Owning something makes people value it more, and the gap is large enough to matter in pricing, negotiation and retention. The original evidence for that claim is real. The size of the gap is the part that has not survived intact.
What the endowment effect is
The endowment effect is the tendency to ask more for an object you own than you would pay to acquire it. Richard Thaler named the pattern in the early 1980s. Owners set a selling price above what non-owners will pay for the same thing, even when the only thing that changed hands is the possession itself.
It belongs to a wider family of reference-dependent effects. Kahneman and Tversky’s prospect theory (1979) explains the general shape: losses weigh more than equal gains. The endowment effect is the ownership-specific version. The current state becomes the reference point, and giving it up registers as a loss.
The original evidence: mugs, tokens and a Coase test
The canonical study is Kahneman, Knetsch and Thaler (1990, Journal of Political Economy). Participants received a coffee mug at random or received nothing. Those who held a mug stated the minimum price at which they would sell it. Those without a mug stated the maximum they would pay to buy one. The median selling price was $7.12 and the median buying price was $2.87, a ratio of roughly 2.5 to 1.
Random assignment carries the inference. The two groups differ only in who received the mug, so the gap cannot come from different tastes for mugs. The same paper also ran a market with repeated trading. Trading volume came in well below what the Coase theorem predicts for a market with no transaction costs. The authors read that shortfall as evidence that ownership changes valuation, not only the trading process.
Two caveats belong next to that number. The mug sample was small, and the $7.12 and $2.87 figures are medians from one study with one good. Treat the ratio as one estimate from one design, not a constant of human psychology.
Replication and boundary conditions
The biggest challenge came from Plott and Zeiler (2005, American Economic Review). They reran mug-style elicitations with procedural changes. Subjects received training and practice trials, and the authors tested whether participants understood that stating their true value was the best strategy. Under those conditions the willingness-to-pay to willingness-to-accept gap shrank or disappeared.
Plott and Zeiler argue that much of the earlier gap came from subject misconceptions about the price-elicitation method, not from a stable preference. Defenders of the original result reply that the gap survives under some well-designed procedures and that the critique does not rule out a real ownership effect. The dispute is partly about method and partly about what the effect is supposed to explain. The practical lesson holds either way: a design that never checks whether subjects understand the incentives can produce a gap that is really confusion.
Three boundary conditions come out of this debate and a broader review literature:
- Good type. Horowitz and McConnell (2002) reviewed many WTA/WTP studies and found that the gap is generally larger for goods without a market price than for goods traded routinely. Their sample mixes lab experiments with survey valuations, so the review is weaker evidence for any single ratio.
- Experience. Gaps tend to shrink when people trade the same kind of good repeatedly. Dealers who buy to resell show little or none of the gap that consumers do.
- Mechanism. Morewedge and Giblin (2015) review competing explanations, including loss aversion, attention to what is owned, and expectations about future use. They treat the endowment effect as a family of mechanisms, not one switch.
The practical reading is narrower than the textbook version. Ownership raises valuations in many settings, but the magnitude depends on procedure, good and experience.
| Source | Design | Key result | Caveat |
|---|---|---|---|
| Kahneman, Knetsch and Thaler (1990) | Random assignment of mugs; sellers vs buyers | Median selling $7.12, median buying $2.87 | Small sample, one good |
| Plott and Zeiler (2005) | Same elicitation with training and incentive checks | Gap shrank or disappeared | Authors read it as misconception; disputed |
| Horowitz and McConnell (2002) | Review of WTA/WTP studies | Gap larger for non-market goods | Mixed designs, survey valuations included |
| Morewedge and Giblin (2015) | Integrative review | Several mechanisms, loss aversion among them | Review, no new experiment |
Everyday and business examples
These are illustrations of the mechanism, not measured effects in those settings.
- Selling a home. The owner anchors on the price they paid or hoped for, and offers below that feel like a loss. The buyer sees a normal price. Both can be rational and still fail to close.
- Free trials. A user who has spent two weeks configuring a tool now has a workspace to lose. The cancellation decision becomes a loss decision, not a purchase decision.
- Vendor and salary negotiations. The party holding the status quo asks for more to give it up. Whoever can name a neutral reference, such as a comparable deal, usually moves the number.
- Removing a perk. Taking away an existing benefit draws louder pushback than offering a new one of equal value. Staff compare against what they have, not against what they would have chosen from scratch.
- Retail stock rooms. Display stock and demo units are priced above what a buyer would pay for the same item new in the box, because the store treats them as its own.
How to reduce it
There is no proven switch. These steps have the logic behind them, and the evidence is mostly from lab and field studies that aim at the same mechanism.
- Reset the reference point. Ask what you would pay for the item if you did not already own it. If the answer is far below your asking price, the gap is ownership, not value.
- Run the offer test. Imagine you are offered the item today at the market price. Would you take it? A yes means you keep it for a reason; a no means you are holding it out of attachment.
- Agree on a neutral valuation first. In negotiations, settle on a reference such as a comparable transaction before anyone names a number. Sellers and buyers anchor on different things otherwise.
- Describe the choice as keeping, not losing. For cancellations and retention, show what the user keeps, such as data, configuration or access, in terms that do not frame the decision as surrender.
- Trade or test repeatedly. Gaps shrink with experience in the same kind of exchange. Practice with clear procedures does what Plott and Zeiler’s changes did in the lab.
Frequently asked questions
Is the endowment effect real?
Yes, in some settings, and the lab evidence is broad enough that it is not a single lucky study. The strength varies with the good, the procedure and the experience of the people involved. The Plott and Zeiler critique removed the claim that every gap is real. It did not remove the phenomenon.
How large is the effect?
The mug study reports a ratio of about 2.5 to 1 in medians. That is one small study and one good. Across the wider review literature, ratios differ widely by good type. Quote the range, not the single headline number.
How is it different from loss aversion?
Loss aversion is the general asymmetry between losses and gains. The endowment effect is a specific case where ownership creates the reference point. Some researchers treat it as one of loss aversion’s expressions. Others, including Morewedge and Giblin (2015), argue that other mechanisms contribute, so the two are related but not identical.
References
- Horowitz, J. K., & McConnell, K. E. (2002). A review of WTA/WTP studies. Journal of Environmental Economics and Management. https://doi.org/10.1006/jeem.2001.1215
- Kahneman, D., Knetsch, J. L., & Thaler, R. H. (1990). Experimental tests of the endowment effect and the Coase theorem. Journal of Political Economy, 98(6), 1325-1348. https://doi.org/10.1086/261737
- Kahneman, D., & Tversky, A. (1979). Prospect theory: An analysis of decision under risk. Econometrica, 47(2), 263-291. https://doi.org/10.2307/1914185
- Morewedge, C. K., & Giblin, C. E. (2015). Explanations of the endowment effect: An integrative review. Trends in Cognitive Sciences, 19(6), 339-348. https://doi.org/10.1016/j.tics.2015.04.004
- Plott, C. R., & Zeiler, K. (2005). The willingness to pay-willingness to accept gap, the “endowment effect,” subject misconceptions, and experimental procedures for eliciting valuations. American Economic Review, 95(3), 530-545. https://doi.org/10.1257/0002828054201387
In my view the endowment effect deserves a place in pricing and retention work, but not as a fixed 2 to 1 multiplier. The ownership pattern is robust enough to design around, while the size of the gap depends on the good, the procedure and how often people trade it. Research still has to pin down the boundary conditions with preregistered field trials that measure real transactions, not only stated prices.
If you are deciding where this bias costs your business money, applied behavioural science for business is the place we start.