Neither snap judgments nor sleeping on a problem are any better than conscious thinking for making complex decisions, according to UNSW research.

The finding debunks a controversial 2006 research result asserting that unconscious thought is best for complex decisions, such as buying a house or car. If anything, the new study suggests that conscious thought leads to better choices.

Since its publication two years ago by a Dutch research team in the journal Science, the earlier finding had been used to encourage decision-makers to make "snap" decisions (for example, in the best-selling book Blink, by Malcolm Gladwell) or to leave complex choices to the powers of unconscious thought.

But in the new study, to be published in the Quarterly Journal of Experimental Psychology, scientists ran four experiments in which participants were presented with complex decisions and asked to choose the best option immediately ("blink"), after a period of conscious deliberation ("think"), or after a period of distraction ("sleep on it"), which is claimed to encourage "unconscious thought processes".

In all experiments, there was evidence that conscious deliberation can lead to better choices and little evidence for superiority of choices made "unconsciously".

"Claims that we can make superior 'snap' decisions by trusting intuition or through the 'power' of unconscious thought have received a great deal of attention in the media," says UNSW psychologist, Dr Ben Newell, lead author of the study.

"At best, these sorts of reports are misleading," says Dr Newell. "At worst, they're outright dangerous. In stark contrast to claims made by the Dutch research team and in the media, we found very little evidence of the superiority of unconscious thought for complex decisions.

"In fact, our research suggests that unconscious thought is more susceptible to irrelevant factors, such as how recently information has been seen rather than how important it is. If conscious thinkers are given adequate time to encode material, or are allowed to consult material while they deliberate, their choices are at least as good as those made 'unconsciously'."

Watch the online video courtesy of the BBC's Horizon program.

Media Contact: Dan Gaffney | +61 411 156 015 | d.gaffney@unsw.edu.au