How bad was it? Differences in the time course of sensitivity to the magnitude of loss in problem gamblers and controls.

Previous research has shown that pathological gamblers show various cognitive distortions, especially in interpreting near losses. Using a modified blackjack task, we investigated the electrophysiological responses to near and full losses in problem gamblers and controls. We assessed the event-related brain potentials (ERPs) of 20 problem gamblers and 21 controls at two time points following negative game outcomes. We also studied the behavioral changes after near and full loss experiences. Between 270 and 320 ms following a loss, controls but not gamblers showed a differential ERP response to near and full losses suggesting that a near loss is evaluated more negatively than a full loss. However, between 430 and 480 ms after a loss, the ERPs of both, gamblers and controls, showed a differential response as a function of the type of loss. Both groups became more cautious in their subsequent gambling behavior following near loss. The present study revealed differences in the time course of processing negative feedback in problem gamblers and normal controls, which might be due to gamblers preoccupation with gains rather than with losses.

The influence of the magnitude, probability, and valence of potential wins and losses on the amplitude of the feedback negativity.

We assessed the influence of the variables outcome potential, feedback valence, magnitude, and probability on the amplitude of the feedback negativity (FN). Outcome potential was defined as the a priori valence of an upcoming feedback, that is, is there a potential win or potential loss? All these variables have been studied previously, although never together, but the findings have been contradictory. We analyzed the event-related potential (ERP) after feedback presentation in a reinforcement-learning task to examine the effects of all the variables on feedback negativity. Our results show that outcome potential, feedback valence, probability, and magnitude all influence feedback related ERPs. Taken together, the findings suggest that ERPs in the time range of the feedback negativity are primarily driven by positive outcomes (reinforcement) rather than negative outcomes (punishment).