Executive functions are higher level cognitive functions which are involved in control and regulation of lower level cognitive processes (Alvarez & Emory , 2006). They are responsible for processes like planning, decision-making, problem solving and shifting between tasks. Moreover, they also manage emotional regulation, self-monitoring and inhibition of impulses. In simple terms, they are the dispatchers of cognitive resources of the brain.
Executive functions help us with fluid cognitive processing and are major contributors to our fluid intelligence (Busch, Booth & McBride, 2005). Fluid intelligence is based on cognitive processes which place minimal demand on prior learning and contribute in novel problem solving. In contrast, crystallized intelligence is dependent on utilizing prior knowledge, skills and experiences as a source for cognitive processing. A simple way to make a distinction between these two is to consider fluid intelligence to be dependent only on short term memory while crystallized intelligence is dependent on short-term as well as long-term memory.
For a long time, executive control of the brain was considered to be managed by a central executive (Baddeley, 1996). The central executive was considered to be responsible for managing all cognitive resources in the brain. However, it faced two major issues. First, task impurity problem, which is the issue regarding tasks being dependent on other cognitive processes which leads to low correlation between performance on different EF tasks. For example, subjects would do good on some executive function tasks like Tower of Hanoi (TOH) task but would fail at the Wisconsin card sorting task (WCST). Second, construct validity problem, which is the lack of knowledge about what complex executive tasks like TOH and WCST really measure (they don’t measure the same thing, as subjects might perform good at one task and fail at the other task).
The latent variable model which is at the core of this project provides support for a non-unitary distributed structure of executive functions. It states that there are distinct core executive functions which feed into other complex executive functions. This model, identified by Miyake and colleagues (2000), identifies 3 core executive functions which are separable to some extent but are the underlying processes of more complex executive tasks. The 3 core executive functions are identified as: updating, shifting and inhibition. Updating is defined as updating and monitoring of working memory representations, shifting is defined as shifting between tasks or mental and inhibition is referred as inhibition of dominant or prepotent responses.
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