Education level moderates learning on two versions of the Iowa Gambling Task.

The Iowa Gambling Task (IGT) is the major plank of behavioral support for the Somatic Marker Hypothesis--a prominent theory of emotionally-based decision making. Despite its widespread use, some have questioned the ecological and discriminative validity of the IGT because a substantial proportion of neurologically-normal adults display a response pattern indistinguishable from those with ventromedial prefrontal cortical brain lesions. In a large sample of healthy adults, we examined the statistical influence of several demographic variables on two versions of the IGT, with the specific prediction that educational attainment would moderate learning across trials. Results confirmed a highly significant effect of education. On the commonly used original version of the IGT, performance tended to improve more rapidly, and reach a higher eventual positive score, as the level of education increased. Age and gender were nonsignificant effects in the model, and Caucasians had slightly better IGT performance than their non-Caucasian counterparts. Conclusions are that education level, among neurologically-normal adults, should be treated as a stratification or matching variable in case-control research using this task.