The relationship between personality level of affect and habituation of electrodermal and respiratory measures was examined in two groups of normal subjects designated Low P (LP) and High P (HP) according to the P scale of the Eysenck Personality Questionnaire. Experiment 1 examined changes as a function of repeated presentation of simple visual stimuli. Group HP displayed reduced habituation rates for both respiratory pause and skin resistance response (SRR), although initial reactivity levels were similar for both groups. This effect was confirmed more strongly in Experiment 2, which utilized a simple counting task and groups separated more widely on P. The implications of these group differences were discussed in relation to the psychophysiological functioning of autistic children. © 1980.