Your brain can figure it out without you

New Scientist has a piece about research in Science this week looking into subconscious decision making.

This is just weird:

In one of the tests, half of the participants were asked to ponder on the information they were given and then decide which among similar products to buy. The other half were shown the information but then made to perform a series of puzzles including anagrams and simple arithmetic. At the end of the puzzle session, the participants were asked to make a snap decision about the products.
"We found that when the choice was for something simple, such as purchasing oven gloves or shampoo, people made better decisions - ones that they remained happy with - if they consciously deliberated over the information," says Dijksterhuis.
"But once the decision was more complex such as for a house, too much thinking about it led people to make the wrong choice. Whereas, if their conscious mind was fully occupied on solving puzzles, their unconscious could freely consider all the information and they reached better decisions."

Notice that "unconscious" vs. "conscious" might or might not mean the same thing as "subconscious" vs. "conscious". Maybe a better term would be "nonconscious" in this context, where "conscious" thought processes are those that involve deliberation and rehearsal -- proceptive prediction about the consequences of decisions. Nonconscious would be nondeliberate, nonattentive thought.

I wonder to what extent this ability depends on cognitive processes that evolved before conscious thought -- or at least before humans evolved the conscious thought processes to their current extent. Primates must have very sophisticated cognitive adaptations to social living that are not fully conscious, in that they don't involve proceptive deliberation.

Evidently, you have to set your mind to thinking before you get right answers this way:

"It was only when people were told before the puzzles that they would need to reach a decision that they were able to come up with the right one," Dijksterhuis told New Scientist.
If they were told that none of what they had been shown was important before being given the puzzles, they failed to make satisfactory choices.
"At some point in our evolution, we started to make decisions consciously, and we're not very good at it. We should learn to let our unconscious handle the complicated things," Dijksterhuis says.

I guess that depends on the extent to which the decision matches the kind that those nonconscious processes evolved to handle. My guess would be that social decisions would work well this way, algebraic ones poorly.