Abstract
When viewing social scenes, humans and nonhuman primates focus on particular features, such as the models’ eyes, mouth, and action targets. Previous studies reported that such viewing patterns vary significantly across individuals in humans, and also across closely-related primate species. However, the nature of these individual and species differences remains unclear, particularly among nonhuman primates. In large samples of human and nonhuman primates, we examined species differences and the effects of experience on patterns of gaze toward social movies. Experiment 1 examined the species differences across rhesus macaques, nonhuman apes (bonobos, chimpanzees, and orangutans), and humans while they viewed movies of various animals’ species-typical behaviors. We found that each species had distinct viewing patterns of the models’ faces, eyes, mouths, and action targets. Experiment 2 tested the effect of individuals’ experience on chimpanzee and human viewing patterns. We presented movies depicting natural behaviors of chimpanzees to three groups of chimpanzees (individuals from a zoo, a sanctuary, and a research institute) differing in their early social and physical experiences. We also presented the same movies to human adults and children differing in their expertise with chimpanzees (experts vs. novices) or movie-viewing generally (adults vs. preschoolers). Individuals varied within each species in their patterns of gaze toward models’ faces, eyes, mouths, and action targets depending on their unique individual experiences. We thus found that the viewing patterns for social stimuli are both individual- and species-specific in these closely-related primates. Such individual/species-specificities are likely related to both individual experience and species-typical temperament, suggesting that primate individuals acquire their unique attentional biases through both ontogeny and evolution. Such unique attentional biases may help them learn efficiently about their particular social environments.
Highlights
Human and nonhuman primates attend to other individuals to gain valuable social information about them and their shared surroundings, and even to infer others’ goals and intentions based on their actions
We examined individual and species variation in the viewing patterns of movies depicting the natural behaviors of nonhuman primates in rhesus macaques, three species of great apes, and humans
From an animal welfare perspective, it is important to highlight that the patterns exhibited by chimpanzees who had poor experiences with media, cognitive experiments, and social and physical enrichments in youth. These chimpanzees had been isolated from their mothers and conspecifics and reared by human caregivers at a biomedical laboratory during their infant and juvenile periods, and only later they were transferred to more naturalistic groups in sanctuaries
Summary
Human and nonhuman primates attend to other individuals to gain valuable social information about them (such as identity and emotions) and their shared surroundings (such as nearby dangers and resources), and even to infer others’ goals and intentions based on their actions. Primates selectively attend to others’ faces, eyes, and targets of ongoing actions [4,5,6,7]. They follow others’ gaze and attend to the same objects and locations that others are manipulating [8,9,10,11,12]. Via subcortical routes, rapidly processes crude social information such as others’ faces, eyes, and gaze direction; the other pathway, via cortical routes, processes nuanced social information such as others’ social and emotional status and communicative intentions [2, 9, 16, 17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
