A new paradigm was then developed to examine the distribution of visual attention by combining the attention task and the FAE task. In four experiments, attention was manipulated by counting digits while the subject adapted to two counterphasing Gaussian blobs. After adaptation, subjects judged the relative position of two test blobs. The magnitude of the FAE was measured by the apparent position shift of the two test blobs, which, in turn, served as an index of the distribution and magnitude of attention. The results rule out the possibilities that the span of attention is of restricted and specific shape and that one's attention can be narrowly focused on nonadjacent locations.
Perceptual load affects the magnitude and distribution of visual attention.