Introversion-extraversion and the effects of arousal level and type of reinforcement on learning: Gray vs. Eysenck

Two theories of introversion-extraversion were tested. One of the theories tested was developed by H.J. Eysenck. That theory states that introverts tend to be more sensitive to sensory input from the environment, while extraverts are less sensitive to sensory input. The other theory tested was developed by J. A. Gray. That theory states that introverts are more sensitive to signals of reward, while extraverts are more sensitive to signals of punishment. To test these two theories within the same study, forty subjects were chosen. Ten introverts and ten extraverts were exposed to positive verbal reinforcement, and the remainder of subjects were exposed to negative verbal reinforcement while learning to perform arithmetic problems in Base 6. During two final tests of subjects' ability to perform such problems, loud and soft noise conditions were presented to all subjects. It was predicted that, if Gray's theory were correct, introverts would perform better on the final tests when given negative reinforcement than when given positive reinforcement, while extraverts would perform better when given positive reinforcement than when given negative reinforcement. If Eysenck's theory were correct, it was predicted that extraverts would perform better when exposed to loud noise than when exposed to soft noise, while introverts would perform better when exposed to soft noise than when exposed to loud noise. Results showed no support for Eysenck's theory; all groups performed the same under each noise condition. Results showed partial support for Gray's theory: introverts who were punished performed better than those who were rewarded. All extraverts performed about the same; their scores were similar to those of the introverts who were punished. This interaction between personality type and reinforcement condition did not obtain statistical significance, though main effects for each of these variables were significant. It was concluded that the most probable reason that extraverts in the punishment group performed as well as those in the reward group was that the punishment variable as it was defined and administered failed to present extraverts with a true punishment condition. Ways to remediate this problem were suggested for further research.