Supervisory attentional system
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.
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 limited in capacity and accountable for the initiation, consolidation, regulation, and inhibition of cognitive, language, motor and emotional processes.
[2] 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.
In 1980/1986, psychologists Donald Norman and Tim Shallice proposed a framework of attentional control of executive functioning.
For an example, entering your kitchen to find a pile of unclean dishes (input) could initiate a behavioural response to clean (schema).
[1] Contention scheduling ensures the proper schema is activated and, through inhibition, prevents multiple competing actions from executing simultaneously.
[1] The SAS monitors conscious, deliberate planning of actions, novel situations that cannot be solved by previously learned schemata and/or when preventing error or habitual responses is critical.
However a reduced activity in the SAS is corresponded to momentary inadequacies of attention resulting in irrelevant behaviour known as a capture error.
[1] Similarly, patients with a dysfunctional SAS show complication in recalling memories for specific events and problems with focusing attention, planning, and initiating actions.
When humans are faced with a threatening situation there is often limited time to generate the fight-or-flight response ideally suited to increase survival.
The supervisory attentional system provides individuals with the ability to predict and prepare for situations mentally prior to any possible encounter.
[9] Over time, the supervisory attentional system was incorporated into research on age, brain injuries, psychological disorders, degenerative diseases, substance abuse and more.
Patients with damaged frontal lobes exhibit characteristic symptoms of people who have executive dysfunction, for instance impaired retrieval of autobiographical information.
Patients with frontal lesions showed no significant impairment on the Tower of London, Halying, or Brixton tests, despite being slower on the TOL and Hayling tasks.
It is reasonable to conclude that the Supervisory Attentional System, located in the frontal lobes, works together with processes in other areas of the brain.
Additionally, areas of the brain connected to the dysfunctional component may have demonstrated neuronal plasticity to incorporate some of the impaired functions into their own processes.
Elderly persons, in comparison to young adults, are generally slower and took more moves to solve problems, made more erroneous responses, and had more difficulty understanding and applying logical rules.
[3] Frontal lobe lesions and age influence executive functioning processes in similar, but different ways.
[3] A fairly recent focus has been placed on understanding the impact Attention deficit hyperactivity disorder has on individuals’ executive processes.
People with ADHD share several similar behavioural manifestations with patients confirmed with disruption to executive functions, characteristic of SAS deficiencies.
Detoxified, chronic alcoholic males showed reduced inhibition and flexibility in planning, rule detection, coordination between tasks, and made more errors.
Positron emission topography results verified frontal lobe activation during tests of executive functions in which alcoholic participants showed poor performance.
[2] Schizophrenic's executive functions were examined on planning, inhibition, and abstraction of logical rules using the Tower of London, Hayling, and Brixton tests.
Patients were significantly worse on all three tasks compared to control individuals matched for education level, age, and gender.
[20] Children with autism have an impaired capability to solve problems, engage in thoughtful and appropriate behaviours, sustain relevant tasks and self-monitor.
Autistic individuals have an enlarged cortex characterized by irregular neuronal growth, a reduced volume of corpus callosum (impairing communication between hemispheres), abnormal structure and function of the frontal lobe, cerebellum, medial temporal lobe, related limbic systems (amygdala and hippocampus), and elevated levels of serotonin.
[12] The influence of Parkinson's disease on the SAS are consistent with those found for carbon monoxide poisoning,[22] and both confirm frontal lobe dysfunctions.
