22 March 2007
NewScientist.com
Roxanne Khamsi
Mr Spock, the
fictional Vulcan famously logical and lacking in emotion, sacrificed himself
for his comrades in the movie Star Trek II: The Wrath of Khan with the
following words to Captain Kirk: "The needs of the many outweigh the needs
of the few, or the one…"
Now, revealing new
research shows that people with damage to a key emotion-processing region of
the brain also make moral decisions based on the greater good of the community,
unclouded by concerns over harming an individual.
It is the first study
to demonstrate how emotion impacts moral judgement and sheds light on why
people often act out of respect for an individual rather than choosing to act
in a more logical, utilitarian way. The findings could cause a rethink in how
society determines a "moral good", and challenge the 18th-century
philosophies of Immanuel Kant and David Hume.
Antonio Damasio at
the University of Southern California in Los Angeles, US, and colleagues
recruited 30 people for their experiment. Six of the subjects had suffered
damage to a region in the front of the brain known as the ventromedial
prefrontal cortex (VMPC), which regulates emotions. The participants had this
brain injury as a result of an aneurism or tumour growth in the VMPC region.
Twelve participants
in the study had damage to other parts of the brain but not the VMPC. And the
remaining 12 subjects had no brain injury whatsoever.
The researchers
presented participants with various scenarios (scroll to the bottom for several
examples) and asked them to make decisions based on the information provided.
Some of the situations involved moral decision-making. For example, subjects
had to say whether they would throw a person in front of a train if doing so
would stop the train from barrelling into five workmen, killing all five.
In such a situation,
most people would find it morally unacceptable to push someone to his or her
death – even if doing so would save the lives of others. And this was the
reaction of the healthy participants or those that had injury to brain regions
excluding the VMPC. But people with damage to the VMPC showed a willingness to
take this type of "utilitarian" action.
"You have one
group that is ready to endorse what we would regard as an overly utilitarian
judgment and the other far less" willing to do so, explains Damasio. He
notes that the patients with VMPC damage generally made the same decisions as
their control counterparts when it came to non-moral scenarios.
Notably, people with
VMPC damage were just as likely as their counterparts to endorse
"impersonal" moral decisions that involved indirectly putting
strangers at risk for the greater good. These impersonal moral scenarios
involved, for example, encouraging the use of a vaccine that would protect the
public but cause an adverse reaction in a few individuals.
These results suggest
that emotions play a crucial role in moral decisions involving personal contact
– but not in moral judgments involving distant, indirect impacts on other
people. "What's beautiful to me is how subtly different the situations
are," says Marc Hauser at Harvard University in Cambridge, Massachusetts,
US, one of the researchers involved.
The finding that some
moral judgments involve emotions while others do not supports the supposedly
diametrically opposed thinking of philosophers Immanuel Kant and David Hume.
"It means both
Kant and Hume are right. Philosophers will have a fit because they like to
choose sides," says Frans de Waal at Emory University in Atlanta, Georgia,
US. Hume believed that people could be motivated to make proper moral decisions
based on their sympathy for others. Kant, meanwhile, warned that moral judgments
might be corrupted by emotions.
Philip Kitcher, who
teaches philosophy at Columbia University in New York, US, notes that the study
of brain damaged individuals presents a unique challenge to Kant's philosophy.
While Kant cautioned against the corruptive influence of emotions, he also
argued that individuals have personal dignity, which must be respected.
Yet in the new study,
subjects who had impaired emotion processing due to VPMC damage showed the
least concern for individual dignity in the personal moral dilemmas that
involved directly harming another person to save others. This provides strong
biological evidence that emotions enable us to respect individual dignity, says
Kitcher.
"Emotions are an
anchor for our moral systems. If you remove that anchor you can end up
anywhere," says de Waal.
Examples of
scenarios used in the experiment:
Non-Moral
Scenario: Investment Offer
You are at home one
day when the mail arrives. You receive a letter from a reputable corporation
that provides financial services. They have invited you to invest in a mutual
fund, beginning with an initial investment of one thousand dollars.
As it happens, you
are familiar with this particular mutual fund. It has not performed very well
over the past few years, and, based on what you know, there is no reason to
think that it will perform any better in the future.
Would you invest a
thousand dollars in this mutual fund in order to make money?
Impersonal Moral
Scenario: Standard Trolley
You are at the wheel
of a runaway trolley quickly approaching a fork in the tracks. On the tracks
extending to the left is a group of five railway workmen. On the tracks
extending to the right is a single railway workman.
If you do nothing the
trolley will proceed to the left, causing the deaths of the five workmen. The
only way to avoid the deaths of these workmen is to hit a switch on your
dashboard that will cause the trolley to proceed to the right, causing the
death of the single workman.
Would you hit the
switch in order to avoid the deaths of the five workmen?
Personal Moral
Scenario: Submarine
You are the captain
of a military submarine travelling underneath a large iceberg. An onboard
explosion has caused you to lose most of your oxygen supply and has injured one
of your crew who is quickly losing blood. The injured crew member is going to
die from his wounds no matter what happens.
The remaining oxygen
is not sufficient for the entire crew to make it to the surface. The only way
to save the other crew members is to shoot dead the injured crew member so that
there will be just enough oxygen for the rest of the crew to survive.
Would you kill the
fatally injured crew member in order to save the lives of the remaining crew
members?
Personal Moral
Scenario: Infection
Someone you know has
AIDS and plans to infect others, some of whom will die. Your only options are
to let it happen or to kill the person.
Do you pull the
trigger?
Journal reference: Nature
(DOI: 10.1038/nature05631)