N-Back Test — free working memory game in your browser

A square lights up somewhere in a three-by-three grid, once every two seconds. Your job is to press MATCH whenever the square is in the same place it was N steps earlier. At 1-back that means the position just before. At 3-back it means three flashes ago, while two more have arrived on top of it, and that is where it stops being easy.

Every block holds exactly three matches, at every level, so a block is never a free pass. Clear one and N goes up by one. You get three lives for the whole run: a missed match costs one, and so does pressing MATCH when there was not one. Your score is the highest N you completed, so failing the first block scores zero. Free, instant, and it works the same on a phone as on a desktop.

How to play

• Watch which cell lights up. Press MATCH if it is the same cell as N flashes ago.
• Do nothing if it is not. Silence is an answer, and a correct one — five of the eight judgeable flashes in a block are not matches.
• The first N flashes of a block have nothing to compare to, so the button is disabled for them.
• A wrong press and a missed match both cost a life. Three and the run ends.
• On a keyboard, Space, Enter or M all press MATCH.
• Finish a block and N goes up. Your score is the highest N you finished.

Why 3-back is so much harder than 2-back

The jump does not feel like one extra item, and there is a reason for that. At 2-back you can hold the last two positions as a pair and swap them: the new one comes in, the older of the two goes out, and the pair is the whole task. At 3-back that trick stops working, because the item you are being asked about is no longer at either end of what you are holding. You have to keep a queue in order, know which end you are reading from, and update it every two seconds while a new item arrives. That ordering work is what makes it expensive, not the extra item.

The habit that helps most is to stop trying to memorise and start rehearsing. Name the cells as they arrive, in a steady rhythm, and let the oldest one drop off the front as the newest arrives. A verbal loop of three or four items runs almost by itself; a visual snapshot of the grid does not, and it decays in a couple of seconds. Naming positions in a fixed vocabulary — top left, middle, bottom right — is what turns a picture into something you can rehearse.

The second habit is to trust silence. Every block holds exactly three matches among its eight judgeable flashes, so five times out of eight the correct answer is to do nothing. Pressing MATCH because you are not sure costs exactly as much as missing one, and uncertainty pushes people towards pressing. If you cannot remember, do not press.

One honest caveat: n-back is a standard laboratory measure of working memory, and it is also the task most often sold as brain training. Whether practising it makes you better at anything other than n-back is disputed, and the evidence for transfer to general reasoning is weak. Treat this as a game with a score you can chase, which it is, rather than as a workout. If you want a memory test with a cleaner meaning, Number Memory measures digit span, which is the oldest and best-understood memory measurement there is, and Visual Memory asks you to hold a whole pattern at once instead of a moving window.

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