Study sheds light on neurological basis of moral decision-making

May 9th, 2008 - 3:49 pm ICT by admin  

Washington, May 9 (ANI): Most people would choose letting some food go to waste instead of giving more food to a few hungry people if they were given a choice between the two, according to a new study.

The study by researchers at the University of Illinois and the California Institute of Technology shows that the brain responds in unique ways to inefficiency and inequity.

Published in the journal Science, the study involved functional magnetic resonance imaging (fMRI) to scan the brains of people making a series of tough decisions about how to allocate donations to children in a Ugandan orphanage.

Ming Hsu, one of the lead researchers, revealed that the study was undertaken with a view to zeroing in on the neurological underpinnings of moral decision-making.

Morality is a question of broad interest. What makes us moral, and how do we make tradeoffs in difficult situations, Hsu said.

During the study, each participant was told that each child would start out with a monetary equivalent of 24 meals. However, an undetermined number of meals would have to be cut from some childrens allotments.

The number of meals cut and the individual children who would be affected depended on how the subjects selected from options the researchers presented.

The researchers said that each decision pitted efficiency (the total number of meals given) against equity (how much the burden of lost meals was shared among the children).

One could choose to take 15 meals from a single child, for example, or 13 meals from one child and five from another. In the first option the total number of meals lost would be lower. Efficiency would be preserved, but one child would bear the brunt of all the cuts. In the second option more children would share the burden of lost meals but more meals would be lost.

The researchers observed that the equity was better, but at a cost to efficiency.

This dilemma illustrates the core issues of distributive justice, which involves tradeoffs between considerations that are at once compelling but which cannot be simultaneously satisfied, the authors wrote.

The researchers said that they had designed the study to address the psychological and neurological dimensions of two longstanding debates about distributive justicefirst, is equity or efficiency more critical to our sense of justice, and the second, are such questions solved by reason alone, or does emotion also play a role.

Participants in the study were shown an animation on a computer screen, wherein a ball travelled from right to left toward a lever that could direct the ball toward one or the other option. The photographs of the affected children represented each option, with numbers for the number of meals that would be lost to those children if that option were selected.

The participants steered the ball to the option they preferred by moving the lever, and their choice was highlighted in red at the end of each trial.

The researchers observed that the subjects overwhelmingly chose to preserve equity at the expense of efficiency.

They were all quite inequity averse, said Hsu, adding that the findings support other studies that show that most people are fairly intolerant of inequity.

When the researchers analysed the data they gathered through the fMRI, they found that different brain regionsthe insula, putamen and caudatewere activated differently, and at different points in the process.

Hsu revealed that activation of the insula varied from trial to trial in relation to changes in equity, while activity in the putamen corresponded to changes in efficiency. He said that the caudate, on the other hand, appeared to integrate both equity and efficiency once a decision was made.

The researcher further said that the involvement of the insula appeared to support the notion that emotion plays a role in a persons attitude towards inequity.

Youre seeing the signal in the insula and the putamen initially. When they hit the lever you see the insula activation. And when the ball gets to the end you see (activation of) the caudate, Hsu said.

The putamen is responding only to the chosen efficiency, which is how many meals get taken away from the kids or how many meals they end up with, Hsu added.

The insula, however, responded to how equitably the burden of lost meals was distributed.

(Together, the results) show how the brain encodes two considerations central to the distributive justice calculus and shed light on the cognitivist/sentimentalist debate regarding the psychological underpinnings of distributive justice, the authors wrote. (ANI)

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