Abstract
Although perceptual learning of simple visual features has been studied extensively and intensively for many years, we still know little about the mechanisms of perceptual learning of complex object recognition (e.g. face). In a series of seven experiments, human perceptual learning in discrimination of the orientation of face view was studied using psychophysical methods. We trained subjects to discriminate face orientations around a face side view (e.g. 30 deg) over eight days, which resulted in a dramatic improvement in sensitivity to face view orientation. This improved sensitivity was highly specific to the trained face side view and persisted for six months. Different from perceptual learning of simple visual features, this view-specific learning effect could strongly transfer across changes in retinal location, face size and face identity. A strong transfer also occurred between two partial face images that were mutually exclusive but constituted a complete face. However, the transfer of the learning effect between upright and inverted faces and between face and paperclip object was very weak. These results shed light on the mechanisms of perceptual learning of face view discrimination. They suggest a large amount of plastic changes at a level of higher visual processing where size-, location- and identity-invariant face views are represented, but not at a level of early visual processing or cognitive decision.
the National Natural Science Foundation of China (Project 30870762, 90920012 and 30925014).