback without- i n s t r u c t i o n s ) 1. What do you think that tone was for? 2. Do you think the tone made any difference to your speech? Clf so, what?) Study 5 CFalse feedback) 1. Do you think the tone made any d i f f e r e n c e to your speech? . Clf so, what?) 2. Did you do anything to t r y to prevent the tone from coming on? Clf so, what?) 3. Do you think you did any better a t c e o h t r o l l i n g the tone the f i r s t time i t was on, or the second time? 4. Do you think the tone was the same each time? 

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