Perceptual and Mofor Skills, 1775, 41,457-463. @ Perceptual and Motor Skills 1775
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PERSONALITY, REINFORCEMENT A N D LEARNING1 0. M. SEUNATH
Instirilre of Psychiatry, University of London Denmark Hill, London Summary.-Conflict in predictions resulting from Eysenck's (1957) and Gray's (1770) theoretical formulations on personality and conditioning were tested at the behavioural level. Given conditions which do not produce overarousal, it would be predicted from Eysenck's position that Introverts would condition better than Extraverts. From Gray's formulation it would follow that Introverts condition better if negative reinforcement is used and Extraverts condition better if positive reinforcement is used. The two opposing predictions were tested in pursuir rotor learning by either positively or negatively reinforcing the hit/miss dimension of performance by 166 males aged 14 to 15 yr. The results gave support to Gray's position but if over-arousal is assumed Eysenck's position is tenable.
From extensive factor analytic studies Eysenck proposed the existence of two orthogonal personality dimensions, Extraversion and Neuroticism (Eysenck, 1957). Much of his subsequent work has concentrated on defining the behavioral correlates of these dimensions, and establishing their physiological substrate (Eysenck, 1967). Introverts and Extraverts are placed at the ends of the continuum of Extraversion. Eysenck suggests that the former group have a high level of cortical arousal and condition more strongly than Extraverts providing thar the experimental conditions do not create over-arousal. Introverts also demonstrate a slow build-up of inhibition which dissipates quickly. Extraverts have a low level of cortical arousal and condition more slowly under similar experimental conditions; their rate of inhibition build-up is faster and its dissipation slower. The physiological basis of Extraversion is proposed to be the level of activity in the Ascending Reticular Activating System. Introverts have a high level of such activity which leads to a high level of cortical arousal via the non-specific sensory inputs to the cortex. Extraverts have a low level of such activity which, in a corresponding manner, leads to a low level of cortical arousal. Gray ( 1970) suggested some modifications to the physiological basis and the interpretation of the behavioural correlates of the two personality dimensions. On the dimension of Extraversion he proposed that the difference in coaditioning berween Extraverts and Introverts stems from their relative sensitivity to positive and negative reinforcement situations. Extraverts are more sensitive 'This srudy formed part of a thesis submitted to the University of London for a Ph.D. degree. 1 wish ro thank Dr. C. D. Frith and Professor H. J. Eysenck for their h e l ~ throughout this investigation and in the preparation of this Financial support Provided by the Canada Council is gratefully acknowledged. 'Now at The D e p a m e n t of Psychology, University of Saskatchewan, Saskatoon, Saskatchewan, S7N OWO, Canada.
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to positive reinforcement and therefore condicion better in positive reinforcement situations. The level of sensitivity to reinforcement is controlled by a physiological system comprising the orbital frontal cortex, the medial septa1 area and the hippocampus. This system has a feedback loop with the ascending reticular activating system. Gray states that increased activity in the system triggers the hippocampal theta rhythm which monitors furcher increases and regulates behavioural acts which may produce negative reinforcement. At the behavioural level [he conflict between the cwo views may be stated as follows. Eysenck maintains that Introverts condition better under both positive and negative reinforcemenc providing the experimental conditions do not create over-arousal. Given the same conditions Gray would predict that Introverts would condition better if negative reinforcement is used and Extraverts would be better if positive reinforcement is used. The results of two previous studies may be considered in reference to chis conflict. The results of a study by Barr and McConaghy (1972) seem to give support to Eysenck's theory by showing a general conditionabilicy factor. They found significant correlations becween appecitive and aversive conditioning of penile and GSR responses. Since the theoretical question was the conditionability factor implied in Eysenck's theory, it is most unfortunate no personality measures were used. Consequently, the results are also acceptable from Gray's position if the subjects were ambiverts. The results of one early study (Thompson & Hunnicutt, 1944) contradicted the predictions by Gray and also failed to support predictions from Eysenck's rheory. The results showed that praise motivated Introverts more than Extraverts and blame had che opposite effecc on performance on a digit-cancellacion task. From Gray's theory the opposite effect would be predicted and from Eysenck's Incroverts should have been better in both reinforcemenc condicions. One questionable aspect of this study is whether learning is involved in a digit-cancellation task. Given the problems of the two previous studies, it seemed necessary to invescigate further the points of conflict between the two theories. This was done in the present study using the pursuit rotor.
METHOD Sab jects One hundred and sixty-six male subjects aged 14 to 1 5 yr. were assigned to eicher a positive, negative or no reinforcement condition. For the no and positive reinforcement groups the apparatus was a standard pursuit rotor with a 10-in. diameter turntable. The turntable revolved at 65 rpm. The target was a translucent, lighted disc of 0.75-in. diameter set flush to the level of the turntable. An L-shaped hollow, rigid rod was used as a stylus.
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Contact with the target activated a photocell inserted into the tip of the stylus. This drove an oscillator and the tone thereby produced was recorded directly on magnetic tape using a tape recorder. The performance so recorded was later analysed by a LINC-8 computer. With negative reinforcement a white-noise generator was added to the above. This produced an 85-db noise through earphones whenever the stylus was off target. Procedure
The testing procedure was that outlined by Ammons (1947). Briefly, this comprised a period of familiarization with the cask followed by two test sessions of 5 min. separated by a 10-min. rest interval. During the rest period subjects completed the Junior Personality Questionnaire (Eysenck & Eysenck, 1973) from which Extraversion scores were determined. The sample was divided at the median of these scores into Introverts (median 15, range 5 to 1 8 ) and Extraverts (median 21, range 19 to 24). For the no reinforcement condition subjects were given a demonstration and instructions on how to perform the task. For the other two conditions reinforcements were administered in the first session only. The second session was used to determine whether the reinforcements produced a permanent effect. Subjects in the negative reinforcement condition were told that the noise through the earphones was used to inform them when they were wrong. In the condition of positive reinforcement, there was a competition among the subjects for four record albums which went to the four subjects with the highest scores. During performance a token was given for each hit or contact with the target. Each hit was audible via the rape recorder. An oral count was kept of the total hits accumulated, thus the possibility exists that additional reinforcement was given via the counting procedure. Because of the procedure adopted it was not possible to control or equate the number of reinforcements received in the two conditions.
A LINC-8 computer was programmed to give the time-on-target score and hits for each successive 10-sec. period (trials) by session. A time-on-target score was defined as the total time-on-target for each trial and a hit score as the number of contacts made with the target for each trial. Trials 8 to 30 were used in further analysis since the initial part was necessary for acquiring some stability in performance (Eysenck & Frith, in press). The dependent measure used for assessing performance was the number of hits associated with 2.5 sec. time-on-target (hics/2.5 sec.). This is essentially a measure of style of performance (Frith, 1968) and represents the calculated number of hits each subject made when the time-on-target was 2.5 sec. The
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standard 2.5 sec. was selected since it was a level of performance achieved by most subjects and therefore required a minimum of extrapolation from actual performance. The measure hits/2.5 sec. was calculated by a computer program, the operations of which were as follows. For each subject the time-on-target scores were plotted against the corresponding hits scores. The line of best fit was then determined from this graph and the number of hits corresponding to 2.5 sec. time-on-target was read from this line. This was done independently for each session. . The use of the dependent measure hits/2.5 sec. requires some justification. It is a measure of style rather than level of performance. Style rather than levels of performance was varied since the latter is not influenced by the level of motivation (Eysenck, 1965). ( I t is also difficult to conceive of a method of negatively reinforcing time-on-target and still requiring performance of the task.) The style of performance therefore seemed an appropriate variable for manipulation. This was done by reinforcing the Hir/Miss dimension of performance. As a result the effect of the reinforcements would be reflected in the measure hits/ 2.5 sec. with the 2.5 sec. controlling for differences in level of ability. RESULTSAND DISCUSSION The results indicated support for Gray's hypothesis. An analysis of variance produced a significant Personality X Reinforcement interaction ( P < .02) across sessions. Post hoc tests (Newman-Keuls) on the means showed that Extraverts had a significantly higher mean score ( p < .05) than Introverts with positive reinforcement while with negative reinforcement Introverts were higher and this difference approached significance. The means and SDs are presented in Table 1. There were no significant effects on the hits, indicating that the above effect was not created by differences in the number of reinforcements. TABLE 1 MEANS AND SDS FOR HITS/2.5 SEC. TIME-ON-TARGET. SESSIONS 1 AND 2 COMBINED Group
Reinforcement Conditions Negative Positive None
N Introverts
GO
M
9.88 3.72 9.06
SD
5.63
M
SD Extraverts
GO 8.94 3.73 10.87 10.96
45 9.21
3.15 8.91 3.12
The results gave support to Gray's formulations that Introverts learn better under negative reinforcement while Extraverts do so under positive reinforcement. It should be noted that reinforcements were administered in the first session only but the predictions were supported in both sessions combined. This
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indicates that the style of performance created during the first session became a relatively permanent feature, thus learning is implicated. Since the number of reinforcements administered to the positive and negative reinforcement groups were not controlled, it was possible that differences in the number may have influenced performance style. This possibility was eliminated by the lack of significant differences on the hits variable since this measure represents the number of reinforcements received. It may therefore be tentatively concluded that the changes created in performance style were due to personality and reinforcement variables. There is, however, one way in which the results may be explained according to Eysenck's theory. If it is assumed that over-arousal occurred in the positive condition, then this would have affected Introverts more than Extraverts thereby producing the lower scores in the former group. The trend in the negative condition is consistent with both Eysenck's and Gray's formulations since they both lead to the prediction of higher scores for Introverts. While it may be more likely for over-arousal to occur in the negative rather than the positive condition, the argument cannot be clarified here since no physiological measures of arousal were taken. Thus while the evidence rends to support Gray's position there is still room for debate. REFERENCES AMMONS. R. B. Acquisition of motor skills: 11. Rotary pursuit performance with continuous practice before and after a single rest pause. Jor~rnalo f Experimental Psychology, 1947, 37, 393-341. BARR,R. F., & MCCONAGHY,N. A general factor of conditionability. Behavior Research and Therapy, 1972, 10, 215-228. EYSENCK, H. J. T h e dynamics o f anxiety and hysteria. London: Routledge & Kegan-Paul, 1957. EYSENCK, H. J. T h e biological basis o f personality. Springfield: Thomas, 1967. EYSENCK, H. J., & EYSENCK,S. B. G . Test-retest reliability of a new Personality Questionnaire for children. Biitish Joirrnal o f Educational Psychology, 1973, 43, 126130. EYSENCK,H. J., & FRITH, C. D. Reminiscence: a case study in experimenral psychology. London: Wiley, in press. FRITH, C. D. Strategies in rotary pursuit tracking and their relation to inhibition and personality. Life Sciences, 1968, 7, 65-76. GRAY, J. A. The psychophysiological basis of introversion-extraversion. Behavior Research and Therapy, 1970, 8, 249-266. THOMPSON, G . S., & HUNNICUTT, C. W . The effect of repeated praise or blame on the work achievement of introverts and extraverts. Journal o f Educational Psychology, 1944, 35, 257-266.
Accepted July 10, 1975.