In July 2009, at TEDGlobal, Dan Pink opened his talk with a confession. He had gone to law school. He had never practiced. And today, against his wife’s advice, he was going to try his old skills on the audience. “I don’t want to tell you a story,” he said. “I want to make a case.”
“So, ladies and gentlemen of the jury, take a look at this.”
What he showed them was a candle, some thumbtacks and some matches. The job was to attach the candle to the wall so the wax wouldn’t drip onto the table. Pink walked through what people try. They tack the candle to the wall, which doesn’t work. They melt the side of the candle and try to stick it on, which doesn’t work either. After five or ten minutes, he said, most people see it: empty the box, tack the box to the wall, stand the candle in it.
Then he told the jury about money. The psychologist Sam Glucksberg had timed people on this puzzle, and offered some of them cash: $5 if they were in the fastest quarter, $20 for the fastest of all. The group playing for money, Pink said, took about three and a half minutes longer.
Pink had a second picture to show.
The box with nothing in it
Glucksberg had also run the puzzle with one detail changed. The tacks lay on the table, next to an empty box. Same prizes, same clock. This time the group offered money was faster.
A prize can speed up an easy task and slow down one that needs a fresh idea.
The two versions differ in a single thing: what the box looks like it’s for. The puzzle comes from the psychologist Karl Duncker, whose monograph On Problem-Solving appeared in English in 1945, and it is used to study what psychologists call functional fixedness. A box full of tacks reads as a container. People fail to use it as a shelf, or get there slowly. Hand them the box empty, already free of its usual job, and they do better.
Glucksberg’s paper framed the result in the language of its day, as an effect of “strength of drive.” In a later summary by economists, his suggestion was that extrinsic incentives make functional fixedness worse. Pink put it in plainer words. “Rewards, by their very nature, narrow our focus,” he said. When the goal is right in front of you, a narrow focus gets you there faster. When “the solution is on the periphery,” it keeps your eyes off it.
It’s the feeling of hunting for your keys when you’re late. You check the same coat pocket three times, harder each time. The keys are on the hook by the door, where you’d see them in a calmer moment.
One study, one jury
The pull of the story is that it is clean, and the record is messier.
Glucksberg’s subjects were all men. In 2012 and 2013, three economists, Joachim Ramm, Sigve Tjøtta and Gaute Torsvik, ran the hard version again with 79 students at the University of Bergen, about half of them competing for a cash prize. Paid students took a little longer and solved it a little less often, but the gaps were small and not statistically significant. “We failed to replicate the results in Glucksberg (1962),” they wrote. In a separate group of students working in pairs, paid or unpaid, the pairs did far better than individuals.
So the safe reading is narrower than a TED talk. In one 1962 experiment, a prize for speed helped when the path to the answer was obvious, and hurt when the answer meant seeing an object differently. A later attempt to repeat the hard half found no clear harm. What the 1962 study shows most plainly is the condition: the prize that hurt on one version helped on the other.
The returns spreadsheet
Say the owner of a small online shop notices that returns have doubled since spring, and nobody knows why. It might be the new supplier, the new sizing chart or the new courier. She is tempted to offer a bonus to whichever of her two staff cracks it first.
The candle problem suggests what might go wrong. A race rewards whoever pushes hardest down the first plausible path, and each of them already has a favorite theory. The answer may be somewhere neither is looking, such as a size label that changed when the supplier did.
She could take the race off the puzzle. Ask both of them to list what changed since spring, look at it together, and keep the bonus for the part of the job with an obvious path, like clearing the backlog of returns once the cause is found. That is the tacks-outside-the-box version, and the one where Glucksberg’s prize group won.
The spreadsheet of returns is still open on her screen. The answer is in one of the columns nobody has sorted yet.