Decision Making
Endowment Effect Task
Also called: WTA-WTP gap task, willingness to accept task, selling and buying price task, mere ownership task
Measure how owning an item raises its value: participants set the least they would sell items they own for and the most they would pay for items they do not, scored as the price gap.
4-6 minUntimed
Free to start: 10 free participants per account, then $0.99 per participant for academic research, or any yearly plan. Try it here first, with no account.
- Papers, 2021 to 2025
- 427
- Evidence grade
- D
- Registered clinical studies
- 0
Sell for at least: 45 points
Pay at most: 20 pointsWhat it measures
Measures the endowment effect: people ask more to give up a thing they own than they would pay for one they do not own. Of 12 pictured everyday items in 6 pairs, one of each pair is the participant's in the task and the other is for sale. Participants set the least they would sell each of their items for and the most they would pay for each item for sale, out of 100 points, against a random offer that makes stating the true value best. The main score is the mean selling price minus the mean buying price.
Constructs
- Endowment effect
- Valuation
- Loss aversion
- Reference dependence
Research uses
- Judgment and decision-making research
- Behavioral economics and consumer research
- Loss aversion and valuation studies
- Within-study group comparison
How the paradigm works
The endowment effect task measures the endowment effect: people ask more to give up a thing they own than they would pay to get the same kind of thing. Kahneman, Knetsch and Thaler (1990) gave coffee mugs to half a class and found the owners' median selling price more than twice the others' median buying price, also with a random price that makes stating the true value best (Becker, DeGroot and Marschak, 1964), while tokens worth a set amount of money showed no gap. Here the comparison is made within each person, as Knutson and colleagues (2008) gave each person some products to sell and others to buy. 12 pictured everyday items form 6 pairs of the same sort: a pen and scissors, a candle and a mirror, sunglasses and a necktie, socks and jeans, a balloon and a soccer ball, a hammer and a broom. The session's seed gives the participant one item of each pair, shown as theirs, and puts the other up for sale, so each item is sold in half the sessions. The participant sets the least they would sell each of their items for and the most they would pay for each item for sale, out of 100 points, on a bar with no starting value. A random offer from 0 to 100 points decides each price's outcome: an item owned is sold at the offer when the offer is not lower than the price, and an item for sale is bought at the offer when it is not higher. Only one price, drawn at the end, is played out, so each price is best set to what the item is worth, which the instructions say plainly.
More about the paradigm
The rule comes first, with a check question on selling and one on buying and feedback, then one practice price in each role played out at once, then the items given and the items for sale side by side, then the selling and the buying prices in two blocks whose order comes from the seed. There is no time limit. The items are pictures and the points are not exchanged for money, which the instructions say.
The main score is the price gap: the mean selling price minus the mean buying price, in points. The two means, their ratio, the medians Kahneman and colleagues reported, the shares of selling prices at 100 and of buying prices at 0, the check answers and price time are also given. The gap depends on how the prices are asked: Plott and Zeiler (2005) found none after extensive training on the procedure, Kahneman and colleagues saw weaker effects in pilot work when the good was not handed over, and Maddux and colleagues (2010) found a smaller effect among East Asian than among Western participants. One person's gap mixes the endowment effect with differences between the items, so compare groups. Scores are research measures and do not diagnose.
Scores
- Price Gappoints
- Mean selling price of the items owned minus mean buying price of the items for sale.
- Positive is the endowment effect; 0 means owning made no difference
- Mean Selling Pricepoints
- Mean of the least prices, 0 to 100, at which the items owned would be sold.
- Informational
- Mean Buying Pricepoints
- Mean of the most, 0 to 100, that would be paid for the items for sale.
- Informational
- Selling to Buying Ratioscore
- Mean selling price over mean buying price; empty when the mean buying price is 0.
- Above 1 is the endowment effect
- Median Selling Pricepoints
- Median of the selling prices.
- Informational
- Median Buying Pricepoints
- Median of the buying prices.
- Informational
- Selling Prices at 100%
- Share of selling prices at 100 points, the top of the bar.
- Quality check: when high, the gap may be understated
- Buying Prices at 0%
- Share of buying prices of 0 points.
- Informational
- Checks Correctcount
- Check questions on the rule answered correctly, out of 2.
- 2 supports interpretation
- Pricescount
- Prices set, out of 12.
- Informational
- Price Timems
- Mean time from an item appearing to its price being confirmed.
- Informational
Use and evidence
427 papers from 2021 to 2025 name this task in their title or abstract, up 21% compared with 2016 to 2020. That ranks it 62 of 495 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 86 |
| 2024 | 85 |
| 2023 | 96 |
| 2022 | 93 |
| 2021 | 67 |
| 2020 | 70 |
| 2019 | 73 |
| 2018 | 73 |
| 2017 | 78 |
| 2016 | 59 |
| 2015 | 68 |
| 2014 | 74 |
| 2013 | 58 |
| 2012 | 60 |
| 2011 | 60 |
| 2010 | 40 |
| 2009 | 44 |
| 2008 | 40 |
| 2007 | 33 |
| 2006 | 25 |
| 2005 | 24 |
| 2004 | 25 |
| 2003 | 21 |
| 2002 | 12 |
| 2001 | 15 |
| 2000 | 16 |
Use grade B
300 to 999 papers from 2021 to 2025.
Evidence grade D
Little published measurement evidence found.
- Papers on test-retest reliability
- 0
- Papers on reliability or validity
- 29
- Registered clinical studies using it as an outcome
- 0
Note on the counts: includes economics papers that run no task.
How the grades work
Use: A is 1,000 or more papers from 2021 to 2025, B 300 to 999, C 100 to 299, D 30 to 99 and E fewer than 30. Evidence: A means at least 25 papers report its test-retest reliability and at least 25 registered clinical studies use it as an outcome; B, at least 8 test-retest papers, and either 5 registered clinical studies or 150 reliability or validity papers; C, at least 2 test-retest papers, 30 reliability or validity papers or 3 registered clinical studies; D, little published measurement evidence found. The counts measure use. They include every paper that names the task in its title or abstract. Grades describe the published research on this task, not ConductCognition's version of it.
Source: ConductCognition test census 0.22.0, counted 3 November 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Items
- 12 everyday things shown as pictures with their names, in 6 pairs of the same sort, a list written for this test.
- Owned
- The session's seed gives the participant one item of each pair and puts the other up for sale, so each item is sold in half the sessions. The items given and the items for sale are shown side by side first.
- Prices
- The least the participant would sell each item owned for, and the most they would pay for each item for sale, 0 to 100 points on a bar with no starting value. Two blocks, selling and buying, in an order from the seed. No time limit.
- Rule
- An offer is drawn from 0 to 100, every whole point equally likely. An item owned is sold at the offer when the offer is not lower than the price; an item for sale is bought at the offer when the offer is not higher.
- Practice
- A check question on selling and one on buying, with feedback, then one practice price in each role played out at once.
- Draw
- One price drawn from the seed is played out at the end and its outcome shown.
- Points
- The items are pictures, nothing is really given, sold or bought, and the points are not exchanged for money.
Kahneman, Knetsch and Thaler (1990) gave real mugs and pens to half of each class and compared owners with others. This test compares the items each person owns with the items they do not, as Knutson and colleagues (2008) did, using pictures and points. The gap depends on the procedure (Plott and Zeiler, 2005, found none after extensive training on it), and one person's gap mixes the effect with differences between the items, so compare groups. The scores support research and do not diagnose.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: endowment_effect_price from the scored run, one per price. A price has no correct answer, so accuracy is not judged against chance. Prices confirmed under 200 ms on at least half the items invalidate. Fewer than half the planned prices invalidate, and any missing price is flagged. The same price on every item, selling prices at 100 points on 50% or more of the items owned, and a wrong answer to a check question on the rule are flagged.
Why these rules
There is no correct option to compare with chance, so accuracy is not judged against chance. An answer under 200 ms is faster than a simple visual reaction, so it cannot reflect the item. Following response-time effort screening for untimed tests (Wise and Kong 2005), the session is invalid only when at least half the answers are that fast. The gap compares the items sold with the items bought, so a run that stopped early is not comparable. The procedure works only when its rule is understood (Plott and Zeiler, 2005, found no gap after extensive training on it), and the bar stops at 100 points, so a wrong check answer, prices that do not separate the items and selling prices held at the top are flagged and never exclude.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
This test runs with fixed settings.
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Devices and languages
- Untimed test: runs on desktops, laptops, tablets and phones. Participant devices
- Languages: English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese.
- Available on: Every plan, including the free plan.
- No percentile. Scores and quality flags only. How norms work
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Cite and describe
Participants completed the Endowment Effect Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Kahneman, Knetsch & Thaler, 1990). The main score was price gap (mean selling price of the items owned minus mean buying price of the items for sale).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- 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
- Becker, G. M., DeGroot, M. H., & Marschak, J. (1964). Measuring utility by a single-response sequential method. Behavioral Science, 9(3), 226-232. https://doi.org/10.1002/bs.3830090304The random offer that makes stating the true value best.
- Knutson, B., Wimmer, G. E., Rick, S., Hollon, N. G., Prelec, D., & Loewenstein, G. (2008). Neural antecedents of the endowment effect. Neuron, 58(5), 814-822. https://doi.org/10.1016/j.neuron.2008.05.018Selling and buying within the same people, with the products in each role counterbalanced.
- 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/10.1257/0002828054201387Why the rule is explained, checked and practised.
- Maddux, W. W., Yang, H., Falk, C., Adam, H., Adair, W., Endo, Y., Carmon, Z., & Heine, S. J. (2010). For whom is parting with possessions more painful? Cultural differences in the endowment effect. Psychological Science, 21(12), 1910-1917. https://doi.org/10.1177/0956797610388818A smaller effect among East Asian participants.
Source papers
- Kahneman, Knetsch and Thaler (1990): median selling prices more than twice median buying prices for mugs and pens, and no gap for tokens of set value. Knutson and colleagues (2008): selling at 65% and buying at 32% of the retail price within the same 24 people.Paradigm source, Adults
Questions
How long does the Endowment Effect Task take?
About 4 to 6 minutes, as listed in the test library.
What device does a participant need?
Untimed test: runs on desktops, laptops, tablets and phones. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Price Gap, Mean Selling Price, Mean Buying Price, Selling to Buying Ratio, Median Selling Price, Median Buying Price, Selling Prices at 100, Buying Prices at 0, Checks Correct, Prices and Price Time. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Endowment Effect Task used in research?
427 papers from 2021 to 2025 name it in their title or abstract, up 21% compared with 2016 to 2020. That ranks it 62 of 495 test families in the ConductCognition test census (use grade B). Source: ConductCognition test census 0.22.0, counted 3 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Endowment Effect Task have?
In the published research, 0 papers report its test-retest reliability and 0 registered clinical studies use it as an outcome (evidence grade D in the ConductCognition test census).
Does it report a percentile?
No. Scores and quality flags only.
Which languages can participants use?
Participants can take this test in English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese. English is on every plan, and the other languages come with yearly plans. Have a native speaker read the machine-translated text before launch.
Is this a clinical test?
No. ConductCognition is for research use only. It runs, scores and exports the test; clinical interpretation is outside the platform.
Every test: the full test list.
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