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Description

A coffee mug

Source

Janko Ferlic · original page

Licence

CC0 Public domain

Original photo, unretouched. The background is a version of it stylised by the site.

The endowment effect

As soon as something is ours, it is worth more in our eyes, and we ask much more to give it up than we would have paid to get it.

In brief

• What: the same thing is valued higher by the person who owns it than by the person who does not.
• Why: giving it up is experienced as a loss, and a loss weighs more than an equivalent gain; ownership also creates attachment.
• Detect: “we can't remove that,” scope that only grows, an existing solution defended by those who built or obtained it.
• Avoid: ask “would I buy it today, at this price?”, make trade-offs from zero, have it assessed by someone who is not the owner.

On this page

1. Definition
2. The mechanism
3. Where you encounter it
   1. In project management
   2. In management
4. Famous cases
   1. The Cornell and Simon Fraser mug experiments 1990
   2. Does market experience erase the effect? 2003
5. Detection signals
6. Avoidance reflexes
7. With AI: detect, fix, mitigate
   1. Detect
   2. Fix
   3. Mitigate
   4. Prompts to integrate into your practices
   5. How to integrate them
   6. Precautions
8. Limitations
9. Sources and verification
10. See also
    1. Combines with, or reinforces
    2. Related biases
    3. Counterweights and related reflexes

Definition#

Fictitious illustration

Illustration inspired by the person

The endowment effect (endowment effect) is the tendency to assign more value to an item because we own it. The gap is easy to measure: the minimum price one accepts to sell (willingness to accept) is clearly higher than the maximum price one would have agreed to pay for the same object (willingness to pay).

The term was introduced by economist Richard Thaler in 1980. It was tested in the lab by Kahneman, Knetsch, and Thaler in 1990, using coffee mugs. In organizations, “ownership” is broader: a feature we requested, a module we wrote, a position, a budget, a team, a tool whose purchase we secured.

The mechanism#

• Giving up = losing. For the owner, selling is a loss, while for the buyer, buying is a gain. But a loss weighs more than an equivalent gain (see Loss aversion).
• The reference point shifts. Once acquired, the thing becomes part of the starting situation: giving it up is a negative deviation, not a return to normal.
• Attachment. The more time, money, or identity we have invested, the more we value the thing (see The IKEA effect and Sunk costs).

Where you encounter it#

In project management#

• Scope: once a feature is written into the specifications, removing it is experienced as a loss by the client, even when its usefulness has become questionable. Hence scope that only grows.
• Content negotiation: each party overvalues what it “obtained” or “conceded.” Trades (“I give up A if you give up B”) fail because each side claims what it gives up is worth more than what it receives.
• Replacing an existing solution: the current tool or component is valued more highly by its users than by people discovering it. Migrations run into “what we had before did that really well.”
• Code and design: the team that wrote a module defends it in review or rewrite more than its usefulness justifies.

In management#

• Budgets and resources: a budget line, a position, or staffing level is defended because we have it, not because need is demonstrated. Every year, a “rolled-over” budget is easier to defend than a new budget to create.
• Teams and responsibilities: a manager who must give a team member or topic to another department asks more in return than they would have paid to get it.
• Titles, scope, habits: a reorganization is seen as a loss by those who own a role or territory, even if it is neutral for them.

Famous cases#

Detection signals#

• “We can't remove that, it's in the contract”: removal is treated as a loss, whatever the usefulness.
• Scope grows and never shrinks: trade-offs add, and almost never remove.
• An existing solution is defended by those who obtained or built it and judged poor by newcomers.
• In a negotiation, each side values what it gives up far more than what it receives: no trade is ever balanced.
• The rolled-over budget passes without question; the new budget demands heavy justification.

Avoidance reflexes#

1. The reverse test. “If we were starting from zero, would we buy this today, at this price, with this maintenance cost?” If the answer is no, ownership is the only reason to keep it.
2. Start again from zero. For budgets and scope, periodically build a zero-based version: each line must be justified as if it were new.
3. Have a non-owner evaluate it. A code or architecture review by someone who did not write the module; a scope trade-off by someone who did not request the feature.
4. Talk in opportunity costs. “Keeping this module means giving up these two others”: this makes visible the loss of not giving it up.
5. Remove by default, keep with evidence. A feature with no measured usage over a given period is removed; bringing it back must be justified.
6. Plan the exit before the entry. When adding, write down under what condition it will be removed: the removal decision is easier before ownership.
7. Trade packages, not objects. In negotiation, present several concessions simultaneously rather than one-for-one trading, so the loss is offset by a visible gain.

With AI: detect, fix, mitigate#

Prompts to integrate into your practices#

1. Zero-based evaluation. Use with a list of features, budget lines, or existing modules.

Here is a list of existing items: [list, with known usage, maintenance cost, and age for each].
You are an evaluator with no connection to them. For each item, answer: “if we were starting from scratch, would we add it today?” with yes, no, or maybe, and the reason in one sentence.
Do not assume any value for what already exists. End with the three items for which the only reason to keep them seems to be that we own them.

2. Scope negotiation without ownership. When two parties each say they are giving up more than they receive.

Two parties are negotiating scope. Here is what each says they are giving up: [list A] and [list B].
Describe the situation from the perspective of a third party that owns nothing. Propose a <em>bundled</em> trade-off (several simultaneous concessions on each side) and, for each concession, indicate what it really costs the side making it, without repeating the emotional value assigned to it.
Flag items whose value clearly depends on attachment.

How to integrate them#

• Scope review: run prompt 1 before the committee meeting, and discuss its “no” items first.
• Negotiation: prompt 2 prepares the session; it does not replace it.
• Annual budget review: apply prompt 1 to any line renewed for more than three years.

Precautions#

• AI does not know what you had to pay to obtain an item (negotiation, contract): verify before removing.
• If you present an item as “our best module,” the response will reflect that. Describe it neutrally.
• Do not submit named budgets or contractual information to an unauthorized tool.

Limitations#

• The effect is debated: some studies (for example Plott and Zeiler, 2005) find a much smaller gap once protocol ambiguities are removed, and others attribute it to loss aversion rather than ownership itself.
• It depends on the type of good: it appears for a use object, much less for a good intended for exchange (tokens, money), as the 1990 authors noted.
• Valuing what you have is not always a bias: a reliable existing asset has real value (change cost, migration risk). The bias starts when you can no longer quantify that value.

Sources and verification#

• Kahneman, Knetsch & Thaler (1990), “Experimental Tests of the Endowment Effect and the Coase Theorem”, Journal of Political Economy, 98(6) — the mugs; the median prices of $7.12, $3.12, and $2.87 are from experiment 6 (Simon Fraser University).
• Thaler (1980), “Toward a positive theory of consumer choice”, Journal of Economic Behavior & Organization, 1(1) — origin of the term.
• Kahneman, Knetsch & Thaler (1991), “Anomalies: The Endowment Effect, Loss Aversion, and Status Quo Bias”, Journal of Economic Perspectives, 5(1) — synthesis.
• List (2003), “Does Market Experience Eliminate Market Anomalies?”, Quarterly Journal of Economics, 118(1)
• Plott & Zeiler (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) — the methodological critique.

See also#