| Lesion studies have established that ventromedial prefrontal cortex (VMPC) is critically involved in emotion, personality, and decision-making. However, previous studies of decision-making impairments in VMPC patients have been narrowly focused, almost exclusively involving financial risk. To explore a more broad range of social, emotional, and cultural factors that may impact decision-making, seven patients with documented impairments in social/emotional function following bilateral VMPC lesions were studied in a novel series of laboratory contexts. The VMPC group was compared to matched samples of normal individuals and VMPC-intact lesion patients on four tests. (1) In a test of the effect of emotional arousal on directed cognition, subjects performed a mental rotation task with black, neutral, and emotional background pictures. Contrary to hypothesis, the emotional pictures did not affect task performance in any of the groups. (2) In a test of moral judgment, subjects evaluated a series of moral scenarios. The VMPC group's responses differed from comparison groups' only for moral scenarios that proposed committing a highly emotionally aversive action in order to maximize aggregate welfare. On these scenarios the VMPC group exhibited an abnormally utilitarian pattern of judgments. (3) In a test of economic decision-making, subjects acted as responders in the Ultimatum Game. VMPC patients rejected a significantly greater proportion of unfair offers than either comparison group, suggesting that proper modulation of emotional reactions, a faculty impaired by VMPC damage, is necessary for normal responses in situations of unfair treatment. (4) On a test of brand preference, subjects performed taste tests of Coke and Pepsi with and without the availability of brand information to determine whether taste preference is influenced by brand information and whether brand preference is based solely on taste preference. Each group's taste preferences were affected by the availability of brand information, but only the VMPC group demonstrated brand preferences consistent with blind taste preferences. These experiments reveal that VMPC-mediated emotional processes may facilitate rational behavior in some contexts, but engender irrational behavior in others. This work advances the basic understanding of the neuroanatomical substrates that process social, emotional, and cultural factors to influence human choice. |
