ABSTRACT
Two frequently encountered ideas in cognitive neuroscience are that there is a hierarchical organisation in the control of action with its culmination in prefrontal cortex, and that there are two domains in the control of action, one automatic and the other controlled. The Norman and Shallice model (1986) was where these ideas were first combined. The model essentially has three levels. The lowest level is of a set of separable functionally specific computational systems, a standard neuropsychological perspective. The second level – contention scheduling – contains units (schemas) which represent well-learned individual motor and cognitive skills, organised, as skills are, in hierarchical structures. The schema units are activated by environmental trigger units and are in mutually inhibitory interaction. The highest level – that of the Supervisory System – comes into play in non-routine situations.
