Overjustification effect
The reduction in intrinsic motivation for an activity that occurs after an extrinsic reward for that activity is introduced and then removed. Counterintuitively, rewarding people for something they already enjoyed doing for its own sake can leave them less motivated to do it once the reward disappears — because the reward causes them to misattribute their own motivation.
The classic study
The foundational demonstration is Lepper, Greene, and Nisbett’s 1973 study “Undermining Children’s Intrinsic Interest with Extrinsic Rewards: A Test of the ‘Overjustification’ Hypothesis” (Journal of Personality and Social Psychology), described in The Gamer’s Brain (book) (Chapter 6): schoolchildren who enjoyed drawing were given a reward for it, and afterward drew spontaneously less often than children who received no reward. A subtlety Hodent highlights — children who received a surprise (unexpected) reward did not show the same drop-off, suggesting the damage comes specifically from expecting the reward, not from receiving one.
Mechanism
Per Hodent’s account: when you do something purely because you enjoy it, you correctly attribute your engagement to intrinsic interest. Once an external reward is introduced, you may start attributing your engagement to the reward instead. When the reward is later withdrawn, the (now-misattributed) reason to continue is gone too — so motivation collapses below where it started, even though the original intrinsic interest was real.
Hodent is careful to flag that the effect is not universal: it shows up most reliably when the activity was already interesting to the person and when the reward is perceived as external to the activity itself (especially monetary rewards), and the picture is further complicated by findings that rewards can support rather than undermine motivation when they confirm competence or provide useful information delivered supportively.
Why it matters for game and app design
Hodent flags this as “particularly damaging for education” — attaching grades (an extrinsic reward) to something like learning, which can be intrinsically motivating on its own, risks the same undermining pattern. The same logic bears directly on this wiki’s existing coverage of engagement mechanics: streaks, daily rewards, and points/badges/leaderboards (PBL fallacy) are all extrinsic-reward layers added on top of activities (playing a game, using an app) that may have started out intrinsically motivating. See Self-Determination Theory, the broader motivational framework this effect sits inside — Hodent introduces SDT in the same section as the dominant framework for studying intrinsic motivation (citing Deci and Ryan 1985 and Ryan and Deci 2000).
Related
- Self-Determination Theory — the broader framework (competence, autonomy, relatedness) this effect is explained through
- PBL fallacy — points/badges/leaderboards as the kind of extrinsic-reward layer this effect warns against
- Streak — a mechanic this effect is directly relevant to critiquing
- Cognitive dissonance — another motivation-chapter phenomenon covered in the same part of the book