Perceived Object Trajectory Is Influenced by Others' Tracking Movements.

In social interactions, it is highly salient to us where other people are looking. The ability to recover this information is critical to typical social development, helping us to coordinate our attention and behavior with others and understand their intentions and mental states [1-3]. The depth and direction in which another individual is fixating are specified jointly by their head position, eye deviation, and binocular vergence [4, 5]. It is hereto unknown, however, whether this dynamic visual information about others' focus of attention affects how we ourselves see the world. Here we show that the perceived depth and movement of physical objects in our environment are influenced by others' tracking behavior. This effect occurred even in the presence of conflicting size cues to object location and generalized to the context of apparent motion displays [6] and judgments about causal interactions between moving objects [7]. Perceived object trajectory was modulated primarily by the object-level motion of the tracking agent (e.g., the head), with less-pronounced effects of eye motion and low-level motion. Interestingly, comparable perceptual effects were induced by non-face objects that displayed similar tracking behavior, indicating a mechanism of distal coupling between the motion of the target and an appropriately moving inducer. These results demonstrate that social information can have a fundamental effect on our vision, such that the visual reality constructed in each brain is determined in part by what others see.