Stop Signal Task (SST)
FREE for use with an Inquisit Lab or Inquisit Web license.Background
The Stop Signal Task (SST) is classic measure of response inhibition created in 1948 by Margaret Vince at Medical Research Council Applied Psychology Unit in Cambridge. The test was further developed by Joseph Lappin and Charles Eriksen in 1960s, and by Gordon Logan and William Cohen in the 1980s, who introduced a method for calculating the covert stop-signal reaction time (SSRT).
While working as a post-doctoral fellow at Vanderbilt, Frederick Verbruggen continued to refine the SST in collaboration with Logan. In 2008, Verbruggen published STOP-IT, an open-source application for running the SST on Windows, with the aim of promoting methological consistency and correctness across different research labs using the task. In 2019 while at Ghent University, Verbruggen published a widely-cited consensus guide that consolodated and updated methodological best practices for the task.
Task Procedure
Participants are presented a series of arrows pointing left or right within a fixation circle, one at a time every 2 seconds. They are instructed to press a corresponding left or right response key as quickly as possible, but to withold their response if an auditory beep (the stop signal) is played immediately after the arrow appears. On go trials, responses to an arrow must be made before the next arrow appears in order be considered correct. The delay between the arrow and the beep starts at 250 ms and is adjusted up or down by 50 ms following stop trials depending on whether the participant successfully stopped their response. The adjustment procedure is designed to keep the probabilty of successful response inhibition around 50%.
The task begins with a practice block of 32 trials followed by 3 blocks of 72 test trials. The stop signal is presented on a randomly selected 3rd of the trials within each block. No error feedback is provided during the practice or test phase.
What it Measures
The Stop Signal Test is a measure of response inhibition.
Psychological Domains
- Executive Function
- Inhibitory Control: Ability to stop a response after it has already been initiated
- Sustained Attention: Ability to maintain focus on a continuous repetitive task
- Impulsivity/Response Caution: Tendency to respond cautiously or to priortize speed over accuracy
Main Performance Metrics
- Stop-Signal Reaction Time (SSRT): Estimates covert speed of inhibitory processes (response inhibition)
- Reaction Times on Go Trial: Mean reaction time (cautious or impulsive style)
- Omission Errors: Rate of misses - no responses on go trials (attentional lapses)
- Comission Errors: Rate of false alarms - responses on stop trials (impulsivity)
Psychiatric Conditions
Performance on the SST tends to be impaired in patients with the following psychiatric conditions:
- Attention Deficit Hyperactivity Disorder (ADHD)
- Obsessive-Compulsive Disorder (OCD)
- Substance Use Disorders
- Schizophrenia
- Bipolar Disorder
- Tourette Syndrome (TS)
- Insomnia Disorder
Available Test Variations
A child friendly Stop Signal task by Bocharov et al (2021)
The Stop Signal Task, a measure of response inhibition as described in Verbruggen et al (2008).
Updated Stop Signal Task incorporating best practices as recommended in Verbruggen et al (2019).
References
Search Google Scholar for peer-reviewed, published research using the Inquisit Stop Signal Task (SST).
Vince, M. A. (1948). The intermittency of control movements and the psychological refractory period. British Journal of Psychology. General Section, 38, 149–157.
Lappin, J. S., & Eriksen, C. W. (1966). Use of a delayed signal to stop a visual reaction-time response. Journal of Experimental Psychology, 72, 805-811.
Logan, G. D. (1994). On the ability to inhibit thought and action: A user’s guide to the stop signal paradigm. In D. Dagenbach & T. H. Carr, Inhibitory processes in attention, memory, and language (pp. 189-239). San Diego: Academic Press.
Verbruggen, F., Logan, G. D., & Stevens, M. A. (2008). STOP-IT: Windows executable software for the stop-signal paradigm. Behavior Research Methods, 40(2), 479-483.
Verbruggen, Frederick, et al. “A Consensus Guide to Capturing the Ability to Inhibit Actions and Impulsive Behaviors in the Stop-Signal Task.” ELife, vol. 8, 2019, pp. eLife, Vol.8.
Bocharov, A. V., Savostyanov, A. N., Slobodskaya, H. R., Tamozhnikov, S. S., Levin, E. A., Saprigyn, A. E., Proshina, E. A., Astakhova, T. N., Merkulova, E. A., & Knyazev, G. G. (2021). Associations of Hyperactivity and Inattention Scores with Theta and Beta Oscillatory Dynamics of EEG in Stop-Signal Task in Healthy Children 7–10 Years Old. Biology (Basel, Switzerland), 10(10), 946-. https://doi.org/10.3390/biology10100946