Reflexive gaze following in common marmoset monkeys
The ability to extract the direction of the others gaze allows us to shift our attention to an object of interest to the other and to establish joint attention. By mapping ones own expectations, desires and intentions on the object of joint attention, humans develop a Theory of (the others) Mind (TOM), a functional sequence possibly disrupted in autism. Although old world monkeys probably do not possess a TOM, they follow the others gaze and they establish joint attention. Gaze following of both humans and old world monkeys fulfills Fodors criteria of a domain specific function and is orchestrated by very similar cortical architectures, strongly suggesting homology. Also new world monkeys, a primate suborder that split from the old world monkey line about 35 million years ago, have complex social structures. One member of this group, the common marmoset (Callithrix jacchus), has received increasing interest as a potential model in studies of normal and disturbed human social cognition. Marmosets are known to follow human head-gaze. However, the question is if they use gaze following to establish joint attention with conspecifics. Here we show that this is indeed the case. In a free choice task, head-restrained marmosets prefer objects gazed at by a conspecific and, moreover, they exhibit considerably shorter choice reaction times for the same objects. These findings support the assumption of an evolutionary old domain specific faculty shared within the primate order and they underline the potential value of marmosets in studies of normal and disturbed joint attention.\n\nHIGHLIGHTSO_LICommon marmosets follow the head gaze of conspecifics in order to establish joint attention.\nC_LIO_LIBrief exposures to head gaze are sufficient to reallocate an animals attention.\nC_LIO_LIThe tendency to follow the others gaze competes with the attractional binding of the conspecifics face\nC_LI