Endowment effect
A bias in valuation: people demand more to give up something they own than they would pay to acquire it in the first place. The act of ownership — even very brief, even purely psychological — increases the perceived value of the thing. Documented and named by Richard Thaler in 1980; later studied extensively in classic mug experiments by Kahneman, Knetsch, and Thaler (1990).
The classic experiment
Half a room of subjects is given a coffee mug; the other half isn’t. Both groups are asked their reservation price — owners say what they’d accept to sell, non-owners say what they’d pay to buy. Owners consistently demand roughly 2× what non-owners are willing to pay, even though only minutes earlier they had no relationship to the mug at all. The mug didn’t change; the position did.
Underlying mechanism is closely related to Loss aversion — losing something you own is felt more strongly than the symmetric gain.
Where it appears in game and product design
The endowment effect is exploited any time a system gives the player something first and then asks them to pay or commit to keep it. Two well-documented cases in this wiki:
- Mobile-game piggy banks. Mobile Game Monetization Psychology (video) cites the Egg Inc. piggy bank as the canonical example: the player accumulates “earned” rewards in a virtual piggy bank for free, then must pay real money to break it open. The rewards feel like the player’s already, so paying to unlock them feels like recovering value rather than buying something new.
- Idle games retention. The Psychology of Idle Games (video) (where the author calls it the “endowed value effect”) names it as one of three reasons players don’t quit: the longer you’ve played, the more value you ascribe to your accumulated progress, and the harder it becomes to delete the app — even when you’re no longer enjoying it.
Generalizations
- Free trials — give the user the product first; cancellation feels like a loss.
- In-game cosmetics earned over time — losing access (e.g., expired pass) feels worse than the symmetric “you never had it.”
- Default-included options — anything pre-checked or pre-included is more likely to be kept than the symmetric add-on would be.
- House you’ve lived in for years — the asking price is almost always above the market price.
Related
- Richard Thaler — first named and studied the effect (1980); 2017 Nobel partly for this body of work
- Loss aversion — the underlying valuation asymmetry
- Mental accounting — adjacent; how the brain partitions value
- Idle games — endowment effect as retention mechanism
- Hook, habit, hobby framework — relevant to Habit and Hobby stages where “your collection” emerges
Sources
- Mobile Game Monetization Psychology (video) — piggy bank example
- The Psychology of Idle Games (video) — labeled “endowed value effect”; named as one of three quit-resistance mechanisms