Serotonin (5-HT) modulates emotional and cognitive functions such as fear conditioning (FC) and decision making. This study investigated the effects of a functional polymorphism in the regulatory region (5-HTTLPR) of the human 5-HT transporter (5-HTT) gene on observational FC, risk taking and susceptibility to framing in decision making under uncertainty, as well as multidimensional anxiety and autonomic control of the heart in healthy volunteers. The present results indicate that in comparison to the homozygotes for the long (l) version of 5-HTTLPR, the carriers of the short (s) version display enhanced observational FC, reduced financial risk taking and increased susceptibility to framing in economic decision making. We also found that s-carriers have increased trait anxiety due to threat in social evaluation, and ambiguous threat perception. In addition, s-carriers also show reduced autonomic control over the heart, and a pattern of reduced vagal tone and increased sympathetic activity in comparison to l-homozygotes. This is the first genetic study that identifies the association of a functional polymorphism in a key neurotransmitter-related gene with complex social-emotional and cognitive processes. The present set of results suggests an endophenotype of anxiety disorders, characterized by enhanced social learning of fear, impaired decision making and dysfunctional autonomic activity.

Recent theories have argued that emotions play a central role in moral decision-making and suggested that emotion regulation may be crucial in reducing emotion-linked biases. The present studies focused on the influence of emotional experience and individual differences in emotion regulation on moral choice in dilemmas that pit harming another person against social welfare. During these "harm to save" moral dilemmas, participants experienced mostly fear and sadness but also other emotions such as compassion, guilt, anger, disgust, regret and contempt (Study 1). Fear and disgust were more frequently reported when participants made deontological choices, whereas regret was more frequently reported when participants made utilitarian choices. In addition, habitual reappraisal negatively predicted deontological choices, and this effect was significantly carried through emotional arousal (Study 2). Individual differences in the habitual use of other emotion regulation strategies (i.e., acceptance, rumination and catastrophising) did not influence moral choice. The results of the present studies indicate that negative emotions are commonly experienced during "harm to save" moral dilemmas, and they are associated with a deontological bias. By efficiently reducing emotional arousal, reappraisal can attenuate the emotion-linked deontological bias in moral choice.

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