Scan a grid of letters. Click every instance of the target letter. Tests sustained attention + scan accuracy.
The cancellation paradigm dates to Bourdon (1895) and remains in clinical use as the d2 test.
You scan a dense grid for targets and mark them. Misses + false alarms = attention errors.
It's a visual analog of go/no-go: you go on targets, withhold on distractors.
Used to assess ADHD, neglect, and visual attention deficits.
Cancellation tasks are sensitive to right parietal damage (visual neglect).
Performance plateaus at adolescence and degrades gracefully with healthy aging.
It isolates how efficiently you sweep a cluttered field and catch every target.
This task taps selective visual attention paired with systematic search. To find every target letter, you must hold the target template in mind while suppressing visually similar distractors. A strong result reflects an organised scan path and stable focus across the whole grid, so the score captures both detection accuracy and your ability to sustain that effort to the last row.
Unlike a reaction-time test that probes a single response, cancellation rewards methodical coverage over raw speed, and unlike visual search experiments with a few items, it forces you to track which cells you have already checked. The everyday correlate is proofreading or scanning a timetable: spotting the one entry that matters among many that look almost identical.
Build a fixed search route first, then push speed without breaking it.
Start with a single target and a target that looks distinct from its neighbours, then move toward distractors that share strokes (such as cancelling E among F and B). Adopt one consistent path, usually left to right, top to bottom, and finish every row before glancing ahead. Add a second target letter or a denser grid only once you are clearing easy boards with no misses.
The common failure is abandoning your route to chase letters that pop out, which leaves scattered gaps you never revisit. Resist jumping around the grid. If your misses cluster on one side or in the final rows, slow down there deliberately rather than speeding up everywhere; lapses usually come from fading vigilance, not from poor eyesight.
Weigh hits against misses and false marks together, not time alone.
Two numbers matter: omissions (targets you missed) and commissions (non-targets you marked). Clearing the grid quickly means little if omissions are high. Rather than chasing a fixed benchmark, watch your own trend across sessions on the same difficulty: fewer omissions at a steady or faster time signals real improvement, while creeping false marks suggests you are trading accuracy for pace.
The score is highly state-dependent: fatigue, caffeine, screen glare and time of day all shift it, so judge yourself on rested averages, not one bad run. A clean grid here does not certify attention in general; it reflects this specific scanning demand and says nothing about memory, reasoning, or how you cope with auditory or moving distractions.