Sustained (P) and Transient (M) Channels in Vision: A Review and Implications for Reading
Dale M. Willows, Richard Kruk, Richard Kruk, Evelyne Corcos · 2012
The visual world is composed of surfaces, objects, and events, whose nearly endless varieties are based on a finite and relatively small set of distinct perceptual dimensions. One of the more evident trends in visual science has been to explore the existence of parallel visual streams, each of which seems to behave as a subsystem specialized to process one or a few of these dimensions. As pointed out by Stone (1983), the concept of parallel processing has had a relatively long history in modern visual science. As an obvious example, over the past century the existence of separate cone and rod systems and their respective relation to photopic and scotopic vision has been widely studied. In more recent years, separate chromatic and achromatic (luminance) channels (de Lange, 1958), direction, orientation, and spatial-frequency selective mechanisms (Blakemore & Campbell, 1969; Campbell & Kulikowski, 1966; Sekuler & Ganz, 1963), and pathways separately processing brightness and darkness (Jung, 1973) have been investigated psychophysically and, still more recently, anatomically (Schiller, 1982; Tootell, Silverman, Hamilton, De Valois, & Switkes, 1988b; Tootell, Silverman, Hamilton, Switkes, & De Valois, 1988c).