Testing times: Students writing an examination

Snap judgments about people and places can be remarkably accurate, and there is no substitute for simple logic and reflection in determining questions like which alarm clock or cell phone is the best value.

But many more important decisions ? choosing the right apartment, the optimal house, the best vacation ?turn on such a bewildering swarm of facts that people often throw up their hands and put the whole thing temporarily out of mind. And new research suggests that this may be a rewarding strategy.

In a series of experiments reported last week in the journal Science, a team of Dutch psychologists found that people struggling to make complex decisions did best when they were distracted and were not able to think consciously about the choice at all.

Reasoning capacity

The research not only backs up the common advice to “sleep on it” when facing difficult choices, but it also suggests that the unconscious brain can actively reason as well as it produces weird dreams and Freudian slips.

“This is very elegant work, and like any great work, it opens up as many questions as it answers” about the unconscious, said Timothy D. Wilson, a psychologist at the University of Virginia and the author of the book Strangers to Ourselves: Discovering the Adaptive Unconscious. He was not involved in the research.

Psychologists have known for years that people process an enormous amount of information unconsciously ? for example, when they hear their names pop up in a conversation across the room that they were not consciously listening to. But the new report suggests that people take this wealth of under-the-radar information, combine it with deliberately studied facts and impressions and then make astute judgments that they would not otherwise form.

In the study, the research team, led by A.P. Dijksterhuis of the University of Amsterdam, had 80 students choose among four cars based on a list of attributes for each, like age, gasoline mileage, transmission and handling. After presenting the attributes in quick succession, the researchers instructed some students to think carefully about the decision for four minutes and distracted others by asking them to solve anagrams.

When the list of characteristics was four items, students were more likely to pick the best functioning vehicles if they reasoned through the decision, rather than if they were distracted. But with 12 attributes, the distracted anagram solvers tended to make wiser choices, the study found.

The unconscious brain has a far greater capacity for information than conscious working memory, the authors write, and it may be less susceptible to certain biases.

Complexity score

“One example is people who like a house for its space, but don’t properly weigh in the effect of commuting distance until they’re spending two hours on the train every day,” said Dijksterhuis. The unconscious brain might give the commuting more weight, he said.

The researchers developed a “complexity score” for 40 products and assets based on how many of each item’s attributes people took into account. Cars, computers and apartments were at the top, dresses and shirts in the middle and oven mitts and umbrellas at the bottom.

Using that scale, the psychologists surveyed students who had recently bought some of those items and found that the more the buyers thought about their purchases of simple objects, the more satisfied they were. But the opposite was the case for complex purchases, where the more time spent in conscious deliberation, the less satisfied the students were.