Brain can't make always right decisions


Research in the current issue of the journal Neuron offers a mathematical model for how people make decisions about visual stimuli on a computer screen. They found that humans make accurate judgments about cues they can see.

"We're discovering that humans aren't so stupid after all," said Alexandre Pouget, co-author of the study and associate professor of brain and cognitive sciences at the University of Rochester in New York.

Participants were asked to look at moving dots on a screen. Many of the dots moved randomly, but some moved in one clear direction. Researchers found that people very quickly realized which way the non-random dots were going.

The work complements that of Kahneman and Tversky in that it shows humans are good at lower-level, nonlinguistic tasks, while perhaps not so good at higher-level probability problems involving words, he said.

"In simple perceptual decisions -- you have a visual stimulus on the screen and you have to make decisions about it -- it looks like you do accumulate the evidence optimally, given that uncertainty," Pouget said.

Psychologists believe the human mind has two systems for decision-making: intuitive and reasoning. The intuitive system is emotional, fast, automatic but slow-learning, while the reasoning system is emotionally-neutral, slow, controlled, and rule-governed. Neither, of course, is always right, but there are certain simple problems that reveal flaws in intuition.

A classic example that Kahneman has often used in lectures is this math problem: A bat and a ball together cost $1.10. The bat costs a dollar more than the ball. How much does the ball cost?

Your intuitive system may quickly tell you that the ball costs 10 cents. That would be an easy solution, but it would also be incorrect.

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