Abstract: The present study is a further research of the difhrenon in the changes of Heart Ratej T - wave Amplitude and Respintory Fmquency between introverb and extroverts doing mental arithmetic of three different difficulty levels. 15 introverts and 15 extroverts scmened by Eysenck Penonality Quesdonnaire served as subjects and were nquind to fin- ish the mental a.thmetic of three diffrent diffculty levels. The .result showed that the heart rate of the subjects of both groups increased significantly, while the increasing magnitute of the introverb were greater than the extroverb: the T - wave amplitute decreased significantly while the decreasing magnitude of the introverts were greater than the extroverts, the differ ence was not significant though: the respiratory fhquency increawd signifiantly, but the dif ference of the increasing magnitude between the two groups was not significant. lksides, from the chang. of the heart rate we can see that both of the two groups showed adap. tation to the mental arithmetics, but the adapting speed of the introverts was slower than the extroverts. This experiment suggested that anxiety - induced stress had greater effect on heart rate than intellectual performance stress.

Key words: heart rate, T- wave amplitude, intro -extravertion mental arithmetic, ant xiety - induced strees, intellectual perfonmance strees