Press the arrow direction. If it turns red, do not press. Measures motor inhibition.
The Stop-Signal Task (Logan, 1984) is the cleanest measure of motor inhibition.
Most trials are "go" - press the matching arrow. Rarely, the arrow turns red after a delay (the stop-signal delay, SSD) and you must NOT press.
SSD is adapted dynamically to keep stop success ≈ 50%, allowing computation of SSRT (Stop-Signal Reaction Time) - your inhibition latency.
SSRT under 220ms is excellent. Above 300ms suggests slow inhibition.
SSRT correlates with impulse control in clinical samples (ADHD, addiction, OCD).
Right inferior frontal gyrus activity scales with successful stops in fMRI.
Your ability to abruptly cancel a movement you have already begun.
This task isolates reactive inhibitory control: the braking process that aborts an action after it has been triggered. Because the red stop signal arrives only after the go arrow, your motor plan is already underway. A good result reflects a fast, efficient stop process that can overtake the still-running go response before it reaches the keyboard.
Unlike go/no-go, where you decide whether to respond before acting, here the response is committed and must be countermanded mid-flight, making it a purer test of cancellation. Real-world correlates include slamming the brakes when a light turns red, halting a swing at a bad pitch, or biting back a word already on its way out.
Keep going fast and honest, then let stopping improve on its own.
Treat the go arrows as the priority: respond quickly and accurately to every direction, as if no stop will come. Let the task tighten the gap between the arrow and the red signal automatically as you succeed. Focus on staying committed to going, and only raise difficulty once your go responses stay both fast and consistent.
The classic mistake is strategic slowing: waiting a beat to see if red appears. That inflates your go times, the task widens the delay to compensate, and your true stopping speed is hidden. If you find yourself near a coin-flip on stop trials, that is by design; do not treat failed stops as errors to avoid by going slower.
A lower stopping time means faster cancellation, but only if you played fairly.
The headline metric estimates how long your brain needs to cancel an action once the stop signal appears. Shorter is better. Because absolute values depend on your hardware and how the delay was tuned, treat your own baseline as the reference and watch the trend across sessions rather than fixating on a single number.
The estimate assumes you stopped roughly half the time and did not deliberately wait; obvious slowing or very lopsided stop accuracy makes it unreliable. Stopping speed is also state-dependent, drifting with fatigue, caffeine and time of day. A single score does not capture sustained attention, decision quality, or how well you hold a plan over longer stretches.