Face adaptation without a face

Prolonged viewing of a stimulus results in a subsequent perceptual bias. This perceptual adaptation and the resulting aftereffect reveal important characteristics regarding how perceptual systems are tuned. These aftereffects occur not only for simple stimulus features but also for high-level stimulus properties. Here we report a novel cross-category adaptation aftereffect demonstrating that prolonged viewing of a human body without a face shifts the perceptual tuning curve for face gender and face identity. This contradicts a central assumption underlying perceptual adaptation: that adaptation depends on physical similarity between how the adapting and the adapted features are perceived. Additionally, this aftereffect was not due to response bias, because its dependence on adaptation duration resembled traditional perceptual aftereffects. These body-to-face adaptation results demonstrate that bodies alone can alter the tuning properties of neurons that code for the gender and identity of faces. More generally, these results reveal that high-level perceptual adaptation can occur when the property or features being adapted are automatically inferred rather than perceived in the adapting stimulus.