Two-year-olds engage in many behaviors that ostensibly require the attribution of mental states to others. Despite this, the overwhelming consensus has been that they are unable to attribute false-beliefs at this age. In the current study, we have used an eye-tracker to record infant's looking behaviour while they watched actions on a computer monitor. Our data demonstrate that 25-month-old infants show correct anticipation of an actor's actions that could only be predicted if they had attributed a false belief to the actor.

The "eye contact effect" is the phenomenon that perceived eye contact with another human face modulates certain aspects of the concurrent and/or immediately following cognitive processing. In addition, functional imaging studies in adults have revealed that eye contact can modulate activity in structures in the social brain network, and developmental studies show evidence for preferential orienting toward, and processing of, faces with direct gaze from early in life. We review different theories of the eye contact effect and advance a 'fast-track modulator' model. Specifically, we hypothesize that perceived eye contact is initially detected by a subcortical route, which then modulates the activation of the social brain as it processes the accompanying detailed sensory information.

Humans are extremely sensitive to ostensive signals, like eye contact or having their name called, that indicate someone's communicative intention toward them [1-3]. Infants also pay attention to these signals [4-6], but it is unknown whether they appreciate their significance in the initiation of communicative acts. In two experiments, we employed video presentation of an actor turning toward one of two objects and recorded infants' gaze-following behavior [7-13] with eye-tracking techniques [11, 12]. We found that 6-month-old infants followed the adult's gaze (a potential communicative-referential signal) toward an object only when such an act is preceded by ostensive cues such as direct gaze (experiment 1) and infant-directed speech (experiment 2). Such a link between the presence of ostensive signals and gaze following suggests that this behavior serves a functional role in assisting infants to effectively respond to referential communication directed to them. Whereas gaze following in many nonhuman species supports social information gathering [14-18], in humans it initially appears to reflect the expectation of a more active, communicative role from the information source.

Adults with Asperger syndrome can understand mental states such as desires and beliefs (mentalizing) when explicitly prompted to do so, despite having impairments in social communication. We directly tested the hypothesis that such individuals nevertheless fail to mentalize spontaneously. To this end, we used an eye tracking task that has revealed the spontaneous ability to mentalize in typically-developing infants. We showed that, like infants, neurotypical adults' (N = 17) eye movements anticipated an actor's behaviour on the basis of her false belief. This was not the case for individuals with Asperger syndrome (N = 19). Thus, these individuals do not attribute mental states spontaneously, but may be able to do so in explicit tasks through compensatory learning.

An atypical pattern of eye contact behaviour is one of the most significant symptoms of Autism Spectrum Disorder (ASD). Recent empirical advances have revealed the developmental, cognitive and neural basis of atypical eye contact behaviour in ASD. We review different models and advance a new 'fast-track modulator model'. Specifically, we propose that atypical eye contact processing in ASD originates in the lack of influence from a subcortical face and eye contact detection route, which is hypothesized to modulate eye contact processing and guide its emergent specialization during development.