TASK-SWITCHiNG IN DYSLEXIA. Neurocognitive Mechanisms of Cognitive Flexibility in Dyslexia
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2014-08-01
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en
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Although it is well established that individuals with dyslexia show several deficits in cognitive control functions in addition to their primary reading disorder, studies investigating cognitive flexibility abilities in this population yielded mixed results. The current study therefore further examined cognitive flexibility capacities in dyslexia as well as the underlying neurocognitive mechanisms. To this aim, we assessed task-switching abilities, as measure of cognitive flexibility, in students with dyslexia and in their control peers. Participants were asked to voluntarily respond either to the location (task A) or shape (task B) of presented stimuli. lmportantly, the two tasks differed in difficulty with respect to stimulus-response (S-R) mappings: while the location task had direct S-R mappings, in the shape tast< these mappings were arbitrariiy chosen. Furthermore, to manipulate genera! task demands, each stimulus was preceded by either a short or long preparatory interval. In addition to participants' response times and accuracy, we recorded their brain activity with EEG during task execution. Whereas individuals with dyslexia made more errors immediately after a taskswitch compared to the control group, no significant group differences were found in response times. However, EEG results indicated that individuals with dyslexia needed a stronger preparation in shape-specific switch trials, as reflected by an increased contingent negative variation (CNV), to reach the same performance level in behaviour as controls. Moreover, the stimulus-related P3 component was more susceptible to general task demands in the dyslexia than in the control group. These findings altogether demonstrate that dyslexia is accompanied by cognitive flexibility difficulties.
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Faculteit der Sociale Wetenschappen