Interobject spacing explains the attentional bias toward interacting objects.

Spatio-temporal interactions between simple geometrical shapes typically elicit strong impressions of intentionality. Recent research has started to explore the link between attentional processes and the detection of interacting objects. Here, we asked whether visual attention is biased toward such interactions. We investigated probe discrimination performance in algorithmically generated animations that involved two chasing objects and two randomly moving objects. In Experiment 1, we observed a pronounced attention capture effect for chasing objects. Because reduced interobject spacing is an inherent feature of interacting objects, in Experiment 2 we designed randomly moving objects that were matched to the chasing objects with respect to interobject spacing at probe onset. In this experiment, the capture effect attenuated completely. Therefore, we argue that reduced interobject spacing reflects an efficient cue to guide visual attention toward objects that interact intentionally.