Data from: Sensitivity to line-of sight in tolerant versus despotic macaques (Macaca sylvanus and Macaca mulatta)

Complex social life is considered important to the evolution of cognition
in primates. One key aspect of primate social interactions concerns the
degree of competition that individuals face in their social group. To
examine how social tolerance versus competition shapes social cognition,
we experimentally assessed capacities for flexible gaze-following in more
tolerant Barbary macaques (Macaca sylvanus) and compared to previous data
from despotic rhesus macaques (Macaca mulatta). Monkeys experienced one of
two possible conditions. In the barrier condition, they observed an actor
look upwards into an overheard barrier, so they could not directly see the
target of the actor's gaze without reorienting. In the no barrier
condition, they observed an actor look upwards without a barrier blocking
her line-of-sight, so they could observe the target of the actor's
gaze by also looking upwards. Both species (N = 58 Barbary macaques, 64
rhesus macaques) could flexibly modulate their gaze responses to account
for the demonstrator’s line of sight, looking up more often when no
barrier was present, and this flexible modulation declined with age in
both species. However, neither species preferentially approached to look
inside the barrier when their view of the target location was obscured,
although rhesus macaques approached more overall. This pattern suggests
that both tolerant and despotic macaques exhibit similar capacities to
track other’s line of sight and do not preferentially reorient their
bodies to observe what an actor looks at in this situation. This contrasts
with other work indicating that competitive primates are especially adept
at some aspects of theory of mind. Thus, it is important to understand
both the similarities and differences in the social–cognitive abilities of
primates with different social styles.