‘Do this and you’ll get that’ reduces interest in the activity. Performance-contingent rewards do most damage. ‘The best that carrots — or sticks — can do is change people’s behavior temporarily.‘
Evidence cited (NYT, 2018)
- Pittman et al. (2008): rewards for finishing early → no help or more procrastination.
- HKU/NYU (2015): attendance rewards for 9-year-olds in India → a brief rise, then attendance fell.
- Robinson et al. (Harvard working paper, 2018): >15,000 students in 14 California districts; attendance rewards had no effect or made it worse.
- Gubler et al. (2015): attendance rewards at a laundry company → little effect, some workers came less.
- Framing: “rewards, like punishments, are ultimately about power”.
Counter-evidence (Claude)
- Cameron & Pierce (1994) meta-analysis: overall effects of rewards on intrinsic motivation were small. Verbal rewards increased it.
- Deci, Koestner & Ryan (1999), 128 studies: expected tangible rewards (engagement-, completion- and performance-contingent) reduced free-choice intrinsic motivation. Unexpected rewards and positive feedback didn’t, and verbal feedback increased it.
- So Kohn’s claim is stronger than the evidence, but the core mechanism (expected, tangible, contingent rewards for already-interesting tasks) is well supported.
Design rules for Tanga (Claude’s synthesis)
- Don’t pay coins for things children already enjoy (reading a story, playing a game). That’s where undermining is best documented.
- Prefer unexpected and informational rewards (“You used three new chunks, here’s why that’s good”) over announced, contingent prices.
- Avoid performance-contingent ranking (leaderboards). That’s the most damaging form.
- Use coins for genuinely dull, necessary behaviours (punctuality, homework submission) if at all, and plan to fade them.
- Measure free-choice behaviour (do they still read when no coins are on offer?), not just compliance.
Connections
Descriptive praise beats evaluative praise · Five reasons to stop saying Good job · Against competitiveness and rankings · Beyond discipline - compliance is not commitment
- Already in vault: Kohn: Punished by Rewards (highlights)