How rewards can crowd out intrinsic motivation

To test this theory, a few years ago I ran a study in which two groups of people were asked to take part in an experiment in which they spent an afternoon picking up litter in a London park. Participants were told that they were taking part in an experiment examining how best to persuade people to look after their local parks. One group were paid handsomely for their time, while the others were only given a small amount of cash. After an hour or so of backbreaking and tedious work, everyone rated the degree to which they had enjoyed the afternoon. You might think that those clutching a large amount of well-earned cash would be more positive than those who had given their time for very little money.

In fact, the result was exactly the opposite. The average enjoyment rating of the handsomely paid group was a measly 2 out of 10, while the modestly paid group’s average ratings were a whopping 8.5. It seemed that those who had been paid well had thought, ‘Well, let me see, people usually pay me to do things I don’t enjoy. I was paid a large amount, so I must dislike tidying the park.’

Large payment, enjoyment rating: 2 out of 10.

Small payment, enjoyment rating: 8.5.

That result from litter-picking in a park is awkward and easy to abuse. It says nothing useful about whether tedious labour deserves fair pay. It does suggest that payment can alter how people interpret an activity: perhaps I received a lot because the work was unpleasant.

Before adding a reward, record the existing reasons people act. Neighbours may clear a shared path because reciprocity is normal. Children may read from curiosity or to spend time with an adult. Add points, cash or prizes and those reasons now compete with a public transaction.

The danger appears after the reward period. Pages read may rise for ten weeks while books become a low-paid job. Litter may disappear during the voucher scheme and return when it ends. Measuring only the paid interval hides the part that distinguishes temporary compliance from durable motivation.

Fair compensation and intrinsic motivation can coexist. The practical questions concern framing, autonomy and what happens later. Was the payment recognition, a wage or a bribe? Could people choose how to contribute? Did quality change? Did they continue freely?

The reading scheme ends on Friday. On Monday, the book remains on the bedside table. Nobody yet knows whether it will be opened. That observation belongs in the result.