Abstract
Task switching refers to an ability to switch flexibly from one behavior to another behavior in response to environment contingencies and is associated with the integrity of the prefrontal and anterior cingulate cortices. Task switching and cognitive control have been suggested to be impaired in schizophrenia. However, neuropsychological instruments used in previous studies, such as the Wisconsin Card Sorting test, are multidimensional and it is not easy to separate task switching from other factors in these instruments. We tested task switching in schizophrenia with a novel Arrow-Stroop task, where green or red arrows were used as stimuli. Participants switched between two randomly ordered tasks, where an instruction cue preceded the target stimulus and indicated which task to execute. In the Arrow task, participants were required to respond to the direction of the arrow regardless of its color. In the Color task, they responded to the direction of the arrow when it was green, but to the opposite direction of the arrow when it was red. Overall schizophrenia patients showed the same amount of task switching cost as normal controls did, suggesting that task switching is intact in schizophrenia. In both groups, the switching cost from the Color task to the Arrow task was greater than the switching cost in the reverse direction. These results suggest that the deficit observed in previous studies might not derive from deficit in task switching, but from other aspect of cognitive control, implicating that “cognitive control” as a unitary concept should be re-examined.