Instructional cues modify performance on the Iowa Gambling Task

The current study investigated whether acute alcohol intoxication produces impaired decision-making on tasks assessing ventromedial prefrontal (VMF) cortex functioning and impulsive responding. Participants completed the Iowa Gambling Task (IGT), a decision-making test targeting the VMF, and the Newman Perseveration Task (NT), a measure of impulsivity. Personality measures of impulsivity were assessed using the Barratt Impulsiveness Scale (BIS). To encourage natural responding on both tasks, participants were falsely informed that the study was examining the effects of alcohol on memory; the impulsivity tasks were presented as ‘distractor’ tasks. Advantageous performance on the IGT was related to specific instructional cues as well as to knowledge about the experimental purpose. Performance of intoxicated and sober participants did not differ. A subsequent study in which the true purpose of the experiment was revealed confirmed that alcohol does not affect IGT performance. Most importantly, the instruction-sensitivity of the IGT emphasizes the importance of salient cues for decision-making.