Iowa gambling task
The Iowa gambling task (hereinafter IGT) is a psychological task thought to simulate real-life decision making. It was introduced by Antoine Bechara, António Damásio, Daniel Tranel and Steven Anderson, then researchers at the University of Iowa. It has been brought to popular attention by António Damásio (proponent of the Somatic markers hypothesis) in his best-selling book Descartes' Error.
The task was originally presented simply as the Gambling Task. Later, it has been referred to as the Iowa Gambling Task and, less frequently, as Bechara's Gambling Task. The Iowa Gambling Task is widely used in research of cognition and emotion: A recent review listed more than 100 papers that made use of this paradigm.
Task structure 
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. Occasionally, a card will also have a penalty. The decks differ from each other in the number of trials over which the losses are distributed. Thus, some decks are "bad decks", and other decks are "good decks", because some will lead to losses over the long run, and others will lead to gains.
Common findings 
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. In another test, patients with ventromedial prefrontal cortex (VM) dysfunction were shown to choose outcomes that yield high immediate gains in spite of higher losses in the future. Bechara and his colleagues explain these findings 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.
Critiques of the Iowa Gambling Task 
Although the IGT has achieved prominence, it is not without its critics. Criticisms have been raised over both its design and its interpretation. Published critiques include:
- A paper by Dunn, Dalgliesh and Lawrence
- Research by Lin, Chiu, Lee and Hsieh, 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.
- Research by Chiu and Lin , the "sunken deck C" phenomenon was identified, which confirmed a serious confound embedded in the original design of IGT, this confound makes IGT serial studies misinterpret the effect of gain-loss frequency as final-outcome for Somatic marker hypothesis.
- A research group in Taiwan utilized an IGT-modified and relatively symmetrical gamble for gain-loss frequency and long-term outcome, namely the Soochow Gambling Task (SGT)  demonstrated a reverse finding of Iowa Gambling Task. Normal decision makers in SGT were mostly occupied by the immediate perspective of gain-loss and inability to hunch the long-term outcome in the standard procedure of IGT (100 trials under uncertainty). Richard L. Peterson   in his book, Inside the investor’s brain , considered the serial findings of SGT may be congruent with the Nassim Taleb’s  suggestion on some fooled choices in investment.
- A free implementation of the Iowa Gambling task is available as part of the PEBL Project.
- A customizable version of the web implementation that works with Google Spreadsheets (your own spreadsheet) is here.
- An Italian implementation is available here.
- A free implementation for smartphone and tablet is available here.
- Bechara, A., Damásio, A. R., Damásio, H., Anderson, S. W. (1994). "Insensitivity to future consequences following damage to human prefrontal cortex". Cognition 50 (1–3): 7–15. doi:10.1016/0010-0277(94)90018-3. PMID 8039375.
- Damásio, A. R. (1996). Descartes' error. Emotion, reason, and the human brain. New York: Putnam.
- Busemeyer JR, Stout JC (2002). "A contribution of cognitive decision models to clinical assessment: Decomposing performance on the Bechara gambling task". Psychologicasl Assessment 14 (3): 253–262. doi:10.1037/1040-3522.214.171.124.
- Dunn BD, Dalgleish T, Lawrence AD (2006). "The somatic marker hypothesis: a critical evaluation". Neurosci Biobehav Rev 30 (2): 239–71. doi:10.1016/j.neubiorev.2005.07.001. PMID 16197997.
- Bechara A, Damasio H, Tranel D, Damasio AR (1997). "Deciding advantageously before knowing the advantageous strategy". Science 275 (5304): 1293–5. doi:10.1126/science.275.5304.1293. PMID 9036851.
- Bechara A, Damasio H, Tranel D, Damasio AR (2000). "Characterization of the decision-making deficit of patients with ventromedial prefrontal cortex lesions". Brain 123 (11): 2189–2202. doi:10.1093/brain/123.11.2189. PMID 11050020.
- Fukui H, Murai T, Fukuyama H, Hayashi T, Hanakawa T (2005). "Functional activity related to risk anticipation during performance of the Iowa Gambling Task". NeuroImage 24 (1): 253–9. doi:10.1016/j.neuroimage.2004.08.028. PMID 15588617.
- Lin CH, Chiu YC, Lee PL, Hsieh JC (2007). "Is deck B a disadvantageous deck in the Iowa Gambling Task?". Behav Brain Funct 3: 16. doi:10.1186/1744-9081-3-16. PMC 1839101. PMID 17362508.