APA Dictionary of Psychology

a cognitive model in which action selection is held to be controlled by two distinct processes: the Contention Scheduling System, which makes choices between routine functions that are performed automatically, and the Supervisory Attentional System, which is required in nonroutine situations involving decision making and other executive functions. Also called attentional control of action model; Norman and Shallice model. [proposed in 1980 by U.S. cognitive scientist Donald A. Norman (1935–  ) and British neuropsychologist Timothy Shallice (1940–  )]