PFC lesion can change your ethical philosophy

A set of 6 subjects with bilateral damage to the ventromedial prefrontal cortex (VMPC) answered ethical questions in a way more consistent with utilitarian ethical philosophy than the control subjects. For example, they would be more willing to kill someone by pushing them off a bridge if that would save 5 other people. This supports the view that social emotions underly ethical judgments.

Michael Koenigs, Liane Young, Ralph Adolphs, Daniel Tranel, Fiery Cushman, Marc Hauser and Antonio Damasio.Damage to the prefrontal cortex increases utilitarian moral judgements. Nature. Published online 21 March 2007

Utilitarianism in a nutshell

Utilitarianism is an ethical philosophy where, rather than classifying types of actions into good or evil, you look at the consequences of an action in a given situation and make ethical decisions so as to maximize overall good. So, a utilitarian would consider it ethical to kill one person in order to save five other people (assuming they valued everyone’s life equally, etc). Think Spock, the Vulcan from Star Trek.

Normal people think it is more unethical to directly, personally harm someone else, compared to harming them indirectly in an impersonal way. A good example was given in the nytimes article The Brain on the Stand by Jeffrey Rosen:

Imagine a train heading toward five people who are going to die if you don’t do anything. If you hit a switch, the train veers onto a side track and kills another person. Most people confronted with this scenario say it’s O.K. to hit the switch. By contrast, imagine that you’re standing on a footbridge that spans the train tracks, and the only way you can save the five people is to push an obese man standing next to you off the footbridge so that his body stops the train. Under these circumstances, most people say it’s not O.K. to kill one person to save five.

Dr. Spock would probably think that “normal people” are being illogical when they distinguish between direct, personal and indirect, impersonal harm. The VMPC subjects still made this distinction, but not as strongly. The VMPC subjects acted like control subjects on the second sort of question (the impersonal harm), but were more likely than controls to endorse pushing someone off a bridge to save others. Accordings This is the sense in which they are “more utilitarian”. Dr. Spock would approve.

You can read the exact questions which were asked in the supplementary info (PDF). The questions that the VMPC subjects differed on are those questions in the last section, section “personal moral scenarios”, which were labeled “high-conflict”.

About the VMPC

From the article,

“The VMPC projects to basal forebrain and brainstem regions that execute bodily components of emotional responses, and neurons within the VMPC encode the emotional value of sensory stimuli. Patients with VMPC lesions exhibit generally diminished emotional responsivity and markedly reduced social emotions (for example, compassion, shame and guilt) that are closely associated with moral values, and also exhibit poorly regulated anger and frustration tolerance in certain circumstances. Despite these patent defects both in emotional response and emotion regulation, the capacities for general intelligence, logical reasoning, and declarative knowledge of social and moral norms are preserved. ”

Reminds me of the replicants in the sci-fi movie Blade Runner. Remember that in Blade Runner, replicants were distinguished from humans by the “Voight-Kampff test” which measured empathy response. Replicants were supposed to have less empathy than real humans. However, they do seem to get angry and frustrated.

“All six VMPC patients had impaired autonomic activity in response to emotionally charged pictures (Table 2), as well as severely diminished empathy, embarrassment and guilt (Table 2).”


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