Decision Making
Willingness to Pay Task
Also called: BDM auction, Becker-DeGroot-Marschak task, WTP task, bidding task, valuation task
Measure how much people value everyday foods and objects with bids against a random price, where bidding the true value pays best, scored as the mean bid.
4-6 minUntimed
Free to start: 10 free participants per account, then $0.99 per participant for academic research, or any yearly plan. Preview any test free after you sign up.
- Papers, 2021 to 2025
- 129
- Evidence grade
- C
- Registered clinical studies
- 9
Your bid: 35 pointsWhat it measures
Measures how much people value everyday things. For each of 15 pictured foods and objects, participants bid up to 100 points; a random price then decides whether the item is bought, at the price, so the best bid is what the item is worth. The main score is the mean bid.
Constructs
- Valuation
- Willingness to pay
- Economic preferences
- Value-based decision-making
Research uses
- Food choice and eating behavior research
- Consumer and economic decision research
- Reward valuation in clinical and health studies
- Within-study group comparison
How the paradigm works
The willingness to pay task measures how much people value everyday things, with the bidding procedure of Becker, DeGroot and Marschak (1964) as Plassmann, O'Doherty and Rangel (2007) used it for snack foods. For each of 15 pictured items, 5 foods and 10 small objects shown with their names, the participant has 100 points and bids the most they would pay, on a bar with no starting value. A price is then drawn at random from 0 to 100 points. If the price is not above the bid, the item is bought at the price, not the bid; otherwise nothing is bought and the points are kept. Only one bid, drawn at the end, is played out, so the best bid is exactly what the item is worth to the participant. The instructions say so plainly, because many people misread this procedure (Cason and Plott, 2014). The list of items is this test's own, drawn as Noto Emoji pictures.
More about the paradigm
Two check questions on the rule, one with the price under the bid and one over it, come first with feedback, then one practice bid that is played out at once. The items then run in two rounds as standard (one as a setting), each round in its own order from the session's seed, with no time limit. The bid that counts and its price also come from the seed. No item is given and the points are not exchanged for money unless the study carries out the bid drawn, which the payment line says.
The main score is the mean bid. The median, the spread of the items' mean bids, the mean bids for foods and for objects, the agreement between the two rounds' bids on the same items and the mean change between them, the shares of bids at 0 and at 100, bid time and the check answers are also given. Bids show what things are worth to the participant in points, not prices in money, so compare people within a study and on the same settings. Scores support research and do not diagnose.
Scores
- Mean Bidpoints
- Mean of all bids, 0 to 100 points, both rounds.
- Higher means the items are worth more points to the participant
- Median Bidpoints
- Median of all bids.
- Higher means the items are worth more points to the participant
- Bid Spreadpoints
- Standard deviation of the items' mean bids.
- Higher means the bids separate the items more
- Food Bidpoints
- Mean bid on the 5 foods.
- Informational
- Object Bidpoints
- Mean bid on the 10 objects.
- Informational
- Bid Consistencyscore
- Correlation between the two rounds' bids on the same items; empty with one round.
- Higher means more consistent bids
- Bid Changepoints
- Mean change in an item's bid from the first round to the second, either way.
- Lower means more consistent bids
- Zero Bids%
- Share of bids of 0 points.
- Informational
- Full Bids%
- Share of bids of all 100 points.
- Informational
- Bid Timems
- Mean time from an item appearing to its bid being confirmed.
- Informational
- Checks Correctcount
- Check questions on the rule answered correctly, out of 2.
- 2 supports interpretation
- Bidscount
- Bids made, out of 15 per round.
- Informational
- Drawn Bid Bought0/1
- 1 when the price drawn for the bid that counts was not above the bid.
- Informational
- Points Keptpoints
- Points kept after the bid that counts was played out.
- Informational
Use and evidence
129 papers from 2021 to 2025 name this task in their title or abstract, up 21% compared with 2016 to 2020. That ranks it 162 of 395 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 35 |
| 2024 | 29 |
| 2023 | 23 |
| 2022 | 24 |
| 2021 | 18 |
| 2020 | 28 |
| 2019 | 21 |
| 2018 | 18 |
| 2017 | 16 |
| 2016 | 24 |
| 2015 | 22 |
| 2014 | 16 |
| 2013 | 9 |
| 2012 | 10 |
| 2011 | 6 |
| 2010 | 9 |
| 2009 | 8 |
| 2008 | 11 |
| 2007 | 5 |
| 2006 | 3 |
| 2005 | 1 |
| 2004 | 4 |
| 2003 | 1 |
| 2002 | 0 |
| 2001 | 1 |
| 2000 | 1 |
Use grade C
100 to 299 papers from 2021 to 2025.
Evidence grade C
At least 2 test-retest papers, 30 reliability or validity papers or 3 registered clinical studies.
- Papers on test-retest reliability
- 1
- Papers on reliability or validity
- 24
- Registered clinical studies using it as an outcome
- 9
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 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Items
- 15 everyday things shown as pictures with their names: 5 foods and 10 small objects, a list written for this test.
- Bid
- 100 points for each item; bid 0 to 100 on a bar with no starting value, by drag, tap, keys or 1-point buttons. No time limit.
- Rule
- A price is drawn from 0 to 100, every whole point equally likely. At or under the bid, the item is bought at the price, not the bid; over it, nothing is bought.
- Practice
- Two check questions on the rule, a price under the bid and one over it, with feedback, then one practice bid played out at once.
- Rounds
- 2 (standard, 1 to 2), each in its own order from the session's seed, so each item gets two bids.
- Draw
- One bid drawn from the seed is played out at the end and its outcome shown.
- Points
- No item is given and points are not exchanged for money unless the study carries out the bid drawn, which the payment line says.
Plassmann and colleagues (2007) had participants bid real dollars for snack foods they could eat after the session. This test uses points and pictures of 15 items of its own, so bids show what things are worth within a study, not prices in money. Many people misread the procedure (Cason and Plott, 2014), so the instructions say plainly that the best bid is the item's worth, and two check questions test the rule. 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: willingness_to_pay_bid from the scored run, one per bid. A bid has no correct answer, so accuracy is not judged against chance. Bids confirmed under 200 ms on at least half the items invalidate. Fewer than half the planned bids invalidate, and any missing bid is flagged. The same bid on every item, two rounds whose bids on the same items correlate below 0.3, 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 mean bid is read over all the items, so a run that stopped early is not comparable. A bid of what an item is worth should be much the same the second time, and the procedure works only when its rule is understood (Cason and Plott, 2014, found many people misread it), so bids that do not separate the items, rounds that disagree and a wrong check answer are flagged and never exclude.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Rounds | 2 | 1 to 2 |
| Payment line | Hypothetical (standard) | Hypothetical (standard), The study carries out the bid drawn |
Yearly plans can change settings within these limits. Free and pay-as-you-go studies use the standard settings.
Need a setting this test does not have?
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 Willingness to Pay Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Becker, DeGroot & Marschak, 1964), with the standard settings (rounds: 2; payment line: Hypothetical). The main score was mean bid (mean of all bids, 0 to 100 points, both rounds).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- 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.3830090304
- Plassmann, H., O'Doherty, J., & Rangel, A. (2007). Orbitofrontal cortex encodes willingness to pay in everyday economic transactions. Journal of Neuroscience, 27(37), 9984-9988. https://doi.org/10.1523/JNEUROSCI.2131-07.2007Bids for everyday foods, with one bid played out at random.
- Cason, T. N., & Plott, C. R. (2014). Misconceptions and game form recognition: Challenges to theories of revealed preference and framing. Journal of Political Economy, 122(6), 1235-1270. https://doi.org/10.1086/677254Why the rule is explained plainly and checked.
Source papers
- Becker, DeGroot and Marschak (1964): the bidding procedure. Plassmann, O'Doherty and Rangel (2007): bids for everyday foods. Cason and Plott (2014): how often the procedure is misread.Paradigm source, Adults
Questions
How long does the Willingness to Pay 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?
Mean Bid, Median Bid, Bid Spread, Food Bid, Object Bid, Bid Consistency, Bid Change, Zero Bids, Full Bids, Bid Time, Checks Correct, Bids, Drawn Bid Bought and Points Kept. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Willingness to Pay Task used in research?
129 papers from 2021 to 2025 name it in their title or abstract, up 21% compared with 2016 to 2020. That ranks it 162 of 395 test families in the ConductCognition test census (use grade C). Source: ConductCognition test census 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Willingness to Pay Task have?
In the published research, 1 paper reports its test-retest reliability and 9 registered clinical studies use it as an outcome (evidence grade C in the ConductCognition test census).
Does it report a percentile?
No. Scores and quality flags only.
Which settings can a researcher change?
Rounds (1 to 2) and payment line (Hypothetical (standard), The study carries out the bid drawn). Settings can be changed on yearly plans; free and pay-as-you-go studies use the standard settings.
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.
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