Role of the social actor during social interaction and learning in human-monkey paradigms

•Macaque monkeys can learn based on the observation of nonconspecific actors as humans and nonsocial agents in the ‘ghost display’ condition.•Learning by observation requires to grasp the link between observed action and its outcome even in absence of social identification.•The human-monkey paradigm is a powerful tool to study social processes in macaque monkeys. The social interactions between primates is drawn by their ability to predict others’ behaviours, to learn from others’ actions and to represent others’ intentions. It allows them to extract information by observation to understand which action is leading to which outcome and to maximize the efficiency of their own future behaviours. These processes have mainly been investigated studying non-human primates observing conspecifics, but more recently an increasing body of work has adopted a human-monkey paradigm, and some have now convincingly shown that macaque monkeys understand human choices, consider them and can act accordingly. Two main hypotheses have been developed to explain macaque monkeys’ ability to learn from humans: 1) the similarity between the behaviours of both species 2) the presence of a non-ambiguous link between the observed action and its outcome. Based on the literature examined the recent evidence appears to supports the second. The non-social observational learning, meaning the learning by observation of an inanimate agent, can be a powerful tool to understand the mechanisms underlying the social interactions.