Simulating interaction: Using gaze-contingent eye-tracking to measure the reward value of social signals in toddlers with and without autism.

•Toddlers with ASD show typical social orienting and positive facial expressions in response to predictable social stimuli.•Variable social stimuli provoke an atypical pattern of reward-seeking behaviour in toddlers with ASD.•Simulated social interaction, made possible by gaze-contingent eye-tracking, shows great potential to probe the conditions under which impaired social interaction emerges in ASD.