Selective deficit in personal moral judgment following damage to ventromedial prefrontal cortex

TLDR

fMRI studies show medial prefrontal activation during personal moral dilemmas, suggesting this region contributes to personal moral judgment, though imaging alone cannot prove necessity. The study aimed to test whether the ventromedial prefrontal cortex is required for personal moral judgment by examining patients with focal lesions. Seven vmPFC‑lesioned patients and twelve healthy controls performed personal, impersonal, and non‑moral dilemma tasks. Lesioned patients accepted personal moral violations more readily and more quickly than controls, while performing similarly on impersonal and non‑moral dilemmas, indicating the vmPFC is essential for opposing personal moral violations, likely via anticipatory self‑focused emotional processes.

Abstract

Recent fMRI evidence has detected increased medial prefrontal activation during contemplation of personal moral dilemmas compared to impersonal ones, which suggests that this cortical region plays a role in personal moral judgment. However, functional imaging results cannot definitively establish that a brain area is necessary for a particular cognitive process. This requires evidence from lesion techniques, such as studies of human patients with focal brain damage. Here, we tested 7 patients with lesions in the ventromedial prefrontal cortex and 12 healthy individuals in personal moral dilemmas, impersonal moral dilemmas and non-moral dilemmas. Compared to normal controls, patients were more willing to judge personal moral violations as acceptable behaviors in personal moral dilemmas, and they did so more quickly. In contrast, their performance in impersonal and non-moral dilemmas was comparable to that of controls. These results indicate that the ventromedial prefrontal cortex is necessary to oppose personal moral violations, possibly by mediating anticipatory, self-focused, emotional reactions that may exert strong influence on moral choice and behavior.