Proofread: Focus
Find specific letters
About this trainer
Proofread: Focus is a cancellation task: the screen fills with a dense field of similar-looking characters, and your job is to scan it line by line and tap only the targets that match a given rule while ignoring everything else. It is the digital version of a proofreader hunting for one specific letter, working as fast as you can without missing hits or tapping the wrong symbol.
What it develops
It trains selective and sustained attention, visual scanning speed, and concentration under time pressure, plus the impulse control to keep skipping the look-alike distractors instead of tapping them.
History
Cancellation tasks are one of the oldest tools in attention research. The French psychologist Benjamin Bourdon used letter-cancellation in the 1890s to study visual discrimination, Toulouse and Piéron published their version in 1904, and the format later spread through clinical neuropsychology as a quick paper-and-pencil measure of attention, scanning, and visual neglect.
Who created it — and when
There is no single inventor; the exercise comes from the cancellation-task tradition started by Bourdon (1890s) and Toulouse-Piéron (1904). The best-known modern descendant is the d2 Test of Attention, created by the German psychologist Rolf Brickenkamp and first published in 1962 (later revised as the d2-R), which this kind of game most closely resembles.
How to train
Sweep in a fixed reading pattern, left to right and top to bottom, rather than jumping around the field at random. Lock the target rule in mind before you start so you are not re-reading it mid-line, and aim for a steady rhythm where accuracy comes first and speed builds on top of it. When you notice yourself slowing or missing hits, that fatigue point is exactly the edge worth pushing a little.
How long to practise
Short, frequent sessions work best: roughly 5 to 10 minutes a day, a few times a week. Cancellation work is tiring for the attention system, so stop when accuracy starts to drift rather than grinding through a long block.
Evidence base
Evidence is strongest for exactly what you would expect: with practice you get faster and more accurate at visual search and cancellation tasks themselves, which is why the d2 and similar tests are trusted clinical measures of attention and concentration. Claims that this kind of drill produces broad gains, raises general intelligence, or prevents cognitive decline are far weaker; in cognitive training such far transfer is famously hard to demonstrate and mostly fails to hold up, so treat the grand promises with caution.
Recommendations
Chase clean accuracy first and let speed follow; a fast run riddled with wrong taps trains the wrong habit.
FAQ
Is it better to go fast or to be accurate?
Accuracy first. The skill being trained is filtering out distractors without errors, so a slower clean pass beats a fast one full of wrong taps. Speed grows naturally once your accuracy is solid.
Will this make me more focused in everyday life?
It reliably makes you better at visual search and cancellation tasks, and many people find the focused, scan-without-drifting rhythm pleasant to practise. But broad transfer to unrelated tasks is not well proven, so treat it as targeted attention practice, not a general focus cure.
How is this different from a Schulte table?
A Schulte table has one item of each kind and you find them in a set order, training the field of view around a fixed gaze. Here many items look alike and you must judge each one against a rule, which leans more on filtering distractors and resisting the urge to tap look-alikes.
Variants
Variants change the target rule (one letter, a pair of letters, a shape or colour, or a character only when it carries a specific mark), the density and size of the field, whether the clock is fixed or self-paced, and whether distractors look more or less like the target to make the search harder.