From the prominent author/education expert’s 2001 book Punished By Rewards: The Trouble With Gold Stars, Incentive Plans, A’s, Praise and Other Bribes (great title! ht Ethan Richardson):

“Letting [students] know their performance is going to be evaluated is sometimes said to provide ‘accountability’–a buzzword in both the public and private sectors–and to push people to do their best. Once again, however, control backfires. When people think they will be evaluated, their intrinsic motivation suffers–even if no reward is offered for doing well, and even if the evaluation turns out to be positive. Performance too, declines, especially on tasks demanding creativity. In fact, anytime we are encouraged to focus on how well we are doing at something, it is less likely that we will like the activity and keep doing it when given a choice.”