Response Inhibition
Stop-Change Task
Also called: stop-change paradigm, stop and change task, change-signal task
Measure how quickly people stop a planned key press and make another: arrows call for arrow keys, and a red arrow calls for the space bar instead, scored by stop-signal reaction time and change time.
5-7 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
- 12
- Evidence grade
- D
- Registered clinical studies
- 1
What it measures
Measures how quickly people stop a planned response and make a different one instead. Participants press the arrow key that matches an arrow; when the arrow turns red, they hold back the arrow key and press the space bar.
Constructs
- Response inhibition
- Action cancellation
- Replacing a planned response
- Executive control
Research uses
- Response inhibition research
- Studies that compare stopping an action with replacing it
- Executive control and multitasking research
How the paradigm works
The Stop-Change Task measures how quickly people stop a planned response and make a different one instead. An arrow in a box calls for the matching arrow key, pressed with the right hand. On a quarter of the trials the box and the arrow turn red after a short delay: the participant then holds back the arrow key and presses the space bar with the left hand, a key the arrow task does not use, as in the change condition of Logan and Burkell (1986).
More about the paradigm
The delay follows this library's Stop-Signal Task. It starts at 250 ms and moves 50 ms later after a red arrow with no arrow key and 50 ms earlier after one with an arrow key, between 50 and 900 ms, so people stop on about half of the red arrows. The standard test has 150 go trials and 50 stop-change trials in an order drawn from the session's seed, after 16 practice trials with feedback. Each trial is a 500 ms cross, then the arrow until a response or 2,000 ms, as in Verbruggen, Schneider and Logan (2008). An arrow key on a red arrow does not end the trial, so the change can still follow.
Stopping is scored as the Stop-Signal Task scores it. The main score, the stop-signal reaction time, comes from the integration method with replacement of go omissions (Verbruggen et al., 2019): the nth fastest arrow-key time of the go trials minus the mean delay, with n the go trials times the share of red arrows with an arrow key. The change response time runs from the red to the space bar on red arrows with no arrow key. The task also reports the share of red arrows stopped, how often the space bar followed a stopped arrow, go time and accuracy, the time of arrow keys pressed despite the red, and the Stop-Signal Task's race-model checks. In the first experiment of Verbruggen, Schneider and Logan (2008), where the change was a second judgment of the target's position, stopping took 298 ms on average. Scores support research and do not diagnose.
Scores
- Stop-Signal Reaction Timems
- Integration-method estimate of how long stopping takes: the nth fastest arrow-key time of all go trials minus the mean stop-signal delay, with n the go trials times the share of red arrows with an arrow key. Choice errors count, and a go trial with no arrow key counts at the slowest time (Verbruggen et al. 2019).
- Lower means faster stopping, when the Valid SSRT Flag is 1
- Change Response Timems
- Mean time from the red to the space bar on red arrows with no arrow key, from responses at or after 100 ms.
- Informational
- Stop Success Rate%
- Share of red arrows with no arrow key, leaving out early changes.
- Near 0.50 is expected under a working staircase
- Change Rate%
- Share of the stopped red arrows that the space bar followed.
- Near 1 means the change rule was followed
- Go Reaction Timems
- Mean time of correct arrow keys on go trials, at or after 100 ms.
- Informational
- Go Accuracy%
- Share of go trials answered with the matching arrow key.
- Higher is better
- Failed-Stop RTms
- Mean time of arrow keys pressed on red arrows.
- Should usually be faster than go RT
- Change RT After a Failed Stopms
- Mean time from the red to the space bar on red arrows that also had an arrow key.
- Informational
- Mean Stop-Signal Delayms
- Mean delay from the arrow to the red over the stop-change trials.
- Informational
- Valid SSRT Flag0/1
- 1 when the Stop-Signal Task's race-model checks pass: stop success between 0.25 and 0.75, go accuracy of at least 0.80, failed-stop RT below go RT, an SSRT above 0, at least 20 go times and at least 16 stop-change trials.
- 1 indicates an interpretable SSRT
- Go Omissionscount
- Go trials with no key within 2 seconds.
- Quality check
- False Changescount
- Go trials answered with the space bar.
- Quality check
- Early Changescount
- Stop-change trials with the space bar before the red appeared, left out of stopping and changing.
- Quality check
- Anticipationscount
- Responses under 100 ms: a first key within 100 ms of the arrow, or the space bar within 100 ms of the red.
- Quality check
- Go Trialstrials
- Go trials in the run.
- Quality check
- Stop-Change Trialstrials
- Stop-change trials in the run, leaving out early changes.
- Quality check
Use and evidence
12 papers from 2021 to 2025 name this task in their title or abstract, down 48% compared with 2016 to 2020. That ranks it 446 of 495 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 5 |
| 2024 | 3 |
| 2023 | 1 |
| 2022 | 1 |
| 2021 | 2 |
| 2020 | 2 |
| 2019 | 4 |
| 2018 | 6 |
| 2017 | 9 |
| 2016 | 2 |
| 2015 | 7 |
| 2014 | 4 |
| 2013 | 6 |
| 2012 | 2 |
| 2011 | 0 |
| 2010 | 3 |
| 2009 | 0 |
| 2008 | 3 |
| 2007 | 1 |
| 2006 | 1 |
| 2005 | 2 |
| 2004 | 1 |
| 2003 | 0 |
| 2002 | 0 |
| 2001 | 0 |
| 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
- 1
- Registered clinical studies using it as an outcome
- 1
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 0.22.0, counted 2 November 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Display
- An arrow pointing left or right in a box, after a 500 ms cross. The arrow waits up to 2,000 ms for a response.
- Keys
- The left and right arrow keys with the right hand. The space bar with the left hand, a key the arrow task does not use.
- Red arrows
- On 50 of 200 trials (standard; 16 to 100, with 48 to 300 go trials) the box and arrow turn red after the stop-signal delay. The participant then holds back the arrow key and presses the space bar. An arrow key does not end such a trial, so the change can still follow.
- Delay
- Starts at 250 ms (100 to 600) and moves 50 ms (25 to 100) later after a red arrow with no arrow key and earlier after one with an arrow key, between 50 and 900 ms: the Stop-Signal Task's staircase. The space bar before the red leaves it unchanged.
- Practice
- 16 trials, 4 of them red, each followed by feedback for 1,000 ms. The delay starts again for the test.
- Trial order
- A seeded random order, with each direction equally often among go trials and among red arrows.
- Scoring
- Stop-signal reaction time by the integration method with replacement of go omissions, as in the Stop-Signal Task. The change time runs from the frame that drew the red.
Verbruggen, Schneider and Logan (2008) signaled the change with a spoken word and asked for a second judgment. Here, as in Logan and Burkell (1986), the change is one key the arrow task does not use, and the signal is the arrow turning red, as in the Stop-Signal Task.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: go trials of stop_change_test, two arrows (chance 50%) within 2 s; red arrows are excluded because the delay adapts. Below chance on go trials invalidates and not above chance is flagged. One arrow on 90% of go answers invalidates when accuracy is not above chance. Missed go responses and responses under 100 ms follow the timed-test rule. Data that fail the race-model checks are flagged and the percentile is withheld; few changes after stopped red arrows are flagged.
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. Stopping is scored as in the Stop-Signal Task: the consensus guide (Verbruggen et al. 2019, recommendations 7 and 9) advises against estimating SSRT when p(respond|signal) is outside 0.25 to 0.75 or when failed-stop RT is longer than go RT, and the scorer's validSSRT checks these. A participant who stops but seldom presses the space bar did a plain stop task, so the change times describe few trials.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Go trials | 150 | 48 to 300 |
| Stop-change trials | 50 | 16 to 100 |
| Initial stop-signal delay (ms) | 250 | 100 to 600 |
| SSD staircase step (ms) | 50 | 25 to 100 |
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.
Cite and describe
Participants completed the Stop-Change Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Logan & Burkell, 1986; Verbruggen, Schneider & Logan, 2008), with the standard settings (go trials: 150; stop-change trials: 50; initial stop-signal delay (ms): 250; ssd staircase step (ms): 50). The main score was stop-signal reaction time (integration-method estimate of how long stopping takes: the nth fastest arrow-key time of all go trials minus the mean stop-signal delay, with n the go trials times the share of red arrows with an arrow key).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Logan, G. D., & Burkell, J. (1986). Dependence and independence in responding to double stimulation: A comparison of stop, change, and dual-task paradigms. Journal of Experimental Psychology: Human Perception and Performance, 12(4), 549-563. https://doi.org/10.1037/0096-1523.12.4.549
- Verbruggen, F., Schneider, D. W., & Logan, G. D. (2008). How to stop and change a response: The role of goal activation in multitasking. Journal of Experimental Psychology: Human Perception and Performance, 34(5), 1212-1228. https://doi.org/10.1037/0096-1523.34.5.1212The 2,000 ms response window, the staircase on stopping, and the change response after a failed stop.
- Verbruggen, F., Aron, A. R., Band, G. P. H., Beste, C., Bissett, P. G., Brockett, A. T., et al. (2019). A consensus guide to capturing the ability to inhibit actions and impulsive behaviors in the stop-signal task. eLife, 8, e46323. https://doi.org/10.7554/eLife.46323Scoring stopping and the race-model checks.
- Boecker, M., Gauggel, S., & Drueke, B. (2013). Stop or stop-change: Does it make any difference for the inhibition process? International Journal of Psychophysiology, 87(3), 234-243. https://doi.org/10.1016/j.ijpsycho.2012.09.009Review of stopping in the stop-signal and stop-change tasks.
- Gordi, V. M., Drueke, B., Gauggel, S., Antons, S., Loevenich, R., Mols, P., & Boecker, M. (2019). Stopping speed in the stop-change task: Experimental design matters! Frontiers in Psychology, 10, 279. https://doi.org/10.3389/fpsyg.2019.00279SSRT in the stop-change task by the integration method, and the change reaction time from the change signal.
Source papers
- Logan GD, Burkell J (1986). Dependence and independence in responding to double stimulation: a comparison of stop, change, and dual-task paradigms. Journal of Experimental Psychology: Human Perception and Performance, 12(4):549-563.Paradigm source, Adults
- Verbruggen F, Aron AR, Band GPH, et al. (2019). A consensus guide to capturing the ability to inhibit actions and impulsive behaviors in the stop-signal task. eLife, 8:e46323.Paradigm source, N/A
Questions
How long does the Stop-Change Task take?
About 5 to 7 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?
Stop-Signal Reaction Time, Change Response Time, Stop Success Rate, Change Rate, Go Reaction Time, Go Accuracy, Failed-Stop RT, Change RT After a Failed Stop, Mean Stop-Signal Delay, Valid SSRT Flag, Go Omissions, False Changes, Early Changes, Anticipations, Go Trials and Stop-Change Trials. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Stop-Change Task used in research?
12 papers from 2021 to 2025 name it in their title or abstract, down 48% compared with 2016 to 2020. That ranks it 446 of 495 test families in the ConductCognition test census (use grade E). Source: ConductCognition test census 0.22.0, counted 2 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Stop-Change Task have?
In the published research, 0 papers report its test-retest reliability and 1 registered clinical study uses it as an outcome (evidence grade D in the ConductCognition test census).
Which settings can a researcher change?
Go trials (48 to 300), stop-change trials (16 to 100), initial stop-signal delay (ms) (100 to 600) and ssd staircase step (ms) (25 to 100). 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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