Data from: Individual differences in sociocognitive traits in semi-free-ranging rhesus monkeys (Macaca mulatta)

Characterizing individual differences in cognition is crucial for
understanding the evolution of cognition as well as to test the biological
consequences of different cognitive traits. Here, we harnessed the
strengths of a uniquely large, naturally-living primate population at the
Cayo Santiago Biological Field Station to characterized individual
differences in rhesus monkey performance across two social cognitive
tasks. A total of n = 204 semi-free-ranging adult rhesus monkeys
participated in a data collection procedure, where we aimed to test
individuals on both tasks at two time-points that were one year apart. In
the socioemotional responses task, we assessed monkeys' attention to
conspecific photographs with neutral versus negative emotional
expressions. We found that monkeys showed overall declines in interest in
conspecific photographs with age, but relative increases in attention to
threat stimuli specifically, and further that these responses exhibited
long-term stability across repeated testing. In the gaze following task we
assessed monkeys' propensity to co-orient with an experimenter. Here,
we found no evidence for age-related change in responses, and responses
showed only limited repeatability over time. Finally, we found some
evidence for common individual variation for performance across the tasks:
monkeys that showed greater interest in conspecific photographs were more
likely to follow a human's gaze. These results show how studies of
comparative cognitive development and aging can provide insights into the
evolution of cognition, and identify core primate social cognitive traits
that may be related across and within individuals.