Repeated visual adaptation induces persistent behavioral and neural biases in body size perception

Body size and shape misperception, notably body size overestimation, is prevalent among young people. It has been proposed that such a bias may stem from adaptation aftereffects caused by exposures to distorted bodies, yet whether adaptation can persistently alter daily body perception remains unclear. This study explored the long-term impacts of body size adaptation by having participants repeatedly view thin or large body images for 7 daily sessions, or comparing participants with varied experiences of exposure to the thin-ideal in life. Behavioral results revealed that repeated exposure to distorted body images persistently shifted participants' perception of body normality toward the adapting shape. ERP data showed that repeated adaptation to thin bodies or higher endorsement of the thin-ideal could enhance the early brain response bias to enlarged bodies. These findings collectively suggest that repeated exposure to distorted bodies contribute to the development of perceptual and neural response bias toward body shapes.