Monetary reinforcement and Wisconsin Card Sorting performance in schizophrenia: why show me the money?

The Wisconsin Card Sorting Test (WCST) is a measure of concept formation and cognitive flexibility that has been associated with the integrity of the dorsolateral prefrontal cortex. Although patients show deficits on the WCST, training techniques that rely on enhanced instruction are often effective at improving performance, at least temporarily. The beneficial effects of monetary reinforcement alone, however, have not shown such clear-cut effects. Thirty-two schizophrenic inpatients were initially administered a computerized version of the WCST according to standard instructions and then assigned to one of four groups that differed by type of intervention. The level of reinforcement (high vs. low) and enhanced instruction (present vs. absent) were manipulated across the four groups. All patients received a repeat standard administration of the WCST at a 1-week follow-up. Although enhanced instruction showed an initial effect, performance gains fell off at the 1-week retest and approached baseline levels of performance. The level of reinforcement did not make a significant difference. The results indicate that the addition of enhanced verbal instruction yields a benefit, but that contingent monetary reinforcement does not. It appears that deficits on this test are not easily remediated by incentive manipulations.