Autism is characterised by difficulties in social functioning, notably in interactions with other people. Yet, most studies addressing social difficulties have used static images or, at best, videos of social stimuli, with no scope for real interaction. Here, we study one crucial aspect of social interactionsgaze behaviourin an interactive setting. First, typical individuals were shown videos of an experimenter and, by means of a deception procedure, were either led to believe that the experimenter was present via a live video-feed or was pre-recorded. Participants' eye movements revealed that when passively viewing an experimenter they believed to be live, they looked less at that person than when they believed the experimenter video was pre-recorded. Interestingly, this reduction in viewing behaviour in response to the believed live presence of the experimenter was absent in individuals high in autistic traits, suggesting a relative insensitivity to social presence alone. When participants were asked to actively engage in a real-time interaction with the experimenter, however, high autistic trait individuals looked significantly less at the experimenter relative to low autistic trait individuals. The results reinforce findings of atypical gaze behaviour in individuals high in autistic traits, but suggest that active engagement in a social interaction may be important in eliciting reduced looking. We propose that difficulties with the spatio-temporal dynamics associated with real social interactions rather than underlying difficulties processing the social stimulus itself may drive these effects. The results underline the importance of developing ecologically valid methods to investigate social cognition. Autism Res2017, 10: 359-368. (c) 2016 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research.