Sunday, May 18, 2008

Moral choice: fairness, utility, and the insula

We continue to learn more about the neuropsychological basis of moral thinking and moral emotions in humans:

Justice In The Brain: Equity And Efficiency Are Encoded Differently (5/8/08)
Which is better, giving more food to a few hungry people or letting some food go to waste so that everyone gets a share" A study appearing in Science finds that most people choose the latter, and that the brain responds in unique ways to inefficiency and inequity.

The study, by researchers at the University of Illinois and the California Institute of Technology, used 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.

There are two main issues regarding moral decision making here.

The first involves two separate principles often used in analyzing moral/ethical problems related to the distribution of goods within a group of people. (The group might be children in a family or different classes of people in a society, among many possibilities.) On one hand, it is generally regarded as "good" to maximize "equity" in moral decisions, so that some individuals are not favored over others without significant justification. (I prefer the term "fairness" for this.)

On the other hand, it is also regarded as "good" to maximize "efficiency", so that the greatest total amount of benefit accrues to a group as a whole. (I prefer the term "utility" for this.)

But these principles can come into conflict, and the research discussed here investigates a contrived, but sharp, example. Philosophers of ethics call such dilemmas the problem of "distributive justice".

The second issue concerns the style of thinking that a decision maker faced with this kind of dilemma does use, and also, perhaps, what style the decision maker "should" use. On one hand, the decider might try to systematically and logically apply some standard set of rules that are considered appropriate for the situation. But on the other hand, the decider might rely more on emotional factors that indicate what "feels right", the "gut feeling", about what seems "right" in a concrete situation.

Philosophers often describe these two alternatives as "cognitivist" vs. "sentimentalist". The former is sometimes associated with the philosopher Immanuel Kant, and the latter with David Hume.

What emerges from the research is (not surprisingly) that individual decision makers differ in the degree that they favor "equity" vs. "efficiency", and also whether they tend to rely more on logic or emotion to make their decisions.

More interestingly, most people normally process considerations of both equity and efficiency in order to reach a decision, but different parts of the brain are used for the two. Likewise, in making the decision, distinct parts of the brain which normally handle emotional or logical processing can become involved in processing the equity/efficiency trade-off.

One way to think of this is that there are separate calculations of both equity and efficiency that are made for each available choice. And then the result of those calculations are fed to separate subsystems to weigh the alternatives.

The different moral and ethical decisions that different people will arrive at can be attributed to individual differences as to how the various stages of the decision process are handled. For instance, an individual may favor equity over efficiency, and tend to use emotion rather than logic to reach the decision.

Here's what the study found:
In these trails, subjects overwhelmingly chose to preserve equity at the expense of efficiency, Hsu said. "They were all quite inequity averse." The findings support other studies that show that most people are fairly intolerant of inequity.

The animation, in conjunction with the fMRI, allowed the researchers to view activity in the brain at critical moments in the decision-making process. After analyzing the data, they found that different brain regions -- the insula, putamen and caudate -- were activated differently, and at different points in the process, Hsu said.

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.

In contrast, the caudate appeared to integrate both equity and efficiency once a decision was made.

The role of the insula (or, more formally, insular cortex) is especially interesting, since this brain region has been associated with quite a few other types of social-emotional mental processing. We'll come back to that in a moment. But here are the conclusions of the researchers:
The involvement of the insula appears to support the notion that emotion plays a role in a person's attitude towards inequity, Hsu said.

The insula is known to play a key role in the awareness of bodily states and emotions. Studies have shown that it is activated in people experiencing hunger or drug-related cravings, and in those feeling intense emotions such as anger, fear, disgust or happiness. Other research has implicated the insula in mediating fairness. ...

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.

Here's how another report about this research summed it up:

Your Brain on Ethics (5/8/08)
The fMRI scans contain hints of how these two factors might be encoded by the brain. The insula, a brain region linked to processing emotion, became more active when subjects considered more inequitable distributions of meals; it was also more active in subjects whose choices suggested a greater-than-average aversion to inequity. Activity in another region, the putamen, seemed to track the common good, rising in proportion to the total number of meals that could be donated in a given case.


Now let's have a quick overview of the insula. Turns out that it's involved in a lot more than just moral decision-making. Here's a general article from a bit over a year ago:

A Small Part of the Brain, and Its Profound Effects (2/6/07)
According to neuroscientists who study it, the insula is a long-neglected brain region that has emerged as crucial to understanding what it feels like to be human.

They say it is the wellspring of social emotions, things like lust and disgust, pride and humiliation, guilt and atonement. It helps give rise to moral intuition, empathy and the capacity to respond emotionally to music. ...

If it does everything, what exactly is it that it does?

For example, the insula “lights up” in brain scans when people crave drugs, feel pain, anticipate pain, empathize with others, listen to jokes, see disgust on someone’s face, are shunned in a social settings, listen to music, decide not to buy an item, see someone cheat and decide to punish them, and determine degrees of preference while eating chocolate.

Damage to the insula can lead to apathy, loss of libido and an inability to tell fresh food from rotten. ...

Of course, like every important brain structure, the insula — there are actually two, one on each side of the brain — does not act alone. It is part of multiple circuits.

The insula itself is a sort of receiving zone that reads the physiological state of the entire body and then generates subjective feelings that can bring about actions, like eating, that keep the body in a state of internal balance. Information from the insula is relayed to other brain structures that appear to be involved in decision making, especially the anterior cingulate and prefrontal cortices.

Stay tuned. We'll be discussing the insula quite a bit more here, I think.

Further reading:

  • The Right and the Good: Distributive Justice and Neural Encoding of Equity and Efficiency – Original research report published 5/8/08 at Science Express (sub. rqd. for full access)

  • Which Orphans Do You Want to Starve? – Blog article by Sharon Begley at Newsweek

  • How Fairness Is Wired In The Brain – 5/28/08 press release about the research dealing with fairness and the insula

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