Amygdala damage eliminates monetary loss aversion

TLDR

Loss aversion, the tendency to avoid risky choices that involve potential losses, is thought to be mediated by the amygdala, yet empirical support for this link has been lacking. The authors examined two rare patients with focal bilateral amygdala lesions, having them complete a battery of monetary gamble tasks to assess loss sensitivity. Both patients displayed normal expected‑value and risk responses but markedly reduced loss aversion, indicating the amygdala is essential for generating loss‑aversion behavior.

Abstract

Losses are a possibility in many risky decisions, and organisms have evolved mechanisms to evaluate and avoid them. Laboratory and field evidence suggests that people often avoid risks with losses even when they might earn a substantially larger gain, a behavioral preference termed “loss aversion.” The cautionary brake on behavior known to rely on the amygdala is a plausible candidate mechanism for loss aversion, yet evidence for this idea has so far not been found. We studied two rare individuals with focal bilateral amygdala lesions using a series of experimental economics tasks. To measure individual sensitivity to financial losses we asked participants to play a variety of monetary gambles with possible gains and losses. Although both participants retained a normal ability to respond to changes in the gambles’ expected value and risk, they showed a dramatic reduction in loss aversion compared to matched controls. The findings suggest that the amygdala plays a key role in generating loss aversion by inhibiting actions with potentially deleterious outcomes.