Eysenck's 'personality sphere' was examined in relation to performance measures of verbal and visual attention and memory in 200 male and female adolescent and adult outpatients. Factors, sex, age, and personality (Extraversion, Neuroticism) played a significant multivariate role in the performance of attention and memory tasks. In the second phase of this research, and following an exclusion of 90 'ambiverts', extreme scorers on Extraversion were further dichotomized about the mean score on Neuroticism. Multivariate tests suggested a significant role for sex, age, interaction between age and sex of subjects, Extraversion and Neuroticism, in the performance of attention and short-term memory tasks. The present findings for outpatients suggested that introversion and higher than average neuroticism tended to improve upon outpatients' attention efficiency and short-term memory whereas extraversion and low emotionality did not. Age and sex of subjects appeared to have interacted with personality in the differential performance of attention and memory tasks. The present findings for outpatients were related to findings of other researchers. The MMPI's clusters on emotionality (TSC PS) paralleled the Eysenckian measures of Extraversion and Neuroticism (JEPI, EPI) suggesting a possible redundancy of measures.