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Clear Pictures of How We Think

Posted by admin on December 9, 2009 at 2:28 am · Under Uncategorized

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We’ve all had recourse to say: “My head tells me to do one thing, but my heart says do the other.” Sometimes we are forced to make a decision but we feel ourselves to be pulled in opposite directions by reason and emotion.

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Thanks to an innovation that has transformed the study of the mind, scientists are now able to see precisely what happens in the brain in situations like this. For the first time in history we are getting close to answering the question of whether the heart rules the head.

The progress is due to functional magnetic-resonance imaging, or fMRI.

This technique allows the measurement of the level of oxygen in the blood, and tells scientists which parts of the brain are most active. It can show, for example, the parts of the brain that operate when we fall in love and when we have food cravings. It has even recently revealed the differences in the brains of Democrats and Republicans.

But the technique also holds out the promise of answering deep questions about our most cherished human characteristics. For example, do we have an inbuilt moral sense, or do we learn what is right and wrong as we grow up? And which is stronger: emotions or logic?

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Before fMRI, information about the parts of the brain involved in different tasks could only be gathered by studying people who had suffered brain damage from trauma or stroke, and seeing how their brain function changed. Now, the brains of healthy people can be scanned as they are given different tasks.

“fMRI has provided striking evidence in favor of some theories and against others,” said Joshua Greene, of Princeton University’s Department of Psychology. “But I don’t think the real payoff has hit yet. That will come when we have successful computational theories of complex decision-making, ones that describe decision-making at the level of neural circuits.”

Greene, together with Jonathan Cohen, professor of psychology at Princeton, is using fMRI to look at the factors that influence moral judgment.

To do so, the researchers scan the brains of volunteers while posing them fiendishly tricky dilemmas. For example, imagine you and your neighbors are hiding in a cellar from marauding enemy soldiers. Your baby starts to cry. If he continues, the soldiers will discover your hiding place and kill you all. The only way to save yourself and the others is to silence your baby — by smothering him to death. What do you do?

Clearly, you would feel intense emotions, and this shows on the brain scan. But you would also be forced to make a logical assessment of the situation, and this shows up on the brain scan too. Areas involved in abstract reasoning and those that process emotions light up.

In other words, when processing a difficult and personal moral dilemma, we really are of two minds. Greene found that if the dilemma is not so personal, the reasoning part of the brain is dominant.

When a dispute exists between two sides, say in a court of law or in a territorial land claim, there is often a mediator. So too, it seems, the brain has one too. Researchers found a region called the anterior cingulate cortex, believed to be involved in mediating conflict, was highly active in brains struggling with the crying baby scenario.

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Greene and colleagues showed a neurological basis for the phrase “of two minds,” and that both compete for dominance. So does the heart rule the head? Answer: Sometimes. But the head doesn’t give in without a fight.

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