Saturday, June 26, 2010

The brain and behavior, part 1 million

Regular readers know I spend a lot of time talking about how the brain influences behavior. Yesterday's Science Daily had three articles related to that issues.

Where courage is located
They took a bunch of people who were or were not afraid of snakes and had them move a neutral object or a harmless snake toward them or away from them, and they found the part of the brain that lights up when someone who is afraid of a snake overcomes that fear and pulls it toward them. If you care about details, it was the subgenual anterior cingulate cortex. In addition, "a series of temporal lobe structures" decreased activity.

Brain structure and personality
This study looked at the Big Five personality traits (conscientiousness, extraversion, neuroticism, agreeableness, and openness/intellect) and the size of different parts of the brain. "(C)onscientious people tend to have a bigger lateral prefrontal cortex, a region of the brain involved in planning and controlling behavior." Extraverts have  a bigger medial orbitofrontal cortex, which is involved in rewards. Neuroticism and agreeableness each had its big area, though the article didn't say where. Only openness/intellect was not associated with a big area.

One problem with this is that they didn't look at all areas of the brain for each personality trait. After a personality test, they predicted which areas would be bigger than normal and then tested those areas. There may be other areas involved, on the principle that everything is more complicated than you think it is.

It's also not clear which way the causal relation goes. It may be that having a big lateral prefrontal cortex makes you conscientious, or it may be the other way around. I expect we'll find out. In the meantime, it's another strong correlation between brain and behavior.

What you feel affects what you think

  • People reading a resume on a heavy clipboard think the person is weightier and better than people reading the same resume on a light clipboard. 
  • People negotiating while sitting in harder chairs are less flexible and drive harder bargains. 
  • People judged a case-study employee as being more rigid and strict if they had just touched a hard wooden block than if they had just touched a soft blanket.
  • People who had been putting together a puzzle with rough pieces described a social interaction as harsher than those who had been handling a puzzle with smooth pieces.
Yup, the brain is god-awful complicated, but a lot of what we think is determined by it. Makes you wonder about free will, doesn't it? More on that some time.

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