A meta-analytic review of experiments examining the effects of extrinsic rewards on intrinsic motivation.
Deci, Edward L.; Koestner, Richard; Ryan, Richard M.
Psychological Bulletin, Vol 125(6), Nov 1999, 627-668.
A meta-analysis of 128 studies examined the effects of extrinsic rewards on intrinsic motivation. As predicted, engagement-contingent, completion-contingent, and performance-contingent rewards significantly undermined free-choice intrinsic motivation (d = –0.40, –0.36, and –0.28, respectively), as did all rewards, all tangible rewards, and all expected rewards. Engagement-contingent and completion-contingent rewards also significantly undermined self-reported interest (d = –0.15, and –0.17), as did all tangible rewards and all expected rewards. Positive feedback enhanced both free-choice behavior (d = 0.33) and self-reported interest (d = 0.31). Tangible rewards tended to be more detrimental for children than college students, and verbal rewards tended to be less enhancing for children than college students. The authors review 4 previous meta-analyses of this literature and detail how this study's methods, analyses, and results differed from the previous ones. (PsycINFO Database Record (c) 2012 APA, all rights reserved)