Protocol - Inhibitory Control (Stop Signal Paradigm)

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STOP-IT task


Publicly available


STOP-IT is a computer-administered stop-signal task. Participants react as quickly as possible to a visual stimulus unless it is followed by an auditory stop signal presented after a variable delay. STOP-IT includes an analysis module (ANALYZE-IT) that calculates several summary variables.

For more conceptual information about the stop-signal task, please refer to the entry for the Stop-signal task in the Cognitive Atlas: [link[www.cognitiveatlas.org/term/stop_signal_task|http://www.cognitiveatlas.org/term/stop_signal_task]]


Summary of the STOP-IT Stop Signal Task

The stop-signal procedure consists of a visually based primary task, followed 25 percent of the time by an auditory-based stop signal. For the primary task, participants differentiate between a square or circle by pressing a specific key as quickly as possible. The visual cues remain on the screen until the participants respond or 1,250 milliseconds (msec) expire. For the stop-signal task, the visual cue is followed, after a variable length of time (initially 250 msec), by a tone that signals to the subject not to respond. If the participant successfully inhibits their response, the stop-signal delay increases by 50 msec. If the participant does not successfully inhibit their response, the stop-signal delay decreases by 50 msec.

STOP-IT includes a practice phase of 32 trials followed by an experimental phase of three blocks of 64 trials (total). The number of practice and experimental phase trials can be adjusted.


Results are written to an output file that includes block number, trial number, type of trial, whether the response was correct, reaction time, and stop signal delay. The ANALYZE-IT software calculates the means for a variety of summary variables including an estimation of stop signal reaction time (SSRT), where longer stop signal reaction time indicates greater motor impulsivity.

Personnel and Training Required

STOP-IT can be administered by research assistants trained in the ethical and competent use of psychological tests.

Equipment Needs

STOP-IT can be installed on computers running Windows 2000/XP.


Requirement CategoryRequired
Average time of greater than 15 minutes in an unaffected individualNo
Major equipmentNo
Specialized requirements for biospecimen collectionNo
Specialized trainingNo

Mode of Administration


Life Stage:

Child, Adolescent, Adult

Specific Instructions:

A compilation of research that has utilized this program can be found at [link[www.psy.vanderbilt.edu/faculty/logan/#stopit|www.psy.vanderbilt.edu/faculty/logan/#stopit]]

The task itself as compiled executable code for Windows 2k/XP can be downloaded from https://ore.exeter.ac.uk/repository/handle/10871/13860

Research Domain Information

Release Date:

November 21, 2016


This measure assesses the ability of the participant to inhibit a response that has already been initiated.


Inhibitory control is a component of impulsivity, and poor response inhibition is a risk factor for substance use disorders (Monterosso et al., 2005; Nigg et al., 2006).

Selection Rationale

The stop-signal task is a well-established, validated test of inhibitory control. STOP-IT is a freely available, precompiled executable program to perform the stop-signal task, which does not require further programming by the investigator.




Common Data Elements (CDE)Neurobehavioral Inhibitory Nerve Control Questionnaire Assessment Score3371867CDE Browser

Process and Review

The [link[phenx.org/node/101|Expert Review Panel #3]] (ERP 3) reviewed the measures in Alcohol, Tobacco and Other Substances, and Substance Abuse and Addiction domains.

Guidance from ERP 3 includes:

• Changed name of Measure

• Updated protocol

• New Data Dictionary

Back-compatible: Back-compatible: Partially back-compatible (updated/similar protocol which would require some changes to the data dictionary), variable mapping between current and previous protocols can be found [link[www.phenxtoolkit.org/index.php?pageLink=browse.archive.protocols&id=530000|here]].

Previous version in Toolkit archive ([link[www.phenxtoolkit.org/index.php?pageLink=resources.archive|link]])


Verbruggen, F., Logan, G. D., & Stevens, M. A. (2008). STOP-IT: Windows executable software for the stop-signal paradigm. Behavior Research Methods, 40, 479-483.

Executables for the STOP-IT task and the accompanying ANALYZE-IT analysis program can be downloaded from Frederick Verbruggen’s website (Department of Psychology, University of Exeter, UK).

General References

Boucher, L., Palmeri, T. J., Logan, G. D., & Schall, J. D. (2007). Inhibitory control in mind and brain: An interactive race model of countermanding saccades. Psychological Review, 114, 376-397.

Monterosso, J. R., Aron, A. R., Cordova, X., Xu, J. S., & London, E. D. (2005). Deficits in response inhibition associated with chronic methamphetamine abuse. Drug and Alcohol Dependence, 79, 273-277.

Nigg, J. T., Wong, M. M., Martel, M. M., Jester, J. M., Puttler, L. I., Glass, J. M., Adams, K. M., Fitzgerald, H. E., & Zucker, R. A. (2006). Poor response inhibition as a predictor of problem drinking and illicit drug use in adolescents at risk for alcoholism and other substance use disorders. Journal of the American Academy of Child and Adolescent Psychiatry, 45, 468-475.

van den Wildenberg, W. P. M., & van der Molen, M. W. (2004). Developmental trends in simple and selective inhibition of compatible and incompatible responses. Journal of Experimental Child Psychology, 87, 201-220.

Verbruggen, F., & Logan, G. D. (2009). Models of response inhibition in the stop-signal and stop-change paradigms. Neuroscience & Biobehavioral Reviews, 33, 647-661.

Smith, J.L., Mattick, R.P., Jamadar, S.D., & Iredale, J.M. (2014). Deficits in behavioural inhibition in substance abuse and addiction: a meta-analysis. Drug and Alcohol Dependence, 145, 1-33.

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