Abstract
Faces processes require early and long-lasting visual experience and are finely tuned towards own-race and same-age faces in adults. Using the well-known composite face illusion as a marker of the integration of facial features (holistic face perception) we demonstrate here how prolonged visual experience with a specific face category (4- to 6-year-old children faces) alters the face perception system in adulthood. In line with the classical composite paradigm, we created composite stimuli of adult and children faces and asked 18 female preschoolers' teachers (children-face experts) with at least 1 full year of experience with children faces to match the top parts of pairs of either children or adult faces presented sequentially. Similarly to 18 additional female participants (children-face novices), experts were better and faster at matching 2 top parts when they were misaligned as opposed to aligned to distinct bottom parts. Most interestingly, when considering differential response times between aligned and misaligned conditions as a marker of holistic face perception, we found a significantly stronger composite face illusion for adult compared to children faces in novice participants, while it was of equal magnitude in experts. Moreover, the magnitude of the differential face composite illusion between adult and children faces was significantly correlated with the number of years that teachers experienced children faces. Consistent with previous evidence of visual plasticity in adulthood, these results demonstrate the impact of extensive visual experience with faces presenting differential morphological features than adult faces on face perceptual processes, even when the face processing system is fully matured. Moreover, visual experience affects perceptual processes qualitatively, the facial features being not only processed more efficiently but also more holistically for faces that are experienced extensively.