Negative emotional changes that sometimes occur during aging are inherently important for quality of life and also may influence cognitive performance. Studies of the neuroscience of aging are increasingly focusing on affective changes and their interactions with cognition. Therefore it is of interest to examine the differential patterns of change of cognitive performance and emotional responsiveness with age and their interaction with gender and steroid hormone status. We assessed behavioral reactivity of rhesus monkeys with a home-cage test that scored reactions to a series of 6 objects and 6 social stimuli. The test was a modification of one shown to be sensitive to limbic system damage (Zola-Morgan and Squire, Hippocampus 1:207,1991). We previously reported that older female rhesus monkeys showed increased reactivity to social stimuli compared with young females or with males of either age group (SFN 2001). We now have completed assessment of 30 males (18 old, 18-32 years, and 12 young, 6-15 years) and...