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The effects of arousal induced by physical exertion upon mental performance Jickling, Robert James Lindsay 1976

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THE EFFECTS OF AROUSAL INDUCED BY PHYSICAL EXERTION UPON MENTAL PERFORMANCE by ROBERT JAMES LINDSAY JICKLING B . P . E . , Univers i ty of B r i t i s h Columbia, 1972 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION in the School of Physical Education and Recreation We accept th i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA January 1976 In presenting t h i s thes is in p a r t i a l f u l f i l l m e n t of the requirements for an advanced degree at the Univers i ty of B r i t i s h Columbia, I agree that the L ib rary sha l l make i t f r e e l y ava i lab le for reference and study. I fur ther agree that permission fo r extensive copying of t h i s thes is f o r scho la r l y purposes may be granted by the Head of my Department or by his representat ives . I t i s understood that p u b l i c a t i o n , in part or in whole, or the copying of t h i s thes is f o r f i n a n c i a l gain sha l l not be allowed without my wr i t ten permission. Robert James Lindsay J i c k l i n g School of Physical Education and Recreation The Univers i ty of B r i t i s h Columbia, Vancouver V6T 1W5, Canada i i ABSTRACT The purpose of t h i s study was to invest igate the re la t ionsh ip between physical exert ion and mental performance and then to in terpret th is information in terms of arousal theor ies . More s p e c i f i c a l l y , th i s study has attempted to determine the e f fec t that physical exert ion has upon mental performance and to determine what, i f any, i s the nature of t h i s re la t ionsh ip between physical exert ion and mental performance. Varying degrees of physical exert ion were induced, by b icyc le ergometer r i d i n g at a rate of f i f t y revolut ions per minute with a resistance of four ki lograms. Treatment condit ions of 0 , 2 , 4 , 6 , and 8 minutes of r i d ing were randomly assigned to each of f i v e conse-cut ive days. On completion of each d a i l y exercise bout the subject performed a task designed to measure mental performance. This task required the subject to l i s t e n to a l i s t of random numbers, pre -recorded at one second i n t e r v a l s , with the object ive of detecting a sequence of d i g i t s which occurred in the order "odd number - even number - odd number", and to respond by saying "yes" before the next d i g i t was presented. The test consisted of 150 d i g i t s and the score was the number of ser ies co r rec t l y i d e n t i f i e d out of a maximum of twenty-eight . i i i Twenty male students res id ing in campus dormitories volun-teered as subjects . The r e s u l t s , although not s i g n i f i c a n t in terms of the e f f e c t of the physical exert ion cond i t ions , did tend to ind icate that physical exert ion had a pos i t i ve e f f e c t upon mental performance, Further invest igat ion of the resu l ts led to the conclusion that the e f f e c t of physical exert ion upon mental performance cannot always be described by a simple inverted U r e l a t i o n s h i p . TABLE OF CONTENTS ABSTRACT . . . . . . . . . . . . . . . TABLE OF CONTENTS LIST OF TABLES . . . . a . . . LIST OF FIGURES . . . . . . . . . . . . . . . ACKNOWLEDGEMENTS Chapter I. INTRODUCTION TO THE PROBLEM . . . . . . . . . . . P 1T*0 b 1 601 • o « » a a » o o « o o ( » o » « « o 3 Hypotheses . . . . . . . . . . . . . . . . . . D e f i n i t i o n s . . . . . . . . . . . . . . . . . . Del imitat ions . . . . . . . . . . . . . . . . Importance . . . . . . . . . . . . . . . . . . I I . REVIEW OF THE LITERATURE . . . . Phys io log ica l Basis of Arousal Theories . . . The Ef fects of Arousal Induced by Physical Exertion , . . . . I I I . METHODS AND PROCEDURES . . . . Subjects • • o • » » . • • • • • • * • • • » » » Mental Task . . . . . . . . . . . . . . . . . Physical Task . . . . . . . . . . . Chapter v Page Experimental Design and Considerations 41 Apparatus . . . . . . . . . . . . . . . . . . . . . 44 Procedure 44 Analys is of Data . . . . . . . . . . . . . 45 IV. RESULTS AND DISCUSSION . . . . . . . . . . 46 Results . . . . . . . . . . . 46 Discussion . . . . . . . . . . . . . . 51 V. SUMMARY AND CONCLUSIONS . . . . . . . . . . . 61 Problem . . . . . . . . . . . . . . . . 61 Subjects . . . . . . . . . . . . 62 Methods and Procedures . . . . . . . . . . . . . . . 63 Analys is of Data . . . . . . . . . . . . . . . . . . 64 Results and Discussion . . . . . . . . . . 64 Conclusions . . . . . . . . . . . 66 REFERENCES . . . . . . . . . . . . . . . . . . 69 APPENDIX A - INSTRUCTIONS TO STUDENTS . . . . . . . . . . . . . 75 APPENDIX B - SAMPLE SCORE SHEETS . . . . . . . . . 78 APPENDIX C - TESTING SCHEDULE 82 APPENDIX D - RAW SCORES 84 APPENDIX E - HEART RATES 86 vi LIST OF TABLES Table P a 9 e Mean Scores Obtained from the Test of Mental Performance fo r Each Order, Treatment, Day and Test 47 I I . Results of the Analysis of Variance Applied to Raw Scores Obtained from the Test of Mental Performance . . . . . . . . . 47 I I I . Mean Scores Obtained from the Test of Mental Performance for the Exercise Treatments During Each of the Two Weeks of Testing . . . . . . 48 IV. Analys is of the Treatment Ef fects for Week 1 . . . , 49 V. Analys is of the Treatment Ef fects fo r Week 2 . . . . 50 VI. Results of the Trend Analys is for Week 1 and Week 2 50 LIST OF FIGURES The re la t ionsh ip of arousal to performance (based on Hebb, 1955) . . . . . . . . . . . . The Ret icu lar Formation . . . . . . . . . . . Routtenberg's schema to describe arousal systems . . . . . . . . . . . . . . Corcoran's Inverted U . . . . . . . . . . . . Wood and Hokanson's Inverted U . . . . . . . Mean Z-scores of the three groups as a funct ion of percent of maximum exert ion involved Greco-Lat in Square Design . . . . . . . . . . Mean scores of mental performance f o r the f i v e treatment condit ions . . . . . . . . . . Indiv idual scores obtained from the tes t of mental performance (Week 1) . . . . . . . . . Individual scores obtained from the test of mental performance (Week 2) . . . . . . . . Mean scores of mental performance f o r the f i v e treatment condit ions obtained during Week 1 and Week 2 . . . . . . . . . . . . . . v i i i ACKNOWLEDGEMENT The author would l i k e to thank a l l of those persons who have helped in the preparation of th is t h e s i s : the thesis committee for i t s support and ass is tance , the subjects f o r p a r t i c i p a t i n g , Mrs. E l l i s fo r t yp ing , and Wendy J i c k l i n g fo r her encouragement. The author would espec ia l l y l i k e to thank Dr. G.D. S i n c l a i r f o r a l l o f the help and patience which he has extended as advisor to t h i s t h e s i s , and Dr. R.W. Schutz fo r his continued support throughout the author's graduate program. 1 CHAPTER I INTRODUCTION TO THE PROBLEM Act i va t ion can be described as the degree of neural a c t i v i t y of an ind iv idual at any given time and i s manifested by a general dr ive to perform conscious funct ions . The terms a c t i v a t i o n and arousal are used synonymously. L indsley (1951), Hebb (1955), Malmo (1959), Berlyne (1960), Duffy (1962), and Corcoran (1965) have a l l expanded upon the basic premise of the Yerkes-Dodson law in descr ib ing arousal as a continuum ranging from low to high leve ls with an optimum degree of arousal for the execution of any p a r t i c u l a r type of behaviour l y i n g wi th in these extremes. Hebb (1955) c l a r i f i e s t h i s concept of arousal by presenting a curve (Figure 1) , described as an inverted U. This curve i l l u s t r a t e s that as an i n d i v i d u a l ' s level of arousal increases from awakening to alertness there i s a gradual increase in the ef fect iveness of pe r fo r -mance u n t i l an optimal leve l of arousal i s reached. I f the arousal leve l continues to increase beyond t h i s optimum there i s a gradual decrease in performance. Arousal has been a t t r ibuted to several stimulus condit ions inc luding fea r , anx iety , emotion, shock, no ise , heat, and physical a c t i v i t y . B i l l s (1927) conducted experiments which indicated that Low Arousal High Arousal Figure 1 The re la t ionsh ip of arousal to performance (based on Hebb, 1955) 3 muscular exe r t ion , induced by means of a hand dynamometer, p o s i t i v e l y af fected the performance of various mental tasks such as learning paired associates or adding d i g i t s . More recent l y , S tockfe l t (1968) and Davey (1973) have con-ducted studies using a dynamic form of physical exer t ion , r id ing a b icyc le ergometer, to induce varying degrees of arousal . S tock fe l t (1968) suggests that the performance of his subjects on simple addi t ion and subtract ion problems was re lated to the degree of arousal and that th i s re la t ionsh ip took the form of an inverted U curve. Davey (1973) reported s i m i l a r resu l ts when using a task designed to measure mental performance. This task required the subjects to respond to audible d i g i t s when they were presented in a predescribed sequence. Evidence ex is ts which ind icates that leve ls of a c t i v a t i o n , induced by dynamic physical a c t i v i t y , can be interpreted in terms of ex i s t ing arousal theor ies . Physical education, by i t s very nature, i s concerned with physical exert ion and i f the stimulus of physical a c t i v i t y can be shown to inf luence behaviour, s p e c i f i c a l l y , enhance mental performance,then physical educators should be aware of the e f f e c t s of such a r e l a t i o n s h i p . I t i s hoped that t h i s study w i l l contr ibute more information toward the understanding of the ef fects of physical a c t i v i t y upon mental performance, and help to make i t a p r a c t i c a l app l i ca t ion among physical educators. 4 PROBLEM The research in th i s area has provided evidence to suggest that physical exert ion may be an important stimulus cont r ibut ing to one's arousal l e v e l . This study was designed to further invest igate the re la t ionsh ip between physical exert ion and mental performance and then to in terpret t h i s information in terms of arousal theor ies . More s p e c i f i c a l l y , t h i s study has attempted to determine the e f f e c t that physical exert ion has upon mental performance and to determine what, i f any, i s the nature of th i s re la t ionsh ip between physical exert ion and mental performance. HYPOTHESES In l i g h t of the present evidence r e l a t i n g to the problem, the fo l lowing hypotheses were proposed for i n v e s t i g a t i o n : ( i ) Varying the amounts of physical exert ion d i f f e r e n t i a l l y af fected the level of arousal and thereby influenced mental performance. ( i i ) The inf luence of physical exert ion on mental performance corresponded to the inverted U hypothesis, i . e . , inc reas -ing exert ion improved performance un t i l a maximum level of prof ic iency was obtained, beyond which the level of performance began to deter io rate . 5 DEFINITIONS Activation: The degree of neural a c t i v i t y wi th in an i n d i v i d -ual at any given time i s referred to as his level of ac t i va t ion and i s manifested by a general drive to perform conscious funct ions . The terms ac t i va t ion and arousal are used synonymously. Mental Performance: Mental performance i s defined as the i n d i v i d u a l ' s a b i l i t y to perceive cer ta in s t i m u l i , process information from these s t i m u l i , and respond appropr iately to th i s processed information. Physical Exertion: Physical Exertion is defined in t h i s study as voluntary behaviour which induces a c t i v i t y of the ske leta l musculature. The degree of a c t i v i t y and the qua l i t y of musculature concerned may vary. Inverted U: This i s a funct ional re la t ionsh ip between two factors which, when expressed graphica l l y resembles an inverted U. In the context of th is study the inverted U re la t ionsh ip refers to theories which have evolved from the Yerkes-Dodson law described by Eysenck (1963). According to th is law, complex tasks are performed best when one's dr ive or motivation i s r e l a t i v e l y low, but optimal prof ic iency in simple tasks occurs when drive is h igh. As drive increased so does performance, to a po int , continued increased in dr ive lead to poorer performance. 6 Ascending Reticular Activating System (ARAS): The ARAS i s a network of neurons in the brain which seems to function through a network of d i f fuse f ibers extending throughout the b ra in , espec ia l l y to the cortex, the st imulat ion of which i s responsible for the level of neural a c t i v i t y c a l l e d a c t i v a t i o n . The main areas which seem to be associated . with the ARAS are the r e t i c u l a r formation, the hypothalamus, and the l imbic system. Recent evidence suggests that the ARAS can be func t ion -a l l y d iv ided into two systems, ARAS I and ARAS I I . ARAS I may be associated with ac t i va t ion leve ls i n i t i a t e d by s t imulat ion of sensory af ferents whereas a c t i v a t i o n leve l s associated with ARAS II may have been i n i t i a t e d by st imulat ion of emotions. Reticular Formation: This i s a core of nervous t issue located in the center of the brainstem, c lustered around the central cana l . I t runs through the medulla, pons, and midbrain and connects, at i t s upper end, with the hypothalamus and thalamus. I t consists of pre -dominantly short nerve f i b e r s , of small diameter, c r i s s - c r o s s i n g i n a l l d i r e c t i o n s . Synapses and dendrites are abundant. The r e t i c u l a r formation i s the primary locat ion of arousal structures in the brainstem and midbrain (Wright et a l_ . , 1970). The Limbic System: The l imbic system comprises a funct ional uni t composed of subcort ical regions of the brain and seems to be involved with motivational and emotional behaviour. The exact way in which the l imbic system subserves arousal i s unknown, but i t may be involved with ARAS I I . 7 The structures usual ly included are: the cingulate and hippocampal g y r i , hippocampus, amygdala, septum, epithalamus, and the dorso-medial and anter ior thalamic n u c l e i . The Hypothalamus: The hypothalamus i s part of the arousal system located i n the midbrain. This structure receives input from higher brain centers as well as from other internal organs of the body. I t i s thus in a c r i t i c a l pos i t ion for integrat ing messages from the higher centers as well as those from internal organs (Sage 1971). DELIMITATIONS This study was l i m i t e d by an i n a b i l i t y to control fo r the e f fec ts of motivation on the subjects whi le they were being tested . Physical exert ion was induced by b icyc le ergometer r i d i n g . The study was therefore l i m i t e d to t h i s s p e c i f i c type of a c t i v i t y . This study was further l i m i t e d to one tes t of mental a c t i v i t y to be used as a gauge fo r mental performance. In addi t ion th is study was r e s t r i c t e d to volunteer male co l lege students res id ing in a un ivers i t y dormitory. 8 IMPORTANCE I t was ant ic ipated that a re-examination of the e f fec ts of physical exert ion on mental performance would supplement previous work and help to more accurately c l a r i f y the re la t ionsh ip e x i s t i n g between exert ion and mental performance, Duffy (1957) suggested that in d i f f e r e n t st imulus s i tuat ions the same ind iv idua l w i l l d i f f e r in his degree of arousal.. The importance of th i s study was that i t attempted to control as many factors as possible that could cause di f ferences in tes t ing condi t ions . For t h i s reason the tes t ing was conducted at the same time each day and in surroundings f a m i l i a r to the subject , a room in his student dormitory. Since normal da i l y a c t i v i t y could d i f f e r e n t i a l l y a f fec t the subjects ' arousal l e v e l s , tes t ing was conducted upon r i s i n g from bed between 6:30 and 8:00 am. Each of the treatment condi t ions , designed to i n -duce arousa l , were randomly assigned to d i f fe ren t days to control fo r e f fec ts which could extend over minutes or hours and, to minimize learning e f fec ts the tests of mental performance were var ied , F i n a l l y , the analys is was designed to reveal any di f ferences which may have ex is ted between the tests of mental performance, the days of the week, or the order in which the treatment condit ions were administered, Duffy (1957) further suggested that i n the same stimulus s i t u a t i o n there are d i f ferences between ind i v idua ls in t h e i r degree of a rousa l . These d i f fe rences , she s a i d , tended to pe rs i s t and could frequently be c l a s s i f i e d as c h a r a c t e r i s t i c of ce r ta in personal i ty t r a i t s . 9 Recent studies have considered some of the factors which contr ibute to i n t e r - i n d i v i d u a l d i f ferences and could occur when arousal i s induced by physical exer t ion . S t o c k f e l t (1968) d ist inguished be-tween phys ica l l y w e l l - t r a i n e d students and those who were in a r e l a t i v e l y poor state of t r a i n i n g and Davey (1973) f e l t that int rovers ion and ext ravers ion , and neuroticism and s t a b i l i t y would a f fec t arousal leve ls induced by physical exer t ion . Duffy (1957) went on to report that anxiety and aggressiveness may a lso be c h a r a c t e r i s t i c s which a f f e c t a rousa l . I t was thought that many factors which are , as ye t , undefined a lso contr ibute to an i n d i v i d u a l ' s degree of arousal . For t h i s reason i t was f e l t that an important contr ibut ion could be made i f th i s study included a subject ive observation of each sub ject ' s resu l ts in an attempt to i d e n t i f y any i n t e r - i n d i v i d u a l d i f ferences which may have occurred. In summary, the importance of t h i s study was th reefo ld . F i r s t l y , i t has attempted to c l a r i f y the re la t ionsh ip between physical exert ion and mental performance. Secondly, i t attempted to control fo r as many factors as possib le which could a f fec t an ind iv idual and his level of a rousa l . F i n a l l y , the resu l t s for each ind iv idual were sub ject i ve ly analyzed in an attempt to i d e n t i f y any i n t e r -ind iv idual d i f ferences which might have occurred and were not evident as a resu l t of the analys is of group data. 10 CHAPTER II REVIEW OF THE LITERATURE PHYSIOLOGICAL BASIS OF AROUSAL THEORIES This review begins with a b r i e f descr ipt ion of neural t r a n s -mission and proceeds to out l ine the main stages in the development of the phys io log ica l theories which describe arousa l . There are two d i s t i n c t kinds of a c t i v i t y in the nerve c e l l , the dendr i t i c potent ia l and the act ion p o t e n t i a l . The dendr i t i c potent ial does not funct ion on an " a l l or none" basis but ind iv idual potent ia ls summate u n t i l a cer ta in threshold i s reached. At t h i s point the " a l l or none" act ion potent ia l i s i n i t i a t e d which accounts fo r nervous t ransmission. An increase in dendr i t i c potent ia l would f a c i l i t a t e prospective act ion potent ia ls by decreasing the d i f ference between the actual potent ia l in the dendrite and threshold potent ial required fo r the act ion potent ia l to be generated. In other words, i f the dendrite potent ia l i s higher than normal i t w i l l require less subsequent af ferent s t imulat ion to i n i t i a t e the act ion potent ia l in that c e l l . It has been suggested by L i and Jasper (1953) that t h i s dendr i t i c potent ia l often occurs separately from the af ferent sensory s t imul i and may make up the greater part of the electroencephalogram (EEG) record. The brain is therefore always act ive but t h i s a c t i v i t y i s not always t ransmitted. 11 This information regarding neural transmission c l a r i f i e s the p r inc ip les of neural ac t i va t ion presented by Lorente de No (1939) who stated that the transmission of neural impulses occurs in a closed chain of neurons,the funct ioning of which may be f a c i l i t a t e d by im-pulses a r i s i n g outside the brain ( i . e . r e t i c u l a r a c t i v i t y system). Such impulses would have the e f f e c t of s t imulat ing cer ta in neurons sub l imina l l y and therefore make i t possible for an impulse from with in the chain to reach i t s required threshold potential,when alone, w i t h -out the p r i o r a c t i v i t y , i t would have f a i l e d to do so. He further explains the deleter ious e f fec ts of over -s t imulat ion from impulses outside the chain as causing neurons in the chain to f a i l in response to s t imulat ion i f , owing to repeated a c t i v i t y , they acquire a high threshold . This f a i l u r e to transmit the c i r c u l a t i n g impulses would mean cessation of a c t i v i t y in a c e l l assembly. Hebb (1955) s i m i l a r l y f e l t that c o r t i c a l synaptic function was f a c i l i t a t e d by a d i f fuse bombardment of the arousal system. He d i f f e r e d , however, in that he f e l t that when the leve l of arousal was high, the greater bombardment may i n t e r f e r e with de l i ca te adjust -ments involved with the sensory a f f e r e n t s , perhaps by f a c i l i t a t i n g inappropriate responses. Moruzzi and Magoun (1949) provided evidence fo r the e x i s -tance of a non -spec i f i c or d i f fuse project ion system in the brainstem responsible for arousal and, whose funct ion ing , makes c o r t i c a l a c t i v i t y poss ib le . 12 Further, they found that EEG changes, seemingly i den t i ca l with those in the phys io log ica l arousal reac t ions , could be produced by d i rec t s t imulat ion of the r e t i c u l a r formation. They reported a general ized response, in c o r t i c a l areas, which consisted of cessation of synchronized alpha discharge in the EEG and i t s replacement with low voltage fast a c t i v i t y , that i s , alpha to beta a c t i v i t y . This suggested to them that c o r t i c a l a c t i v i t y i s mediated by neural connections between the r e t i c u l a r formation and the cerebral hemisphere, S i m i l a r responses could also be e l i c i t e d by s t imulat ion of the dorsal hypothalamus and subthalamic regions, Moruzzi and Magoun (1949) further reported that les ion ing (mesencephalic t ransect ion) of the ascending r e t i c u l a r ac t i va t ing system (ARAS) resulted in an EEG pattern which resembled that of an in tac t brain in natural s leep . Sleep may therefore be due to e l iminat ion of arousal caused by the bombardment of c o r t i c a l areas by information ascending from the r e t i c u l a r a c t i v a -t ing system. The behavioral response to t h i s s t imulat ion of the ARAS in monkeys was invest igated by Fuster (1958) who found that by s t imulat ing the same region of the ARAS that produces the EEG recording of ac t i va t ion (beta waves) he produced improved performance in the t ra ined a b i l i t y to d iscr iminate between objects of d i f f e r e n t geometric shapes. He fur ther found that moderate i n t e n s i t i e s of s t imulat ion increased the animal 's e f f i c i e n c y but that greater i n t e n s i t i e s resulted in a deleter ious e f f e c t . 13 It was proposed by Hebb (1955) that af ferent s t imul i are conducted v ia two pathways. The f i r s t , termed the cue funct ion , t rans -mits the information quick ly and e f f i c i e n t l y from the sensory nerve, to the sensory t r a c t , through the corresponding nuclei of the thalamus and terminates in one of the sensory pro ject ion areas of the cortex. The second pathway i s slow and i n e f f i c i e n t as the information passes through a maze of f ibe rs and synapses before the messages are del ivered ind i sc r iminate l y to wide c o r t i c a l areas. They serve to tone, or arouse the cortex with a background of supporting a c t i v i t y that i s necessary i f the messages proper are to have t h e i r e f f e c t . Arousa l , according to Hebb,is an energizer , not a guide, without which the af ferent sensory information cannot e x i s t . I t i s , i n a sense, synonymous with a general dr ive s t a t e . Findings by French (1957) support the theory by Hebb (1955) that two sensory af ferent pathways e x i s t . He found that sensory s ignals from a l l parts of the body go to the cortex by d i rec t path-ways but, on the way to the brain stem, they also st imulate the r e t i c u -l a r formation. When the r e t i c u l a r formation i s so st imulated i t sends arousing s ignals to the cortex which can then in terpret the s ignals being received d i r e c t l y (See Figure 2 ) . Recent invest igat ions have provided some evidence which i s inconsistent with the descr ipt ion of the r e t i c u l a r ac t i va t ing system provided to t h i s po int . Myers, Roberts and Domino (1964) demon-st rated that animals could be behavioural ly awake yet record slow wave a c t i v i t y when t h e i r r e t i c u l a r systems were under the inf luence 14 Figure 2 The RETICULAR FORMATION i s the area s t ipp led in t h i s cross sect ion of the b ra in . A sense organ (lower r ight ) i s connected to a sensory area in the brain (upper l e f t ) by a pathway extending up the spinal cord. This pathway branches into the r e t i c u l a r formation. When a stimulus t rave ls along the pathway, the r e t i c u l a r formation may "awaken" the ent i re brain (arrows), (from French, 1957). 15 of a t rop ine , a chemical which blocks neurologic a c t i v i t y . Further-more, work by Chow and Randall (1964) has shown that les ions r e s t r i c t e d to the r e t i c u l a r formation i t s e l f do not necessar i l y render animals comatose and that recovery may even occur. This recovery was i l l u s t r a t e d by V i l l a b l a n c a (1965) who found that seven to eleven days a f t e r t ransect ion between the diencephalon and midbrain, low vol tage, fas t a c t i v i t y occurred, and by Doty, Beek, and Kooi (1959) who showed that animals with r e t i c u l a r les ions were able to perform complex behavioural condit ioning tasks . Many instances of s i m i l a r resu l t s have been provided by other workers. I t i s apparent that the o r i g i n a l concept of a s i n g l e , ascending r e t i c u l a r ac t i va t ing system, described by Moruzzi and Magoun, i s not s u f f i c i e n t to describe the events j u s t discussed. I t has been proposed, through studies of the l imbic system, that a second arousal system i s present. Samuels (1959) div ided the r e t i c u l a r formation in to two funct ional systems; the brain stem r e t i c u l a r formation and the d i f f u s e l y pro ject ing thalamic nuclei or l imbic systems. When a c t i v a t e d , they both would evidence desynchroniza-t ion of res t ing alpha rhythms. Eysenck (1967) elaborated upon t h i s concept- by suggesting that c o r t i c a l arousal can be produced by two d i s t i n c t and separate pathways. One pathway, ARAS I, ascends d i r e c t l y from the r e t i c u l a r formation without involv ing the v iscera l b ra in . The second, ARAS I I , involves the v i sce ra l brain and the hypothalamus. He fur ther states that c o r t i c a l arousal a r i s i n g from v iscera l brain a c t i v i t y i s produced by emotions whereas the r e t i c u l a r formation i s responsible* 16 for what Eysenck c a l l s autonomic ac t i va t ion ( i . e . from sensory a f f e r -ents ) . Subsequent invest igat ion by Routtenberg (1968) has led to a further refinement of th is dual ac t i va t ing system theory which w i l l be discussed l a t e r . Kawamura, Nakamura and Tokizane (1961) produced evidence that the media forebra'in bundle (MFB) system may be involved with arousal funct ions . They found that s t imulat ion of the MFB at the level of the hypothalamus produced neocort ical desynchronization and hippo-campal theta a c t i v i t y (hippocampal arousal response). A f t e r t rans -ect ion they found that neocort ical desynchronization from the r e t i c u l a r formation disappeared but the hippocampal theta a c t i v i t y remained. This observation provides a possib le explanation of the resu l ts c i t e d by V i l l a b l a n c a and suggests that i f s u f f i c i e n t time i s allowed f o r recovery t h i s hippocampal system might be able to produce neocort ical desynchronization s i m i l a r to that produced by the r e t i c u l a r formation. From th is information i t seems that arousal system I (AS I) i s the primary system producing neocort ical desynchronization and that destruct ion of i t w i l l reduce or e l iminate neocort ica l desyn-chron izat ion . Arousal system I must, therefore , be act ive for the production and se lec t ion of appropriate responses. These responses are more probable when AS I i s act ive and less probable when i t i s i n a c t i v e . Arousal system II (AS II) can, however, s u f f i c i e n t l y st imulate the neocortex to maintain at least the wakefulness of the organism when AS I i s damaged. Routtenberg (1968), goes on to suggest that AS I sustains the tonic inf luence with respect to neocort ical 17 desynchronization. AS II appears to be more c r i t i c a l for maintaining basic "vegetative" a c t i v i t i e s . Each may cont r ibute , in the other 's absence, to the funct ion of the other. Routtenberg (1968) in reviewing data on s e l f s t imulat ion (Olds and Mi lner 1954) says that AS II i s a reward system, and i t re inforces or increases the p robab i l i t y that the response w i l l reoccur,, on the other hand, AS I organizes the response aspect. Olds (1960) found that rats would v o l u n t a r i l y s e l f - s t i m u l a t e the hypothalamus but , i f p o s s i b l e , t r y to escape dorsal midbrain (DM) s t i m u l a t i o n . This indicated that separate regions wi th in the midbrain mediate pos i t i ve and negative reinforcement. Olds and Olds (1962) found evidence fo r one-way i n h i b i t i o n of poster ior hypothalamic s e l f -s t imulat ion when a continuous DM st imulat ion was present. Brady (1958), on the other hand, found that s t imulat ion of the septal reward-ing s i t e in the brain can reduce or even el iminate emotional aspects of an aversive st imulus. This suggests that poss ib ly two rewarding s i t e s , septal area and poster ior hypothalamus, could produce opposite e f fects with respect to aversive s t imu la t ion . In general , septal s t imulat ion tends to reduce the e f fec ts of aversive s t imulat ion while hypothalamic s t imulat ion tends to augment i t . Routtenberg (1968) has devised a schema (see Figure 3) to explain the funct ional d i f ference between septal and hypothalamic areas although they both y i e l d s i m i l a r reward s t imu la t ion . He has attempted to organize anatomical and phys io logical f indings with respect to behaviour. I t can be seen that the septal area and hypothalamic area A R O U S A L S Y S T E M S Neocortical DesynchronizatioiJ' Lateral Septal Area Arousal I Drive-Response Energy| Reticular Formation Hyppo-campal Theta Posterolateral Hypothalamus Medial Septal Area Arousal II Reward-Positive Incentive Limbic System Dorsal Midbrain Negative Incentive Fac i l i ta t ion Suppression Figure 3 Routtenberg's schema to describe arousal systems 19 have d i f f e r e n t e f fec ts on AS I. The septal area dampens i t whereas the p o s t e r o l a t e r a l hypothalamus act ivates i t . Hypothalamic st imulat ion i s rewarding because i t suppresses AS I which resu l ts in suppression of the dorsal midbrain negative incentive which in turn ceases to suppress AS I I . The net resu l t i s that AS II i s ac t i va ted . AS I suppress ion, a rousa l , or both lead to rewarding e f f e c t s . This schema can help to explain the behavioural c h a r a c t e r i s t i c s a t t r ibu ted to the arousal theory. Each of the two a c t i v a t i o n systems can suppress the other depending on the nature of the input . Both systems are constantly ac t i ve and a rec iprocal suppression of the imbalances of the other allows AS I and AS II to be in dynamic- equi l ibr iurn. I t i s possib le that high leve ls of ac t i va t ion may produce adversive st imu-l a t i o n in AS II which would cause i n h i b i t i o n of AS I a c t i v i t y and corresponding performance decrements. At more optimal leve ls of arousal the AS I a c t i v i t y would st imulate a c t i v i t y of the dorsal midbrain which would cause suppression of AS I I , thus f a c i l i t a t i n g AS I a c t i v i t y and optimal performance. In a more recent study Routtenberg (1971) has s l i g h t l y e labor -ated his o r i g i n a l concept of a rousa l . He c i t e s evidence to suggest that the extrapyramidal system i s involved with the ac t i va t ing systems and that i t , together with the r e t i c u l a r formation, i s involved in the organizat ion of motor patterns. System I i s therefore the motor execution system. In contrast,System II i s associated with s t imulus -processing. He states that both the extrapyramidal system and the 20 l imbic receive sensory input from a l l major moda l i t i es . They are both in a s i g n i f i c a n t p o s i t i o n , therefore , to engage in the stimulus processing funct ion suggested for System I I . Routtenberg (1971) fur ther reports that the hippocampus plays an important r o l l in the a c t i v i t y of these two systems. The a c t i v i t y of System I and modulation of II i s indicated by hippocampal desyn-chronizat ion and the a c t i v i t y of System II and modulation of I i s indicated by hippocampal theta a c t i v i t y . This l i t e r a t u r e r e l a t i n g to the phys io log ica l descr ipt ion of arousal supports the notion that physical exert ion may a f f e c t mental performance. Evidence suggests that af ferent s t i m u l a t i o n , from d i f f e r e n t parts of the body, ar r i ves at locat ions in the lower b r a i n -stem and in turn provides s t i m u l a t i o n , or a rousa l , to the cortex. This arousal i s then responsible fo r the f a c i l i t a t i o n of various types of behaviour. More recent invest igat ions suggest, however, that the mechanisms subserving arousal may be more complex than pre-v ious ly thought and that a second arousal system ex is ts which may be st imulated by emotions. To date no studies have been conducted to invest igate the in te rac t ion between these two systems when the stimulus of physical exert ion has been used to inf luence mental performance. 21 THE EFFECTS OF AROUSAL INDUCED BY PHYSICAL EXERTION The study of the e f fec ts of arousal induced by physical exer t ion , or exert ion arousa l , on mental performance was begun in 1927 by B i l l s who conducted an experiment which involved four female and f i ve male advanced col lege students. His resu l ts showed that performance, as measured by the memorization of nonsense s y l l a b l e s , was f a c i l i t a t e d by the squeezing of a hand dynamometer. Inconsistant r e s u l t s , however, were found by other i n v e s t i -gators . Zartman and Cason (1934) studied s i x male and twelve female subjects in fur ther invest igat ing the e f fec ts of exert ion arousal on mental performance. The subjects were administered f o r t y - e i g h t short ar i thmet ic problems. Twenty-four of them were answered while the subject depressed a pedal , with his r ight l e g , which required a force of 25-40 pounds. The resu l ts showed nei ther a d e f i n i t e increase nor decrease in the e f f i c i e n c y of so lv ing ar i thmet ic problems. An experiment by Block (1936) provided evidence to suggest that physical exert ion has a negative e f f e c t on mental performance. F i f teen male col lege students were tested in a continuous addit ion task, the a b i l i t y to make analogies, and the q u a l i t y of s y l l o g i s t i c reasoning with and without the presence of induced muscle tensions. The tension condit ion required the subjects to squeeze hand dynamometers in both hands with a force of t h i r t y - f o u r pounds each, and to exert a pressure of f o r t y - e i g h t pounds against a pedal with the r igh t foot . 22 Duffy (1932) conducted experiments which provided somewhat s i m i l a r resu l ts to those of Block. She tested eighteen ch i ldren between the ages of two years eleven months and three years eleven months on a task chosen to measure t h e i r a b i l i t y to press a key when pictures of an automobile were shown amongst other randomly arranged p ic tu res . At the same time hand dynamographs were held . She found that the resu l t s obtained from ch i ldren who exerted a high degree of muscular tension while holding the dynamograph were usual ly associated with a performance of poor q u a l i t y although she fur ther suggests, on the basis of her l i m i t e d data, that good performance most f r e -quently occurred when the dynamograph was held with moderate to low degrees of muscular tens ion. The conclusions of a more recent study bv Corcoran (1965) can be appl ied to some of these e a r l i e r studies to o f f e r a possib le explanation fo r some of the apparently divergent data. He suqqests (Figure 4) that i f a person's arousal leve l increased from X-j to X£, performance could be shown to be f a c i l i t a t e d from to Y 2 - Pe r fo r -mance would remain the same i f arousal increased from X-j to Xg, or i t would be reduced from Y-j to Y^ i f arousal increased from X-j to X^. He says that as an i n d i v i d u a l ' s leve l of arousal i s increased his a b i l i t y to perform conscious functions also increases. A po int , in t h i s case X 2 , marks the degree of arousal f o r optimum performance. Further increases beyond th is point resu l t in decreased qua l i t y of performance. Previous studies may be regarded as having explored 23 Arousal •> Figure 4 Corcoran's Inverted U 24 only one part of the whole range. Subsequent s tud ies , however, began to consider the importance of inves t iga t ing the r e s u l t i n g e f fec ts on performance caused by physical exert ion condit ions which were var ied in i n t e n s i t y . When th is approach was employed, invest igators began to f i n d evidence to suggest that the re la t ionsh ip between physical exert ion and mental performance was of an inverted U nature. Stauffacher (1937) tested fo r ty un ivers i t y students in a study which covered a range of muscular tensions generated by l i f t -ing weights with an arm. Treatment condit ions ranged from zero through one-quarter and one-hal f to three-quarters of the maximum weight that the subject could l i f t . He found that the learn ing of nonsense s y l l a b l e s was f a c i l i t a t e d , and that the best resu l t s were obtained at one-hal f the maximum tension. Tensions of less than t h i s , however, gave l i t t l e or no evidence of f a c i l i t a t i o n of learn ing . In th i s experiment the orders of the treatments were randomized and one was administered d a i l y f o r four consecutive days. Courts (1939) conducted a s i m i l a r study. He found, in t e s t -ing s i x t y male col lege students, that memorization was progressively more e f f i c i e n t u n t i l an optimum tension was reached. Tension was induced by having the subjects squeeze a hand dynamometer. In th i s case the optimum tension was equivalent to one-quarter the measure of i n t e n s i t y at the end of t h i r t y seconds of maximum e f f o r t on a prel iminary t r i a l . A more recent study was conducted by Wood and Hokanson (1965) who div ided the range of muscular exert ion into f i ve treatment 25 condi t ions : 0, 1/4, 1/2, 3/4, and maximum. This task consisted of l i f t i n g weights with the arms and supporting them at the side whi le performing a digi t -symbol subst i tu t ion task. The resu l ts ind icate that tens ion , induced by one-hal f the maximum weight l i f t e d , allowed fo r optimal performance whi le greater or lesser amounts resu l t in sub-maximal performance (Figure 5) . The subjects were fo r ty male and s i x t y female undergraduate students who had a normal basal heart rate between seventy-two and ninety-two beats per minute. Heart rate was a lso monitored and used as an i n d i c a t o r of arousal . These studies were a l l interpreted as being consistent with the inverted U hypothesis which predicts that performance on a learning task would be f a c i l i t a t e d by increased leve ls of induced tension up to some maximum p o i n t , a f t e r which i t would begin to f a l l o f f with fur ther increases in tens ion . In addit ion to the above studies several experiments have been conducted to invest igate the e f f e c t of muscular tension on motor performance. Freeman (1938), while tes t ing ten male students, found that performance, measured by the frequency of f inger o s c i l l a t i o n s , increased as muscular tens ion , induced by l i f t i n g against a leg lever increased u n t i l an optimum was reached. Further increases resul ted in deter io rat ion of the qua l i t y of performance. Freeman a lso found that a f t e r d i v i d i n g h is subjects in to two d i f f e r e n t groups, d i f f e r -ent degrees of tension indicated optimal tensions for each group. 0 1/4 T/2 3/4 1 Induced Tension Figure 5 Wood and Hokanson's Inverted U 27 He f e l t that t h i s could be accounted fo r by ind iv idua l d i f ferences wi th in such small groups. Marteniuk (1968) conducted a fur ther study to invest igate the e f fec ts of induced muscular tensions on motor performance. In t h i s experiment the subjects , fo r t y -n ine male col lege students, were required to press a react ion lever loaded with an adjustable c o i l spring which would enable the experimenter to vary the force necessary to push the lever . The task required the subjects to depress the lever at a given tension l e v e l , one of 0 , 5 , 10, 15 or 20 pounds, then, at a s i g n a l , they were to grab a suspended b a l l . Both react ion times and movement times were measured. The resu l ts indicated that react ion time was a function of induced arousal . The f i f t e e n pound treatment condit ion was s i g n i f i c a n t l y fas te r than e i t h e r the zero or twenty pound cond i t ion . Movement t ime, however, was not f a c i l i t a t e d . There was instead, a l i n e a r trend toward slower speed with increased tens ion. Marteniuk concluded that f a c i l i t a t i o n of react ion t ime, through the use of prel iminary tens ion , could be accounted for by applying arousal theory to motor performance. Inh ib i t ion of move-ment time was probably caused by an increasing s h i f t of attent ion from the movement phase to the react ion phase of the task at higher l eve l s of tens ion . Pinneo (1961), however, found resu l t s which d i f fe red from those of Marteniuk in that the inverted U re la t ionsh ip was not supported. In t h i s case the subjects were required to perform a 28 t racking task which required the depression and release of a foot pedal at a constant speed with auditory s ignals to ind icate v a r i a t i o n s . He found that errors in t h i s task increased as muscle tens ion , induced by means of a hand dynamometer, increased over a ser ies of increments. His subjects were t h i r t y - e i g h t male undergraduates ranging in age from eighteen to t h i r t y years . Up to t h i s point the researchers have been concerned with the e f fec ts of s t a t i c muscle tensions as a method of inducing arousal and the tes t of performance has been administered concurrently with the treatment condit ion of physical exer t ion . This design does not allow fo r the e f fec ts of in teract ions between the execution of the performance task and the exert ion task. More s p e c i f i c a l l y , decrements in performance, which have been reported to have occurred a f t e r some optimum has been reached, may have been due to at tent ion being di rected towards execution of the physical exert ion task and not due to fur ther increases in leve ls of a rousa l . This may, fo r example, explain the apparently divergent resu l t s obtained by Pinneo (1961). More recent ly an a l t e r n a t i v e design in experimentation has been included in the inves t iga t ions . Arousal has been induced by a var ie ty of dynamic methods inc lud ing running, bench stepping, and r id ing a b icyc le ergometer and tests of mental performance have been administered a f t e r the period of exer t ion . In addi t ion to reducing possible a r t i f a c t s a r i s i n g from the simultaneous execution of the performance task and the exert ion t a s k , t h i s design has enabled the invest igat ion of the prolonged e f f e c t of physical exer t -ion on arousal over a period of several minutes. 29 McAdam and Wang (1967) studied the e f f e c t of mild physical exert ion as a method of arousing an ind iv idual p r io r to a mental task. He used a combination of running, jogging, and walking to induce mild work but not fa t igue . Immediately before and a f t e r exerc ise the 108 male adult subjects were administered a ten minute symbol subst i tu t ion task. The r e s u l t s , although n o n - s i g n i f i c a n t , tended to favour exercise before the mental task. In 1966 Gutin conducted a study to test his hypothesis that increased physical f i tness would have a pos i t i ve e f f e c t on the a b i l i t y to perform mental tasks a f t e r a period of physical and mental s t r e s s . The subjects were f i f t y - f i v e male col lege students. A f te r a p re - tes t cons is t ing of physical and mental st ress (Indiana motor f i tness index I I , push-ups, ch ins , standing broad jump, long a d d i t i o n , and subt rac t ion ) , the subjects were administered mental tes ts in verbal comprehension, v isual pursu i t , verbal reasoning, and symbolic reasoning. During the fo l lowing twelve weeks the tes t group underwent a physical development program designed to ra ise t h e i r f i t n e s s l e v e l s . At the end of t h i s period both test and control groups were tested in the same fashion as before. Gutin found no s i g n i f i c a n t d i f ferences between h is control group and the experimental group in a b i l i t y to perform complex mental tasks . However, there was evidence of a moderate re la t ionsh ip between the degree of f i t n e s s improvement and mental task a b i l i t y fo l lowing s t r e s s . 30 A study by Gutin and DiGennaro (1968a) tested three t r e a t -ment condit ions to study the e f fec ts of physical exert ion on mental performance. The treatments: r e s t , one minute of bench stepping, and f i v e minutes of bench stepping, were preceeded and fol lowed by f i v e minute tests of simple a d d i t i o n . The f i f t y - e i g h t male col lege students p a r t i c i p a t i n g in t h i s experiment were div ided into two groups: those enro l led in a development c lass and therefore accustomed to step-ups and those not performing bench-stepping regu la r l y . These groups were fur ther d iv ided into three treatment groups each of which would perform under a d i f f e r e n t condi t ion . The invest igators found, amongst the subjects accustomed to step-ups, that the one minute group scored s i g n i f i c a n t l y worse than the zero minute group and the f i v e minute group in speed of a d d i t i o n . There was a lso a t rend , although n o n - s i g n i f i c a n t , towards the condit ioned subjects improving in accuracy of addi t ion but the unconditioned group doing more poorly . These resu l t s are d i f f i c u l t to expla in in terms of the inverted U hypothesis, however, Gutin and DiGennaro suggest the p o s s i b i l i t y that subjects accustomed to the exercise may have found the f i v e minutes of step-ups to have induced moderate rather than heavy ranges of a c t i v a t i o n . A s p e c i f i e d degree of ac t i va t ion may, therefore , r e s u l t in d i f f e r e n t degrees of ac t i va t ion depending upon the f i t n e s s of the subjects for the a c t i v i t y involved. They could not o f f e r any explanation as to why the one minute group should have done worst of a l l in speed of a d d i t i o n . 31 A second study by Gutin and DiGennaro (1968b) invest igated the e f f e c t of a t readmi l l run to exhaustion on the performance of long a d d i t i o n . Each of the subjects , seventy-two col lege students, acted as his own cont ro l . The experimental treatment consisted of a run to exhaustion on a t readmil l while the control treatment had no exer t ion . These treatments were administered on a l ternate days. The tes t of performance—addition of ten d i g i t columns—was given p r i o r t o , and a f t e r , the treatment condit ion for a period of four minutes during which time subjects were scored fo r both speed and accuracy. The resu l ts showed that the exert ion had a s i g n i f i c a n t negative e f fec t on accuracy fo r the to ta l four minute tes t period as wel l as for the second and fourth minute of the t e s t . The e f f e c t , however, was not negative during the f i r s t minute a f te r exert ion during which time there was no s i g n i f i c a n t e f fec t on the accuracy of a d d i t i o n . Apart from the expected f ind ing that numerical accuracy was hindered when preceeded by heavy muscular exer t ion , two other in te res t ing factors were observed. F i r s t , the e f f e c t was not found to be negative during the f i r s t minute a f t e r exercise suggesting that exert ion had a la tent negative e f f e c t . Second, there was no trend observed showing improvement during recovery which would p a r a l l e l the cardiovascular recovery. This was i l l u s t r a t e d during the fourth minute a f t e r exert ion where negative resu l ts were s t i l l observed. Fi tness was again used as a var iable when analysing the 32 data. I t was found that the low f i tness groups were more affected by the exert ion than e i ther high or medium f i t n e s s groups. Speed of a d d i t i o n , however, was not affected by exer t ion . Neither of Gutin and DiGennaro's experiments re fer to a mental warm-up p r io r to the task or to the subject 's f a m i l i a r i t y with the task. Davey (1972), a lso conducted experiments to study the e f fec ts of strenuous physical exert ion on mental performance. In t h i s experiment twelve male undergraduate students acted as subjects , ha l f as an experimental group and hal f as a control group. The task chosen to measure mental performance incorporated a button pressing task in which the subject received auditory i n -formation in the form of a ser ies of random s ing le d i g i t numbers (0-9) and was required to press corresponding buttons on a key board in the order in which he heard the numbers. During the fourth of a ser ies of t r i a l sessions a score was obtained and used as a pre -treatment score. The treatment consisted of rest fo r the control group and physical a c t i v i t y f o r the experimental group, in the form of pedaling a b icyc le ergometer at a set power r a t i o and a constant speed fo r t h i r t y seconds. The b icyc le ergometer was so constructed that 6,000 foot pounds of work was done by each subject . A f te r the treatment the subjects repeated the task g iv ing a post treatment score. 33 The resu l t s were found to show a s i g n i f i c a n t improvement during the f i r s t and second minutes a f te r exerc ise . A range of physical exert ion leve l s were studied in an experiment conducted by S tock fe l t (1968). Treatments consisted of 0, 25, 45, 65, 85, and again 0 percent of the maximum exert ion that the ind iv idua l could induce while pedaling a b icyc le ergometer. Three groups of subjects were tested : p h y s i o l o g i c a l l y " w e l l -t ra ined" students, p h y s i o l o g i c a l l y "poor l y - t ra ined" students, and phys io log ica l l y "poor l y - t ra ined" non students who were not accustomed to mental work. In each group there were eight males and eight females between twenty and twenty - f ive years o l d . The tests of mental performance were f i v e s e r i e s , each of fo r t y mathematical problems comprised of simple addit ion and subt rac t ion . The order of the treatment condit ions was randomized f o r each of the subjects except that the zero percent exert ion t r i a l s were administered f i r s t and l a s t . Between t r i a l s the subject rested u n t i l the heart pulse rate decreased to less than 100 beats per minute, or f o r at least f i v e minutes. The resu l t s (Figure 6) showed that there was a tendency fo r the w e l l - t r a i n e d students to score less wel l on the e i g h t y - f i v e percent exert ion l e v e l . The d i f ferences fo r t h e i r other exert ion l e v e l s were not s i g n i f i c a n t . For non-students and poor l y - t ra ined students there were s i g n i f i c a n t d i f ferences between the d i f f e r e n t exert ion l e v e l s . S t o c k f e l t suggest that the reason fo r th i s i s that 3 4 Figure 6 Mean Z-scores of the three groups as a function of percent of maximum exert ion involved (S tockfe l t 1968) 35 the performance curves over the exert ion leve ls take the form of an inverted U with maximum performance at the level of f o r t y - f i v e percent exert ion and a minimum at the level of e i g h t y - f i v e percent exer t ion . Further invest igat ion of Figure 6 shows that the scores for the f i n a l zero percent t r i a l are higher than the i n i t i a l zero percent t r i a l . This indicated that there may be an accumulated arousal e f f e c t despite rest per iods. D i f fe rent resu l ts may have been obtained i f each of the t r i a l s had been on a separate day. Davey (1973) conducted a further study to examine the e f f e c t of physical exert ion on mental performance. He also introduced the factors of in t rovers ion and ext ravers ion , and neuroticism and s t a b i l -i t y to determine the e f f e c t , i f any, that they might have an arousal induced by physical exer t ion . Eighty subjects were div ided in to four groups of twenty based on t h e i r extreme scores on the Eysenck Personal i ty Inventory, a tes t measuring personal i ty in terms of extraversion and in t rove r -s i o n , and neuroticism and s t a b i l i t y . Each subject was required to perform a ser ies of treatment condit ions invo lv ing 0, 1/2, 1, 2, 4 and 6 minutes of r id ing on a b icyc le ergometer a f t e r which the mental performance of the subjects was measured. This involved short - term memory r e c a l l of random d i g i t s and the Brown and Poulton test which required the subject to l i s t e n to a ser ies of random d i g i t s and detect sequences which occurred in the order of odd number, even number, odd number. 36 The short term memory scores were found to deter iorate s i g n i f i c a n t l y a f t e r the four and s i x minute exercise condit ions but to remain constant with exert ion of less than four minutes. The mental performance scores, as measured by the Brown and Poulton t e s t , however, improved a f t e r 1/2, 2 and 4 minutes of exert ion and deter iorated a f t e r s i x minutes of exer t ion . These resu l ts suggest that mental performance was consistent with the inverted U hypothesis, but, short term memory was not shown to be f a c i l i t a t e d by physical a c t i v i t y . Some in te rac t ion e f fec ts between personal i ty var iables were found to be s i g n i f i c a n t . In t rover ts , with the same amount of exe r t ion , seemed to deter iorate more, in mental performance, than ext raver ts . This f ind ing i s consistent with Eysenck's theory that in t rover ts are more highly aroused, in a res t ing s t a t e , than ext rover ts , and that in t rover ts reach t h e i r optimum level of performance e a r l i e r with increased arousa l . There was no s i g n i f i c a n t d i f ference between stable subjects or those who tended to be more neurot ic . Davey did not, however, consider the prolonged, or c a r r y -over e f fec ts of induced arousa l . His treatment condit ions were administered in order from the l eas t to the most strenuous. Further-more, only a b r i e f period of t h i r t y seconds of rest was allowed between the tes t and the fo l lowing treatment cond i t ion . V e r i f i c a t i o n of his resu l ts by experiments which attempt to control the possible prolonged e f fec ts of exert ion arousal would, therefore, be des i rab le . 37 In summary, i t can be seen that evidence to support the inverted U hypothesis has been found by many researchers. Stauffacher (1937), Courts (1939), Wood and Hokanson (1965), and Freeman (1938) a l l explained the resu l t s of the i r experiments in terms of the inverted U hypothesis. In these studies the invest igators were concerned with the e f fec ts on mental performance caused by arousal induced by some kind of s t a t i c muscle tens ion. In each case the subjects were given a test of mental performance while undergoing the physical treatment cond i t ion . Important information was gained from these works but fur ther studies were required. I t could have been that t h e i r resu l ts were caused by a s h i f t in at tent ion from the mental performance task to the physical treatment task, as i t became more d i f f i c u l t , when both tasks were administered simultaneously. A l s o , i t was thought that a more useful task would be one which involved some sort of dynamic physical a c t i v i t y involv ing larger areas of the body and c l o s e l y resembling sports and physical education a c t i v i t i e s . McAdam and Wang (1967), Gutin (1966), Gutin and DiGennaro (1968 a , b ) , and Davey (1972) used a c t i v i t i e s such as running, walk-ing> jogging, push-ups, ch ins , standing broad jump, step-ups, and b icyc le ergometer r id ing as means of inducing arousal . Further invest igat ions were needed, however, as only port ions of the range of the i n t e n s i t y of physical a c t i v i t y were studied and consequently the resu l ts indicated only part of the inverted U curve. 38 S tock fe l t (1968) conducted a study which invest igated a range of physical exert ion l e v e l s . In doing so he found evidence to suggest that an inverted U re la t ionsh ip ex is ts between physical exert ion and mental performance. Evidence also appeared which predicted the possible cumulative e f f e c t of a rousa l , despite rest per iods, i nd ica t ing that fur ther study, with each treatment condit ion being administered on a d i f f e r e n t day, would be des i rab le . Davey's (1973) study of a range of physical exert ion also supported the inverted U hypothesis but, f a i l e d to consider the cumulative e f fec ts of a rousa l . V e r i f i c a t i o n of his r e s u l t s , by experiments which control fo r the p o s s i b i l i t y of prolonged e f fec ts of a rousa l , would be des i rab le . This study was designed to add further refinements to the preceding work and to contr ibute to the c l a r i f i c a t i o n of the re la t ionsh ip between physical exert ion and mental performance. 39 CHAPTER III METHODS AND PROCEDURES SUBJECTS Twenty male students were selected from volunteers who resided in campus dormitor ies . This s i t u a t i o n minimized p re - tes t a c t i v i t y by permitt ing tes t ing immediately upon r i s i n g from bed. Each subject was required to complete one of f i v e experimental condit ions on f i v e consecutive days. MENTAL TASK The Brown and Poulton Test (Davey, 1973) was selected on the basis of the fo l lowing three considerat ions: (a) previous experience would be of no ass is tance , (b) the task would be free from l e a r n -ing e f fec ts during performance, (c) the task should be e a s i l y q u a n t i f i a b l e . This task required continuous at tent ion to auditory s ignals and involved memory spans of a few seconds, that i s , i t required the subject to l i s t e n to a l i s t of numbers, pre-recorded at one second in te rva ls (See Appendix B). The object was to detect a sequence of d i g i t s which occurred in the order "odd-even-40 odd", and to respond by saying "yes" before the next d i g i t was pre-sented. The score was the number of ser ies co r rec t l y i d e n t i f i e d . The ser ies was formulated randomly from the numbers 1-9 with the r e -s t r a i n t that no numbers would occur twice in succession. The task was divided into two parts d a i l y . Part one en-t a i l e d a shor t , one minute pract ice t r i a l to f a m i l i a r i z e the subjects with the tes t each day. Part two was the tes t t r i a l of two and a ha l f minutes durat ion. The t e s t battery consisted of f i v e sets of randomly generated d i g i t s and each subject was randomly assigned a d i f f e r e n t tes t set for each day of t e s t i n g . PHYSICAL TASK I t was desirable that the physical task be such that the amount of work done could be e a s i l y measurable and could be maintained for the desired lengths of t ime. This experiment also required that the change from physical exert ion to mental performance should not in te r fe re with the l a t t e r task. The work controls offered by the b icyc le ergometer s a t i s f i e d these requirements and i t was, therefore , used to induce physical exer t ion . To induce s u f f i c i e n t e f f o r t a resistance of 4 kg was appl ied to the ergometer, and the subject was required to r ide at the rate of f i f t y revolut ions per minute. To vary the work done in each treatment condit ion the duration of 41 the exercise bout was var ied . The f i v e treatment condit ions were 0 , 2 , 4 , 6 and 8 minutes of exer t ion . The subject 's heart rate was monitored during the l a s t f i f t e e n seconds of each r ide by the use of a stethoscope. The purpose of t h i s was to confirm that the eight minute treatment condit ion was s u f f i c i e n t l y demanding to induce a heart rate of approximately 180 beats per minute. This indicated to the invest igator that the subjects were exposed to a f u l l range of physical a c t i v i t y beginning with none and increasing s t e a d i l y , by two minute increments, to the exhausting eight minute treatments. The resu l t ing heat rates are l i s t e d in Appendix E. EXPERIMENTAL DESIGN AND CONSIDERATIONS The design of the experiment was such that as many as possib le of the factors which could inf luence the resu l ts were considered and t h e i r e f fec ts were invest igated in the a n a l y s i s . These factors were: (a) The treatment e f f e c t , or the e f f e c t of the various amounts of physical exer t ion . (b) The order e f f e c t to determine i f the order in which the subjects received t h e i r treatments made any d i f fe rence . (c) The day's e f f e c t to determine i f any d i f ference ex is ts between the days of the week. 42 (d) The t e s t ' s e f f e c t , to detect any d i f ferences that may have ex is ted between the f i v e tests of mental performance. This study u t i l i z e d a repeated measures design where each subject acted as h is own c o n t r o l . To reduce the p o s s i b i l i t y that one treatment may a f f e c t the next, only one condit ion was tested each day. The sequence of these treatments was randomized and presented in f i ve d i f f e r e n t orders as were the f i v e d i f f e r e n t tests of mental performance. A 5 x 5 Greco-Latin squares design (Figure 7) was chosen as being most su i tab le in l i g h t of the above requirements. The subjects were assigned to four 5 x 5 Greco-Lat in squares. . . .Sg represent the f i r s t f i v e subjects . The second Lat in square would be fo r Sg. . -S-JQ, the t h i r d fo r S ^ . . » S ^ , and the fourth f o r S 1 6 . . . S 2 Q . D-j. . .Dg represent the days from Monday D-j to Friday Dg on which the tes t ing took p lace . The l e t t e r s w i th in the squares represent the f i v e treatment cond i t ions : A, 0 physical exer t ion ; B, 2 minutes; C, 4 minutes; D, 6 minutes; E, 8 minutes. The numbers wi th in the squares, 1. . . 5 , represent the d i f f e r e n t tests of mental performance. A fur ther experimental considerat ion was scheduling the tes t ing between 6:30 and 8:00 am each morning (See Appendix C). This 43 °1 D2 D3 D4 D5 A2 E3 D l C4 B5 S2 C l D5 A3 B2 E4 S3 B3 A4 C5 E l D2 S4 E5 C2 B4 D3 A l S5 D4 B l E2 A5 C3 Figure 7 Greco-Lat in Square Design ( rep l i cated four times) 44 was done to standardize as much as possible the arousal leve ls of the subjects p r i o r to being tested . Due to the l im i ted time su i tab le for tes t ing each morning subjects 1. . .10 were tested during the f i r s t week of tes t ing and subjects 11. . .20 were tested during a second consecutive week. APPARATUS The apparatus used fo r t h i s experiment was: a Monarch b icyc le ergometer, tape recorder, metronome, stop watch, and a stethoscope. PROCEDURE Instruct ions (See Appendix A ) , in the form of a wr i t ten out -l i n e and personal in terv iew, were given p r i o r to t e s t i n g . The subject ar r i ved at the tes t ing s ta t ion and was inst ructed to take his pos i t ion on the b icyc le ergometer. He then excecuted the desired exercise task which enta i led r i d i n g the ergometer fo r the spec i f ied length of time at a rate of 50 revolut ions per minute. A stethoscope was posit ioned during the l a s t 30 seconds of the r ide and heart rate was monitored fo r the l a s t f i f t e e n seconds. Immediately upon completion of the exercise treatment a tape recorder , s i tuated beside the subject , was turned on and the test of mental performance was i n i t i a t e d . During th is time the sub-jec t remained posit ioned on the b icyc le ergometer. 45 ANALYSIS OF DATA The data was analysed with an ANOVA fo r a 5 x 5 Greco-Lat in square to tes t the e f fec ts of the treatments and t h e i r o rder , the days, and the t e s t s . Since no computer program was ava i lab le that could provide a l l of the required informat ion, the sums of squares fo r each of the e f fec ts were ca lcu lated separately using the UBC program BMD 08V. The mean squares and F ra t ios were then computed with a c a l c u l a t o r . In a d d i t i o n , the resu l t s fo r each ind iv idua l were expressed g raph ica l l y to permit fur ther analys is of the data by subject ive means. This subject ive analys is resul ted i n a decis ion to segregate the data into two groups—that which was obtained during the f i r s t week of t e s t i n g , and that obtained during the second week. The data fo r each week was then subjected to a separate one-way ANOVA to test fo r the e f fec ts of the treatments during Week one and then Week two. These ca lcu la t ions were car r ied out by another UBC computer program, BMD 02V, which provided a repeated measures analys is of variance with an or tho -gonal breakdown of each source of va r ia t ion to tes t fo r t rend. 46 CHAPTER IV RESULTS AND DISCUSSION RESULTS The resu l ts of t h i s invest igat ion regarding the re la t ionsh ip between mental performance and physical exert ion are presented in t h i s chapter. The i n i t i a l phase of the analys is examined the raw scores compiled from a l l subjects observed during the two week tes t ing period (See Appendix D f o r raw scores) . The mean scores of a maximum of twenty-eight on the tes ts of mental performance, were ca lcu lated fo r each tes t ing order, exercise treatment, day of tes t ing and mental performance tes t and are presented in Table I. This table i l l u s t r a t e s that the mean score obtained in the f i r s t order of tes t ing was 20.55, the mean score fo r the f i r s t treatment or 0 exert ion was 18.25, the mean score on day one or Monday was 16.45, and the mean score obtained when using tes t one was 19.25. The data was then subjected to an analys is of var iance, the resu l ts of which are expressed in Table II. From t h i s table i t can be seen that : (a) The e f f e c t of the order of presentation of the t r e a t -ments was n o n - s i g n i f i c a n t , (F^ ^ = .56 , p > . 0 5 ) , (b) The e f f e c t of the various treatment condit ions was n o n - s i g n i f i c a n t , (F^ gg = 2 .32 , p > .05 ) . In t h i s case the c r i t i c a l F at the .05 leve l was 2 .50 . 47 TABLE I Mean Scores Obtained from the Test of Mental Performance fo r Each Order, Treatment, Day, and Test 1 2 3 4 5 Testing Order 20.55 18.25 17.05 22.30 20.30 Exercise Treatments 18.25 20.45 19.75 19.65 20.35 Days of Testing 16.45 20.40 20.25 21.15 20.20 Mental Performance Tests 19.25 20.05 19.55 20.80 18.80 TABLE II Results of the Analysis of Variance Applied to Raw Scores Obtained from the Test of Mental Performance Source df SS MS F P Order of Treatments 4 339.34 84.84 .56 >.05 S W Order 15 2265.65 151.04 Exercise Treatments 4 61.84 .15 .46 2.32 >.05 Days of Testing 4 274.14 68.54 10.28 <.01 Mental Performance Tests 4 47.34 11.84 1.78 >.05 Error 68 453.28 6.67 F . 0 5 ; 4 , 1 5 = 3 ' 0 6  F . 0 5 ; 4 , 6 4 = 2 , 5 0 ,01;4,64 3.60 48 (c) The day's e f f e c t was s i g n i f i c a n t at the .01 l e v e l , ( F 4 > 6 8 = 10.28, p < .01 ) . (d) The e f fec ts of using f i v e d i f f e r e n t tests to measure mental performance was n o n - s i g n i f i c a n t , (F^ g g = 1.78, p > .05 ) . The degree to which the e f fec ts of the treatments approached s ign i f i cance at the .05 level ind icated that a more deta i led i n v e s t i -gation of the resu l t s might be appropriate in order to provide addi t ional ins ight into the problem under i n v e s t i g a t i o n . The second phase of the a n a l y s i s , therefore , treated the resu l ts of the f i r s t week of tes t ing separately from those of the second week and required two separate analyses of var iance. The mean scores obtained f o r each of the treatment condit ions are presented for Week one and Week two in Table I I I . The resu l t s of the analys is of variance for the f i r s t week data are presented in Table IV. I t can be seen that the e f f e c t s of TABLE III Mean Scores Obtained from the Test of Mental Performance fo r the Exercise Treatments During Each of the Two Weeks of Testing 0 min 2 min 4 min 6 min 8 min Week 1 17.00 19.90 .18.80 19.90 18.60 Week 2 19.50 21.00 20.70 19.40 22.10 49 TABLE IV Analysis of the Treatment Ef fects fo r Week 1 Source df SS MS F P Subjects 9 1599.16 177.68 Exercise Treatments 4 56.92 14.23 1.38 >,05 Error 36 388.68 10.80 F . 0 5 ; 4 , 3 6 ~ 2 ' the treatment condit ions were n o n - s i g n i f i c a n t (F^ 35 = 1.38, p > .05) . Furtherfore, the resu l ts of the trend analys is , (Tab le VI) ind icate that the l i n e a r , quadrat ic , and cubic e f fec ts inherent in the data are a l l n o n - s i g n i f i c a n t . The resu l ts of the analys is of variance fo r the Week 2 data are expressed in Table V. Here again the ef fects of the t r e a t -ment condit ions were non -s ign i f i cant (F^ ^5 = 1-37, p > .05) . The . resu l ts of the trend a n a l y s i s , Table VI are also n o n - s i g n i f i c a n t . Note: Subject 13 was considerably less phys ica l l y capable than the others . The resu l t was that he was unable to perform the same treatment condit ions as the others and these were therefore modified to 0 , 2 , 3 , 4, and 5 minutes of exer t ion . It was decided that t h i s subject was quite exhausted a f t e r f i ve min-utes and his resu l ts would, therefore , not be inconsistent with those of the others . 50 TABLE V Analysis of The Treatment Ef fects for Week 2 Source df SS MS F P Subjects 9 933.62 103. 74 Exercise Treatments 4 50.52 12 63 1.37 >.05 Error 36 340.77 9 45 F . 0 5 ; 4 , 3 6 2 ' TABLE VI Results of the Trend Analys is for Week 1 and Week 2 Week 1 MS F P L inear 10.24 .95 >.05 Quadratic 27.46 2.55 >.05 Cubic 2.56 .24 >.05 Remainder 16.66 Total 10.80 Week 2 Linear 12.96 1.37 >.05 Quadratic 1.40 .15 >.05 Cubic 33.64 3.56 >.05 Remainder 2.52 Total 9.45 P = 4 11 \ 0 5 ; 1 , 3 6 50a The mean scores of the heart r a t e s , recorded in Appendix E, ind icate that there was a rapid increase from the rest ing rate of 17.5 beats per f i f t e e n seconds to 36.2 beats for the l a s t f i f t e e n seconds of the two minute exercise treatment. Further increases in the exercise requirements resulted in gradual increases in heart rates unt i l a maximum mean of 46.4 beats was recorded during the l a s t f i f t e e n seconds of the eight minute treatment. This indicated that the subjects had been subjected to strenuous physical a c t i v i t y , p a r t i c u l a r l y during the treatment condit ion cons is t ing of eight minutes of b icyc le ergometer r i d i n g . 51 DISCUSSION Analys is showed that there was no di f ference between t r e a t -ment condi t ions . The hypothesis: "Varying the amounts of physical exert ion w i l l d i f f e r e n t i a l l y inf luence mental performance," i s not supported, and can, therefore , not be accepted on the basis of these r e s u l t s . The resu l ts d i d , however, tend towards s ign i f i cance with an F r a t i o fo r treatments being 2.32 when the c r i t i c a l F ra t io at the .05 level was 2.50. These resu l ts are expressed graphica l l y in Figure 8. Observation of t h i s f igure reveals that physical exert ion p r i o r to the mental task has appeared to a l t e r performance. In each case the mean scores of mental performance were higher when preceded by exercise than they were a f t e r the treatment condit ion cons is t ing of no exerc ise . This tendency towards s ign i f i cance could ind icate that although the hypothesis could not be accepted, i t should not automatical ly be re jected,as l i m i t a t i o n s wi th in the experimental design have resul ted in the f a i l u r e to control a l l the factors which could inf luence mental performance other than physical exer t ion . The order and tests e f fec ts were both n o n - s i g n i f i c a n t . This i s " i n t e r p r e t e d to mean that the order i n which the subjects received t h e i r treatment condit ions made no d i f fe rence . I t a lso ind icates that there were no d i f ferences between the tests in degree of d i f f i c u l t y . The day's e f f e c t was, however, s i g n i f i c a n t at the .01 l e v e l . Examination of the mean scores (Table I) reveals that day one, 52 Figure 8 Mean scores of mental performance for the f i v e treatment condit ions 53 or Monday, of each week had a much lower mean score than the other days, a l l of which were s i m i l a r . This was interpreted to mean that the students were not adequately prepared f o r t h e i r f i r s t tes t ing sess ion. I t appears that more than one minute of pract ice would be necessary f o r the subjects to become f a m i l i a r with t h i s t e s t . Perhaps more accurate resu l t s would have been obtained i f the subjects had each undergone a pract ice t r i a l during the week p r i o r to t e s t i n g , Observation of the mean scores ind icates that only one t r i a l was necessary to s t a b i l i z e the scores. The randomizing of treatments d i s t r i b u t e s the day's e f f e c t evenly amongst the treatment cond i t ions , but i t i s uncertain how i t has af fected the analys is of the r e s u l t s . For example, Figure 9 shows the graph of each subject 's ind iv idual performances. Subject two scored p a r t i c u l a r l y poorly a f t e r h is t h i r d treatment condit ion which was undertaken on day one. This i s e n t i r e l y opposite to the expected response and t h i s descrepancy cou ld , there -f o r e , be due to the novelty of the t e s t i n g s i t u a t i o n on day one. A second fac tor which could have inf luenced the resu l ts was that several of the subjects ' scores were perfect or nearly perfect on one or more of the t e s t s . The ind iv idua l graphs fo r subjects 7, 8 , and 19 (Figures 9 and 10) show high scores with l i t t l e f luc tuat ion f o r each treatment. This could mean that some subjects have a p a r t i c u l a r aptitude f o r t h i s type of test o r , that i t was general ly too easy. The degree of d i f f i c u l t y could possib ly have been i n -creased by speeding up the presentation of d i g i t s from one per second to one every 3/4 or even 1/2 a second. Subject 1 30 ., 20 Subject 3 cu 8 10 oo 0 30 20 10 0 Subject 5 Subject 7 Subject 9 • • • I I 0 2 4 6 8 Min. of Exertion 30, Subject 20 2 10 0 AT -i—i—i—i—"— 0 2 4 6 8 i i i i i 0 2 4 6 8 30* 20. 10. 0 i • i i i 0 2 4 6 8 30 204 10 0 i i i i • •• 0 2 4 6 8 30 204 10 0 l l — i — I — r — 0 2 4 6 8 301 Subject 20J 4 4 10 0 i r" i i • 0 2 4 6 8 30 « Subject 20 6 10 0 • i I I I 1 0 2 4 6 8 30 Subject 20 ] 8 10 0 i i i i i 0 2 4 6 8 30 Subject 20 10 10 0 1» i i 'i i 0 2 4 6 8 Figure 9 Individual scores obtained from the test of mental performance (Week 1) 30 Subject a> 20 1 1 8 °° 10 Subject 13 Subject 15 Subject 17 Subject 19 0 30 20 10 0 30 20 10 0 30 20 10 J 0 30 20 J 10 0 i • » » i 0 2 4 6 8 Min. of Exertion 301 Subject 20 12 18 0 i i i i i 0 2 4 6 8 i i i i • 0 2 4 6 8 i « i i i 0 2 4 6 8 \ i i i i i 0 2 4 6 8 • i i < i 0 2 4 6 8 30 Subject 20 14 10 0 i i i i i 0 2 4 6 8 30 1 Subject 20 16 10 J 0 0 2 4 6 8 30 Subject 20 \ 18 104 0 i > i i i 0 2 4 6 8 30 Subject 20 20 10^ 0 • i i i i i 0 2 4 6 8 Figure 10 Individual scores obtained from the - tes t of mental performance (Week 2) 56 The second hypothesis: "The inf luence of physical exert ion on mental performance w i l l be of an inverted U nature" must also be re jected . On the basis of the resu l t s in th i s study i t must be accepted that the inf luence of physical exert ion on mental performance w i l l not always be of an inverted U nature o r , that the experimental procedures (some of which have been mentioned previously) have resulted in inconclusive r e s u l t s . The nearness to s ign i f i cance of the ef fects of the t r e a t -ments, however, indicated that a more deta i led invest igat ion of the resu l ts was i n order . Inspection of the graphs of ind iv idual scores (Figures 9 and 10) revealed that the behaviour of many ind iv idua ls could indeed be described by an inverted U re la t ionsh ip even though the highest scores, that i s , the peak of the curves, varied amongst i n d i v i d u a l s . Closer examination revealed some in te res t ing trends and provided a basis fo r fur ther a n a l y s i s . Some graphs showed improved scores a f t e r the f i f t h treatment cond i t ion , which was contrary to predicted behaviour. This was p a r t i c u l a r l y evident during the second week of tes t ing where s i x of the ten graphs showed improvement a f t e r the most exhausting treatment cond i t ion . I t was thought, on the basis of these observat ions, that the subjects tested during the second week may have reacted d i f f e r e n t l y to the treatment condit ions than the subjects who were tested f i r s t . The two weeks of tes t ing were, therefore , analyzed separately . 57 Analys is of the treatment e f fec t again y ie lded n o n - s i g n i f i -cance fo r both Week one and Week two (Tables IV and V). A trend analys is done f o r each week also y ie lded non-s ign i f icance (Table VI ) . I t d i d , however, suggest that there was a much greater quadratic e f f e c t during the f i r s t week but a s h i f t to a larger cubic e f fec t during the second week. The second week's r e s u l t s , although n o n - s i g n i f i c a n t , do tend towards showing a s i g n i f i c a n t cubic e f f e c t with a ca lcu lated F-j = 3.56 and c r i t i c a l F Q 5 # 1 3 g = 4 .11 . Graphic presentation of the scores (Figure 11) i l l u s t r a t e s t h i s e f f e c t . During Week two there i s a d i s t i n c t change in d i rec t ion of the graph to describe the f i f t h treatment con-d i t i o n which appears to be responsible f o r the tendency toward a cubic re la t ionsh ip during t h i s week. A corresponding change i s not observed in the presentation of the mean scores for Week one. This resu l t i s opposite to what was expected and probably contr ibuted great ly to the non -s ign i f i cance of the overa l l r e s u l t s . I t i s , therefore , important to speculate as to why such resu l ts were obtained. Observations during tes t ing sessions indicated that the subjects during the second week of tes t ing were very aware of the exhausting nature of the f i f t h treatment condit ion ( r id ing the b icyc le ergometer for eight minutes). They had been inst ructed not to discuss the experiment amongst themselves but th i s request was d i f f i c u l t fo r young subjects , l i v i n g i n such close quarters as the campus dormitor-i e s , to adhere t o . Most of the subjects appeared to be very competitive and anxious to perform well even though they d id not receive any 58 Figure 11 Mean scores of mental performance fo r the f i v e treatment condit ions obtained during Week 1 and Week 2 59 knowledge of r e s u l t s . The outcome was that many subjects were p a r t i c u l a r l y keyed up and became highly motivated, or aroused when informed that they were to perform the eight minute r ide which was rumoured to be very d i f f i c u l t . Subjective evaluation revealed therefore that the second group of subjects was much more highly motivated to do well on the f i f t h treatment condit ion during the second week than were those tested during the f i r s t week. The importance of these'observations of the e f fec ts of physical exert ion on mental performance i s that they may be explained in terms of some of the more recent theories of arousal which have not been considered in the l i t e r a t u r e r e l a t i n g arousal to physical exer t ion . Samuels (1959) and Eysenck (1967) both suggest that two d i s t i n c t pathways e x i s t which produce c o r t i c a l a rousa l . Eysenck described the f i r s t arousal system (AS I ) as ascending d i r e c t l y from the r e t i c u l a r formation which was stimulated by sensory a f fe rents . The second arousal system (AS I I ) , he suggested, involves the l imbic system and the hypothalamus and i s st imulated by emotions. Routtenberg (1968) expanded th is concept and suggested that AS II may a lso be a reward system. In terms of th i s study i t would seem that AS I may have been act ivated by sensory af ferents r e s u l t i n g from physical exer t ion . According to Routtenberg (1968) high leve ls of a c t i v a t i o n could produce adverse st imulat ion in AS II which would cause i n h i b i t i o n of 60 AS I and r e s u l t in corresponding performance decrements. This would have been the expected r e s u l t . I t seems poss ib le , however, that the high level of motivation and incent ive of subjects during the second week could have resul ted in the pos i t i ve s t imulat ion of AS I I . This could have caused more e f f i c i e n t leve ls of arousal during the f i f t h , or most exhausting, of the treatment cond i t ions . I t seems, therefore , that in p rac t i ca l s i tuat ions AS I I , st imulated by emotions or reward, may make an important contr ibut ion to the overa l l degree to which an ind iv idua l may be aroused. In t h i s study, d i f f e r i n g mot ivat ions, which may provide one of these s t imu l i to AS I I , were not ant ic ipated and therefore not measured. I t was only in the explanation of the possible factors which have inf luenced the r e s u l t s , in a way that was not expected, that motivat ional l eve l s were suspected to be very important in cont r ibu -t ing to a rousa l . I f th is i s true i t could expla in why some athletes continue to perform b r i l l i a n t l y when apparently exhausted, whereas, less motivated ath letes may demonstrate behaviour predictable by the inverted U hypothesis. Perhaps the increased arousal a t t r ibuted to high motivation compensates fo r the expected performance decrement as a r e s u l t of increasing fa t igue . Future research w i l l be required to invest igate the e f fec ts of motivation and reward on arousa l . Nevertheless, the tentat ive suggestions of th i s study, which l i e wi th in the bounds of current arousal theor ies , ind icate that performance may not always fo l low a simple inverted U curve as leve ls of physical exert ion are increased. 61 CHAPTER V SUMMARY AND CONCLUSIONS A c t i v a t i o n , or a rousa l , has been described as the degree of neural a c t i v i t y of an ind iv idua l at any given time and i s manifested by a general dr ive to perform conscious funct ions . Furthermore, i t has been sa id that as an i n d i v i d u a l ' s leve l of arousal increases there i s an increase in his ef fect iveness of performance for any p a r t i c u l a r type of behaviour. I f the arousal leve l continues beyond t h i s optimum, a gradual decrease in performance i s predicted and i s de-scr ibed as an inverted U r e l a t i o n s h i p . Arousal has been a t t r ibu ted to several stimulus condit ions inc luding f e a r , anxiety , emotion, shock, no ise , heat, and physical a c t i v i t y . Evidence also ex is ts which indicates that leve ls of a c t i v a t i o n , induced by dynamic physical a c t i v i t y , can a f fec t mental performance. PROBLEM This study was designed to fur ther invest igate the r e l a t i o n -ship between physical exe r t ion , of a more p r a c t i c a l nature, and mental performance and then to in terpret t h i s information in terms of arousal theor ies . 62 The hypotheses under invest igat ion were: ( i ) Varying the amounts of physical exert ion d i f f e r e n t i a l l y af fected the level of arousal and thereby inf luenced mental performance, ( i i ) The inf luence of physical exert ion on mental performance corresponded to the inverted U hypothesis, i . e . inc reas -ing exert ion improved performance un t i l a maximum leve l of p rof ic iency was obtained, beyond which the leve l of performance began to deter io ra te . This study was l im i ted to b icyc le ergometer r i d i n g as a method of inducing physical exer t ion . The study was also l i m i t e d by an i n a b i l i t y to control fo r the e f fec ts of the motivation of the subjects while they were being tested . A fur ther l i m i t a t i o n was the use of one test of mental a c t i v i t y to be used as a gauge for mental performance. SUBJECTS Twenty male students res id ing in campus dormitories volun-teered as subjects . 63 METHODS AND PROCEDURES Each volunteer was subjected to one of f i v e d i f f e r e n t physical exert ion treatments on each of f i v e consecutive days. These treatment condit ions were randomly assigned to f i v e d i f fe ren t orders and consisted of r id ing a b icyc le ergometer for 0, 2, 4, 6, and 8 minutes at a rate of f i f t y revolutions per minute with a resistance of four ki lograms. This resistance was appl ied to ensure that s u f f i c i e n t e f f o r t , to exhaust the subjects a f te r eight minutes of r i d i n g , would be induced. A stethoscope was posit ioned during the l a s t t h i r t y seconds of the r ide and heart rate was monitored f o r the l a s t f i f t e e n seconds. (Appendix E indicates that during t h i s treatment the heart rates of a l l subjects reached 176 beats per minute or greater ) . On completion of each da i l y exercise bout the subject per -formed a task designed to measure mental performance. This task required the subject to l i s t e n to a l i s t of random numbers, pre-recorded at one second in te rva l s with the object ive of detect ing a sequence of d i g i t s which occurred in the order "odd number - even number - odd number", and to respond by saying "yes" before the next d i g i t was presented. The score was the number of ser ies co r rec t l y i d e n t i f i e d . Furthermore, the task was div ided into two parts d a i l y . Part one was a short one minute pract ice t r i a l to f a m i l i a r i z e the subjects with the test each day. Part two was the test t r i a l of two and one hal f minutes duration which consisted of 150 d i g i t s . Five d i f f e r e n t sets of d i g i t s were randomly assigned to each of the tes t ing sessions. A l l treatments and tests were administered between 6:30 am and 8:00 am d a i l y during two consecutive weeks of t e s t i n g . The subjects were assigned to four 5 x 5 Greco-Latin squares enabling simultaneous randomizing of the order of the treatments, the tests of mental performance, and the day's e f f e c t . ANALYSIS OF DATA The data was analyzed with an ANOVA for a 5 x 5 Greco-Lat in squares to tes t fo r the e f fec ts of the exercise treatments and t h e i r order, the days of t e s t i n g , and the d i f f e r e n t tests of mental performance. The sums of squares f o r each of the e f fec ts were c a l -culated with the UBC computer program BMD 08V. The second phase of the analys is incorporated two one-way ANOVA's to tes t the e f fec ts of the exerc ise treatments during Week 1 and then Week 2. These ca lcu la t ions were car r ied out by another UBC computer program, BMD 02V, which provided a repeated measures analys is of variance with an orthogonal breakdown of each source of va r ia t ion to tes t f o r t rend. RESULTS AND DISCUSSION Analys is of variance y ie lded no s i g n i f i c a n t d i f ference between the various treatment cond i t ions . These resu l ts d i d , however, tend towards s ign i f i cance and are expressed graphica l l y in Figure 8 . Inspection of t h i s f igure indicated that physical exert ion p r i o r to the mental task seemed to a l t e r performance. In each case the mean 65 scores of mental performance were higher when preceded by exercise than they were a f t e r the treatment condit ion cons is t ing of no exerc ise . The order of treatments and test administered e f fec ts were also n o n - s i g n i f i c a n t . The e f f e c t of the day was, however, s i g n i f i c a n t . This seemed to be due to p a r t i c u l a r l y low scores obtained on day one of t e s t i n g , or Monday of each week, and was interpreted to ind icate that the subjects were not adequately prepared fo r t h e i r f i r s t tes t ing session.. The degree to which the e f fec ts of the treatments tended towards s ign i f i cance indicated that a more deta i led invest igat ion of the resu l t s might provide more ins ight into the problem under i n v e s t i -gat ion. Therefore, inspect ion of the i n d i v i d u a l ' s graphs of performance scores (Figures 9 and 10) was undertaken and revealed di f ferences between those scores obtained during Week 1 and those obtained during Week 2 of t e s t i n g . Consequently, a separate analys is of variance fo r each week's data was conducted, but y ie lded no s i g n i f i c a n t d i f fe rences . A trend analys is of the data also y ie lded non-s igni f icance but did suggest that there was a greater quadratic e f f e c t during the f i r s t week, but a s h i f t to a larger cubic e f fec t during the second week. This cubic re la t ionsh ip i s contrary to the expected inverted U re la t ionsh ip which would be described by a s i g n i f i c a n t quadratic e f f e c t . I t was f e l t that t h i s unexpected resu l t could possibly be accounted f o r by the subject 's strong motivation to do well on the treatment condit ion which required a strenuous eight minute r i d e . Recent theories, which predict that arousal i s a resu l t of components from two ac t i va t ing systems, ind icate that the e f fec ts evident may well have been st imulated by emotions or reward as i t was expected that high exert ion would r e s u l t in low mental performance. This could account f o r the high mental performance scores observed a f t e r the most exhausting of the treatment cond i t ions . These resu l ts suggest that s t imulat ion o f a second arousal system which deals with emotions may be s u f f i c i e n t , at t imes, to a l t e r ind iv idua l behaviour in such a way that the e f fec ts on performance cannot always be described i n terms of a predictable inverted U r e l a t i o n s h i p . CONCLUSIONS On the basis of the resu l t s obtained in t h i s study the hypothesis: "Varying the amounts of physical exert ion w i l l d i f f e r e n -t i a l l y a f f e c t the level of arousal and thereby inf luence mental performance" cannot be accepted. However, as these resu l t s did tend toward s ign i f i cance in terms of the e f f e c t of the physical exert ion cond i t ions , and they indicated that physical exert ion seemed to have a pos i t i ve e f f e c t upon mental performance, fur ther research in t h i s area would be desi rable before t h i s hypothesis i s completely re jected . 67 The second hypothesis: "The inf luence of physical exert ion on mental performance w i l l correspond to the inverted U hypothesis ," that i s , increasing exert ion w i l l improve performance u n t i l a maximum level of prof ic iency i s obtained, beyond which the level of per for -mance w i l l begin to deter io ra te , i s also unsupported and, on the basis of the resu l ts must be re jected . I t i s concluded, therefore , that the e f f e c t of physical exert ion upon mental performance cannot always be described by a simple inverted U r e l a t i o n s h i p . These conclusions are, however, contrary to those found in other s i m i l a r s tud ies . S tock fe l t (1968) u t i l i z e d the b icyc le ergometer to induce exert ion of 0, 25 , 45, 65 , 85, and 0 percent of the ind iv idual sub ject ' s maximum. His tes t of mental performance was comprised of fo r t y mathematical problems invo lv ing simple addi t ion and subt ract ion . The resu l t s indicated support fo r the inverted U hypothesis. Davey's (1973) study also supported the inverted U hypothesis. He found that mental performance scores , as measured by the Brown and Poulton t e s t , improved a f t e r 1/2, 2 , and 4 minutes of b icyc le ergometer r i d i n g , but deter iorated a f t e r s i x minutes of exer t ion . Davey, however, grouped his subjects according to t h e i r tendencies towards ext ravers ion , i n t r a v e r s i o n , neuroticism and s t a b i l i t y . The inconsistency between the resu l ts and conclusions of t h i s study and other s i m i l a r studies ind icate that there i s a great deal yet to be learned about the re la t ionsh ip between a rousa l , included by physical exe r t ion , and mental performance. The e f fec ts 68 of motivation on arousal leve ls may prove to be very important but fur ther research inves t igat ing the in te rac t ion between mot ivat ion, mental performance, and physical exert ion i s required. Experiments which could control motivation and others which could s e l e c t i v e l y induce high motivational leve ls would be des i rab le . 69 REFERENCES Andreass i , J . L . "Ef fects of Induced Muscle Tension and Auditory St imulat ion on Tachistoscopic Percept ion ," Perceptual and Motor S k i l l s . 20 :829 -841 ,1965. Berlyne, D.E. C o n f l i c t , Arousal and C u r i o s i t y . New York: McGraw-H i l l , 1960. B i l l s , A.G. 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"Ef fects of Induced Muscular Tension on Performance and the Inverted U Funct ion," Journal of  Personal i ty and Social Psychology. 1:506-510, 1965. Yerkes, R.M. and Dodson, J . D . "The Relat ion of Strength of Stimulus to Rapidity of Habit Formation," Journal of Comparative  Neurology and Psychology. 18:1908. Zartman, E.N. and Cason, H. "The Influence of an Increase in Muscular Tension on Mental E f f i c i e n c y , " Journal of Experimental  Psychology. 1 7 : 5 , 671-679, 1934. APPENDIX A INSTRUCTIONS TO STUDENTS 76 INSTRUCTIONS TO SUBJECTS You are taking part in a s c i e n t i f i c experiment which w i l l invest igate one aspect of how physical exert ion a f fec ts you. A f u l l explanation of resu l ts w i l l be sent to you upon completion. During the tes t period you are requested to fo l low the ins t ruc t ions c a r e f u l l y to ensure the c r e d i b i l i t y of the experiment. 1. You have been assigned a test time between 7 and 9 AM. I t i s important that i f you wake before t h i s time that you remain as inact i ve as poss ib le . Preferably t r y to go to sleep again or , at l e a s t , stay in bed. 2. When your time comes you w i l l be requested to come to the tes t s i t e and to s i t on a b icyc le ergometer. I f you have any questions or do not understand any of the i n s t r u c t i o n s , ask at t h i s time f o r c l a r i f i c a t i o n . 3. You w i l l be asked to s t a r t peddling in time with a metronome at the rate of one revolut ion per beat, i . e . : each time the metronome beats , your r ight foot should be at the bottom of the revo lu t ion , or s t ra igh t down. 4. You w i l l be asked to stop at a given t ime, known by the experimenter. Remain s i t t i n g on the ergometer. 5. A tape recorder w i l l be switched on and you are to l i s t e n to t h i s . You w i l l hear a ser ies of numbers at one second i n t e r v a l s . Your task w i l l be to detect a sequence of d i g i t s which occur in the order "odd-even-odd," and to respond by saying "yes" before the next d i g i t i s presented, i . e . i f you hear " . . . 7 , 4 , 9 , . . . " ( that i s "odd-even-odd") you respond "yes". I f you hear 7 , 4 , 9 , 2 , 3 , you must respond "yes" a f t e r 9 and a f t e r 3 . In these f i v e numbers there are two "odd-even-odd" sequences, the 9 being in both of them, i . e . 7 , 4 , 9 , and 9 , 2 , 3 . 6. You are to r e f r a i n from discussing the experiment with fe l low students u n t i l the tes t ing i s complete. 7. You w i l l be c a l l e d each day at the same time fo r a to ta l of f i v e tests (Monday to F r iday ) . The tests w i l l average about f i v e minutes each and range from about two minutes to ten minutes. Thank you very much for p a r t i c i p a t i n g in t h i s experiment. Your e f f o r t i s great ly appreciated. APPENDIX B SAMPLE SCORE SHEETS 79 SAMPLE SCORE SHEETS Test Number 1 Treatment Subject Heart Rate ( l a s t 15 sec) 6 1 7 6 3* 4 3* 7 3 9 7 5 4 1* 4 9* 3 7 1 9 4 5* 8 5 9 5 9 8 4 3 4 9* 3 2 4 8 7 6 5* 6 5* 6 8 2 8 6 5 3 9 8 7* 5 8 4 3 6 8 3 5 1 5 2 6 3 8 2 5 9 6 2 3 5 3 4 1* 8 3* 9 2 5* 7 5 8 4 8 6 1 3 6 7* 4 6 3 8 2 6 9 3 4 2 5 4 1* 4 1* 5 1 4 9* 5 1 4 3* 9 2 3* 2 5* 8 3* 1 8 1* 8 1* 7 9 5 7 4 3* 8 5* 3 9 6 9 7 3 4 1* 7 5 7 5 8 5* 3 1 4 Total Number Correct Responses Test Number 2 Treatment Subject Heart Rate ( l a s t 15 sec) 3 9 1 7 9 8 3* 8 1* 7 3 1 9 4 5* 3 5 3 4 1* 2 8 7 2 9* 5 8 2 7 2 8 9 1 9 2 1* 8 1* 9 3 4 5* 2 1* 2 4 7 3 7 5 8 7* 8 2 9 4 1* 5 3 9 7 2 9* 4 3* 7 9 2 3* 1 2 5* 8 7* 2 4 8 9 4 9* 4 3* 4 5* 2 8 6 1 4 9* 1 6 1* 7 8 9* 3 8 2 7 8 6 7 1 6 4 8 3 4 5* 9 5 9 3 2 4 3 5 3 2 3* 8 1* 8 7* 4 5* 6 8 2 8 2 4 7 2 3* 8 4 6 2 4 8 1 8 4 7 1 9 2 4 Total Number Correct Responses Test Number 3 Treatment Subject Heart Rate ( l a s t 15 sec) 4 2 8 2 4 8 2 7 4 5* 4 7* 5 4 5* 3 6 5* 9 4 7* 8 6 9 8 7* 1 2 1* 5 9 1 2 7* 3 6 2 6 1 2 8 2 3 4 6 9 1 6 1* 2 1* 2 3* 8 4 2 7 3 7* 6 4 1* 6 7* 8 9* 5 7 8 3* 9 3 2 3* 4 9* 3 2 4 8 3 4 1* 3 8 7* 6 7* 3 5 8 3* 9 8 3* 5 4 8 7 8 6 9 3 2 9* 5 6 4 6 4 5 3 6 3 * 2 6 2 3 4 6 4 7 4 8 4 6 1 4 3* 5 3 8 6 5 9 5 6 1* 7 8 4 9 5 7 8 7* 4 5 * 2 Total Number Correct Responses Test Number 4 Treatment Subject Heart Rate ( l a s t 15 sec) 3 8 1 * 8 3* 2 3* 5 3 4 2 3 9 5 9 5 4 3* 8 4 1 7 6 8 7 2 8 3 9 8 7* 1 6 1* 9 4 1* 6 8 2 5 4 3* 4 9* 4 9* 8 4 2 7 8 5* 2 1* 3 2 9* 2 4 9 5 4 1* 2 7* 9 4 3* 9 3 6 4 9 4 2 3 9 7 2 7* 4 1* 6 7* 9 5 4 8 2 1 9 6 7* 3 6 4 6 9 6 2 7 8 3* 7 1 9 2 5* 3 2 8 1 3 8 5* 3 7 4 8 2 4 8 2 5 6 8 3 4 6 5 4 9* 6 9* 2 4 7 9 5 4 3* 5 1 5 4 3* 9 6 1* Total Number Correct Responses 81 Test Number 5 Treatment Subject Heart Rate ( l a s t 15 sec) 8 9 2 1* 2 3* 6 2 5 7 8 7* 4 7* 3 5 1 2 7* 2 3* 2 1* 3 9 2 4 1 3 9 6 5* 1 4 5* 9 8 1* 8 6 3 9 1 8 2 9 3 2 9* 4 1* 2 4 2 3 6 3* 1 2 6 1 6 5* 9 8 5* 4 6 3 8 6 5 8 5* 6 7* 5 4 5* 4 6 4 5 2 8 4 1 5 3 2 5* 4 1* 2 5* 4 1* 7 1 9 8 4 1 5 9 2 6 1 3 1* 4 5* 4 5* 8 1* 4 3* 9 8 4 9 8 6 5 7 9 2 8 7 2 4 8 6 2 1 5 4 6 3 9 8 9* 4 6 8 1 2 6 4 Total Number Correct Responses APPENDIX C TESTING SCHEDULE 83 TESTING SCHEDULE Due to the varying lengths of treatments and degrees of promptness,the subjects were assigned to the fo l lowing time periods. When a subject completed his test the next subject was c a l l e d to the tes t ing s t a t i o n . Subjects 6 :30-7 :00 AM i) 3 4 5 } 7 :00-7:30 AM 6 7:30-8:00 AM 10 } 8:00 AM Subjects 1 \ 2 ) 6 :30-7 :00 AM 3 X 4\ 5 } 7 :00-7:30 AM 6 / 7:30-8:00 AM 9^ 20 } 8:00 AM Week 1 Week 2 APPENDIX D RAW SCORES 85 RAW SCORES FOR EACH TREATMENT CONDITION (Maximum 28) Subject Treatments A (0 min) B (2 min) C (4 min) D (6 min) E (8 min) 1 9 14 22 19 19 2 12 17 8 18 14 3 8 12 6 9 5 4 13 15 15 17 7 5 19 24 15 17 16 6 17 24 27 25 26 7 26 24 24 25 28 8 26 24 24 25 28 9 20 26 27 27 22 10 20 19 20 17 21 11 14 22 23 22 18 12 22 26 21 19 27 13 17 10 20 18 22 14 24 26 28 24 24 15 23 23 25 21 26 16 20 25 22 22 21 17 10 16 5 8 15 18 21 16 16 16 18 19 26 27 27 27 24 20 18 19 20 17 26 APPENDIX E HEART RATES 87 HEART RATES MEASURED DURING THE LAST 15 SECONDS OF EACH TREATMENT CONDITION Subject Treatments A( 0 min) B (2 min) C (4 min) D (6 min) E (8 min) 1 - 37 38 40 45 2 - 38 38 43 45 3 - 35 38 38 46 4 20 39 35 43 46 5 14 38 40 45 50 6 - 39 40 40 48 7 - 36 41 41 44 8 - 31 34 49 -9 21 35 41 45 47 10 17 36 43 47 44 11 12 37 40 41 45 12 14 39 45 a 45 45 13 22 26 42 46 48 14 - 42 44 43 47 15 16 36 42 38 46 16 14 - 47 - -17 23 40 38 45 48 18 21 38 28 46 48 19 13 39 45 46 45 20 18 26 43 48 . 48 Mean 17.3 36.2 40.1 43.6 46.4 

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