Iowa gambling task
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The Iowa gambling task is a psychological task thought to simulate real-life decision making. It was introduced by Bechara, Damasio, Tranel and Anderson (1994), then researchers at the University of Iowa. It has been brought to popular attention by Antonio Damasio, proponent of the Somatic markers hypothesis and author of Descartes' Error. The task is sometimes known as Bechara's Gambling Task, and is widely used in research of cognition and emotion.
Participants are presented with 4 virtual decks of cards on a computer screen. They are told that each time they choose a card they will win some game money. Every so often, however, choosing a card causes them to lose some money. The goal of the game is to win as much money as possible. Every card drawn will earn the participant a reward ($100 for Decks A and B; $50 for Decks C and D). Occasionally, a card will also have a penalty (A and B have a total penalty of $1250 for every ten cards; C and D have a total penalty of $250 for every ten cards). Thus, A and B are "bad decks", and C and D are "good decks", because Decks A or B will lead to losses over the long run, and Decks C or D will lead to gains. Deck A differs from B and Deck C differs from D in the number of trials over which the losses are distributed: A and C have five smaller loss cards for every ten cards; B and D have one larger loss card for every ten cards.
Most healthy participants sample cards from each deck, and after about 40 or 50 selections are fairly good at sticking to the good decks. Patients with orbitofrontal cortex (OFC) dysfunction, however, continue to perseverate with the bad decks, sometimes even though they know that they are losing money overall. Concurrent measurement of galvanic skin response shows that healthy participants show a "stress" reaction to hovering over the bad decks after only 10 trials, long before conscious sensation that the decks are bad. By contrast, patients with OFC dysfunction never develop this physiological reaction to impending punishment. Bechara and his colleagues explain this in terms of the somatic marker hypothesis. The Iowa gambling task is currently being used by a number of research groups using fMRI to investigate which brain regions are activated by the task in healthy volunteers as well as clinical groups with conditions such as schizophrenia and obsessive compulsive disorder.
[edit] Critiques of the Iowa Gambling Task
Although the IGT has achieved prominence, it is not without it critics. Criticisms have been raised over both its design and its interpretation. Published critiques include:
- A paper by Dunn, Dalgliesh and Lawrence [1]
- Research by Lin, Chiu, Lee and Hsieh. [2], who argue that a common result (the “prominent deck B” phenomenon) argues against some of the interpretations that the IGT has been claimed to support.
[edit] References
Bechara A, Damasio AR, Damasio H, Anderson SW (1994). Insensitivity to future consequences following damage to human prefrontal cortex. Cognition, 50: 7-15.
[edit] External links
- A free implementation of the Iowa Gambling task is available as part of the PEBL Project [3]
- Another, web based, implementation is available here.
- An italian implementation is available here.
