Does dual n-back training work? What the evidence actually says

The question behind the question

Does dual n-back improve performance on the exercise, on other memory tasks, or on reasoning in daily life? These are three different outcomes. Studies commonly find gains on the trained task. Evidence for broader benefits is less consistent, and does not justify promising an IQ increase or better grades. This guide separates task learning from transfer and explains the main studies, their differences and their limits.

Where the excitement started

In 2008, Susanne Jaeggi and colleagues published a study in PNAS in which healthy young adults trained on a dual n-back task for between eight and nineteen sessions. The trained groups improved on a matrix-reasoning test more than untrained controls, and the improvement appeared to scale with the amount of training. The paper was striking because fluid reasoning had long been treated as largely fixed in adults. It was widely covered, and it is the origin of most of what you will read online about n-back training today. Understanding what happened next matters more than the original result.

What the task is actually made of

A dual n-back trial gives you two things at once: a square lights up somewhere on a three-by-three grid, and a letter is spoken. Your job on each turn is to answer two independent questions. Is this position the same as the one N turns ago? Is this sound the same as the one N turns ago? Nothing is stored for you. To answer, you must hold a rolling window of the last N positions and the last N sounds, add the newest pair, discard the oldest, and keep the order intact while a new pair arrives every couple of seconds. That constant rewriting is the reason the task is tiring in a way that memorising a list is not. It is also why the research literature classes it as an updating task rather than a storage task.

What a better score can mean

A higher score can reflect several changes: familiarity with the response buttons, better timing, a new strategy, or improved performance at remembering and updating the sequence. The score alone cannot separate these explanations. This is why research includes untrained outcome tests and comparison groups. Difficulty and effort do not themselves prove that an exercise produces general cognitive benefits.

What transfer means, and why it decides everything

Researchers describe improvement in two ways. Near transfer means the gain shows up on tasks that closely resemble the trained one: another n-back variant, a similar updating task. Far transfer means the gain appears on something genuinely different, such as a reasoning test, reading comprehension or attention in daily life. Near transfer is comparatively easy to produce and easy to explain, because you are partly measuring familiarity with the task format. Far transfer is the claim that makes brain training commercially interesting, and it is the claim that has failed most often when tested carefully.

Near transfer: the part nearly everyone accepts

Training studies commonly report gains on the practiced n-back task, and some find transfer to similar n-back tasks. That does not guarantee progress for every person or every session. Nor does it identify the mechanism: familiarity, timing and strategy can contribute. Keep the task, scoring formula and settings comparable before interpreting a change in your own scores.

Far transfer: where the evidence thins out

In 2013, Redick and colleagues ran a larger study with an active control group, meaning the comparison group also did a demanding computer task rather than nothing at all. They found no improvement in fluid intelligence after n-back training. The same year, Melby-Lervåg and Hulme published a meta-analysis of working-memory training across many studies and reported short-lived near effects and no reliable far transfer. Later work by the same authors in 2016 reached a similar conclusion after pooling a larger set of studies and paying close attention to control-group design.

Why the meta-analyses disagree

In 2014, Au and colleagues pooled n-back studies specifically and reported a small positive effect on fluid intelligence. In 2016, Melby-Lervåg, Redick and Hulme pooled a broader set and reported essentially none. In 2017, Soveri and colleagues published a multi-level meta-analysis of n-back training and found clear improvement on n-back tasks themselves, some improvement on closely related tasks, and little beyond that. The disagreement is not mysterious. It comes from which studies are included, whether control groups were active or passive, and how outcomes are grouped. Small differences in those decisions move the headline number a lot.

The control group problem

An active control group also takes part in a comparison activity. It helps researchers test whether an apparent benefit is specific to the training rather than to participation, practice with tests or expectations. It cannot automatically eliminate every difference between groups. Random assignment, appropriate outcome measures, adequate sample size and reporting all planned outcomes also matter.

What the field concluded

In 2016, a group of researchers led by Daniel Simons published a long review in Psychological Science in the Public Interest examining brain-training claims as a whole. Their conclusion was that the evidence supports improvement on trained tasks, provides some support for closely related tasks, and does not support broad claims about improved cognitive performance in everyday life. That review is worth reading in full if you want the full picture rather than a headline, and it applies to commercial brain-training suites as much as to n-back specifically.

So is it worth doing?

It may be worth trying if you enjoy the exercise and want to track your performance on it. It is not an established route to higher IQ, better grades or better work performance. Dual N-Back is available on the App Store; consult the listing for current pricing and in-app purchases. Choose it for what it lets you practice, and judge whether that activity is useful or enjoyable for you.

What people report anecdotally, and how to read it

Personal accounts can suggest questions worth investigating, but they do not establish that training caused a change. Expectations, other changes in routine and ordinary variation are possible alternative explanations. A controlled study is better suited to distinguishing them. You can record what you notice without treating an individual experience as proof of a benefit for other people.

What would change the picture

Larger preregistered trials, well-matched active controls, follow-up after training and outcomes chosen before analysis could clarify remaining uncertainties. Claims that particular people benefit more also need direct evidence; an average near zero does not identify a subgroup of responders. Until stronger evidence is available, keep conclusions tied to the tasks and outcomes actually measured.

A reasonable way to think about it

An exercise can be enjoyable without producing a measurable gain in general intelligence. You may value the challenge and the opportunity to track a skill. Those are personal reasons to practice, distinct from scientific claims about transfer. Treat any promise of a guaranteed cognitive transformation as a claim that needs strong independent evidence.

Training without fooling yourself

Compare accuracy at the same level and with the same settings, and review several sessions rather than one personal best. Record relevant changes in conditions without assuming they caused a result. A higher level alone does not describe the pattern of hits, misses and false alarms. Use the scoring guide to interpret those outcomes, and keep progress on the exercise separate from untested benefits elsewhere.

Further reading

• Jaeggi, Buschkuehl, Jonides & Perrig (2008), Improving fluid intelligence with training on working memory, PNAS
• Redick et al. (2013), No evidence of intelligence improvement after working memory training, Journal of Experimental Psychology: General
• Melby-Lervåg & Hulme (2013), Is working memory training effective? A meta-analytic review, Developmental Psychology
• Au et al. (2015), Improving fluid intelligence with training on working memory: a meta-analysis, Psychonomic Bulletin & Review
• Melby-Lervåg, Redick & Hulme (2016), Working memory training does not improve performance on measures of intelligence or other far transfer, Perspectives on Psychological Science
• Soveri et al. (2017), Working memory training revisited: a multi-level meta-analysis of n-back training studies, Psychonomic Bulletin & Review
• Simons et al. (2016), Do “Brain-Training” Programs Work?, Psychological Science in the Public Interest