The Science of Brain Training: Does Dual N-Back Really Work? [2026 Research]

Does Brain Training Really Work?

"Brain training makes you smarter"—is this claim true? Or is it marketing without scientific basis?

What You'll Learn

The scientific debate among researchers about brain training
Current evidence from meta-analyses
What's certain and what's debated about Dual N-Back
A scientifically sound approach to brain training

The brain training industry is rapidly growing, but scientists remain divided on its scientific basis. This article examines brain training effectiveness from a scientific perspective, focusing on Dual N-Back.

The Scientific Debate: Two Open Letters

The 2014 "Brain Training Skeptics" Letter

In 2014, over 70 cognitive scientists signed an open letter claiming "there's no scientific basis for brain training."

Skeptics' Arguments

Scientific evidence supporting brain training games is insufficient
Training effects are limited to trained tasks and don't transfer to daily life
Brain training companies exaggerate science in their marketing

The Response: 2 Months Later

However, 2 months later, a group of over 100 scientists published a rebuttal letter.

Supporters' Arguments

Numerous studies demonstrate cognitive training effects
Critics overemphasize selective negative findings
Working memory training effects are confirmed in multiple studies

This debate continues today, with no scientific consensus reached.

Evidence from Meta-Analyses

While individual study results vary, meta-analyses combining multiple studies provide more reliable evidence.

Brain Training Overall (2020 Meta-Analysis)

A 2020 meta-analysis of 16 studies (1,543 participants) found:

Cognitive Function	Effect Size (SMD)	Statistical Significance
Processing Speed	0.40	✓ Significant
Working Memory	0.21	✓ Significant
Executive Function	0.21	✓ Significant
Verbal Memory	0.12	✓ Significant
Attention	-	✗ Not significant
Visuospatial	-	✗ Not significant

Dual N-Back Meta-Analyses

Au et al. (2014)

Analyzed 20 studies and reported small-to-moderate effects on fluid intelligence (equivalent to 3-4 IQ points).

Soveri et al. (2017)

Confirmed medium effects of N-Back training on untrained N-Back tasks and small effects on related working memory tasks.

Melby-Lervåg (2013)

Confirmed that working memory training improves working memory itself, but noted limited transfer effects.

Comparative Study (2021)

Dual N-Back showed superior transfer effects compared to the Method of Loci memory technique.

Criticisms and Rebuttals: What's Being Questioned

Criticism 1: Control Group Problems

Passive vs Active Control Groups

Studies comparing to passive control groups (doing nothing) may overestimate effects.

Control Group Type	Reported Effect Size
Passive control	d = 0.38 (medium)
Active control	d = 0.00 (no effect)

Critics argue that much of the effect comes from placebo effects or motivational differences.

Rebuttal: Au et al. (2015) argue that control group type doesn't moderate effect sizes.

Criticism 2: Limited Transfer Effects

Two 2012 studies failed to replicate Jaeggi et al. (2008) findings.

Training effects were limited to trained tasks
No transfer to other cognitive tests was confirmed

Criticism 3: Replication Issues

Some researchers suggest observed cognitive improvements may result from task familiarization rather than genuine intelligence enhancement.

What's Scientifically Certain vs. Still Debated

✅ Scientifically Certain

1
Working Memory Improvement
Consistently confirmed in multiple meta-analyses. Even critical researchers acknowledge this.
2
Processing Speed Improvement
This domain shows the largest effect size (0.40) in overall brain training meta-analyses.
3
Improvement on Trained Tasks
Practice Dual N-Back and you get better at Dual N-Back. This is undisputed.
4
Attention Control Improvement
Improvements in focus and attention switching are reported in multiple studies.

❓ Still Being Debated

Topic	Supporters' View	Critics' View
IQ Improvement	Effects equivalent to 3-4 IQ points	Effects exaggerated due to control group issues
Daily Life Transfer	Many report effects in conversation and work	Scientifically measured transfer effects are small
Effect Duration	Effects continue after training stops	Long-term follow-up studies are lacking
Age Differences	Larger effects in older adults	Limited effects in healthy adults

Dual N-Back's Scientific Standing

For detailed benefits, see Dual N-Back Benefits and Effects. Here we summarize the scientific evaluation.

Why Dual N-Back Is Studied

Working Memory Load

The dual visual-auditory task effectively loads working memory

Adaptive Difficulty

N-level adjusts based on performance, maintaining optimal difficulty

Standardized Protocol

A standard training method comparable across studies

Accumulated Research

Effects have been examined in numerous studies since 2008

The 2021 Comparative Study

A 2021 study published in Scientific Reports compared Dual N-Back with the Method of Loci (memory technique).

Result: The Dual N-Back group showed superior transfer effects on untrained working memory tasks.

A Sound Approach to Brain Training

Based on scientific evidence, how should we approach brain training?

What NOT to Do

❌ Expect dramatic IQ increases
❌ Think brain training alone will improve all cognitive functions
❌ Expect immediate effects

A Scientifically Sound Approach

✅ Approach it as working memory and attention control training
✅ Continue with appropriate duration and frequency (20 min/day, 4-5 times/week, 4+ weeks)
✅ Combine with exercise, sleep, meditation, and other cognitive enhancement methods
✅ Avoid excessive expectations and aim for steady improvement

Future Research Directions

Brain training research is ongoing. Future studies are expected to clarify:

Long-term effects - How long do effects persist after training stops?
Individual differences - Who benefits most (age, baseline ability, etc.)?
Optimal protocols - What training methods are most effective?
Neural mechanisms - What brain changes occur?

Frequently Asked Questions (FAQ)

Q: Does brain training really work?

There are scientifically confirmed effects and effects still being debated. Improvements in working memory and processing speed have been confirmed in multiple meta-analyses. However, effects on overall IQ and transfer to daily life remain controversial.

Q: What scientific evidence supports Dual N-Back?

A 2014 meta-analysis of 20 studies reported effects equivalent to 3-4 IQ points on fluid intelligence. A 2021 study showed Dual N-Back demonstrated superior transfer effects compared to memory techniques. Working memory improvements are consistently confirmed.

Q: What are the criticisms of brain training?

Three main criticisms: (1) Control group problems (passive control groups may overestimate effects), (2) Limited transfer effects (effects beyond trained tasks are small), (3) Replication issues (some findings haven't been replicated).

Q: What was the 2014 scientists' open letter about?

In 2014, over 70 scientists signed an open letter stating there's no scientific basis for brain training. However, 2 months later, over 100 other scientists published a rebuttal claiming evidence for brain training effects is plentiful. This debate continues today.

Q: Is Dual N-Back worth doing?

Working memory improvement is scientifically certain. Effects on IQ are debated but not zero. If 20 minutes of daily training can improve focus and attention control, it's worth trying. Don't have excessive expectations, but there's also virtually no risk.

For more questions, see Dual N-Back FAQ.

Summary

The scientific debate around brain training is complex, but here's what we can say now:

Certain: Improvements in working memory, processing speed, and attention control
Likely: Some transfer effects to related cognitive tasks
Debated: Effects on overall IQ, generalization to daily life, long-term effects

Dual N-Back is one of the most scientifically studied brain training methods, and at minimum, it's certainly effective as working memory training.

Expecting "magical IQ increases" isn't realistic, but continuous training to improve some cognitive functions is scientifically supported.

If you want to start Dual N-Back, see How to Start Dual N-Back.