The classic priming experiment was one in which college students had been asked to form various sentences from a given set of words. Those in one group were given words that included several associated with older people (like bingo, gray and Florida). Those in a second group were given words with no such associations. After the linguistic exercise, each participant was instructed to leave the building by walking down a hallway. Without letting the participants know what was going on, the experimenters timed their walks down the hall. They found that those in the group given words associated with old people walked significantly slower than those in the other group. The first group had been primed to walk more slowly.And, after reviewing claims made for the power of priming techniques to alter our behavior, Gutting notes:
...that priming experiments seldom tell us how important priming is in realistic situations. We know that it has striking effects under highly simplified and controlled laboratory conditions, where the subjects are exposed only to the stimuli that the experimenters provide. But it is very difficult to know how significant priming stimuli (thinking about money, large numbers, abstract questions) would be in a real-life, uncontrolled environment, where all sorts of stimuli might be conflicting with one another. Also, there is seldom any reason to think that even a strong priming effect will last very long. As Jonathan Ellis has noted, even Kahneman ignores these points when, after summarizing the walking-like-the-elderly experiment, he says: “Although you surely were not aware of it, reading this paragraph [which contained many words relating to the elderly] primed you as well. If you had needed to stand up to get a glass of water, you would have been slightly slower than usual to rise from your chair . . . ”
These limits are well illustrated by Richard Thaler and Cass Sunstein’s best-selling book, Nudge. The authors begin with excellent discussions of priming and similar experimental results and then put forward numerous public policy proposals, most of them quite sensible, allegedly inspired by these results. But hardly any of their proposals depend on the results of behavioral economics. Their ideas are mostly a matter of common sense or of strategies long practiced in the business world: in giving people options (regarding decisions like retirement plans or organ donations), make the choice you prefer the default option; provide more or less information on a credit card bill depending on whether you want people to pay just the minimum each month; arrange food in a cafeteria or supermarket so the items you want chosen are most accessible. As Benjamin Friedman pointed out in his review of the book, “we don’t need behavioral economics . . . to think such proposals might be helpful.”
Priming experiments remain important sources of information about the details of how our minds work. It’s possible that they might someday yield valuable techniques for modifying real-world behavior. (Here is one promising if very preliminary example.) But for now claims that they have deep philosophical significance or major practical consequences have scant support.