16207Heart Rules Head In Moral Decisions
- May 9, 2008From Medical New Today site:
Heart Rules Head In Moral Decisions
US scientists studying how the brain behaves during decision
making have discovered that when people are confronted with
moral decisions, they think about efficiency in one part of the
brain, and equity in another part of the brain that deals with
emotions, and the latter tends to win, suggesting that a sense
of fairness is fundamental to human nature.
The study is the work of researchers at University of Illinois and
the California Institute of Technology, and appears in the 8th May
issue of Science.
What is the better decision: to give more food to a few hungry
people (the efficient choice), or let some food go to waste so that
everyone gets a fair share (the more equitable choice)?
This was the dilemma faced by participants in the study, whose
brains were scanned by functional magnetic resonance imaging
(fMRI) while they considered a series of tough decisions in a
involving allocating food to children in a Ugandan orphanage.
In setting up this study the researchers wanted firstly to explore
whether equity or efficiency was stronger to our sense of justice,
and secondly, they wanted to find out how big a role emotions
played in resolving such questions.
These two questions have been at the heart of longstanding
debates about "distributive justice".
Co-principal investigator Ming Hsu, a fellow of the Beckman
Institute for Advanced Science and Technology at the University
of Illinois, said that what makes us moral, and how we make trade
offs, the fundamentals of moral choices, is a question that interests
Hsu said many of the subjects said afterwards that "This is the worst
experiment I've ever been in. I never want to do anything like this
The participants were given the following scenario.
Each child in the orphanage starts with a monetary equivalent of
24 meals, an actual gift from the researchers to the orphanage.
Then, a number of meals is to be cut from the children's allotments.
The number that is cut depends on choices the participant makes.
Each decision, where the participant has to choose one of two
options, comprises a moral dilemma where one option is efficient,
and the other option is equitable. For instance, one could choose to
take 15 meals from one child (option 1) or 13 meals from one child
and 5 meals from another child (option 2). In option 1 fewer meals
are lost (more efficient), and in option 2 more meals are lost (less
efficient) but the burden is more "fairly" distributed.
Hsu and colleagues said that this type of decision is a good example
of a distributive justice dilemma, where each option is compelling,
but you can't have both, so you have to trade one off against the
The participants made their decisions by watching a computer
where they were shown pictures of two choices at a time, each being a
photograph of the children affected and a number showing the number
of meals that would be lost if they chose that option. They chose
option by selecting a lever that changed the path of a ball that was
slowly moving across the screen.
The results showed that participants overwhelmingly chose equity over
"They were all quite inequity averse," said Hsu, who explained that
the findings support other research that suggests people are fairly
intolerant of inequity.
While the participants watched the screen and made their selections,
the researchers observed their brains with fMRI scanners. They were
particularly interested in the brain activity at the time they made
Three regions of the brain, the insula, putamen and caudate, were
involved in different ways, at different points in the decision
The insula was active when equity changes were being considered,
the putamen was active when efficiency changes were being considered.
And the caudate appeared to integrate equity and efficiency when the
decision was taken.
Hsu said that the involvement of the insula suggests that emotion is
involved when a person is thinking about inequity.
Studies have shown that the insula, which is involved in awareness of
bodily states and emotions, becomes active when people feel hungry,
crave drugs, or have intense feelings like anger, fear, disgust and
happiness. Other studies have also suggested it mediates fairness.
The authors said the putamen and the caudate regions of the brain
become activate during reward-related learning.
Hsu described what they saw. At first "you're seeing the signal in
and the putamen," he said, but "when they hit the lever you see the
activation. And when the ball gets to the end you see (activation of)
caudate," he added.
Hsu explained that:
"The putamen is responding only to the chosen efficiency, which is
many meals get taken away from the kids or how many meals they end up
"The insula, however, responded to how equitably the burden of lost
meals was distributed," said Hsu.
The authors wrote that the results showed how the brain "encodes two
considerations central to the distributive justice calculus and shed
on the cognitivist/sentimentalist debate regarding the psychological
underpinnings of distributive justice".
They suggested the findings support the notion that "a sense of
fairness is fundamental to distributive justice, but, as suggested
by moral sentimentalists, is rooted in emotional processing".
On a more general level they suggested that:
"Emotional responses related to norm violations may underlie
individual differences in equity considerations and adherence to
"The Right and the Good: Distributive Justice and Neural Encoding of
Equity and Efficiency."
Ming Hsu, Cédric Anen, and Steven R. Quartz.
Science.Published Online May 8, 2008.
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