Can You Increase Your IQ? What the Research Says Works (and What Doesn’t)

Search “can you increase your IQ” and you’ll find promises everywhere: apps that claim to grow your brain, playlists that boost focus, 30-day plans that add 20 points. The research is less exciting and more useful. Some things really do raise IQ, a few things protect it, and a lot of popular advice does almost nothing for the ability an IQ test measures.

Can you increase your IQ, or is it fixed?

IQ is not fixed, but it is stubborn. To see why, it helps to separate two things that often get mixed up: your score on a test and your underlying ability. Your score can jump a few points because you slept well or recognized a question format. Your underlying ability moves far more slowly, if at all.

Psychologists also split intelligence into two broad parts. Fluid intelligence is your ability to solve new problems and spot patterns on the spot. Crystallized intelligence is the knowledge and vocabulary you build over a lifetime. Crystallized ability tends to keep growing into middle age; fluid ability is much harder to push upward. Our guide to fluid vs crystallized and other types of intelligence covers the models in more depth, and what IQ is and how it is calculated explains the scoring.

The last key idea is transfer. Practice a task and you get better at that task: that is near transfer. The real question is whether the improvement spreads to things you never practiced, like reading comprehension, math or an IQ test. That is far transfer, and almost every “boost your brain” claim depends on it.

What works and what doesn’t: the evidence at a glance

Here is the scorecard, drawn from large reviews and meta-analyses rather than single small studies.

How to increase IQ: education is the strongest lever

People with more years of school score higher on IQ tests. For decades, the hard question was which way that arrow points: do smarter people stay in school longer, or does school make people smarter? Ritchie and Tucker-Drob’s 2018 meta-analysis in Psychological Science tackled it with three kinds of natural experiments, pooling 42 data sets and 615,812 participants.

The authors summarize the effect as roughly 1 to 5 IQ points per extra year, depending on the design. In the studies that tracked people over decades, the effect shrank with age but was still statistically significant into the eighth and ninth decades of life. They do flag one caveat: no study yet shows whether the large school-entry effect lasts into adulthood.

Finished school years ago? Formal education is the best-documented route, but the likely active ingredient is sustained, effortful learning. A community college course, a new language, statistics or programming fits that description far better than another round of a puzzle app you already know. No study has tested whether adult courses raise IQ the way school years do; this is our inference.

Can you improve your IQ with brain training?

In 2014, two groups of scientists published open letters with opposite conclusions. More than 70 scientists said brain games offer no scientifically grounded way to improve cognition; 133 scientists and practitioners replied that the benefits were well documented. To settle it, a team led by Daniel Simons reviewed every peer-reviewed study cited by leading brain-training companies. Their 2016 review appeared in Psychological Science in the Public Interest. Their findings:

• Extensive evidence that brain training improves performance on the trained tasks.
• Less evidence for gains on closely related tasks.
• Little evidence for gains on distantly related tasks or in everyday cognitive performance.
• None of the cited studies met all the best practices needed to draw clear conclusions.

Regulators reached a similar verdict. In January 2016 the Federal Trade Commission announced that Lumos Labs, maker of Lumosity, would pay $2 million to settle charges that it advertised unsupported claims, including that its games improve performance at work and school and delay age-related cognitive decline. The full judgment was $50 million, suspended because of the company’s financial condition.

The n-back controversy

One exercise briefly looked like the exception. In a 2008 study in PNAS, Jaeggi and colleagues trained 70 young adults (35 in training groups) on the “dual n-back,” a demanding task where you track a sequence of squares and spoken letters at the same time and flag repeats from n steps back. Fluid intelligence scores rose, and the more days people trained, the bigger the gain. The paper made headlines and spawned a wave of apps.

Then came the replications. Redick and colleagues (2013) gave young adults 20 sessions of adaptive dual n-back and compared them with an active placebo group doing visual search practice and a no-contact group. Both trained groups got better at their tasks, but with high statistical power there was “no positive transfer” to any of the cognitive ability tests.

The two sides kept arguing through meta-analyses. A 2015 meta-analysis of 20 n-back studies, co-authored by Jaeggi, found a small but significant effect on fluid intelligence. A larger 2016 meta-analysis by Melby-Lervåg, Redick and Hulme, covering 87 publications and 145 experimental comparisons, found reliable short-term gains on working memory tasks but “no convincing evidence” of far transfer when trained groups were compared with active control groups. The pattern is telling: the more carefully a study controls for expectation and effort, the smaller the effect.

Chess, music and the Mozart effect

Chess masters and skilled musicians tend to score above average on cognitive tests, which makes it tempting to think the activity caused the difference. Sala and Gobet’s 2017 review pooled experiments on chess instruction, music instruction and working memory training in children. The effects shrank as study quality improved: with active control groups, music training came out at 0.03 standard deviations and working memory training at 0.05, both less than one IQ point on a scale with SD 15 (our conversion).

The “Mozart effect” fared worse. A University of Vienna meta-analysis of about 40 studies with more than 3,000 participants found no support for the idea that listening to Mozart boosts spatial ability. Lead author Jakob Pietschnig put it plainly: he recommends Mozart to everyone, but “it will not meet expectations of boosting cognitive abilities.”

Chess and piano are still worth learning for their own sake. Just don’t buy them as an IQ supplement.

Does practicing IQ tests raise your score?

Yes, and that is exactly why practice gains need careful reading. A meta-analysis by Scharfen, Peters and Holling in Intelligence, covering 122 studies and 153,185 participants, found significant score gains when people retook cognitive ability tests, with no further gains after the third administration. The size of the gain depended on the type of test, whether the same form was reused, the time between attempts and the person’s age.

In other words, practice teaches you the test. That’s useful on a first attempt: knowing what a matrix puzzle or a number series looks like means you won’t lose points to surprise. Our guide to IQ test question types with examples is a quick way to get there. What practice can’t do is turn a retest score into evidence that your intelligence went up.

Sleep, exercise and nutrition: protect the IQ you have

Healthy habits rarely make you smarter than your baseline, but neglecting them can keep you from performing at it.

Sleep. A meta-analysis of 70 articles by Lim and Dinges found that short-term sleep deprivation hits simple attention hardest, with sharp increases in lapses, while the effect on reasoning accuracy was small and not statistically significant. Your intelligence doesn’t disappear after a bad night, but the attention you need to use it does. The CDC recommends at least 7 hours a night for adults aged 18 to 60.

Exercise. In adults over 50, a 2018 meta-analysis in the British Journal of Sports Medicine (Northey et al.) pooled 36 randomized trials and found a small, significant improvement in cognitive function, with the best results from sessions of 45 to 60 minutes at moderate intensity or higher. For the healthy population overall, a 2023 umbrella review in Nature Human Behaviour (Ciria et al.) re-examined the trials behind 24 meta-analyses: the benefit fell from d = 0.22 to 0.13 after accounting for active controls and baseline differences, and to a negligible 0.05 after correcting for publication bias. Exercise is still worth doing, and the US Physical Activity Guidelines recommend 150 to 300 minutes of moderate activity a week for adults, but not as an IQ strategy.

Iodine and lead: where IQ really does move

The biggest documented swings in IQ come not from clever training but from basic biology in early life. A meta-analysis of 37 studies covering 12,291 children in China found that children in severely iodine-deficient areas scored about 12.45 IQ points lower than children in iodine-sufficient communities, and that iodine supplementation before and during pregnancy recovered about 8.7 points.

The United States has its own version of this story. Salt iodization began here in 1924, and economists Feyrer, Politi and Weil used WWI and WWII military data to estimate that it raised IQ by approximately one standard deviation for the quarter of the population most deficient in iodine, enough to explain roughly one decade’s worth of the US rise in IQ scores.

Lead is the other side of the coin. The CDC states that no safe blood lead level in children has been identified and that even low levels are associated with developmental delays, difficulty learning and behavioral issues. Both lessons apply to children and pregnancy rather than to adults with an adequate diet: if you are pregnant, planning a pregnancy or worried about a child’s exposure, talk with your doctor or pediatrician.

The Flynn effect: proof that IQ isn’t fixed

If you need evidence that environment shapes IQ, look at whole populations. A meta-analysis by Pietschnig and Voracek covering 271 samples, nearly 4 million people and 31 countries from 1909 to 2013 found that full-scale IQ scores rose by about 0.28 points a year, roughly 2.8 points per decade. The gains were larger for fluid and spatial tasks than for crystallized knowledge, and they have slowed in recent decades.

In some countries the trend has even reversed. Using military conscription data for Norwegian men born from 1962 to 1991, Bratsberg and Rogeberg showed that average scores rose until the 1975 cohort and then declined. Because the rise and the fall both appeared within families, between brothers, the authors concluded that both were environmentally caused, not genetic.

The takeaway: environment can shift IQ across a population over decades. That is real change, just not the kind you can buy in an app.

How to develop IQ-related skills: a realistic plan

Here is what we would actually do with the evidence above.

1. Keep learning hard things. Pick something structured and demanding, such as a language, a math or programming course, or an instrument, and stick with it for months. This is the closest everyday equivalent to an extra year of school, though that link is our inference, not a tested result.
2. Choose new over familiar. In the Synapse Project, Park and colleagues had adults aged 60 to 90 spend about three months, averaging 16.5 hours a week, learning digital photography, quilting or both. The photography learners improved episodic memory more than a placebo group doing puzzles and documentaries at home. It’s a memory finding, not an IQ finding, but it points the same way: novelty and challenge beat routine.
3. Protect the basics. Aim for at least 7 hours of sleep, move regularly, and treat health problems that sap your attention.
4. Treat games as games. Sudoku, chess or an n-back app are fine hobbies. Expect to get better at them, not at everything else.
5. Don’t treat a retest as proof of change. Practice alone raises scores, so your first attempt at a test is the most honest one.

Remember too that IQ is only one slice of what makes people effective. Social and emotional skills matter a great deal at work and in relationships, and they are measured separately; see IQ vs EQ for what the research says about them.

Can IQ be improved? Start by knowing where you stand

So, can you increase your IQ? Yes, modestly and slowly: years of learning move it, deficiencies drag it down, and most quick fixes do little beyond the task they train. The honest first step is to find out where you are now, so you can see your strengths rather than guess at them.

When you’re ready, take the IQtonics IQ test. It has 40 questions across patterns, spatial reasoning, numbers, logic and memory, gets progressively harder, and runs with a 20-minute time limit. Your result is placed on the standard IQ scale with mean 100 and standard deviation 15 (our methodology explains how it is scored), with a percentile and a profile of your strongest and weakest areas. Starting the test is free; your full results unlock with a trial membership, which renews automatically unless you cancel. It is an online test, not a clinical assessment, so for diagnostic or educational decisions, see a licensed psychologist.