N-Back Lite — Match the Letter From N Steps Ago
Letters flash one at a time. Press Match when the current letter is the same as the one shown N steps earlier.
How to play
- Pick a level: 1-back (easy) up to 3-back (hard).
- Click Start — letters flash one at a time, about every 2 seconds.
- Press the MATCH button (or Space) when the letter equals the one N steps ago.
- Do nothing if it isn't a match — the game auto-advances.
- After 20 trials you see hits, misses, false alarms and overall accuracy.
The N-back is a classic working-memory task. Letters appear one at a time. Whenever the current letter matches the one shown N positions earlier, press Match. At 2-back you compare with the letter from two steps ago — which means holding a moving window of letters in mind. It's deceptively demanding.
How it works
N-Back is a working-memory task widely used in cognitive psychology research. In this lite version, letters appear one at a time on screen. Your job is to press the Match button whenever the current letter is the same as the letter that appeared exactly N steps earlier in the sequence. For example, in 2-back, if the sequence so far is B, K, R, K, you press Match on the second K because it matches the letter two positions back (also K).
The task is harder than it sounds because you must simultaneously remember the recent history, update it with each new letter, and decide whether a match has occurred — all under time pressure. The N parameter controls difficulty: 1-back is straightforward, 2-back requires genuine effort for most people, and 3-back is challenging even for trained participants.
N-Back training has been studied as a method for improving fluid intelligence and working-memory capacity, though the evidence for transfer to non-trained tasks is mixed. What is clear is that the task itself is a demanding and measurable workout for the mental systems that hold and manipulate recent information.
Use N-Back Lite for a focused 5-minute mental workout, to measure your working memory under controlled conditions, or to explore how attention and memory interact when demands exceed comfortable capacity.
Worked example
Play one round of 2-back
- The game starts at N=2. Letters flash: M appears — just watch.
- Q appears — still just two letters in, no match possible yet.
- M appears again — this letter matches the letter two steps back (the first M). Press Match.
- T appears — the letter two steps back was Q. T does not match Q. Do not press.
- Continue, pressing Match only when the current letter equals the one shown exactly 2 steps ago.
Your hits (correct matches), misses (missed matches), and false alarms (pressed when no match) are tallied at the end.
Common mistakes to avoid
- Tracking the wrong position — remembering what appeared 1 step ago instead of N steps ago when N is 2 or 3 is a very common error that tanks accuracy.
- Pressing Match too eagerly when a letter simply looks familiar rather than matching the letter exactly N steps back.
- Not updating your memory buffer at each step: you must mentally shift your remembered window forward with every new letter, dropping the oldest and adding the newest.
Key terms
- N-Back
- A continuous performance task where the stimulus N steps earlier must be matched to the current stimulus; N is the level of working memory demand.
- Working memory
- The cognitive system that holds a small amount of information in an accessible state for use in ongoing mental tasks; N-Back directly stresses its capacity and updating function.
- False alarm
- Pressing Match when the current letter does not match the letter N steps back; a measure of impulsivity or confusion rather than genuine memory.
Frequently asked questions
- What does N-back train?
- The N-back task is widely used in cognitive research to engage working memory and fluid attention. You hold a rolling sequence of items in mind and continually update it.
- How do I score well?
- Press Match only when the current letter truly equals the one N steps back. Hits raise your score; missing a real match or pressing on a non-match both hurt your accuracy.