"Want to make a complicated decision? Just stop thinking", was one of hundreds of headlines spawned by a study published in 2006 by Ap Dijksterhuis and colleagues. The team of Dutch researchers reported that students made "better" decisions after being distracted by an anagram task, compared with when they spent the same number of minutes deliberating over their choices.
While the conscious mind was busy solving anagrams, the researchers claimed the unconscious, with its unlimited process capacity, was left free to sift through the information pertinent to making the best decision.
But now, Ben Newell and colleagues have copied the experimental set up used by Dijksterhuis and failed to find that the outcome of unconscious deliberation is any better than consciously chewing over a decision.
Student participants were presented with a choice of apartments or cars (depending on the experiment), and were told whether each available option ticked the box or missed the mark for one of ten attributes, such as security or rent. Participants then made their favoured choice either immediately, or after a 4 or 8 minute period of conscious deliberation or distraction.
The actual "best" choice was identified later, by asking the participants to score how much each attribute mattered to them on a scale of one to ten. For each item, the weight of those attributes it lacked was subtracted from those it performed well at, thus revealing the "best" option.
Regardless of how participants made their choice - immediately, or after either conscious or subconscious deliberation - they tended to choose the best option. "In stark contrast to claims in the literature and the media," the researchers wrote, "we found very little evidence of the superiority of unconscious thought for complex decisions."
In fact, a final experiment suggested that we make our choices "on-line" as new information is gathered, rather than after deliberation, conscious or unconscious. Moreover, a period of unconscious deliberation led participants to place disproportionate weight in the most recently acquired information. This suggests "that a period of distraction can enhance recency effects and, in this case, lead to poorer choices," the researchers concluded.
Ben Newell, Kwan Yao Wong, Jeremy Cheung, Tim Rakow (2008). Think, blink or sleep on it? The impact of modes of thought on complex decision making The Quarterly Journal of Experimental Psychology, 1-1 DOI: 10.1080/17470210802215202
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.