How long and how often to train dual n-back: what the studies actually did

What the original study did

The 2008 study by Jaeggi and colleagues that made dual n-back famous trained four groups for 8, 12, 17 or 19 sessions of about 25 minutes each, on working days. The task adapted its level to each participant, moving up after high accuracy and down after low accuracy, which is the same principle used by most dual n-back apps today.

What later research found

The 2008 paper reported that gains on a fluid-intelligence test grew with the number of sessions. Later work is more cautious. Meta-analyses published in 2013 and 2016 by Melby-Lervåg and colleagues found that working-memory training reliably improves performance on tasks close to the one trained, while transfer to broader abilities was small or absent once study quality was accounted for. A 2015 meta-analysis by Au and colleagues, focused on n-back training in healthy adults, reported a small positive effect on fluid-intelligence measures. A 2013 study by Redick and colleagues with a placebo control group found no transfer. In short: expect to get better at the task itself; treat anything beyond that as an open question.

A schedule you can keep

If you want a plan that resembles the research, aim for sessions of 15 to 25 minutes, four or five days a week, for several weeks. If that is too much, a shorter daily session you actually complete beats an ambitious plan you drop after ten days. Consistency matters more than any single long session.

Let the level move both ways

Adaptive training means the level should go down as well as up. A drop after a tired day is information, not failure. Keep conditions similar when you compare sessions: same time of day, same volume for the letters, no music. Dual N-Back shows your accuracy per session so that you can compare like with like.

What to expect, and what not to

Progress on dual n-back typically shows as a higher stable N and fewer errors on both streams. The app does not measure IQ, and this guide does not claim that training raises it. Use the exercise for what it demonstrably offers: a demanding, measurable working-memory task that you can practise in short, regular sessions.

Further reading

• Jaeggi, Buschkuehl, Jonides & Perrig (2008), Improving fluid intelligence with training on working memory, PNAS
• 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
• Redick et al. (2013), No evidence of intelligence improvement after working memory training, Journal of Experimental Psychology: General
• Melby-Lervåg, Redick & Hulme (2016), Working memory training does not improve performance on measures of intelligence or other measures of “far transfer”, Perspectives on Psychological Science