US neuroscientists have demonstrated that moral decisions such as whether you would kill one person in order to save many others are strongly influenced by a part of the brain that involves emotion.
The study is published in the journal Nature.
The research team, comprising scientists from the University of Southern California (USC), Harvard University, Caltech and the University of Iowa, presented 30 men and women with dilemmas where they had to say which decision they would take.
Some of the decisions involved making moral judgements about whether to cause harm or death to one person in order to save others from immediate or future harm or death.
One example of a dilemma was: you know someone who has a deadly disease plans to infect others, some of whom will die. Your only options are to let it happen or shoot the person with the disease. Would you pull the trigger?
Most people would say they knew the logical choice is they should sacrifice the one to save the many, but they would not be able to bring themselves to pull the trigger.
The difference, say the researchers, is emotion; not emotions in general, but a particular combination of two emotions. One is a general aversion to the act of harming or killing another person, a sort of social compassion, and the other is a more specific compassion, or empathy, for the particular individual concerned.
The 30 people the researchers presented with dilemmas were in three groups. One group of 6 had suffered damage to the ventromedial prefrontal cortex (VMPC), a small region of the brain just behind the forehead. Another group of 12 also had brain damage, but to a different part of the brain, and the remaining 12 had no brain damage at all.
The 6 who had suffered damage to the VMPC stood out in their willingness to adopt the “utilitarian” option: to harm or kill the one to save the many in those scenarios that presented difficult moral dilemmas for the other 24 participants.
In scenarios where no moral dilemma was present, the 6 did not stand out but chose much the same options as the other 24. For instance, would it be OK to change a cake recipe if you didn’t like it.
A co-senior researcher on the study, Antonio Damasio, director of the Brain and Creativity Institute and holder of the David Dornsife Chair in Neuroscience at USC said of the 6 who responded differently to the moral dilemmas, “In those circumstances most people without this specific brain damage will be torn. But these particular subjects seem to lack that conflict”.
“They lack empathy and compassion,” explained Ralph Adolphs, Bren Professor of Psychology and Neuroscience at Caltech, “Because of their brain damage, they have abnormal social emotions in real life,” he said.
Co-senior researcher Marc Hauser, professor of psychology at Harvard and Harvard College Professor said the study “Provides the first causal account of the role of emotions in moral judgments”.
Hauser also explains how astonishingly selective the deficit incurred by the VMPC frontal lobe damage is.
While the VMPC damage leaves intact a whole range of moral problem solving abilities, it damages those aspects of moral judgements where “aversive action is put into direct conflict with a strong utilitarian outcome,” he said.
Commenting on the study, assistant professor of psychology at Harvard University, Joshua Greene, who first suggested that utilitarian decisions involve overcoming a conflicting emotional element, said it nicely demonstrates “the idea that moral decisions, at least in cases like these, are not driven by a single moral faculty but rather by two different kinds of processes that can be in competition with each other.”
“The question is, are the social emotions necessary to make these moral judgments?” Adolphs asked.
Damasio pointed out that “The decisions of VMPC patients are not amoral, they are just different from the decisions of other subjects.”
The findings of this study inform at least two philosophical debates.
One is do humans make moral judgments according to social norms or personal emotions? And the other is, if, as this study suggests, humans are neurologically incapable of making strict utilitarian decisions, then will neuroscience be able to test the compatibility between different philosophies and human nature?
Antonio Damasio is author of the highly acclaimed book Descartes’ Error: Emotion, Reason, and the Human Brain.
“Damage to the prefrontal cortex increases utilitarian moral judgements.”
Michael Koenigs, Liane Young, Ralph Adolphs, Daniel Tranel, Fiery Cushman, Marc Hauser, and Antonio Damasio.
Nature Advance online publication 21 March 2007.
doi:10.1038/nature05631.
Written by: Catharine Paddock
Writer: Medical News Today