This thesis first focused on the effect of anticipated emotions upon decision-making. Using a Trust Game, we found that some individuals were more sensitive to disappointment than others, making impulsive and counterproductive decisions to avoid experiencing it again. As revealed by EEG recordings, these least tolerant individuals used the same neural system to process all types of outcomes, whereas the most tolerant ones relied on a different system when confronted to unexpected outcomes. In a second study, we found that the impulsive behaviour and its neural correlates can be modified by giving different instructions to the subjects. Using another game, the Ultimatum Game, we found again inter-individual differences in the use of dual system. Finally, intra-cranial recordings revealed that the modification of behaviour following disappointment in the Trust Game was due to an implicit learning process mediated by theta oscillations in the hippocampal region.