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Vol 446 | 19 April 2007 |doi:10.1038/nature05631
LETTERS
Damage to the prefrontal cortex increases utilitarian moral judgements
Michael Koenigs1{*, Liane Young2*, Ralph Adolphs1,3, Daniel Tranel1, Fiery Cushman2, Marc Hauser2 & Antonio Damasio1,4
The psychological and neurobiological processes underlying moral judgement have been the focus of many recent empirical studies111.
Of central interest is whether emotions play a causal role in moral judgement, and, in parallel, how emotion-related areas of the brain contribute to moral judgement. Here we show that six patients with focal bilateral damage to the ventromedial prefrontal cortex (VMPC), a brain region necessary for the normal generation of emotions and, in particular, social emotions1214, produce an abnormally utilitarian pattern of judgements on moral dilemmas that pit compelling considerations of aggregate welfare against highly emotionally aversive behaviours (for example, having to sacrifice one persons life to save a number of other lives)7,8. In contrast, the VMPC patients judgements were normal in other classes of moral dilemmas. These findings indicate that, for a selective set of moral dilemmas, the VMPC is critical for normal judgements of right and wrong. The findings support a necessary role for emotion in the generation of those judgements.
The basis of our moral judgements has been a long-standing focus of philosophical inquiry and, more recently, active empirical investigation. In a departure from traditional rationalist approaches to moral cognition that emphasize the role of conscious reasoning from explicit principles15, modern accounts have proposed that emotional processes, conscious or unconscious, may also play an important role16,17. Emotion-based accounts draw support from multiple lines of empirical work: studies of clinical populations reveal an association between impaired emotional processing and disturbances in moral behaviour14; neuroimaging studies consistently show that tasks involving moral judgement activate brain areas known to process emotions59; and behavioural studies demonstrate that manipulation of affective state can alter moral judgements10,11. However,
neuroimaging studies do not settle whether putatively emotional activations are a cause or consequence of moral judgement; behavioural studies in healthy individuals do not address the neural basis of moral judgement; and no clinical studies have specifically examined the moral judgements (as opposed to moral reasoning or moral behaviour) of patients with focal brain lesions. In brief, none of the existing studies establishes that brain areas integral to emotional processes...