Short-term visual adaptation to body shape induces sustained aftereffect on body size estimation.

Visual adaptation to thin or large bodies was found to shift the subjective body normality towards the adapting body shape. Here we investigated the persistency of such adaptation effect by tracking the timecourse of decay of short-term body size adaptation in young healthy Chinese women. Participants adapted to contracted or expanded body images of unfamiliar female volunteers with a top-up paradigm. Their subjective point of normal body size (PNS) was measured before, immediately after and 10/20/30 min after adaptation. The results showed that about 12 min of adaptation to contracted or expanded body stimuli could shift participants' estimations of body normality towards the adapting body shape, with the effect sustaining for more than 30 min after the end of adaptation. In addition, by fitting the timecourse of decay of adaptation with the exponential, power or logarithmic functions, we found that the recovery of body size adaptation effect could be best described with the logarithmic models. These findings indicated that short-term exposure to distorted body shapes of other people could lead to a lingering bias on body size estimation.