Processing Speed
Simple Reaction Time Task
Measure psychomotor speed and baseline alertness with a fast browser-native paradigm suitable for remote research workflows.
2-3 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
- 417
- Evidence grade
- A
- Registered clinical studies
- 210
What it measures
Measures basic processing speed by asking participants to respond as quickly as possible when a stimulus appears on screen.
Constructs
- Psychomotor speed
- Alertness and vigilance
- Basic sensorimotor processing
- Peripheral and central processing speed
Research uses
- Baseline processing speed assessment
- Fatigue and drowsiness monitoring
- Medication side-effect screening (sedation)
- Traumatic brain injury recovery tracking
- Age-related cognitive slowing detection
How the paradigm works
The Simple Reaction Time task is the most fundamental measure of processing speed in cognitive neuroscience. A single stimulus (a colored circle) appears on screen after a variable delay, and the participant must press the spacebar as quickly as possible upon detection.
More about the paradigm
The variable inter-stimulus interval (1000-3000ms) prevents anticipatory responses and ensures each trial requires genuine stimulus detection. Practice trials allow participants to calibrate their responses before scored trials begin.
SRT provides a baseline measure of the sensorimotor processing chain: visual detection, signal transduction to motor cortex, and motor execution. Because the response mapping is fixed (one stimulus, one response), decision-making load is minimal, isolating pure processing speed from higher-order cognitive demands.
Scores
- Mean Reaction Timems
- Average reaction time across valid trials, excluding anticipatory responses (<100ms).
- Lower is better
- Median Reaction Timems
- Median reaction time, more robust to outliers than the mean. Preferred when the RT distribution is skewed.
- Lower is better
- RT Standard Deviationms
- Standard deviation of reaction times. Reflects response consistency (intraindividual variability). Elevated IIV is a biomarker for cognitive decline.
- Lower is better
- Minimum RTms
- Fastest response recorded. Useful for detecting anticipatory or invalid responses.
- Informational
- Maximum RTms
- Slowest response recorded. May indicate lapses in attention.
- Informational
- Accuracy%
- Proportion of trials with a valid response. Expected near ceiling for healthy participants.
- Higher is better
Use and evidence
417 papers from 2021 to 2025 name this task in their title or abstract, down 21% compared with 2016 to 2020. That ranks it 66 of 582 test families in our census. The Quick Circles Game page shows these counts too, as those of the published test the game is compared with. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 102 |
| 2024 | 86 |
| 2023 | 68 |
| 2022 | 73 |
| 2021 | 88 |
| 2020 | 88 |
| 2019 | 137 |
| 2018 | 102 |
| 2017 | 105 |
| 2016 | 98 |
| 2015 | 115 |
| 2014 | 110 |
| 2013 | 112 |
| 2012 | 88 |
| 2011 | 75 |
| 2010 | 91 |
| 2009 | 82 |
| 2008 | 80 |
| 2007 | 63 |
| 2006 | 83 |
| 2005 | 68 |
| 2004 | 58 |
| 2003 | 67 |
| 2002 | 54 |
| 2001 | 55 |
| 2000 | 40 |
Use grade B
300 to 999 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
- 31
- Papers on reliability or validity
- 198
- Registered clinical studies using it as an outcome
- 210
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 this task, not ConductCognition's version of it.
Source: ConductCognition test census 0.39.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: srt_test. One key and no response window, so accuracy and missed responses are not judged. More than max(2, 20%) responses under 100 ms invalidate; any is flagged.
Why these rules
There is no correct option to compare with chance, so accuracy is not judged against chance. 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.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Number of trials | 30 | 20 to 60 |
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.
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Included in these batteries
Each battery runs this test with others in a fixed order, with standard settings.
- Reaction Time Study2 tests, 7 minutes per participant
- Pilot Screening Battery4 tests, 15 minutes per participant
- Language-Minimized Screening Battery8 tests, 30 minutes per participant
- Sleep and Fatigue Battery4 tests, 23 minutes per participant
- Medication Studies Battery5 tests, 26 minutes per participant
Cite and describe
Participants completed the Simple Reaction Time task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Donders, 1869), with the standard settings (number of trials: 30). The main score was mean reaction time (average reaction time across valid trials, excluding anticipatory responses (<100ms)).
Paradigm source: Donders (1869).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
Source papers
- Woods DL, Wyma JM, Yund EW, Herron TJ, Reed B (2015). Factors influencing the latency of simple reaction time. Frontiers in Human Neuroscience, 9:131.Paradigm source
Questions
How long does the Simple Reaction Time Task take?
About 2 to 3 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?
Mean Reaction Time, Median Reaction Time, RT Standard Deviation, Minimum RT, Maximum RT and Accuracy. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Simple Reaction Time Task used in research?
417 papers from 2021 to 2025 name it in their title or abstract, down 21% compared with 2016 to 2020. That ranks it 66 of 582 test families in the ConductCognition test census (use grade B). Source: ConductCognition test census 0.39.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Simple Reaction Time Task have?
In the published research, 31 papers report its test-retest reliability and 210 registered clinical studies use it as an outcome (evidence grade A in the ConductCognition test census).
Which settings can a researcher change?
Number of trials (20 to 60). 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.
Every test: the full test list.
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