Moral decisions are based on reason and feeling, show brain scans. Image: Fastfission,
Reading aloud Some situations plunge people into moral dilemmas: should they sacrifice one life to save five others? How they decide not only depends on the mind, brain researchers could now show with the help of people with brain injuries: Even the emotions play an essential role. Emotions and reason are partners, not opponents. There are situations that throw you into a moral dilemma at the mere thought of it. What would you do if, for example, a tram went down a mountain out of control and five people were standing in front of the car on the tracks? And if it were possible to change a switch, but a person on the neighboring track would be killed - should one switch the switch? Or you might hit a fat man on the rails, so that he stops the raging train?

No question: If one uses a kind of ethical cost-benefit calculation, both actions would be better than simply waiting. Surveys revealed, however, that for most the two alternatives are not equivalent despite the same 5-to-1 trade-off. Thus, it would be easier for the majority to change the switch than to push a bystander to certain death, writes the magazine "bild der wissenschaft" in his January issue. But why is that? Why is it easier to imagine the death of a human being as a necessary evil than to use it as a means to an end?

The decisive role in such decisions play the emotions, many will answer probably purely intuitive. And that's exactly what a number of brain scans have revealed in the meantime, in which US researchers led by Joshua Green from Princeton monitored the brain activity of volunteers as they envisioned different situations. Whenever the subjects thought of a so-called personal moral dilemma - such as the tram example - areas in their brain become active that generate and process emotions.

To delineate the area of ​​such moral decision-making more thoroughly when examining people with brain damage, as two research teams around Michael Koenigs of the University of Iowa and Elisa Ciaramelli of Toronto do. Particularly in the focus of the scientists is the middle lower forebrain, also called VMPFC. It lies above the eyes and processes or emotional reactions. display

The importance of VMPFC can be seen, for example, in the fact that the personality of people with a forehead injury sometimes changes dramatically: they tend to lack feeling, lack of empathy, show little sympathy, shame or guilt and tend to social norms to disregard. Many also stand out through outbursts of rage, risky acts and financial transactions as well as criminal acts. Their decision-making ability is also impaired, especially when it comes to complex situations in which the "gut feeling" plays an important role. On the other hand, they can judge purely logical relationships as well as healthy ones.

On the tram dilemma or similar situations, however, such people react completely different than the average - they would sacrifice without hesitation to the thick passers-by, Koenigs and Ciaramelli could prove. For researchers, this is important evidence that emotions play a key role in moral decisions, reports bild der wissenschaft.

However, what complicates matters is the discovery that the VMPFC is not the only one responsible for emotional reactions. Because the very people who approach the tram problem perfectly coolly and logically become emotional when they feel treated unfairly. This shows a game in which two participants split amounts of money among each other and with which such situations are typically simulated. It happens again and again that one of the two players renounces his money - especially when the other grants him only a small amount and makes use of the large batzen.

Interestingly, this behavior is especially prevalent among players with injured VMPFC: their emotional motivation, resulting from a sense of frustration and unfairness, is stronger, and they are more likely to accept the low amounts. Conversely, it is in people in which another part of the forebrain is temporarily switched off with the help of strong magnetic impulses: they are fully aware of injustice, but also accept very low offers in the game. In both cases, the normal conflict between egoism and the sense of justice which the brain exercises in such situations seems to be dispensed with, but with different results.

All in all, these results show one thing above all else: Making a moral decision is a very complex matter. It is based on intuition and emotions as well as on the ability to think rationally, after all, some decisions are made consciously against their own feelings. For the first part, the VMPFC is indispensable. Where the other crucial brain regions are, further studies have to be found.

=== R diger Vaas: "How the brain makes its judgment" in: bild der wissenschaft 1/2008, p. 88 ddp / === R diger Vaas

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