[Decision making and the Iowa Gambling Task: relevance to dependence study].

The Iowa Gambling Task (IGT) is an experimental tool to study decision making. In this task, participants choose a card from four decks of cards. Each card indicates either gain or loss of money. Participants are instructed to earn as much money as possible. Two of the four decks are "risky", containing cards with bigger gains and losses than the other two decks. The sustained selection of the risky decks ends up in overall loss. Therefore, the choice behavior becomes "cautious" in healthy participants during the task. However, patients with lesions in the prefrontal cortex and substance abusers persist on the risky decks. This tendency is interpreted to reflect impulsivity. Thus, the task has been used to detect impulsiveness in certain neurological/psychiatric disorders. Our recent study found that even in health participants, some people persisted in selecting from the risky deck as the number of big losses increased. This tendency was prominent in self-rated deliberative people. However, they were implicitly impulsive, as revealed by the matching familiar figure test. These results suggest that the gap between explicit deliberation and implicit impulsivity drew them into risky decision making. In this article we introduce theoretical backgrounds, practical procedure, and several applicative studies from the IGT literatures and suggest the usefulness of the IGT in dependence and addiction study.