Turning play into work: Effects of adult surveillance and extrinsic rewards on children's intrinsic motivation.

Preschool children engaged in a novel activity in individual sessions. In the expected reward conditions, subjects expected to win a chance to play with highly attractive toys by engaging in the activity; in the unexpected reward conditions, subjects had no prior knowledge of this reward. Orthogonally, subjects in the surveillance conditions were told that their performance would be monitored via a television camera; while subjects in the...