Competition for consciousness among visual events: The psychophysics of reentrant visual processes

Advances in neuroscience implicate reentrant signaling as the predominant f orm of communication between brain areas. This principle was used in a seri es of masking experiments that defy explanation by feed-foward theories. Th e masking occurs when a brief display of target plus mask is continued with the mask alone. Two masking processes were found: an early process affecte d by physical factors such as adapting luminance and a later process affect ed by attentional factors such as set size. This later process is called ma sking by object substitution, because it occurs whenever there is a mismatc h between the reentrant visual representation and the ongoing lower level a ctivity. Iterative reentrant processing was formalized in a computational m odel that provides an excellent fit to the data. The model provides a more comprehensive account of all forms of visual masking than do the long-held feed-forward views based on inhibitory contour interactions.