Supervisory attentional system

Executive functions are a cognitive apparatus that controls and manages cognitive processes. Norman and Shallice (1980) proposed a model on executive functioning of attentional control that specifies how thought and action schemata become activated or suppressed for routine and non-routine circumstances. Schemas, or scripts, specify an individual's series of actions or thoughts under the influence of environmental conditions. Every stimulus condition turns on the activation of a response or schema. The initiation of appropriate schema under routine, well-learned situations is monitored by contention scheduling which laterally inhibits competing schemas for the control of cognitive apparatus. Under unique, non-routine procedures the supervisory attentional system (SAS) controls schema activation. The SAS is an executive monitoring system that oversees and controls contention scheduling by influencing schema activation probabilities and allowing for general strategies to be applied to novel problems or situations during automatic attentional processes.

Executive functions are cognitive processes that control other brain activities and are predominantly functioning in the prefrontal areas of the frontal lobe. Executive functions are limited in capacity and accountable for the initiation, consolidation, regulation, and inhibition of cognitive, language, motor and emotional processes. These processes underlie such functions as self-evaluation, planning, problem solving, controlling impulses and attention, and strategic selection or sequencing of behaviour to reach desired goals.

Measuring executive functions is often less accurate than measuring non-executive tasks because of the interconnectedness and multi-determined complexity of the brain. Executive functions are hard to measure independently of all other cognitive functions and are often influenced by non-executive factors. Consequently, understanding the relationship between behaviours and cognitive processes can be difficult.

Many models of executive functions have been proposed, none of which completely dominates over all others in validity and acceptability. The underlying complexity of the brain makes it very difficult to verify which model(s) are most correct. This article is most focused on the executive function of the Supervisory Attentional System and research pertaining to the system.

In 1980/1986, psychologists Donald Norman and Tim Shallice proposed a framework of attentional control of executive functioning. The model uses thought and action schemas which are a series of learned thought and action sequences, like scripts, that specify behaviours during situations. Schemas are activated from perceptual stimuli or from the output of recently activated schemata. For an example, entering your kitchen to find a pile of unclean dishes (input) could initiate a behavioural response to clean (schema). It is postulated that an enormous, finite quantity of thought and action schemata exist and that they range in hierarchy. For instance, high-level schemas represent problem solving while low-level schemas typify actions.

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