Looking Round: the Viewpoint Dependence of Body Size Aftereffects

Visual exposure, known as ‘adaptation’ to thin (large) bodies has been shown to induce a perceptual bias where subsequently viewed bodies appear larger (thinner) than they are. This bias is called the body size aftereffect. The current study tested whether the body size aftereffect generalises across viewpoints, such that adaptation to a body seen from one viewpoint (frontal; 0°) causes aftereffects for stimuli over a range of viewpoints (0°, 30°, 60°, 90°, 120°, 150°, 180°). Further, we tested whether the magnitude of the aftereffect was viewpoint dependent. Overall, body size aftereffect was successfully induced after exposure to both low-adiposity and high adiposity adaptors. While viewpoint dependence was shown, we did not observe the classic monotonic decline of aftereffect magnitude as the test viewpoint diverges from the adaptation viewpoint. Instead, results were better described by a parabolic function, showing a decrease then an increase of aftereffect magnitude. The findings provide insight into the neural mechanisms underlying body perception, revealing that bodies are perceived by broadly tuned neural mechanisms, and suggesting that the size and shape of bodies may be evaluated at some level by their overall outline.