Somatic Marker Hypothesis - Iowa Gambling Task

Iowa Gambling Task

The human brain has evolved over time to best benefit oneself in any decision-making circumstance. It is important to understand that “natural selection shapes not only the physical characteristics of organisms, but also their behavioral and cognitive traits”.

The Iowa Gambling Task is the most common experimental paradigm used to test decision-making processes under various contexts and is frequently used in experiments exploring the Somatic Marker Hypothesis. The Iowa Gambling Task is a computerized task in which participants are presented with four decks of cards from which they repeatedly choose. Each deck contains various amounts of rewards of either $50 or $100, and occasional losses that are greater in the decks with higher rewards. The penalty cards are periodically located in the deck so the participant will not know when they will arise and the participants are told to pick cards that will maximize their winnings. The most profitable strategy is to only choose cards from the small reward/penalty decks because although the reward is smaller, the penalty is proportionally much smaller than in the higher reward/penalty deck. Over the course of a session, this deck will yield a significantly higher net profit compared to the alternative deck. Most healthy control participants adopt the beneficial low reward/penalty deck strategy during the duration of the task. Participants with brain damage however, are unable to determine the better deck to choose from, and continue to choose from the high reward/penalty deck despite this action causing a clear lower net profit than the other deck. This experiment has been used to analyze the impairments suffered by people with damage to the ventromedial prefrontal cortex, which has been known to affect neural signaling of prospective rewards or punishments. Since the Iowa Gambling Task measures participants’ quickness in “developing anticipatory emotional responses to guide advantageous choices,” it is helpful in testing the Somatic Marker Hypothesis since it studies how anticipatory signals affect decision-making. The study of human behavior in respect to evolutionary psychology demonstrates “that much, if not all, of our behavior can be explained by appeal to internal psychological mechanisms”. The Iowa Gambling Task and the Somatic Marker Hypothesis relate to this theory by revealing that emotions may have evolved during the course of human evolution to help people make better decisions. Therefore, the brain has been trained to make immediate decisions that will benefit the decision-maker. Evolutionary theory and the Somatic Marker Hypothesis suggest that human emotions have evolved to send signals to the brain which will help someone make quick decisions that will benefit them. The Iowa Gambling Task upholds this evolutionary theory by demonstrating that lesions to the ventromedial prefrontal cortex act as a blockade to the emotional decision-making signals that have evolved help humans make quick and beneficial decisions. As suggested by Comsides and Tooby, “Mechanisms involved in hierarchically ranking goals or calibrating other kinds of motivational and reward systems should be emotion-dependent”.

Although the Iowa Gambling Task is a well-known experimental measure used to explore how emotions may have evolved in humans to guide decision-making, there are “real-life” factors that can be added to the Iowa Gambling Task to test differences in participants’ results. One such study found that people who were given more time to complete the Iowa Gambling Task had better results compared to people that had less time In a more recent study aimed to determine the effects of perceived time constraints, the experimental group was told that they would likely not be able to finish the task in the time allotted, whereas the control group was informed they had a sufficient amount of time to finish. As expected, the participants who were informed they had an insufficient amount of time to complete the task performed more poorly than the participants who were told they had ample time to finish it. The results of this test can be correlated to the real world in which professionals are told they have an adequate amount of time to complete a project are less likely to make mistakes. Thus, recent studies suggest that the Iowa Gambling Task does not appropriately mimic “real-life” decision-making tasks because other factors, such as time, play into one’s success in the task instead of merely the health of the ventromedial prefontal cortex. However, human neuroimaging studies support the validity of the Iowa Gambling Task and show a clear link to “real-life” decision-making situations. Li and colleagues (2010) used functional magnetic resonance imaging (fMRI) to analyze the brain during the Iowa Gambling Task. This imaging reveals brain activity during the Iowa Gambling Task and indicates which parts of the brain are being used during decision-making processes. The results suggest that the brain regions that were activated during the Iowa Gambling Task were consistent with the ones hypothesized to trigger decision-making by somatic markers (i.e. brain regions involved in emotional processing). This adds validity to the Iowa Gambling task in conjunction with the Somatic Marker Hypothesis and suggests emotional processing is causing these regions to be activated as well as regions associated with decision-making.