About turn: the visual representation of human body orientation revealed by adaptation.

Body orientation provides an important cue to other individuals' focus of attention, particularly when one is viewing them at a distance. Single-cell recording in macaques has identified cells in the superior temporal sulcus that show a view-selective response to particular body orientations. Whether similar separable coding is found in humans is not known, and there is currently no functional account of the visual representation of seen body orientation. This study addressed this issue using visual adaptation. Experiment 1 demonstrated distinct channels that code left- and right-oriented bodies. Experiment 2 investigated whether the visual representation of body orientation is best accounted for by an opponent-coding system, which has been shown to account for the visual representation of facial identity, or by a multichannel system, which provides the optimal account of coding line orientation and direction of motion. Our results provide evidence for multichannel coding of seen body orientation, with separate channels (or neuronal populations) selectively tuned to different body directions.