How long does the Simon Task take?
About 2 to 4 minutes, as listed in the test library.
Executive Function
Simon Task
Measure stimulus-response conflict with spatially congruent and incongruent response trials.
Useful for cognitive control, response selection, aging, fatigue, and executive-function protocols.
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.
Executive function2-4 minTimed: desktop or laptop with a mouse or trackpad
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F
J
Respond to color while ignoring location
What this task measures
Measures interference from a location that is irrelevant to the task. Participants press the key for a red or blue square's color while the square appears left or right of center. Half of sessions use F for red and J for blue, the other half the reverse.
Core constructs
- Stimulus-response conflict
- Response selection
- Cognitive control
Research fit
- Conflict and cognitive control research
- Within-study group comparison
- Repeated testing in longitudinal studies
Paradigm overview
The Simon task measures interference from a location that is irrelevant to the task. A red or blue square appears to the left or right of a central cross, and participants press the key for its color. The square's side either matches the side of that key (congruent) or does not (incongruent).
Half of sessions use F for red and J for blue; the other half use J for red and F for blue. The mapping is drawn from the session's random seed, shown in the instructions and practice, recorded on every trial, and used for scoring. Each trial starts with a 500 ms cross, and the square stays until a response or 1500 ms. Half the test trials are congruent and half incongruent, with both colors used equally often, and every session runs a recorded random order after 8 practice trials with feedback.
Responses are usually slower and less accurate on incongruent trials. The Simon effect is the incongruent minus congruent mean response time on correct trials.
Key scoring outputs
Simon Effect
msIncongruent minus congruent mean response time, correct trials only.
Larger values mean more interference
Congruent RT
msMean correct response time when the square is on the side of its key.
Lower is faster
Incongruent RT
msMean correct response time when the square is on the opposite side.
Lower is faster
Mean Correct RT
msMean response time on all correct test trials.
Informational
Accuracy
proportionShare of test trials answered with the key for the square's color.
Higher is better
Congruency Accuracy Cost
proportionCongruent minus incongruent accuracy.
Larger values mean more interference
Task design as built
The trial sequence participants see, as the test runs in ConductCognition. Settings a researcher can change are listed below.
- Display
- A red or blue square, 220 px left or right of a central cross.
- Fixation
- 500 ms.
- Square
- Stays until a response or 1,500 ms.
- Keys
- F and J. Half of sessions use F for red, the other half J for red; the mapping is drawn from the session's seed and saved on every trial.
- Trial mix
- Half congruent and half incongruent, with both colors used equally often.
- Practice
- 8 trials with feedback.
This version shows colored squares on screen, the visual form of the task reviewed by Lu and Proctor (1995).
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Number of trials | 60 | 30 to 120 |
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
- Task text: English and Italian.
- Available on: Every plan, including the free plan.
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Cite this test
ConductCognition versions: task version 2.0.0, scoring version 2.0.0. Every export records the versions each session used, for a methods section.
- Simon, J. R. (1969). Reactions toward the source of stimulation. Journal of Experimental Psychology, 81(1), 174-176. https://doi.org/10.1037/h0027448
- Lu, C.-H., & Proctor, R. W. (1995). The influence of irrelevant location information on performance: A review of the Simon and spatial Stroop effects. Psychonomic Bulletin & Review, 2(2), 174-207. https://doi.org/10.3758/BF03210959
Source papers
Simon JR (1969). Reactions toward the source of stimulation. Journal of Experimental Psychology, 81(1):174-176.
Paradigm sourceAdults
Lu CH, Proctor RW (1995). The influence of irrelevant location information on performance: a review of the Simon and spatial Stroop effects. Psychonomic Bulletin & Review, 2(2):174-207.
Paradigm sourceAdults
Research FAQ
Common questions about this online cognitive test
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?
Simon Effect, Congruent RT, Incongruent RT, Mean Correct RT, Accuracy and Congruency Accuracy Cost. Each session is also marked valid, needs review or invalid, with the reason.
Which settings can a researcher change?
Number of trials (30 to 120). Settings can be changed on yearly plans; free and pay-as-you-go studies use the standard settings.
Which languages can participants use?
The test's own text is in English and Italian. Italian participant pages come with yearly plans.
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.
Run this test in your next study
Start free with 10 free participants on any test, then use participant credits or a yearly plan.