Heart rate (HR) and skin conductance (SC) were measured in males ranging in age from 23 to 87 years while they were performing mental arithmetic tasks, subtractions, and during multiple trial free recall. Performance on the arithmetic tasks was not affected by age. HR but not SC showed greater changes from basal levels in young subjects. Free recall was greater in young than in old subjects, and changes in HR were again greater in the young subjects. During intertrial rest periods HR returned t9 basal levels in young but not in old subjects. These changes are similar to those seen in older people after physical exercise. Correlations between HR and SC changes during arithmetic performance and during free recall indicated that response stereotypy is to some extent age dependent.