ABSTRACT
Introduction
Visual search of a multi-element display leads, under certain conditions, to "popout" or preattentive perception of a unique or highly salient item in the display (Treisman, 1988). What might be the neural locus of mechanisms underlying such preattentive visual perception? Visual processing occurs along two relatively distinct pathways, termed the magnocellular (M) and parvocellular (P) pathways (Livingstone & Hubel, 1987). Since responding and orienting rapidly to salient features in the environment carries a high survival value, we hypothesized that the phylogenetically older M pathway preferentially mediates the preattentive processing leading to eventual capture of attention by the stimulus of immediate interest.
