Percepire l'invarianza tra stimoli non occlusi e stimoli parzialmente occlusi: un esempio di costanza percettiva alla nascita

Three experiments were carried out to investigate whether newborns are able to perceive the invariant shapes of stimuli that differed just for the presence/absence of an occlusion. Newborns were tested with a visual habituation technique and, during the novelty-preference test, they are asked to compare among exemplars belonging to the same perceptual category (a square vs a diamond, Experiment 1 and 2), or to two different perceptual categories (closed vs open shapes, Experiment 3). Results indicated that newborns were capable of recognizing the perceptual similarity between a non-occluded stimulus and the same partly occluded configuration only when they were asked to compare among exemplars belonging to different perceptual categories (Experiment 3). This evidence supports some recent results that showed that, at birth, infants are not able to form categories on the basis of the perceptual similarities among different exemplars of a class (basic level), whereas they demonstrate to form categories at a more global level, such as open versus closed forms.