The Iowa Gambling Task

The Iowa Gambling Task, developed in the early 1990s by Antoine Bechara and Antonio Damasio, is a card-selection experiment that provided the first clean empirical demonstration of the somatic marker hypothesis. Subjects draw cards from four decks; two yield high immediate rewards but produce net losses, two yield modest rewards with smaller penalties and produce net gains. Normal subjects develop skin conductance responses differentiating the decks after about ten draws, and begin avoiding the bad decks long before they can articulate why. Patients with ventromedial prefrontal damage show flat skin conductance and continue drawing from disadvantageous decks even after catastrophic losses. The task demonstrates that the body evaluates before the mind can explain — and that eliminating bodily evaluation eliminates practical wisdom even when cognitive capacity is intact.