Can Dual N-Back Increase IQ? A Scientific Analysis [2026]

Can Dual N-Back Really Increase Your IQ?

You've probably heard claims that Dual N-Back training can boost IQ. In this article, we examine the scientific evidence to determine what research actually says about Dual N-Back and intelligence improvement.

What You'll Learn

Major studies linking Dual N-Back to IQ improvement
Details of Jaeggi's groundbreaking 2008 research
What the latest meta-analyses reveal
The ongoing scientific debate about IQ effects
Realistic expectations for cognitive improvement

The bottom line: Research shows Dual N-Back has a small but significant effect on fluid intelligence. However, the magnitude of this effect and its practical significance remain subjects of scientific debate.

Understanding IQ and Fluid Intelligence

What is Fluid Intelligence (Gf)?

Novel Problem Solving

The ability to solve new problems without relying on past experience or knowledge.

Pattern Recognition

Finding regularities and patterns in complex data and information.

Abstract Reasoning

Deriving general principles from specific cases, or applying principles to new situations.

Logical Reasoning

Drawing conclusions from given information. Measured by tests like Raven's Progressive Matrices.

Fluid vs. Crystallized Intelligence

Type	Description	Age Changes	Trainability
Fluid Intelligence (Gf)	Solving novel problems	Slowly declines from late 20s	Debated
Crystallized Intelligence (Gc)	Accumulated knowledge & skills	Increases with age	Improves with learning

Traditionally, fluid intelligence was thought to be innate and unchangeable through training. Jaeggi's 2008 study challenged this assumption.

The Groundbreaking Study: Jaeggi et al. (2008)

Study Overview

A Landmark Discovery Published in PNAS

In 2008, Dr. Susanne Jaeggi and colleagues at the University of Michigan published "Improving fluid intelligence with training on working memory" in PNAS.

Reference: PNAS - Improving fluid intelligence with training on working memory

Experimental Design

1
Participants
70 healthy young adults (average age 25.6 years). 34 in training group, 35 in control group.
2
Training Protocol
Approximately 25 minutes daily of Dual N-Back training. Visual (position) and auditory (letter) stimuli processed simultaneously.
3
Training Duration
Four groups trained for 8, 12, 17, or 19 days to examine dose-response effects.
4
Assessment
Raven's Advanced Progressive Matrices and BOMAT (fluid intelligence tests) administered before and after training.

Key Results

Jaeggi's Findings

Training group showed significant improvement on fluid intelligence tests

Effects observed even after just 8 days of training
Dose-response relationship confirmed: longer training produced greater effects
The 19-day training group showed approximately 40% improvement in fluid intelligence (vs. control)
Effects transferred to untrained fluid intelligence tests (transfer effects)

These results suggested that working memory training might improve fluid intelligence, challenging conventional wisdom.

Why This Study Was Groundbreaking

Challenged conventional wisdom: Suggested fluid intelligence might be trainable after all
Demonstrated transfer effects: Improvements seen on tests different from training
Dose-response relationship: Clear connection between training amount and effects
Practical implications: Relatively short training periods showed benefits

This research marked a turning point in the history of Dual N-Back.

Subsequent Research: Replications and Controversies

Following Jaeggi's publication, researchers worldwide attempted to replicate and extend these findings. Results have been mixed.

Studies Supporting the Effects

Jaeggi et al. (2010)

Study with children also showed fluid intelligence improvements after Dual N-Back training.

Stephenson & Halpern (2013)

Both single and dual N-Back training showed effects on fluid intelligence.

Rudebeck et al. (2012)

Fluid intelligence test improvements observed after 20 training sessions.

Colom et al. (2013)

24 sessions of Dual N-Back training improved cognitive abilities.

Studies That Failed to Replicate

Some studies did not find the expected effects:

Chooi & Thompson (2012): No significant fluid intelligence improvement after Dual N-Back training
Redick et al. (2013): Rigorous study with proper controls found no fluid intelligence effects
Thompson et al. (2013): Working memory improved but transfer to fluid intelligence was limited

What Meta-Analyses Tell Us

Given inconsistent individual study results, meta-analyses combining multiple studies are crucial.

Au et al. (2015) Meta-Analysis

Analysis of 20 Studies

Dr. Au and colleagues (from Jaeggi's team) conducted a meta-analysis of 20 studies on N-Back training and fluid intelligence.

Reference: Psychonomic Bulletin & Review - Meta-analysis

Key Results:

Effect size (Hedge's g): 0.24 (small but significant)
Equivalent to approximately 3-4 IQ points
Concluded that "short-term cognitive training can produce beneficial effects on fluid intelligence"

Criticism and Rebuttal

Melby-Lervåg & Hulme (2015) challenged these findings:

Issue	Au et al.'s Position	Critics' Position
Effect existence	Small but significant effect exists	Effects may be placebo
Control group issue	Control group type doesn't affect results	Effects disappear with active controls
Effect size	0.24 (3-4 IQ points)	0.00 with active control groups

The Control Group Problem

Passive control group: Does nothing. Effects look larger when compared to training group
Active control group: Does different tasks (e.g., trivia). Allows more rigorous comparison

Critics argue that "studies with active controls show no effect." This suggests effects might be due to motivation or placebo rather than true cognitive enhancement.

Au et al. published a rebuttal titled "There is no convincing evidence that working memory training is NOT effective," and the debate continues.

Soveri et al. (2017) Meta-Analysis

Large-Scale Analysis of 33 RCTs

Researchers at Åbo Akademi University in Finland analyzed 33 randomized controlled trials (2,105 participants).

Reference: PubMed - Soveri et al. 2017

Summary of Results:

Transfer Type	Effect Size	Interpretation
Untrained N-Back tasks	0.44	Medium effect
Other WM tasks	0.22	Small effect
Cognitive control	0.19	Small effect
Fluid intelligence	0.16	Very small but significant

This study showed transfer effects exist, but "the closer to the trained task, the larger the effect."

Current Scientific Consensus

Expert Views

What We Can Say With Confidence

Dual N-Back improves working memory. This is consistently confirmed across multiple studies.

What We Can Probably Say

A small effect on fluid intelligence (equivalent to 2-4 IQ points) likely exists.

What's Uncertain

Whether effects represent true cognitive improvement beyond placebo, and whether they translate to meaningful real-world changes.

What We Cannot Say

Claims that "Dual N-Back dramatically increases IQ" are not supported by science.

Realistic Expectations

Scientifically Realistic Expectations

IQ improvement: If any, around 2-4 points (difficult to notice)
Working memory: Likely to improve clearly
Real-world effects: Some people notice improved focus and information processing
Individual variation: Not everyone experiences the same effects

Rather than a "magic method for dramatically increasing IQ," think of it as "scientifically validated training that may gradually improve cognitive function."

Practical Advice for Those Seeking IQ Improvement

How to Maximize Effects

1
Train at the Right Difficulty
Use apps that automatically adjust N-level based on performance. Always challenge yourself at a slightly difficult level.
2
Commit to Sufficient Duration
At least 2-4 weeks, preferably 8+ weeks. Jaeggi's research showed longer training produces greater effects.
3
20-25 Minutes Daily
The duration used in most studies. Too short and effects are weak; too long and fatigue reduces quality.
4
Prioritize Sleep and Exercise
Cognitive function is affected by overall lifestyle. Adequate sleep and moderate aerobic exercise are also important.

Beyond Dual N-Back

Other approaches associated with IQ and cognitive improvement:

Aerobic exercise: Increases brain-derived neurotrophic factor (BDNF)
Meditation/Mindfulness: Improves attention control and executive function
Adequate sleep: Essential for memory consolidation and cognitive maintenance
Learning new skills: Complex learning (instruments, languages) activates the brain
Social activity: Interpersonal interactions provide cognitive stimulation

Also see Dual N-Back Benefits and Effects.

Frequently Asked Questions (FAQ)

Q: Can Dual N-Back really increase IQ?

Scientific research suggests Dual N-Back training has a small but significant effect on fluid intelligence (a component measured by IQ tests). A 2015 meta-analysis reported effects equivalent to 3-4 IQ points. However, results vary between studies and the debate continues among researchers.

Q: What was Jaeggi's 2008 study?

In 2008, Dr. Susanne Jaeggi and colleagues at University of Michigan published a groundbreaking study in PNAS showing that Dual N-Back training improved fluid intelligence test scores. This suggested that fluid intelligence, previously thought to be fixed, might be trainable.

Q: How much training is needed to improve IQ?

Jaeggi's research showed effects after 8-19 days of training. Most studies recommend 20-25 minutes daily for 2-4 weeks or longer. Longer training periods tend to produce greater effects according to research findings.

Q: Why is there controversy about IQ effects?

The main issue is methodology. Studies using passive control groups (doing nothing) show effects, while those using active control groups (doing different tasks) show smaller or no effects. This raises questions about whether gains are true cognitive improvement or motivation/placebo effects.

Q: What's the difference between fluid and crystallized intelligence?

Fluid intelligence (Gf) is the ability to solve new problems and recognize patterns, independent of prior knowledge. Crystallized intelligence (Gc) is accumulated knowledge and skills from learning and experience. Dual N-Back is thought to primarily affect fluid intelligence.

Summary: The Scientific Truth About Dual N-Back and IQ

Summary of scientific evidence on Dual N-Back and IQ improvement:

Aspect	Scientific Evidence
Effects on working memory	✅ Consistently confirmed across studies
Effects on fluid intelligence	△ Small but significant effect possible (debated)
Degree of IQ improvement	About 2-4 points (if effects exist)
Persistence of effects	❓ Insufficient data
Real-world transfer	△ Some people notice changes (high individual variation)

Conclusion: Dual N-Back isn't "magic for dramatically boosting IQ," but it is scientifically validated brain training with demonstrated working memory benefits and potential fluid intelligence effects. While expectations should be realistic, consistent training may contribute to maintaining and improving cognitive function.

For how to get started, see our How to Start Dual N-Back guide. For basic concepts, see What is Dual N-Back.

References

Jaeggi, S. M., et al. (2008). Improving fluid intelligence with training on working memory. PNAS, 105(19), 6829-6833. DOI: 10.1073/pnas.0801268105
Au, J., et al. (2015). Improving fluid intelligence with training on working memory: a meta-analysis. Psychonomic Bulletin & Review, 22(2), 366-377. DOI: 10.3758/s13423-014-0699-x
Soveri, A., et al. (2017). Working memory training revisited: A multi-level meta-analysis of n-back training studies. Psychonomic Bulletin & Review, 24(4), 1077-1096. PubMed
Melby-Lervåg, M., & Hulme, C. (2016). There is no convincing evidence that working memory training is effective: A reply to Au et al. (2015). Psychonomic Bulletin & Review, 23(1), 324-330.