Emotion Based Learning

Neurological patients such as Phineas Gage had long been a puzzle to the neuropsy-chological community. The disorder is most commonly seen in cases of closed-head injury. Such patients often show relatively normal intelligence, and near-normal performance on a range of tasks specifically designed to test frontal lobe function. However, in spite of this, they choose unsuitable friends, enter inadvisable relationships, and engage in inappropriate activities (Bechara et al., 2000). This behavior typically leads to financial losses, career termination, and loss of affection of family and friends. The role of emotion, and especially emotion-based learning, has recently changed our understanding of the behavior of such patients. It appears that their poor judgment and decision-making abilities follow from an incapacity to use emotion-based learning systems, which provide information about the likely outcome of future decisions (see Damasio, 1994, 1996). Consistent with this claim, participants perform poorly if the task does not have direct emotional consequences for them (Turnbull et al., 2003).

This literature has suggested a biological basis for the substantial role of emotion in cognition, and this aspect of mental life can now be reliably assessed using the Iowa Gambling Task (Bechara et al., 1994). In this task the subject is faced with four decks of cards and asked to choose any deck, in any sequence. The subject wins or loses money with each turn and should learn to choose the decks that offer the best financial return. Some decks have frequent high gains but also occasional substantial losses. Sustained playing of these decks leads to overall financial loss. Other decks have more modest payouts but lead only to small and infrequent loses, so that sustained playing of the decks leads to small but consistent gains. The game is complex, and participants do not appear, subjectively, to understand the contingencies of the game. Nevertheless, participants quite rapidly develop a "feeling" about which decks are good or bad. This probably derives from small activations of emotion in the seconds preceding the choice of a high-risk "bad" deck—when the participant is contemplating which deck to choose (see Damasio, 1994, 1996). Activation of the autonomic nervous system is the physiological correlate of this emotional experience and can be directly measured using changes in skin conductance (see Damasio, 1994, 1996). In other words, participants receive "advance warning" of the consequences of their actions, coded in terms of emotion, allowing them to avoid negative consequences (Bechara et al., 1994).

Participants typically favor the risky decks in the early stages of the game, but neurologically normal participants (even those who regard themselves as "gamblers") rapidly shift to decks where they will accrue the smaller amounts of money over longer periods. Neurological patients with lesions to the ventromesial frontal lobes also show a strong skin conductance response after a bad choice has been made (showing that they still feel emotion), but have no ability to develop the advance warning effect that could alert them of a potentially poor-outcome choice. As a result they do not develop an avoidance of bad choices, and consistently lose money (Bechara et al., 1994). This inability to predict the likely emotional outcome of their actions is probably the cause of their many difficulties in everyday life.

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