Gyula Demeter

elaboration of a series of tasks in use in today`s clinical and experimental setting. Probably
the most well-known ones are the Letter-Number Span Test (Gold, Carpenter, Randolph,
Goldberg, & Weinberger, 1997) and the N-back Test (Callicott et al., 1998). These tests
beside the simple storage of incoming information require also a dynamic maintenance and
manipulation of representations, which tapes the executive component of working memory.
Duncan’s goal neglect theory
In his theory Duncan (Duncan, 1986, 1995; Duncan &Owen, 2000; Duncan et al., 2000)
argues that our behavior is guided by a set of goals and subgoals organized in a hierarchical
pattern. The human behavior is goal oriented and our goals help us accommodate to the
external and internal demands controlling the behavior by activation or by inhibition. Faced
with a new task at the first stage of executive processing we analyze it and determine the
goals and subgoals, weighting them and establishing a hierarchical plan of action which then
will be carried out. Performance then will be monitored and evaluated in order to allow
modifications if necessary. Patients with frontal lobe damage often fail to realize intended
goals, which Duncan called “goal-neglect”: the subjects are able to describe the tasks
requirements, but during completion ignore them.
The authors had proposed that fluid intelligence as characterized by Spearman’s g factor
(1927) depends on the frontal lobe functions Patients with frontal lesions who achieved
higher scores on the Wechsler Intelligence Test scored significantly lower on the fluid
intelligence test, focused on problem solving (Duncan, Burgess, & Emslie, 1995).
Functional neuroimaging studies (Ducan & Owen, 2000; Duncan, 2006) discovered a
common brain activity pattern, called the multiple demand system (MD) during very different
cognitive tasks. This specific activity pattern involves the posterior part of the inferior frontal
sulcus, the anterior insula and adjacent frontal operculum, the pre-supplementary motor area,
the adjacent dorsal anterior cingulated and the intraparietal sulcus (Duncan, 2010). A similar
activity pattern can be seen during problem solving tasks taping fluid intelligence
(Prabhakaran et al., 1997; Duncan et al., 2000).
The MD cortex plays a crucial role in defining and controlling parts of mental programs
which helps us to achieve different set of goals. According to Duncan (2010) while we are
learning new tasks, the processes of fragmenting and assembling different parts of it enables
strong MD activity.
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