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N-back

Letters arrive one at a time; press when one matches the letter n steps back. 1-back, then 2-back, 3-back — and on, as far as you can hold.

  • Memory
  • Timed
  • Endless levels

How it plays

Each item stays a moment, then the next arrives. Press Match (Space, or the button) when the item is the same as the one n steps earlier. Pressing on a non-match costs as much as missing a match.

Levels raise n and then quicken the pace. In the settings, play positions on a 3×3 board instead of letters.

Keys

Space starts and skips ahead · 1–9 pick · Enter submits · Esc stops. On a phone, tap.

What it trains

N-back practice improves n-back performance. The large studies find it does not raise intelligence, and this page does not claim it does.

Learn

How to get better at n-back: the method, the techniques, what each new level asks of you, and the traps the wrong answers are made of.

Your approach to each question

  1. Note n before the run starts. The first n items can never be a match — there is nothing n back yet — so simply load them.
  2. Hold the last n items as a short loop you say under your breath: in 2-back, “B, K”. The first in the loop is the oldest, and it is the only one the next item is compared with.
  3. When an item arrives, compare it with the oldest in the loop. Press Match only if they are the same.
  4. Then update, match or not: drop the oldest, add the new item, and say the new loop. Skip one update and every comparison after it is against the wrong item.

Techniques and tricks

  • The rolling loop

    Keep exactly n items in a spoken loop and slide it one step with every item. Compare first, then slide.

    e.g. Letters B K B D K in 2-back: at the third, the loop is “B K” and B matches the oldest — press; the loop becomes “K B”. D against K: no; loop “B D”. K against B: no.

  • Ignore the near repeat

    A letter that repeats one step too soon or too late is not a match, however familiar it feels. Check it against the oldest in your loop, not against “I saw that recently”.

    e.g. In 2-back, B K K is not a match (that is 1-back), and neither is B K D B (that is 3-back).

  • Keypad numbers for positions

    With positions, give the nine squares the numbers of a phone keypad — 1 2 3 on top, 7 8 9 at the bottom — and run the loop as digits.

    e.g. Top-left, centre, bottom-right in 3-back is the loop “1 5 9”; the next square is compared with 1.

  • Two beats for a long loop

    From 4-back up, say the loop as two halves with a beat between: “B K — D F”. The oldest is always the first sound of the first half.

  • Expect matches

    About three in ten items after the first n are matches. If a long run goes by with no press, your loop has probably drifted; reload it from the last few items.

As the levels climb

  • Levels alternate between a bigger n and a faster pace. Each item shows for 1,500 ms at first, then 1,300, 1,100, 950 and 850 ms, with a 350 ms gap after each. Then only n rises, one a level, without end.
  • The run lengthens with n: 12 items plus 3 for every step back, so 1-back is 15 items and 5-back is 27.
  • The step from 1-back to 2-back is the big one. 1-back only asks whether this item is the one you just saw; 2-back is the first time you must keep and update a loop. Practise the loop slowly there before you push on.
  • At the fastest pace each item gives you 1.2 seconds, item and gap together, to compare and update. By then n is 5 or more: say the loop in two halves, and keep the rhythm going even through a miss.

Traps to avoid

  • The near repeat: the same letter n − 1 or n + 1 back. It tempts because it really did appear a moment ago. Only the oldest in the loop counts.
  • A press in the first n items: nothing there can match, so any press is a false one.
  • A false press costs as much as a miss: the run is scored as matches caught minus false presses, over the matches. With 5 matches, 4 caught and 1 false press scores 3 out of 5.
  • Falling out of step: after a press it is easy to forget to update the loop. Slide it every time, match or not.

How to practise

  • Try “Items” set to “Positions on a board” as well as “Letters”. The loop is the same skill, held as places instead of sounds.
  • Mouth the loop silently at first, lips moving, then move to inner speech once the slide is automatic.
  • After each run, read the working: “Matches at items 4, 7, 11”. Find the ones you missed or pressed wrongly, and check whether a wrong press was a near repeat.

Levels

Each question has a clock that comes from the work it asks for. There is no last level: at least one dial turns without end. Your level is judged on your last ten answers, every ten: 90% moves you up, below 80% moves you down, which holds most people near four in five right.

All of it is in the settings beside Start — how many answers a judgement looks at and how often it recalibrates, the thresholds, the time, which questions, how many options, and whether you see each verdict at once or review them together at the judgement. You can also jump to any level.

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