What does the Go/No-Go task measure?

The Go/No-Go task measures response inhibition — the ability to suppress a planned or automatic motor response. It also captures sustained attention and processing speed, but its defining feature is the No-Go trial, on which the participant must withhold a response that they would otherwise make automatically.

What is the difference between commission and omission errors?

A commission error is responding to a No-Go stimulus when you should have withheld — a failure of inhibition. An omission error is failing to respond to a Go stimulus when you should have — usually a lapse of attention. Commission errors are the headline metric: they index inhibitory control, while omission errors index vigilance.

How is the Go/No-Go task related to ADHD?

Studies consistently show higher commission error rates and more variable reaction times in people with ADHD, which fits the diagnostic emphasis on impulsivity and inattention. The task is a research and screening tool, however, not a diagnostic test on its own — clinical diagnosis requires a structured interview and behavioural history.

Which brain region is most involved in Go/No-Go performance?

The right inferior frontal gyrus and the pre-supplementary motor area, both part of the prefrontal cortex, are most strongly activated when withholding a response. The basal ganglia contribute through the indirect motor pathway. Damage or developmental immaturity in these regions is associated with higher commission error rates.

Can a single online Go/No-Go test diagnose anything?

No. A single online run gives a useful snapshot of your current inhibition and attention, but absolute scores depend on hardware latency, the proportion of No-Go trials, your alertness, and your motivation. Self-tests are best used to track personal trends over time, not to draw clinical conclusions.

Go/No-Go Test Explained: What It Measures and Why to Train It

Most reaction-time tests reward one thing: respond as fast as you can. The Go/No-Go task flips that goal on its head. Sometimes you should respond, and sometimes you absolutely should not — and the harder you trained yourself to be quick, the harder it is to stop. That tension is exactly what the test is designed to expose. It measures response inhibition: the ability of the brain to cancel an action that is already in motion.

Response inhibition is a core component of executive function. It is what stops you from blurting out the wrong word, from reaching for the second cookie, from pressing send on the message you wrote at midnight. Researchers in psychology, neuroscience, and clinical diagnostics have spent the last forty years using the Go/No-Go paradigm to quantify how good any given person is at that braking action — and how it changes with age, fatigue, and disorders like ADHD.

Where the Task Comes From

The conceptual roots reach back to Franciscus Donders, a Dutch physiologist who in 1868 introduced the idea of subtracting reaction times from different conditions to isolate mental processes. His c-reaction — respond to stimulus A, ignore stimulus B — is the direct ancestor of the modern Go/No-Go.

The contemporary form was popularised in the 1980s by neuropsychologists studying frontal lobe lesions. Patients with damage to the right inferior frontal gyrus could see the No-Go cue and report it correctly afterwards, yet still pressed the button on a large fraction of trials. The dissociation between knowing and doing made the task an unusually clean window on motor inhibition. From there it spread into developmental psychology, addiction research, and ADHD assessment, where it has been one of the most heavily cited cognitive paradigms in the literature.

How a Trial Works

A typical Go/No-Go session presents a long stream of stimuli, one at a time. Each stimulus belongs to one of two categories:

Go trials (usually 70–80% of the total): respond as quickly as possible.
No-Go trials (the remaining 20–30%): do nothing. Withhold the response.

The imbalance is deliberate. With Go trials in the majority, the participant's hand starts to anticipate every stimulus — pressing becomes the default. The occasional No-Go trial then catches that prepotent response and forces the brain to stop it. If the No-Go trials were 50% of the total, the test would just be a choice reaction task and would no longer isolate inhibition.

Inter-stimulus intervals are short, often under one second, which compresses the time window for inhibitory control and makes errors more likely. The test usually runs for a few minutes — long enough for fatigue and attention drift to surface as additional signal.

What the Brain Is Doing

Functional MRI studies consistently localise No-Go activity to two regions of the prefrontal cortex: the right inferior frontal gyrus (rIFG) and the pre-supplementary motor area (pre-SMA). Both project into the basal ganglia, where the indirect motor pathway acts like a brake on movement commands queued in the motor cortex.

When a No-Go cue appears, the rIFG fires within roughly 150 ms, the pre-SMA shortly after, and the basal ganglia issue an inhibitory signal that races the already-prepared motor command. If the brake wins, the response is successfully cancelled. If the motor command wins, the finger presses anyway — that is what a commission error looks like at the millisecond level.

This is also why commission errors are so informative. Reacting fast on Go trials is a function of perceptual speed and motor readiness, traits shared across many tasks. Successfully not reacting on No-Go trials is much narrower: it specifically taxes the prefrontal-basal-ganglia inhibition circuit.

Reading Your Results: Commission and Omission Errors

Two error types matter, and they tell very different stories.

Commission errors are responses on No-Go trials. They are the primary index of inhibitory control. A high commission rate means your motor system is winning the race against your prefrontal brake — you are impulsive on the task, regardless of how attentive you feel. In typical adults, commission rates on standard versions of the test sit around 10–25%. Above 30% on a serious attempt usually points to an inhibition deficit, fatigue, or a deliberately speed-biased strategy.

Omission errors are missed responses on Go trials. These are usually attention failures: your mind wandered for a second, the stimulus passed, and you did nothing. A low omission rate (under 5%) is the norm. Higher rates indicate vigilance problems rather than inhibition problems.

A useful third metric is reaction-time variability on correct Go trials. Stable reaction times suggest stable attention; high variability — a mix of very fast and very slow responses — is a robust marker of inattention and is often elevated in ADHD samples. Mean Go reaction time matters less in isolation, because participants can trade speed for accuracy and vice versa.

How Performance Changes with Age

Inhibitory control matures slowly. Children make many more commission errors than adolescents, who in turn lag adults. This tracks the protracted development of the prefrontal cortex, which is one of the last regions of the brain to fully myelinate, often not finishing until the mid-twenties.

Performance on Go trials follows the general age curve for reaction time: peak speed in the late teens and twenties, gradual slowing through middle age, more pronounced slowing past 65. Inhibition itself, measured by commission errors, is more resilient than raw speed — older adults are slower but often no more impulsive than younger ones, provided they accept the slower pace.

Connection to ADHD Research

The Go/No-Go task is one of the most frequently used paradigms in ADHD research. Across hundreds of studies, three findings recur:

Commission error rates are higher in groups with ADHD diagnoses than in matched controls.
Reaction-time variability is higher, even when mean reaction time is comparable.
Stimulant medication (methylphenidate, amphetamines) reduces both commission errors and variability in many participants, with the effect appearing within an hour of dosing.

These results are robust at the group level, but the overlap between distributions is large. Plenty of people without ADHD score in the impulsive range on a single test, and plenty of people with ADHD score normally, especially under the novelty boost of doing a test for the first time. Clinicians use the Go/No-Go as one input among many — alongside structured interviews, behavioural questionnaires, and observation — never as a stand-alone diagnostic.

Limits of the Test as a Self-Assessment

An online Go/No-Go is a useful tool for personal tracking, but the absolute numbers come with caveats:

Hardware latency inflates Go reaction times by roughly 10–50 ms depending on your monitor refresh rate and input device, the same problem as in any browser-based reaction-time test.
The Go/No-Go ratio changes the difficulty. A version with 20% No-Go trials produces more commission errors than one with 50%. Compare scores only across the same version of the test.
Strategy matters. If you respond cautiously and slowly, your commission rate drops and your Go reaction time rises. If you push for speed, commissions climb. The combination of speed and accuracy is what reflects underlying inhibition, not either number alone.
State, not trait. Sleep, caffeine, stress, and time of day swing performance noticeably. Take several runs across different conditions before treating any single score as your true baseline.

Why Train Inhibition?

Direct training on the Go/No-Go task itself shows modest, narrow improvements — you get better at the test, with limited transfer to unrelated impulsivity. The more useful framing is diagnostic: a Go/No-Go session is a quick mirror that shows you how impulsive and attention-stable you are right now, under defined conditions. People recovering from concussion use it to monitor cognitive return to baseline. Athletes and shift workers use it to flag cumulative fatigue. Anyone curious about their own attention can use it to compare a well-rested morning against a sleep-deprived evening and see the effect in numbers.

Try a session yourself with our Go/No-Go Test. It runs entirely in your browser, stores your history locally, and reports both Go reaction time and accuracy so you can watch your inhibition score evolve over time.