Judging social interaction in the Heider and Simmel movie

Simple displays of moving shapes can give rise to percepts of animacy. These films elicit impoverished narratives in some individuals, such as those with an autism spectrum disorder. However, the verbal demand of producing a narrative limits the utility of this task. Non-verbal tasks have so far focused on detecting animate objects. Lacking from previous research is a task that relies less on verbal description but more than animacy perception. Here, we presented data using a new social interaction judgement task. Healthy young adults viewed the Heider and Simmel movie and pressed one button whenever they perceived social interaction and another button when no social interaction was perceived. We measured the time points at which social judgement began, the fluctuation of the judgement in relation to stimulus kinematic properties, and the overall mean of social judgement. Participants with higher autism traits reported lower levels of social interaction. Reversing the film in time produced lower social interaction judgements, though the temporal profile was preserved. Our study suggests that both low-level motion characteristics and high-level understanding contribute to social interaction judgement. The finding may facilitate future research on other populations and stimulate computational vision work on factors that drive social judgements.