Attention
Mental Fatigue Task
Also called: mental fatigue protocol, mental fatigue induction, mentally fatiguing task, modified Stroop task, 30-minute Stroop task, cognitive fatigue induction
Measure how 30 minutes of demanding color words, or an easy control, change rated mental fatigue and a short arrow or reaction test from before to after.
35-40 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. Try it here first, with no account.
- Papers, 2021 to 2025
- 71
- Evidence grade
- C
- Registered clinical studies
- 4
What it measures
Measures what a long, demanding task does to how tired people feel and to a short test afterward. Participants answer color words for 30 minutes by default, by the ink, or by the word when the ink is red, rating mental fatigue and effort before, during and after, with a short arrow or reaction test before and after. An easy version with every word in its own color is the control. The main score is the change in rated fatigue.
Constructs
- Mental fatigue
- Sustained attention
- Response inhibition
- Perceived effort
Research uses
- Sport and exercise science studies of mental fatigue and later performance
- Research on time on task, effort and motivation, at the group level
- Studies of breaks, recovery and other ways to counter fatigue
How the paradigm works
The Mental Fatigue Task brings on mental fatigue the way sport and exercise science does, with a long, demanding task, and measures what follows. Participants answer color words for a set time, 30 minutes by default (10 to 60), with the Stroop Color-Word Test's four colors and keys in their language. In the demanding version every word is written in another color's ink and is answered by its ink, except that a word in red ink is answered by the color it names: the modified incongruent Stroop task of Pageaux and colleagues (2014, 2015). In the easy version, their control, every word is in its own color. Each word follows a 500 ms cross and stays until a key or 2.5 seconds, and the words keep coming until their time adds up to the set minutes, so a faster person answers more words. A Stop button under every word ends the color words at any time, and the session moves on to its last part. Twelve practice words with feedback come first.
More about the paradigm
Participants rate how mentally tired they feel, from 1 (not at all) to 7 (extremely), before the color words, after each 10 minutes of words and after them, and how much effort the words take, from 1 (very little) to 7 (a great deal), during and after. Before and after the color words they do the same short test: 48 rounds of the Eriksen flanker task (the standard) or 30 rounds of simple reaction time, about 1 to 2 minutes each, with a practice the first time. A study chooses the demanding version, the easy version, or a draw for each session from its seed.
The main score is the change in rated fatigue, after the color words minus before. The task also reports each rating, the change in the short test (the time of right answers, the share right and, for the arrows, the flanker effect), the color words' share right and time, their change from the first to the last 5 minutes, the time done and whether Stop was used. Van Cutsem and colleagues (2017) reviewed 11 studies that used 30 to 100 minutes of a demanding task: the general finding was poorer endurance afterward with higher perceived exertion, and 6 of the 11 found higher self-rated fatigue; in Pageaux and colleagues (2015) the demanding version was answered in 834 ms on average and the easy one in 597 ms. Scores support research and do not diagnose.
Scores
- Change in Mental Fatiguescore
- Mental fatigue rated after the color words minus before them, on the scale from 1 (not at all) to 7 (extremely).
- A research measure compared between versions or groups
- Mental Fatigue Beforescore
- Mental fatigue rated before the color words, from 1 to 7.
- Informational
- Mental Fatigue Afterscore
- Mental fatigue rated right after the color words, from 1 to 7.
- Informational
- Mental Fatigue Duringscore
- Mean of the fatigue ratings after each 10 minutes of words, from 1 to 7; empty when the words ran less than 10 minutes.
- Informational
- Effort Duringscore
- Mean of the effort ratings after each 10 minutes of words, from 1 (very little) to 7 (a great deal).
- Informational
- Effort Afterscore
- Effort the color words took, rated after them, from 1 to 7.
- Informational
- Change in Short Test Timems
- Mean time of the right answers on the short test after the color words minus before them, answers under 100 ms left out.
- Positive means slower after the color words
- Change in Short Test Accuracy%
- Share of the short test's rounds answered right after the color words minus before them.
- Negative means fewer right after the color words
- Short Test Time Beforems
- Mean time of the right answers on the short test before the color words.
- Informational
- Short Test Time Afterms
- Mean time of the right answers on the short test after the color words.
- Informational
- Short Test Accuracy Before%
- Share of the short test's rounds answered right before the color words; a round with no key in 2 seconds counts as wrong.
- Informational
- Short Test Accuracy After%
- Share of the short test's rounds answered right after the color words.
- Informational
- Flanker Effect Beforems
- With the arrows as the short test: incongruent minus congruent time of right answers, before the color words.
- Informational
- Flanker Effect Afterms
- With the arrows as the short test: incongruent minus congruent time of right answers, after the color words.
- Informational
- Change in Flanker Effectms
- The flanker effect after the color words minus before them.
- Informational
- Time on Color Wordsseconds
- Seconds of word time done: each word's cross and answer time, or its 2.5 seconds when no key came.
- Informational
- Stopped Early0/1
- 1 when the participant used Stop before the set time ran out, 0 otherwise.
- Informational
- Color Wordscount
- Color words shown, leaving out a word ended by Stop.
- Informational
- Color Word Accuracy%
- Share of the color words answered with the right key; a word with no key in 2.5 seconds counts as wrong.
- Higher is better
- Color Word Timems
- Mean time of the right answers to the color words, at or after 100 ms.
- Informational
- Change in Color Word Timems
- Mean time of the right answers in the last 5 minutes of words minus the first 5; empty when the words ran less than 10 minutes.
- Positive means slower late in the task
- Change in Color Word Accuracy%
- Share right in the last 5 minutes of words minus the first 5; empty when the words ran less than 10 minutes.
- Negative means fewer right late in the task
- Missed Color Wordscount
- Color words with no key within 2.5 seconds.
- Quality check
- Demanding Version0/1
- 1 for the demanding version, 0 for the easy version, as set or drawn for the session.
- Informational
- Anticipationscount
- Answers under 100 ms, on the color words and the short test.
- Quality check
Use and evidence
71 papers from 2021 to 2025 name this task in their title or abstract, up 115% compared with 2016 to 2020. That ranks it 345 of 670 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 22 |
| 2024 | 14 |
| 2023 | 18 |
| 2022 | 9 |
| 2021 | 8 |
| 2020 | 12 |
| 2019 | 5 |
| 2018 | 8 |
| 2017 | 6 |
| 2016 | 2 |
| 2015 | 7 |
| 2014 | 1 |
| 2013 | 3 |
| 2012 | 2 |
| 2011 | 1 |
| 2010 | 0 |
| 2009 | 0 |
| 2008 | 0 |
| 2007 | 0 |
| 2006 | 1 |
| 2005 | 0 |
| 2004 | 0 |
| 2003 | 0 |
| 2002 | 0 |
| 2001 | 0 |
| 2000 | 0 |
Use grade D
30 to 99 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
- 0
- Papers on reliability or validity
- 12
- Registered clinical studies using it as an outcome
- 4
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.
Note on the counts: mostly sport and exercise science.
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 0.48.0, counted 12 November 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Words
- Red, green, blue and yellow, the Stroop test's color words and keys in the participant's language.
- Versions
- Demanding (standard): every word in another color's ink, answered by its ink, or by the word when the ink is red. Easy: every word in its own ink. Random draws one of the two for each session.
- Timing
- Each word after a 500 ms cross, until a key or 2,500 ms. Words keep coming until 30 minutes of them have run (10 to 60), and Stop ends them at any time.
- Ratings
- Mental fatigue from 1 to 7 before the words, after each 10 minutes of words and after them; effort from 1 to 7 during and after.
- Short test
- 48 rounds of arrows (flanker, standard), half incongruent, or 30 rounds of simple reaction time, before and after the words, each answered within 2,000 ms.
- Practice
- 8 arrow rounds or 5 reaction rounds before the first short test, and 12 color words before the timed words, each with feedback for 800 ms.
- Scoring
- The change in rated fatigue, the change in the short test's time and accuracy, and the words' accuracy and time from the first to the last 5 minutes.
Pageaux and colleagues ran both versions for 30 minutes in the laboratory, with colored buttons and feedback after every word. This version runs in the browser with letter or number keys, feedback only in practice, 2.5 seconds to answer each word, and fatigue rated from 1 to 7 in place of their mood questionnaire.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: mental_fatigue_word, four-key color words answered within 2.5 s, leaving out a word ended by Stop. Accuracy below chance invalidates; one key on nearly every word is checked. Missed responses and responses under 100 ms follow the timed-test rule. Stopping the color words early, which the task allows, is flagged.
Why these rules
Each word has four keys, so a guess is right one time in four. 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. Stopping early is the participant's right and keeps the session valid, but the ratings after then follow a shorter task.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Version | Demanding (standard) | Demanding (standard), Easy (control), Random for each session |
| Minutes of color words | 30 | 10 to 60 |
| Short test before and after | Arrows (flanker, standard) | Arrows (flanker, standard), Reaction time |
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 Mental Fatigue Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Marcora, Staiano and Manning, 2009; Pageaux et al., 2014), with the standard settings (version: Demanding; minutes of color words: 30; short test before and after: Arrows (flanker, standard)). The main score was change in mental fatigue (mental fatigue rated after the color words minus before them, on the scale from 1 (not at all) to 7 (extremely)).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Marcora, S. M., Staiano, W., & Manning, V. (2009). Mental fatigue impairs physical performance in humans. Journal of Applied Physiology, 106(3), 857-864. https://doi.org/10.1152/japplphysiol.91324.2008
- Pageaux, B., Lepers, R., Dietz, K. C., & Marcora, S. M. (2014). Response inhibition impairs subsequent self-paced endurance performance. European Journal of Applied Physiology, 114(5), 1095-1105. https://doi.org/10.1007/s00421-014-2838-5The 30-minute incongruent Stroop task and its congruent control.
- Pageaux, B., Marcora, S. M., Rozand, V., & Lepers, R. (2015). Mental fatigue induced by prolonged self-regulation does not exacerbate central fatigue during subsequent whole-body endurance exercise. Frontiers in Human Neuroscience, 9, 67. https://doi.org/10.3389/fnhum.2015.00067The red-ink rule of the demanding version and the reaction times of both versions.
- Van Cutsem, J., Marcora, S., De Pauw, K., Bailey, S., Meeusen, R., & Roelands, B. (2017). The effects of mental fatigue on physical performance: A systematic review. Sports Medicine, 47(8), 1569-1588. https://doi.org/10.1007/s40279-016-0672-0Task lengths of 30 to 100 minutes, time-matched controls and self-rated fatigue across 11 studies.
- Borragán, G., Slama, H., Bartolomei, M., & Peigneux, P. (2017). Cognitive fatigue: A time-based resource-sharing account. Cortex, 89, 71-84. https://doi.org/10.1016/j.cortex.2017.01.023Fatigue that grows with the time pressure of a task rather than its complexity.
Source papers
- Marcora SM, Staiano W, Manning V (2009). Mental fatigue impairs physical performance in humans. Journal of Applied Physiology, 106(3):857-864.Paradigm source, Adults
- No normative data for this task.Paradigm source, N/A
Questions
How long does the Mental Fatigue Task take?
About 35 to 40 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?
Change in Mental Fatigue, Mental Fatigue Before, Mental Fatigue After, Mental Fatigue During, Effort During, Effort After, Change in Short Test Time, Change in Short Test Accuracy, Short Test Time Before, Short Test Time After, Short Test Accuracy Before, Short Test Accuracy After, Flanker Effect Before, Flanker Effect After, Change in Flanker Effect, Time on Color Words, Stopped Early, Color Words, Color Word Accuracy, Color Word Time, Change in Color Word Time, Change in Color Word Accuracy, Missed Color Words, Demanding Version and Anticipations. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Mental Fatigue Task used in research?
71 papers from 2021 to 2025 name it in their title or abstract, up 115% compared with 2016 to 2020. That ranks it 345 of 670 test families in the ConductCognition test census (use grade D). Source: ConductCognition test census 0.48.0, counted 12 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Mental Fatigue Task have?
In the published research, 0 papers report its test-retest reliability and 4 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?
Version (Demanding (standard), Easy (control), Random for each session), minutes of color words (10 to 60) and short test before and after (Arrows (flanker, standard), Reaction time). 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, with its words in the same language. 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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