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The reaction time test: go on green, hold on red

16 August 2026 · 4 min read

Reaction tests look simple. A circle turns green, or a lamp flashes, or a tone sounds. You respond. Then a red one appears, or a pale flicker, and you are supposed to sit on your hands.

People train the first half and skip the second. That is how you get fast and dangerous.

Go / no-go is the point

A driver who is slow to a genuine signal is a problem. A driver who treats every flicker as a genuine signal is also a problem. The test is built to catch both. If you only watch your best time, you are watching the wrong number.

Some batteries use a visual flash. Some add sound. Some want you to ignore near-misses that look almost like the target. Read the live instructions. The family is the same: wait, go, withhold.

How people talk themselves into errors

  • Anticipation. You click because it “must be soon”. It was not.
  • Clicking again after a miss, as if to make up for it. The next trial is a new trial.
  • Tight shoulders and a hovering finger. If you are already halfway to the click, red will take you with it.

How to practise

Practise mixed trials, not a run of pure greens. Watch false alarms as closely as misses. Sit as you will sit on the day: same hand, phone away, no soundtrack.

A practice score out of 100 is a training signal. It is not a pass. Use it to see if you are still responding to red. That is the useful question.

Independent practice notes. Not an official test, and not affiliated with train operators or RSSB.

Practise on the web

Further reading

OverviewTrain driver psychometric tests, explained6 minVigilanceThe vigilance test (WAFV)5 minConcentrationGroup Bourdon, the concentration test4 minVisual searchThe visual search test4 min
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Made in the United Kingdom. Practice scores are not official assessment results.