Brainbay guide
Dual n-back explained: how it works and what it does
In dual n-back you watch a square jump around a grid while hearing a stream of letters, and you say whether each one matches what came N steps earlier. It is a hard working memory workout. You will get much better at it with practice, but careful studies since 2008 find that the gains mostly stay with the task rather than raising intelligence.
What the n-back task is
The n-back task is a simple rule applied to a stream of items. Something appears, then something else, then something else. For each new item you ask one question: is this the same as the one N steps back?
- In 1-back, you compare each item with the one just before it.
- In 2-back, you compare it with the one two before, while keeping the one in between in mind.
- In 3-back, you hold three items and keep shifting them along as each new one arrives.
The task is usually credited to Wayne Kirchner, who published it in 1958 to study age differences in remembering "rapidly changing information". Since then it has become one of the most common working memory tasks in psychology and brain imaging.
What makes it hard isn't the number of items. It's the constant updating: every step you add one item, drop the oldest, and keep track of the order. That is the skill psychologists mean when they talk about updating working memory.
Worked example: 2-back
Letters appear one at a time: K, T, K, R, T, R.
The first two just show. The third, K, matches the K two back: match. R is compared with T: no match. T is compared with K: no match. The last R is compared with the R two back: match.
What makes it "dual"
Dual n-back runs two streams at the same time. In the version used by Jaeggi and colleagues (2008), a square appeared in one of eight places on the screen while a voice spoke a consonant through headphones, one pair every three seconds. You had to watch for position matches and listen for letter matches, each N steps back, and respond to each separately.
So on any step there are four possibilities: a position match, a sound match, both or neither. Doing two at once is far harder than either alone, which is part of why dual n-back gained a reputation as the toughest brain-training task around.
The 2008 study that started the craze
In 2008 Susanne Jaeggi, Martin Buschkuehl, John Jonides and Walter Perrig published a paper in PNAS with a striking title: "Improving fluid intelligence with training on working memory". Fluid intelligence is the ability to solve new problems, and it was widely thought to be hard to change.
About 70 young adults in Bern took part. Those in the training groups played an adaptive dual n-back for about 25 minutes a day, on 8 to 19 days. Everyone took a short, timed matrix reasoning test before and after. The trained groups improved more than the untrained controls, and the more days they trained, the bigger the gain. The authors called the effect "dose-dependent".
The idea that a free, simple game could raise intelligence spread quickly. Universities put out press releases, newspapers wrote it up, and a wave of dual n-back apps appeared. It also prompted many researchers to test the claim properly.
What later research found
To read the follow-up studies, two terms help:
- Near transfer: getting better at tasks similar to the one you trained, such as other working memory tests.
- Far transfer: getting better at something quite different, such as reasoning tests, school work or everyday life.
The 2008 claim was about far transfer. Here is what the larger and better-controlled work found.
| Study | What they did | What they found |
|---|---|---|
| Redick et al. (2013) | Young adults had 20 sessions of adaptive dual n-back, an active placebo game (visual search) or no practice, with many ability tests before, during and after | Both groups improved at their own task. No positive transfer to any of the ability tests, despite high statistical power |
| Melby-Lervåg & Hulme (2013) | Meta-analysis of 23 working memory training studies | Reliable short-term gains in working memory, not always lasting. No convincing evidence of transfer to reasoning, verbal ability, attention, reading or arithmetic |
| Au et al. (2015) | Meta-analysis of 20 n-back studies with a fluid intelligence test (including Jaeggi's group) | A small but significant positive effect on fluid intelligence. Melby-Lervåg and Hulme (2016) disputed the methods and found no convincing evidence in their reanalysis |
| Melby-Lervåg, Redick & Hulme (2016) | Meta-analysis of 87 publications and 145 comparisons | Near transfer to other working memory tests. No convincing far transfer when compared with an active control group |
| Soveri et al. (2017) | Multi-level meta-analysis of 33 randomised controlled n-back trials in healthy adults | A medium-sized gain on untrained n-back tasks; very small effects on other working memory tasks, fluid intelligence and cognitive control. No difference between single and dual n-back |
A pattern stands out. Studies that compared trainees with people who did nothing tended to find bigger effects than studies that gave the control group a different engaging task. Melby-Lervåg, Redick and Hulme (2016) found this difference for nonverbal ability, which suggests that some apparent "intelligence" gains came from expectations, motivation or simply getting used to being tested.
The fairest summary, from Soveri and colleagues (2017), is that much of the transfer from n-back training is task-specific. You get better at n-back, somewhat better at similar n-back tasks, and only slightly, if at all, better at anything else. A wider review of brain-training evidence (Simons and colleagues, 2016) reached the same conclusion for brain games in general. Our guide Does brain training work? covers that wider picture, and What does an IQ test measure? explains what the reasoning tests in these studies actually are.
How to play and how levels work
Most n-back games follow the same steps. Here is how the single version works in Brainbay:
- Watch the first N. The first few tiles just light up; there is nothing to compare them with yet.
- Compare each new tile. When a tile lights, ask: is it in the same place as the one N steps back?
- Answer. Tap Match or No match, or use → and ← on a keyboard. About three in ten tiles are matches, so "no" is the more common answer.
- Learn from slips. If you get one wrong, the game outlines where the tile N steps back actually was.
- Let the level adjust. A round lasts about a minute at your own pace. Two right answers in a row step the level up and one wrong steps it down, so you settle where you get most, but not all, right.
Levels in Brainbay's N-Back go from 1 to 12. Levels 1 to 3 are 1-back, 4 to 7 are 2-back, and 8 to 12 are 3-back. When you cross into a new N, a fresh block starts so you are never comparing across a change of rule.
Dual n-back apps usually work the same way, with two answer buttons (one for position, one for sound) and a fixed pace instead of your own.
Tips for getting better
- Say it under your breath. Many people keep a short rolling list, such as "top-left, middle, top-left", and drop the oldest each step.
- Group by position. Picture the grid as numbers 1 to 9 and rehearse the numbers rather than the pictures.
- Expect 2-back to feel hard. The jump from 1-back to 2-back is the biggest step for most people. Accuracy usually comes back after a few sessions.
- Don't chase "match". Matches are the minority, so answering "no" when unsure is usually the safer bet.
- Play when fresh. Tiredness shows up quickly in n-back. If your accuracy falls, stop for the day.
- Mix it up. Brainbay's daily workout puts N-Back alongside other memory games such as the sequence memory test and the chimp test, which keeps practice varied.
Questions
Does dual n-back increase IQ?
Probably not in any meaningful way. A 2008 study reported gains in fluid intelligence, but later controlled trials and meta-analyses found that most of the improvement stays with the n-back task itself and similar tasks, with very small or no gains on intelligence tests.
What is the difference between n-back and dual n-back?
Single n-back gives you one stream to track, such as positions on a grid. Dual n-back gives you two at once, usually positions you see and letters you hear, and you check each stream against N steps back separately. A meta-analysis of n-back training found no difference in transfer between the single and dual versions.
What is a good n-back level?
It depends on the version, the speed and how much you have practised, so there is no universal benchmark. Most people find 1-back easy and 2-back demanding at first. Compare yourself with your own past results rather than other people's.
How long should I practise n-back each day?
Short, focused sessions are enough. In the best-known study, people trained for about 25 minutes a day, but if you play for enjoyment and practice a few minutes is fine. Stop when your accuracy falls because you are tired.
Does Brainbay have dual n-back?
No. Brainbay's N-Back is the single, position version: a tile lights in a 3 by 3 grid and you answer Match or No match. N rises from 1 to 3 as you improve. It practises the same core skill of updating what you hold in mind.
Sources
- Kirchner, W. K. (1958). Age differences in short-term retention of rapidly changing information. Journal of Experimental Psychology, 55(4), 352–358.
- Jaeggi, S. M., Buschkuehl, M., Jonides, J. & Perrig, W. J. (2008). Improving fluid intelligence with training on working memory. PNAS, 105(19), 6829–6833.
- Redick, T. S. et al. (2013). No evidence of intelligence improvement after working memory training: A randomized, placebo-controlled study. Journal of Experimental Psychology: General, 142(2), 359–379.
- Melby-Lervåg, M. & Hulme, C. (2013). Is working memory training effective? A meta-analytic review. Developmental Psychology, 49(2), 270–291.
- Au, J. et al. (2015). Improving fluid intelligence with training on working memory: A meta-analysis. Psychonomic Bulletin & Review, 22, 366–377.
- Melby-Lervåg, M. & Hulme, C. (2016). There is no convincing evidence that working memory training is effective: A reply to Au et al. (2014) and Karbach and Verhaeghen (2014). Psychonomic Bulletin & Review, 23, 324–330.
- Melby-Lervåg, M., Redick, T. S. & Hulme, C. (2016). Working memory training does not improve performance on measures of intelligence or other measures of "far transfer". Perspectives on Psychological Science, 11(4), 512–534.
- Soveri, A., Antfolk, J., Karlsson, L., Salo, B. & Laine, M. (2017). Working memory training revisited: A multi-level meta-analysis of n-back training studies. Psychonomic Bulletin & Review, 24(4), 1077–1096.
- Simons, D. J. et al. (2016). Do "brain-training" programs work? Psychological Science in the Public Interest, 17(3), 103–186.