Decision Making
Two Jars Game
Also called: delay of gratification game for children, children's delay discounting game
Measure how children aged 5 to 12 choose between 1 star now and more stars after a real wait: two jars, a bar that shows the wait, and a shelf for the stars collected.
3-7 minUntimed
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- Papers, 2021 to 2025
- 2,088
- Evidence grade
- A
- Registered clinical studies
- 257
Figures for the Delay Discounting test, the published test this game is compared with.
How these are countedWhat it measures
Measures how children aged 5 to 12 choose between 1 star now and more stars after a real wait, with an adult reading the screens aloud to children under 8.
Constructs
- Delay discounting
- Choice between a small reward now and a larger reward later
- Executive function
Research uses
- Research on choosing between a small reward now and a larger one later in school-age children
How the paradigm works
The Two Jars Game measures how children aged 5 to 12 choose between a small reward now and a larger one after a wait. It is a game in the family of delay discounting tasks, in which a person picks between an immediate reward of lower value and a delayed reward of higher value. Two jars of the same drawing stand side by side. One gives 1 star now. The other gives 2 or 4 stars after a real wait of 5, 15 or 30 seconds, which a bar of 5-second segments under it shows. The child touches a jar, or presses Enter or Space on a focused jar. After a choice for the star now, the star drops into the jar. After a choice for the wait, the bar empties one segment for every 5 seconds the screen is visible, and then the stars drop. The wait stops while the tab is hidden. The paper counts and grades on this page are those of the Delay Discounting test, the published test the game is compared with, not the game's own.
More about the paradigm
Every star collected stays in view on a shelf above the jars, as small star pictures with no number, no best and no timer, and the stars buy nothing. There are 12 choices in a fixed order, so choosing the later jar makes the session longer: every pair of wait and amount comes twice, once with the later jar on each side, and the two forms swap the sides. Two demonstrations come first, each with one jar that works. The main score is the share of choices for the later jar. No screen says that either jar is right or wrong.
The validation plan also compares the game with the Experiential Discounting and Food Delay Discounting tests, and with a reaction time check that should come out lower. Young children choosing between an immediate reward of lower value and a delayed reward of higher value is the paradigm of Prencipe and Zelazo (2005). Repeated choices between a small reward now and a larger one after a real delay, under a fixed number of trials so that waiting lengthens the session, follow Sonuga-Barke and colleagues (1992). The numbers of stars, waits and choices, the shelf, the bar and the forms are ours.
Scores
- Share of Later Choices%
- The share of the scored choices made for the jar that gives more stars after a wait, from 0 to 1. Empty when fewer than 10 of the 12 choices are scored.
- Higher means more choices for the later jar; compared within a study
- Share of Later Choices, Wait of 5 Seconds%
- The share of the scored choices with a wait of 5 seconds that were made for the later jar.
- Informational
- Share of Later Choices, Wait of 15 Seconds%
- The share of the scored choices with a wait of 15 seconds that were made for the later jar.
- Informational
- Share of Later Choices, Wait of 30 Seconds%
- The share of the scored choices with a wait of 30 seconds that were made for the later jar.
- Informational
- Wait Sensitivity%
- The share of later choices at a wait of 5 seconds minus the share at a wait of 30 seconds. Positive when the longer wait lowered the share.
- Informational; a longer wait is expected to lower the share
- Share of Later Choices, 4 Stars%
- The share of the scored choices where the later jar held 4 stars that were made for the later jar.
- Informational
- Share of Later Choices, 2 Stars%
- The share of the scored choices where the later jar held 2 stars that were made for the later jar.
- Informational
- Median Choice Timems
- The median time from the jars appearing to the choice, in the scored choices.
- Informational
- Usable Choicescount
- Choices counted in the scores. Left out: a choice during which the tab was hidden, the window changed size, or a second finger or a palm touched the screen, and a later choice whose measured wait was more than 250 ms off its wait.
- Quality check
- Share of Key Choices%
- The share of the scored choices made with a key (Enter or Space on a focused jar) and not a tap or a click.
- Informational; the comparison of touch and keys reads this share within each look
- Share of Touch Choices%
- The share of the scored choices made by touch.
- Informational; the comparison of touch and keys reads this share within each look
Use and evidence
2,088 papers from 2021 to 2025 name this task in their title or abstract, down 4% compared with 2016 to 2020. That ranks it 12 of 632 test families in our census. These counts belong to the Delay Discounting test, the published test this game is compared with. This game is a new measure, so its own reliability and norms come from use. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 491 |
| 2024 | 418 |
| 2023 | 360 |
| 2022 | 384 |
| 2021 | 435 |
| 2020 | 397 |
| 2019 | 425 |
| 2018 | 465 |
| 2017 | 441 |
| 2016 | 437 |
| 2015 | 414 |
| 2014 | 369 |
| 2013 | 309 |
| 2012 | 302 |
| 2011 | 274 |
| 2010 | 219 |
| 2009 | 185 |
| 2008 | 140 |
| 2007 | 125 |
| 2006 | 95 |
| 2005 | 67 |
| 2004 | 50 |
| 2003 | 44 |
| 2002 | 38 |
| 2001 | 17 |
| 2000 | 18 |
Use grade A
1,000 or more papers from 2021 to 2025.
Evidence grade A
At least 25 papers report its test-retest reliability and at least 25 registered clinical studies use it as an outcome.
- Papers on test-retest reliability
- 48
- Papers on reliability or validity
- 396
- Registered clinical studies using it as an outcome
- 257
Measured on ConductCognition
Pooled across the studies that feed our platform norms, by device group. A figure needs 50 or more people.
No pooled figure yet.
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 the Delay Discounting test, the published test this game is compared with, not the game's own.
Source: ConductCognition test census 0.44.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Jars
- Two jars of the same drawing stand side by side, each at least 120 px wide. Only the stars above the lid and the bar under the jar differ between them. One jar gives 1 star now. The other gives 2 or 4 stars after a wait of 5, 15 or 30 seconds, which a bar of 5-second segments shows (1, 3 or 6 segments). Everything is drawn in code, with no picture file.
- Choices
- 12 choices in a fixed order. Every pair of wait and amount comes twice, once with the later jar on each side, so 6 on each side. Each half holds each wait twice and each amount 3 times, and no wait comes three times in a row.
- Forms
- 2 forms: form 2 is form 1 with the later jar on the other side in every choice. Each person gets the forms in an order drawn once for them, and each session takes the next form.
- Waits
- Every wait is real. After a choice for the later jar the bar empties one segment for every 5 seconds the screen is visible, and then the stars drop. The wait stops while the tab is hidden, and the export says for how long. A later choice whose measured wait is more than 250 ms off its wait is left out of the scores.
- Stars
- The stars buy nothing. After a choice the star or stars drop into the jar for 1,500 ms and the screen rests for 1,000 ms. Every star collected stays in view on a shelf above the jars, as small star pictures with no number, no best and no timer, and the end screen shows the shelf.
- Demonstrations
- Two demonstrations come first, each with one jar that works: one for the star now, then one for 2 stars after 5 seconds. They are never scored.
- Taps
- The first tap on a jar chooses, and a second tap on it within 300 ms changes nothing and is counted. Enter or Space on a focused jar chooses too, unless the key was held down from before the turn opened. A choice is left out of the scores when the tab was hidden or the window changed size during it, or a second finger or a palm touched the screen.
- Looks
- The game look adds a window scene at the edges of the screen, and the plain look draws the same jars, stars, bars and shelf on white. Colors, shapes, sizes and places are the same in both. The researcher chooses the look for a study; the default is the game look.
- Age and reader
- For children aged 5 to 12. An adult sits beside a child under 8, reads each screen aloud and does not suggest a jar, and no screen or picture says that either jar is right or wrong.
- Schedule
- Use a tablet or a computer for a child under 7, and keep each child on one device class at every visit. For a retest, run a second visit of the same study 7 to 28 days later. The game may take up to about 7 minutes when the child waits.
- Scores
- The share of choices for the later jar (the main score), the same share at each wait and for each amount, how much a wait of 30 seconds lowers the share against 5 seconds, the median choice time and the number of usable choices. The share of choices made with a key and by touch is also kept, so the two can be compared. No percentile is computed.
The design follows the choice between a smaller reward now and a larger one after a wait of Prencipe and Zelazo (2005), with the real waits and the fixed number of choices of Sonuga-Barke and colleagues (1992); the jars, stars, bars, shelf, waits, forms and looks are our own. This game is a new measure for children aged 5 to 12: its reliability and norms come from use, the figures published in those studies are not its own, and it computes no percentiles.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: two_jars_game test choices, one jar for each of the 12 turns (the jar that gives its star now or the one that gives more stars after a wait), leaving out a choice made with the tab hidden, the window resized, or a second finger or a palm on the screen, and a later choice whose measured wait was more than 250 ms off its wait. Fewer than 10 scored choices invalidates the session; the same side on every scored choice, or 4 or more choices faster than 200 ms, flags it for review.
Why these rules
What the game measures is whether a child takes the star now or waits for more, so a child who always takes the star now, or always waits, shows a real preference and is not flagged (a ConductScience choice, as for the delay discounting test). Choosing by side alone means the stars and the bars were not read, so it is flagged for review. An answer under 200 ms is faster than a simple visual reaction (the platform's untimed-choice rule). The share of later choices rests on 12 choices, so a session with fewer than 10 scored is too thin to give it (ours). A run that holds two forms cannot be read against one table and is not scored.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Look | Game | Game, Plain |
Every plan can change the look, which never changes how a result is scored.
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 Two Jars Game in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Prencipe & Zelazo, 2005), with the standard settings (look: Game). The main score was share of later choices (the share of the scored choices made for the jar that gives more stars after a wait, from 0 to 1).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Prencipe, A., & Zelazo, P. D. (2005). Development of affective decision making for self and other: Evidence for the integration of first- and third-person perspectives. Psychological Science, 16(7), 501-505. https://doi.org/10.1111/j.0956-7976.2005.01564.xThe choice this game adapts: young children chose between an immediate reward of lower value and a delayed reward of higher value (abstract read).
- Sonuga-Barke, E. J. S., Taylor, E., Sembi, S., & Smith, J. (1992). Hyperactivity and delay aversion: I. The effect of delay on choice. Journal of Child Psychology and Psychiatry, 33(2), 387-398. https://doi.org/10.1111/j.1469-7610.1992.tb00874.xRepeated choices between a small reward now and a larger one after a real delay, under a fixed number of trials, so that waiting makes the session longer (abstract read).
Source papers
Questions
How long does the Two Jars Game take?
About 3 to 7 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?
Share of Later Choices, Share of Later Choices, Wait of 5 Seconds, Share of Later Choices, Wait of 15 Seconds, Share of Later Choices, Wait of 30 Seconds, Wait Sensitivity, Share of Later Choices, 4 Stars, Share of Later Choices, 2 Stars, Median Choice Time, Usable Choices, Share of Key Choices and Share of Touch Choices. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Delay Discounting test used in research?
These counts belong to the Delay Discounting test, the published test this game is compared with. This game is a new measure, so its own reliability and norms come from use. 2,088 papers from 2021 to 2025 name the task in their title or abstract, down 4% compared with 2016 to 2020. That ranks it 12 of 632 test families in the ConductCognition test census (use grade A). Source: ConductCognition test census 0.44.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Delay Discounting test have?
These counts belong to the Delay Discounting test, the published test this game is compared with. This game is a new measure, so its own reliability and norms come from use. In the published research, 48 papers report the task's test-retest reliability and 257 registered clinical studies use it as an outcome (evidence grade A in the ConductCognition test census).
Does it report a percentile?
No. Scores and quality flags only.
Which settings can a researcher change?
Look (Game, Plain). Every plan can change the look, which never changes how a result is scored.
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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