Processing Speed
Digit Comparison Task
Also called: number comparison task, symbolic number comparison, magnitude comparison task, numerical distance effect, digit magnitude comparison
Measure how quickly people tell which of two digits is larger, and how much longer close pairs such as 4 and 5 take than far pairs.
5-6 minTimed: desktop or laptop with a mouse or trackpad
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
- 24
- Evidence grade
- D
- Registered clinical studies
- 2
What it measures
A measure of how quickly people judge the size of numbers. Two digits from 1 to 9 appear side by side, and participants press the key on the side of the larger one. The main score is the numerical distance effect: how much slower answers are when the two digits are close (1 or 2 apart) than when they are far apart (5 to 8).
Constructs
- Numerical magnitude
- Symbolic number processing
- Processing speed
Research uses
- Math learning and dyscalculia research
- Numerical cognition research
- Aging research
How the paradigm works
The Digit Comparison Task measures how quickly people judge which of two numbers is larger, and how that speed depends on how far apart the numbers are. Moyer and Landauer (1967) found that choosing the larger of two digits takes longer when the digits are close, such as 4 and 5, than when they are far apart, such as 2 and 9: the numerical distance effect. It is read as a sign that digits are compared through an internal sense of quantity rather than as symbols alone.
More about the paradigm
On each trial a cross shows for 500 ms, then two digits from 1 to 9 appear side by side. Participants press F if the left digit is larger and J if the right one is larger. The digits stay until a key or 2,000 ms. Every ordered pair of two different digits appears once per round: 72 pairs, with the larger digit on each side in half of them. The standard session has 3 rounds (1 to 4), 216 trials in a seeded order, after 8 practice trials with feedback, about 5 minutes in all. The cross and the digits switch on screen frames, and response times run from the frame that drew the digits. Desktop and laptop only.
The main score is the distance effect: median correct response time for close pairs (1 or 2 apart) minus far pairs (5 to 8 apart); positive values mean close pairs took longer. The slope of response time on distance, overall speed and accuracy, and the median response time at each distance are also reported. Responses under 100 ms count as anticipations. Distance effects with digits have modest test-retest reliability for one person (Maloney and colleagues, 2010), so they are best used to compare groups.
Scores
- Distance Effectms
- Median correct response time for close pairs (1 or 2 apart) minus far pairs (5 to 8 apart), counting answers at or after 100 ms.
- Positive values mean close pairs took longer
- Distance Slopescore
- Least-squares slope of correct response time on the distance between the digits, in ms per unit of distance.
- Negative values mean answers sped up as the digits grew apart
- Median Correct Response Timems
- Median response time of correct answers over all pairs.
- Lower is faster
- Accuracy%
- Share of all test trials answered with the key on the side of the larger digit.
- Higher is better
- Close Pairs Response Timems
- Median correct response time for digits 1 or 2 apart.
- Lower is faster
- Far Pairs Response Timems
- Median correct response time for digits 5 to 8 apart.
- Lower is faster
- Close Pairs Accuracy%
- Share of close pairs answered correctly.
- Higher is better
- Far Pairs Accuracy%
- Share of far pairs answered correctly.
- Higher is better
- Response Time by Distancems
- Median correct response time at each distance from 1 to 8.
- Usually falls as the distance grows
- Anticipationscount
- Answers under 100 ms from the digits' onset.
- Lower is better
- Missed Responsescount
- Trials with no key press within 2,000 ms.
- Lower is better
- Completed Trialstrials
- Trials shown in the scored run.
- Fewer than planned is flagged for review
- Planned Trialstrials
- Trials the run set out to show.
- Informational
Use and evidence
24 papers from 2021 to 2025 name this task in their title or abstract, up 60% compared with 2016 to 2020. That ranks it 319 of 395 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 3 |
| 2024 | 6 |
| 2023 | 7 |
| 2022 | 2 |
| 2021 | 6 |
| 2020 | 4 |
| 2019 | 2 |
| 2018 | 2 |
| 2017 | 4 |
| 2016 | 3 |
| 2015 | 4 |
| 2014 | 7 |
| 2013 | 2 |
| 2012 | 5 |
| 2011 | 9 |
| 2010 | 1 |
| 2009 | 6 |
| 2008 | 5 |
| 2007 | 2 |
| 2006 | 1 |
| 2005 | 3 |
| 2004 | 1 |
| 2003 | 0 |
| 2002 | 1 |
| 2001 | 1 |
| 2000 | 0 |
Use grade E
Fewer than 30 papers from 2021 to 2025.
Evidence grade D
Little published measurement evidence found.
- Papers on test-retest reliability
- 0
- Papers on reliability or validity
- 3
- Registered clinical studies using it as an outcome
- 2
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.
- Display
- On a dark panel: a cross for 500 ms, then two digits from 1 to 9 side by side, 130 px left and right of the center, until a key or 2,000 ms.
- Keys
- F when the left digit is larger and J when the right one is larger. The two letters stay on the panel under the digits.
- Pairs
- Every ordered pair of two different digits from 1 to 9 once per round: 72 pairs, with the larger digit on each side in half of them, at distances from 1 (16 pairs) to 8 (2 pairs).
- Trials
- 3 rounds (standard; 1 to 4): 216 trials, each round in its own seeded order, with no pair twice in a row.
- Practice
- 8 trials, 4 with the larger digit on each side, with feedback for 800 ms.
- Score
- Median correct response time for pairs 1 or 2 apart minus pairs 5 to 8 apart, counting answers at or after 100 ms. Response times run from the screen frame that drew the digits.
Two digits side by side, choose the larger, as in Moyer and Landauer (1967). The form that compares one digit with a fixed 5 is not used. Distance effects with digits have modest test-retest reliability for one person, so they suit group comparisons best.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: number_comparison_test from the scored run, F or J within 2,000 ms (chance 50%; the larger digit is on each side in half the pairs), graded from the saved digits. Below chance invalidates and not above chance is flagged. One key on 90% of answers invalidates when accuracy is not above chance. Missed responses and responses under 100 ms follow the timed-test rule. A run short of its planned trials, or too few correct answers to compute the distance effect, is flagged for review.
Why these rules
Accuracy significantly below chance (one-sided exact test, p < .05) cannot come from guessing; it means the response mapping was reversed or the task was not followed (Slick, Sherman and Iverson 1999 treat below-chance forced-choice performance as definite response bias). Chance-level accuracy can be a real result in impaired participants, so it is only flagged. One option on at least 90% of answered trials, when the correct options are balanced and accuracy is not above chance, means the answers did not depend on the items (the task counterpart of long-string responding in surveys; Curran 2016). Missed responses and responses under 100 ms keep the platform's timed-test rule: more than max(3, 25%) missed responses or more than max(2, 20%) responses under 100 ms invalidate, and any is flagged. A response under 100 ms cannot be a reaction to the stimulus.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Rounds of the 72 pairs | 3 | 1 to 4 |
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
- Timed test: participants need a desktop or laptop with a mouse or trackpad. 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 Digit Comparison Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Moyer and Landauer, 1967; Dehaene, Dupoux and Mehler, 1990), with the standard settings (rounds of the 72 pairs: 3). The main score was distance effect (median correct response time for close pairs (1 or 2 apart) minus far pairs (5 to 8 apart), counting answers at or after 100 ms).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Moyer, R. S., & Landauer, T. K. (1967). Time required for judgements of numerical inequality. Nature, 215(5109), 1519-1520. https://doi.org/10.1038/2151519a0Choosing the larger of two digits, and the distance effect.
- Dehaene, S., Dupoux, E., & Mehler, J. (1990). Is numerical comparison digital? Analogical and symbolic effects in two-digit number comparison. Journal of Experimental Psychology: Human Perception and Performance, 16(3), 626-641. https://doi.org/10.1037/0096-1523.16.3.626
- Holloway, I. D., & Ansari, D. (2009). Mapping numerical magnitudes onto symbols: The numerical distance effect and individual differences in children's mathematics achievement. Journal of Experimental Child Psychology, 103(1), 17-29. https://doi.org/10.1016/j.jecp.2008.04.001The distance effect with digits as a measure of individual differences.
- Maloney, E. A., Risko, E. F., Preston, F., Ansari, D., & Fugelsang, J. (2010). Challenging the reliability and validity of cognitive measures: The case of the numerical distance effect. Acta Psychologica, 134(2), 154-161. https://doi.org/10.1016/j.actpsy.2010.01.006The reliability of the distance effect with digits.
Source papers
- Holloway ID, Ansari D (2009). Mapping numerical magnitudes onto symbols: the numerical distance effect and individual differences in children's mathematics achievement. Journal of Experimental Child Psychology, 103(1):17-29.Paradigm source, Children 6 to 8 years
Questions
How long does the Digit Comparison Task take?
About 5 to 6 minutes, as listed in the test library.
What device does a participant need?
Timed test: participants need a desktop or laptop with a mouse or trackpad. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Distance Effect, Distance Slope, Median Correct Response Time, Accuracy, Close Pairs Response Time, Far Pairs Response Time, Close Pairs Accuracy, Far Pairs Accuracy, Response Time by Distance, Anticipations, Missed Responses, Completed Trials and Planned Trials. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Digit Comparison Task used in research?
24 papers from 2021 to 2025 name it in their title or abstract, up 60% compared with 2016 to 2020. That ranks it 319 of 395 test families in the ConductCognition test census (use grade E). Source: ConductCognition test census 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Digit Comparison Task have?
In the published research, 0 papers report its test-retest reliability and 2 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 settings can a researcher change?
Rounds of the 72 pairs (1 to 4). 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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