Attention and Blind-Spot Phenomenology

The reliability of visual filling-in at the blind spot and how it is influenced by the distribution of spatial attention in and around the blind spot were studied. Our data suggest that visual filling-in at the blind spot is 1) less reliable than it has been assumed, and 2) easier under diffused attention around the blind spot than under focal attention restricted in the blind spot. These findings put important constraints on understanding the filling-in in terms of its neural substantiation. Recent neurophysiological studies suggest that V1 neurons corresponding to the blind spot in retinotopic map extend their receptive fields far beyond the blind spot and are not silent during the filling-in (Komatsu, Kinoshita, and Murakami, 2000). For those neurons to subserve filling-in, it may be crucially important for top-down attention to match their receptive fields.