Human body motion captures visual attention and elicits pupillary dilation.

The social motivation theory proposes that individuals naturally orient their attention to the social world. Research has documented the rewarding value of social stimuli, such as biological motion, to typically developed individuals. Here, we used complementary eye tracking measures to investigate how social motion cues affect attention and arousal. Specifically, we examined whether viewing the human body moving naturally versus mechanically leads to greater attentional engagement and changes in autonomic arousal (as assessed by pupil size measures). Participants completed an attentional disengagement task in two independent experiments, while pupillary responses were recorded. We found that natural, human-like motion produced greater increases in attention and arousal than mechanical motion, whether the moving agent was human or not. These findings contribute an important piece to our understanding of social motivation by demonstrating that human motion is a key social stimulus that engages visual attention and induces autonomic arousal in the viewer.