LEARNING POP-OUT DETECTION - SPECIFICITIES TO STIMULUS CHARACTERISTICS

Training induces dramatic improvement in the performance of pop-out de tection, In this study, we examined the specificities of this improvem ent to stimulus characteristics. We found that learning is specific wi thin basic visual dimensions: orientation, size and position. Accordin gly, following training with one set of orientations, rotating target and distracters by 30 deg or more substantially hampers performance. F urthermore, rotation of either target or distracters alone greatly inc reases threshold. Learning is not transferred to reduced-size stimuli. Position specificity near fixation may be finer than 0.7 deg. On the other hand, learning transfers to the untrained eye, to expanded image s, to mirror image transformations and to homologous positions across the midline (near fixation). Thus, learning must occur at a processing level which is early enough to maintain fine separability along basic stimulus dimensions, yet sufficiently high to manifest the described generalizations. We suggest that the site of early perceptual learning is one of the cortical areas which receive input from primary visual cortex, V1, and where top-down attentional control is present. Copyrig ht (C) 1996 Elsevier Science Ltd.