Cancellation Task: Sweep the Field, Miss Nothing
A cancellation task drops you into a dense field of characters and asks you to cross out every instance of one target. It's deceptively simple: the difficulty isn't seeing any single target, it's covering the whole field without losing track of where you've already been. That's why what you miss says more than what you find. Free to play, scored instantly, no sign-up required.
Not a diagnostic tool. Cancellation tasks come from neuropsychology, where standardized versions help screen for conditions such as hemispatial neglect. This is a simplified version for practice and self-tracking — it is not validated or normed, and it cannot screen for or diagnose anything.
A quiet round of Cancellation Task — Letters. When you start, everything else fades — just you and the task.
No sign-up needed. Press Esc to exit anytime.
Tip
A missed target costs twice what a wrong tap does. A wrong tap only adds to the total you are measured against; a miss adds to that total and takes one off your count as well, so it lands twice as hard. That is the arithmetic reason thoroughness beats speed here, and it is exact rather than a figure of speech.
Everything here is free
Every test, every difficulty, no limit and no account. If it is useful to you, you can chip in — entirely optional, and nothing changes either way.
How to play
- A target character is named at the top — every copy of it is hidden in the grid below.
- Tap each one you find. Wrong taps count against you.
- Work systematically — row by row beats hunting at random.
- Tap Done when you think you have them all. Missed targets are part of your score.
Cancellation Task tips
Ways to play it better — each one comes from how this version actually scores, not from general advice about concentration.
A missed target costs twice what a wrong tap does
A wrong tap only adds to the total you are measured against; a miss adds to that total and takes one off your count as well, so it lands twice as hard. That is the arithmetic reason thoroughness beats speed here, and it is exact rather than a figure of speech.
Finish the row before you drop down
Misses cluster at the point where a sweep was interrupted and picked up again a row or two off. Committing to one direction and completing each row is worth the small amount of speed it costs, given what a miss is priced at.
Choose letters or symbols before your first tap
The switch locks the moment the round is under way — deliberately, since swapping the field mid-round would leave the visible timer and the scored time disagreeing. If you want the symbol version, take it before you start.
One caveat worth knowing: a change of strategy moves your score for reasons that have nothing to do with attention. Your dashboard reads each session against your own recent ones, so if you adopt something from this list, give it a few sessions before reading anything into the trend.
Frequently asked questions
What does a cancellation task measure?+
Visual scanning efficiency and selective attention — how quickly and how systematically you can sweep a cluttered field for one specific thing. Because you have to cover the entire field rather than stop at the first hit, it also draws on keeping track of where you've already looked.
How is this different from a visual search test?+
A visual search test gives you one target per round and ends the moment you find it, so it measures how fast you can spot a single item. A cancellation task asks you to exhaust the whole field, so it also measures whether your scanning has a strategy. Missing three targets in a corner you never swept is a different failure from being slow.
Should I go fast or be thorough?+
Both count, but not equally. The score multiplies your accuracy by your speed, and a missed target costs exactly twice what a wrong tap does — a wrong tap only adds to the total you are measured against, while a miss adds to that total and takes one off your count as well. So racing through and leaving half the field unswept scores worse than a steady, complete sweep.
Is this a medical or diagnostic test?+
No. Cancellation tasks come from neuropsychology, where clinicians use standardized versions to screen for conditions such as hemispatial neglect after a stroke. This is a simplified version built for practice and self-tracking. It is not validated, not standardized, and cannot screen or diagnose anything. If you have concerns about your attention or vision, talk to a professional.
Where this fits
- Processing Speed Test — Exhaustive scanning. Unlike the others you cannot stop at the first hit, so it also measures whether your sweep has a strategy — what you miss says more than what you find.
- Mind Wandering — Missing targets in a region you never swept is what a drift looks like on paper. Misses are more telling than wrong taps here.
Try another challenge
Finding things fast — closest to this one
Holding a rule under pressure
Stroop Test · Simon Effect Test · Flanker Test · Go/No-Go Task
Staying with it
Sustained Attention to Response Task · Mackworth Clock Test · Psychomotor Vigilance Task
Keeping up with change
Multiple Object Tracking · Change Blindness Test · Task Switching Test