Friday, February 17, 2006

Better decisions without the prefrontal cortex

Ok, I thought all this business about snap judgment decisions was nonsense. I regret to state that maybe I was wrong about that. This research study is seriously interesting:
BBC NEWS | Health | Sleep on it, decision-makers told

A Dutch study suggests complex decisions like buying a car can be better made when the unconscious mind is left to churn through the options.

This is because people can only focus on a limited amount of information, the study in the journal Science suggests.

The conscious brain should be reserved for simple choices like picking between towels and shampoos, the team said.

Psychologists from the University of Amsterdam in the Netherlands divided their participants into two groups and devised a series of experiments to test a theory on "deliberation without attention".

One group was given four minutes to pick a favourite car from a list having weighed up four attributes including fuel consumption and legroom.

The other group was given a series of puzzles to keep their conscious selves busy before making a decision.

The conscious thought group managed to pick the best car based on four aspects around 55% of the time, while the unconscious thought group only chose the right one 40% of the time.

But when the experiment was made more complex by bringing in 12 attributes to weigh up, the conscious thought group's success rate fell to around 23% as opposed to nearly 60% for the unconscious thought group. [jf: so they did better with more attributes? That sounds flaky.]

... the study found that people can think unconsciously and that for complex decisions unconscious thought is actually superior.

The team argued the problem with conscious thought is that the brain can only focus on a few things at the same time, which can lead to some aspects being given undue importance.

Lead researcher Dr Ap Dijksterhuis said: "The take-home message is that when you have to make a decision, the first step should be to get all the information necessary for the decision.

"Once you have the information, you have to decide, and this is best done with conscious thought for simple decisions, but left to unconscious thought - to 'sleep on it' - when the decision is complex."

Jonathan Schooler of the University of British Columbia in Vancouver told Science the study built on evidence that too much reflection could be detrimental in some situations.

"What may be really critical is to engage in [conscious] reflection but not make decision," he added.
Well, there are a few things that seem flaky. The success rate with 12 variables seems unnaturally high. Still this is not entirely implausible. The seat of the conscious mind is roughly the prefrontal cortex, and the human PF is a massive bio-hack with a kludged connection to the rest of the brain. In particular the PF has real problems with multi-variable analysis. On the other hand, the older brain solves these problems all the time (social dynamics, hunting, etc). So it might make sense that it could this well.

In retrospect, smart test takers use techniques consistent with this theory. We read the whole test and scan the hard problems, then go work the easy problems. When you get to the hard problems, the answers may have already come to mind.

I wonder if this goes some way to explaining why some children and adults with poor prefrontal cortex functions (low measured IQ, severe ADHD) may make surprisingly correct decisions given complex problems. If their unconscious reason is less impaired than their PF cortex ...

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