It is a matter of size—manipulating body size with virtual reality modulates reward sensitivity

Body perception, including the perception of body size, plays an important role in shaping cognitive and motivational processes. Variations in body size have been linked to differences in reward processing, involving neural systems underlying appetite, motivation, and behavioral control. Furthermore, rapid changes in body size have been associated with modulation of reward-related neural responses and changes in food-related motivation. Interestingly, the Full Body Illusion (FBI) has been effective in altering perceived body size and eating attitudes. However, it remains unclear whether such illusory manipulations can affect reward-based behavior per se. To address this question, we investigated whether FBI-induced changes in body size influence reward-based learning and implicit attitudes toward both food and body weight. Embodying a larger avatar enhanced reward-based learning and implicit attitudes toward high-calorie foods, whereas the reduction in implicit weight bias occurred independently of the avatar size. This is the first study to establish a link between reward-based learning and the perception of one's body size, emphasizing the critical role of perceived weight, beyond the actual physical weight, in shaping approach behavior.