In order to test Eysenck's hypothesis that introverts would condition faster than extroverts, twenty undergraduates were given muscle tensing and muscle relaxing trials using a feedback myograph to obtain electrical activity levels of the frontalis muscle. The subjects were divided into two groups of ten each. The Myers-Briggs Type Indicator was used to select ten students classified as introverts and ten classified as extroverts. .Both groups were given forty thirty-second trials to learn muscle relaxing and tensing. Analysis of covariance indicated a significant within trials effect for both the relaxation and tensing trials. No significant differences were found, however, between the introverts and the extroverts in either the muscle relaxing or muscle tensing training.