The present study was designed to bring out the differences between extraverts and introverts on Standard Progressive Matrices. A group of 100 subjects of equal number of sexes were given a qualitative analysis of their performance on SPM. The study brought out the initial superiority of extraverts over introverts. But with passage of time and increase in difficulty level the introverts did significantly better as shown both by the t-ratios and the F-ratios. Personality interacted with sex to yield differences in performance of wrong scores only. These findings were discussed in terms of arousal, cortical excitation and reactive inhibition.