for other topics, click a “category” on the right
You have abandoned a sinking cruise ship and are in a crowded lifeboat that is dangerously low in the water. If nothing is done it will sink before the rescue boats arrive and everyone will die. However, there is an injured person who will not survive in any case. If you throw the person overboard, the boat will stay afloat and the remaining passengers will be saved. Would you throw the person overboard in order to save the lives of the remaining passengers?
Eighty percent of subjects with a specific brain injury answered yes to that question. People with uninjured brains said yes only 20 percent of the time. In an article in the NY Times today, Benedict Carey describes a study carried out by researchers at the University of Iowa.
Patients with damage to the ventromedial prefrontal cortex express increased willingness to harm another person for the greater good. This is an area of the brain behind the forehead, inches behind the eye. The cortex is the thick outer wrapping of the brain, where conscious functions of thinking and language reside; where social emotions and “compassion” emerge.
“Ventral” means under, and “medial” means near the middle. In humans, the area is about the size of a plum. Injuries to the area may occur as the result of a tumor or an aneurysm.
Researchers emphasize that the study was small and the questions hypothetical, and no one can predict how choices might be made in a real-life situation. But the findings are the most direct evidence that humans’ native revulsion against hurting others relies on a part of neural anatomy. The results were published on-line yesterday (3/21/07) in the journal Nature.
Previous studies had shown that this region was active during moral decision-making and that damage to it and neighboring areas affected moral judgements. The new study will probably seal the case.
The findings could have implications for legal situations; jurors have reduced sentences on the basis of brain imaging results. People with this kind of injury can be lucid, easygoing, talkative and intelligent, but socially awkward.
They also have many of the same moral instincts that other people do. To a question involving flipping a switch to stop a runaway train, killing one person but saving several others, they agreed to do so, along with their normal peers. They would not do harm in situations that did not involve trading one human life for another. They would not send a daughter to work in the pornography industry, or kill an infant they felt they could not care for.
But a large difference emerged when there was no switch to flip — when they had to choose taking direct action to kill or harm someone for the greater good (push someone in front of a train if that was the only option, or suffocate a baby whose cries would put hidden family members at risk of being found by enemy soldiers). They were twice as likely to do so.
The difference was very clear for all the ventromedial patients, said Dr Michael Koenigs, a neuroscientist at the National Institutes of Health, who led the study while at the University of Iowa.
The ventromedial area is a primitive part of the cortex that appears to have evolved to help humans negotiate social interactions. It has connections with deeper, unconscious regions like the brain stem, which transmits physical sensations of attraction or discomfort, and with the amygdala, a “gumdrop of neural tissue” that registers threats, social and otherwise. This ventromedial area integrates those signals with others from the cortex, including emotional memories, to help generate familiar social reactions.
“This area, when it’s working, will give rise to social emotions, like embarrassment, guilt, and compassion, critical to guiding our social behavior,” said Dr Antonio Damasio, a co-author of the study and a neuroscientist at the University of Southern California. According to Dr Damasio, those sensations put a finger on the brain’s conscious, cost-benefit scale weighing moral dilemmas, creating a tension that even trained snipers can feel when having to pull a trigger on an enemy.
This tension between cost-benefit calculations and instinctive emotion in part reflects the brain’s continuing adjustment to the vast social changes since the ventraomedial area of the cortex first took shape.
The area probably adapted to help the brain make snap moral decisions in small kin groups. As communities became more and more complex, so did the cortical structures involved in parsing ethical dilemmas. But the more primitive ventromedial area continued to anchor it with emotional insistence on respect for the life of another human being.
sole source for this posting was NYT article on 3/22/07 by Benedict Carey.
tutoring in Columbus OH: Adrienne Edwards 614-579-6021 or aedwardstutor@columbus.rr.com
