Can You Get Smarter? What the Science Says About Raising IQ

Yes, you can get smarter, including as an adult, but not in every sense of the word. The knowledge and skills that make up crystallized intelligence keep growing well into your sixties. Schooling reliably raises IQ scores by roughly 1 to 5 points per extra year. Your raw processing speed, on the other hand, is hard to move, and brain-training games mostly make you better at brain-training games.

Picture two people at a dinner party in 2026. One of them spent the last three years doing dual n-back drills every morning, chasing the promise that a smarter working memory would make a smarter everything. The other spent those years reading about Roman history, learning to cook without recipes, and arguing with a friend about interest rates. Which one got smarter?

The research has a surprisingly clear answer, and it is not the one the app store would like you to hear. This page is the evidence: which gains are real, which are small, and which evaporate the moment you leave the lab. For the practical plan, see our guide on how to get smarter.

The short answer: yes, with limits

Can you increase your IQ? Somewhat. Can adults get smarter? Clearly, in the ways that matter most in daily life. Is intelligence fixed? No, but it is less stretchy than self-help books suggest.

What grows: knowledge, vocabulary, expertise, and the reasoning skills you practise on real material. These keep climbing for decades.
What moves a little: measured IQ, mainly through education. The effect is real and durable, but it is a few points, not a transformation.
What barely moves: raw speed and "general" fluid reasoning, especially through short drills that promise to train the whole brain at once.
What you can lose: a lot of your everyday sharpness, temporarily, to bad sleep. Getting it back is the cheapest cognitive upgrade there is.

Two kinds of intelligence, two different stories

In the 1960s the psychologists Raymond Cattell and John Horn split general intelligence into two broad parts, and the split still organizes the field. Fluid intelligence is the ability to solve new problems you have never seen, spot patterns, and hold several things in mind at once. Crystallized intelligence is what you have banked: words, facts, methods, and the knowledge of how things usually work.

When Horn and Cattell compared age groups in 1967, the two parts moved in opposite directions. Fluid scores were lower in older groups; crystallized scores were higher. Half a century later, a study of 48,537 people by Joshua Hartshorne and Laura Germine (2015) sharpened the picture. Raw processing speed peaked around the end of high school. Vocabulary did not peak until the late 60s or early 70s.

That is the first honest answer to "can adults get smarter": the part of intelligence built from knowledge is the part that keeps growing, and it only grows if you feed it. A 45-year-old who reads widely is not fighting biology. They are working with it.

The strongest evidence: education raises IQ

For decades, the correlation between years of schooling and IQ was a chicken-and-egg problem. Do smart kids stay in school longer, or does school make kids smarter? In 2018, Stuart Ritchie and Elliot Tucker-Drob published a meta-analysis in Psychological Science that went after the causal question using only designs that can separate the two. It pooled 142 effect sizes from 42 data sets and more than 600,000 people.

The three designs gave three estimates for one extra year of education:

Controlling for earlier IQ (comparing people who scored the same as children but got different amounts of school): about 1.2 IQ points.
Policy changes (a country raises the school-leaving age, so a whole cohort gets an extra year by law): about 2.1 points.
School-entry cutoffs (children born just before or after a birthday cutoff, so they have a year more or less of school at the same age): about 5.2 points.

Hence the headline range of roughly 1 to 5 points per year. The effects showed up across broad types of ability and were still visible decades later, although in one design they were smaller the older people were when tested, from about 2 points at age 18 to about half a point by the 80s. The authors called education "the most consistent, robust, and durable method yet to be identified for raising intelligence".

Two caveats. A few points per year is modest. And the study cannot tell whether school raises the deep general factor researchers call g, or teaches specific skills that happen to be on IQ tests. Either way, structured learning sustained over time is the one intervention with serious evidence behind it.

The Flynn effect: whole countries got smarter, then some stopped

If you want proof that IQ is not carved in stone, look at your grandparents' test scores. Throughout the 20th century, average IQ scores rose so steadily that test makers had to keep re-norming the tests. The political scientist James Flynn made the pattern famous, and it now carries his name.

A meta-analysis by Jakob Pietschnig and Martin Voracek (2015) pulled together 271 samples, almost 4 million people in 31 countries, covering 1909 to 2013. Full-scale IQ rose by about 0.28 points a year, close to 3 points a decade. Fluid scores rose faster than crystallized ones, which surprised many people, and the gains slowed in recent decades.

Then, in some rich countries, the curve turned around. Using military test data on more than 730,000 Norwegian men born between 1962 and 1991, Bernt Bratsberg and Ole Rogeberg (2018) found scores peaked with the 1975 birth cohort and then declined. The decisive detail: the drop appeared within families. Younger brothers scored lower than their older brothers. Genes cannot change that fast between siblings, so the cause has to be environmental. In the United States, Dworak, Revelle and Condon (2023) found falling scores in matrix reasoning, number series and verbal reasoning among 394,378 online test takers between 2006 and 2018, while 3D spatial rotation went up. That sample was self-selected, so treat it as a signal, not a verdict.

Nobody knows for sure what drove the rise or the reversal; nutrition, health, schooling and a world full of abstract symbols are all candidates. What matters is that environments moved average scores by more than a standard deviation within a few generations. Measured intelligence responds to how people live.

Is intelligence fixed? What heritability does and does not mean

Here is the fact that makes people think the game is rigged. Twin studies show that IQ is substantially heritable, and the heritability rises with age. In a sample of 11,000 twin pairs from four countries, Haworth and colleagues (2010) found heritability climbed from 41% at age 9 to 55% at 12 and 66% at 17. The psychologist Thomas Bouchard named this the Wilson effect and estimated that heritability levels off around 80% in adulthood.

It sounds like destiny. It is not, for three reasons.

Heritability describes differences in a population, not the limits of a person. "66% heritable" means that in that group, at that time, about two-thirds of the variation between people tracked genetic differences. It says nothing about how much any one person could change with a different life.

Highly heritable traits still move. Adult height is about 80% heritable. Yet over the 20th century, according to the NCD Risk Factor Collaboration (2016), South Korean women became 20.2 cm taller and Iranian men 16.5 cm taller. Better food and health did that, with the same gene pool.

Heritability depends on the environment. A meta-analysis by Tucker-Drob and Bates (2016) found that in U.S. studies, genetic influence on test scores was weaker for children from poorer families, as if deprivation held their potential down. In Western Europe and Australia, where schools and health care are more evenly shared, the effect was much weaker or absent. When everyone gets decent conditions, the remaining differences look more genetic, precisely because the environment has stopped holding people back.

The rising heritability with age probably means that people increasingly choose environments that fit their abilities: the curious kid who reads becomes the adult who reads more. What you choose to do with your hours is part of the machine.

Brain training: you get better at the game

In 2008, Susanne Jaeggi and colleagues published a paper in PNAS that launched an industry. Young adults practised the dual n-back, a punishing task where you track a sequence of positions and sounds at once. Their fluid intelligence scores went up, and the more days they trained, the larger the gain appeared. If working memory was the bottleneck of intelligence, the paper suggested, you could widen the bottleneck.

Then came the replications. Redick and colleagues (2013) ran a randomized, placebo-controlled version with 20 sessions of adaptive dual n-back. Participants got much better at the n-back. They showed no improvement on any of the intelligence, multitasking, working memory capacity or perceptual speed tests.

The fairest summary of what followed is a long, loud argument. A 2015 meta-analysis by Jacky Au, with Jaeggi as co-author, pooled 20 n-back studies and found a small positive effect on fluid intelligence (g = 0.24). Monica Melby-Lervåg and Charles Hulme reanalysed the same studies, argued the effect was driven by trials that used do-nothing control groups, and got a smaller estimate that lost significance when only active controls were counted. Au's team disputed that reading. The broader picture is less ambiguous. A 2016 meta-analysis by Melby-Lervåg, Redick and Hulme covering 87 publications and 145 comparisons found reliable gains on other working memory tests, and no convincing improvement in reasoning, reading or arithmetic.

The biggest review came from a panel of seven researchers, Simons and colleagues (2016), in Psychological Science in the Public Interest. Their conclusion was blunt: training improves the trained tasks, improves closely related tasks less, and there is little evidence it improves distantly related tasks or everyday cognitive performance. Sala and Gobet (2019) reached the same place across chess, music and working memory training: near transfer yes, far transfer close to zero once you account for study quality. In 2016, Lumosity's maker paid $2 million to settle U.S. Federal Trade Commission charges that its ads promised benefits at work, at school and against cognitive decline that the science did not support.

Psychologists call this the difference between near transfer and far transfer. Practising a memory game makes you better at that game and its cousins. It does not seem to make you better at reading contracts, learning Spanish or spotting bad arguments. Brain games are fine as a hobby. For the apps that hold up best under this evidence, see our review of brain training apps that actually work, and for the broader trend, is brainmaxing legit?

Exercise and sleep: protect the engine, don't expect a turbo

You will read that exercise makes you smarter. The evidence is more careful than that. An umbrella review in Nature Human Behaviour by Ciria and colleagues (2023) looked only at randomized trials in healthy people. The raw average benefit on cognition was small (d = 0.22), shrank to d = 0.13 after accounting for key moderators, and became negligible after correcting for publication bias. Other researchers have pushed back, arguing the benefits are being underestimated, and the debate is ongoing. The honest reading: move for your heart, mood and long-term brain health, not because a jog will add points before lunch.

Sleep is different, because the effect runs mostly in the other direction. A meta-analysis by Lim and Dinges (2010) of 70 articles found that short-term sleep deprivation hit sustained attention hard and working memory clearly. Interestingly, accuracy on reasoning tasks barely changed. Sleep does not make you smarter than you are. Losing it makes you perform well below what you are, in exactly the functions you need to learn something new. Trying to get smarter on five hours a night is filling a bucket with a hole in it.

Your brain does change: the taxi drivers

To earn a licence, London cab drivers spend years memorizing roughly 25,000 streets, a test known as "the Knowledge". In 2000, Eleanor Maguire's team scanned their brains and found larger posterior hippocampi than in controls, with volume tracking the number of years spent driving. The obvious objection is that people with big hippocampi might become taxi drivers. So Woollett and Maguire (2011) followed 79 trainees and 31 controls for three to four years. At the start, no differences. At the end, only the trainees who qualified showed growth in posterior hippocampal grey matter. Those who failed and the controls did not change.

Two lessons sit inside that study. Adult brains physically adapt to sustained, demanding learning. And the change is specific: the drivers got a better map of London, not a better brain in general. The same study found qualified drivers did worse than controls on one test of complex visual memory. Plasticity is real, but it follows the work. For the full story, read how your brain rewires itself.

Smarter beyond IQ: knowledge, skill and judgement

An IQ score predicts many things, but it is a narrow slice of what people mean by smart. When you call a friend sharp, you usually mean they know things, see through nonsense and make decent decisions.

Most of that lives on the crystallized side, and it is highly trainable. In a classic study, Chase and Simon (1973) showed a chess master, a strong amateur and a beginner a board for five seconds. The master rebuilt real game positions far better than the others. With pieces placed at random, that advantage largely vanished. The master's "superior memory" was really a huge library of familiar patterns. Expertise looks like raw brainpower from the outside. From the inside, it is stored knowledge.

That is why knowledge is the most underrated route to getting smarter. Every concept you truly understand becomes a hook for the next one, which makes new material faster to learn and harder to fool you with. Judgement grows the same way: from examples, feedback and mental models, not from reaction-time drills. There is also a social and emotional side to being smart that IQ tests ignore; our piece on emotional intelligence covers that side of the story.

What raises what: an honest table

What you do	What it raises	Strength of evidence
Schooling and structured learning	Measured IQ (about 1 to 5 points per year) and crystallized knowledge	Strong: large causal meta-analysis
Reading and learning across many topics	Vocabulary, knowledge, crystallized intelligence	Strong: grows into the late 60s
Deep practice in one field	Expertise and pattern memory in that field	Strong, but specific to the field
Brain-training games	The game itself and very similar tasks	Strong for near transfer, weak for far transfer
Dual n-back training	Working memory test scores	Fluid IQ gains disputed, small at best
Aerobic exercise	Health, mood, possibly small cognitive benefits	Mixed: small effects, publication bias
Enough sleep	Attention and working memory back to your baseline	Strong for avoiding losses

How to track your progress honestly

Online "IQ tests" are mostly entertainment, and retaking the same test inflates your score through practice alone. A better approach is to track the things you are actually trying to grow. Our free vocabulary test gives a rough read on one pillar of crystallized intelligence, and the memory test shows how your short-term memory behaves today, which is a useful thing to compare after a good night's sleep and a bad one. Neither is an IQ test, and neither pretends to be. You can find the rest on our free tests page.

Where NerdSip fits

If the evidence says knowledge is the part of intelligence you can grow for decades, the question becomes how to add it without a second job. That is what we built NerdSip for. You type any topic and get a fact-checked five-minute course made of short lessons, each ending with a quick question, and a review mode brings back what you learned so it sticks. It will not raise your IQ overnight, and we would be suspicious of any app that promised to. It will help you bank a little more knowledge every day. You can read how we fact-check our courses.

The bottom line

Can you get smarter? Yes, mostly in the way the dinner-party reader did. The strongest evidence points to education and sustained learning, the brain physically adapts to demanding practice, and crystallized knowledge keeps growing long after raw speed has peaked. Shortcuts that promise to train "the brain" in general have mostly failed their tests. Protect your sleep, move your body for its own sake, and spend your effort on real material.

Ready to turn the evidence into a routine? Our practical guide on how to get smarter lays out the daily plan, and the habits of smart people shows what it looks like in ordinary lives.

References & Further Reading

Frequently Asked Questions

Can you get smarter as an adult?

Yes, in some ways. Crystallized intelligence, the knowledge, vocabulary and expertise you build up, keeps growing for decades; in one large study vocabulary peaked in the late 60s or early 70s. Raw processing speed and fluid reasoning are much harder to raise.

Can you increase your IQ?

Somewhat. The best evidence comes from education: a 2018 meta-analysis of more than 600,000 people found roughly 1 to 5 IQ points per extra year of schooling. Short brain-training programs have not produced reliable IQ gains when tested against active control groups.

Is intelligence fixed?

No. IQ is substantially heritable, and heritability rises with age, but heritability describes differences within a population, not the limits of one person. Average IQ scores rose about 3 points per decade during the 20th century, and in some countries have since fallen, both for environmental reasons.

Does brain training make you smarter?

Mostly it makes you better at the trained task and very similar tasks (near transfer). Large reviews, including Simons et al. (2016) and Melby-Lervåg, Redick and Hulme (2016), found little convincing evidence of far transfer to reasoning, reading, arithmetic or everyday performance.

Does exercise make you smarter?

The effect is smaller than headlines suggest. A 2023 umbrella review of randomized trials in healthy people found a small benefit that became negligible after correcting for publication bias, though other researchers dispute that conclusion. Exercise is clearly good for health and mood.

Does sleep affect intelligence?

Sleep loss does not change your underlying ability, but it lowers your performance, especially sustained attention and working memory. Getting enough sleep brings you back to your baseline rather than above it.

What is the difference between fluid and crystallized intelligence?

Fluid intelligence is solving new problems and spotting patterns on the fly. Crystallized intelligence is accumulated knowledge and skills. Fluid abilities tend to peak early in adulthood, while crystallized abilities keep rising well into later life.

Every NerdSip course clears a four-layer fact-checking pipeline before it reaches the app: grounded in live sources, scored nightly, gated on failure, and reviewable by a person at one tap. Articles on this blog are drafted with AI assistance, then researched, verified, and edited by our team.

Editorial responsibility: ai51 UG (haftungsbeschränkt). Responsible editor named in the imprint.

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Explore the NerdSip learning hubs

The blog is our editorial layer. When you want to move from reading into doing, these hubs organize the rest of NerdSip by format, including the app itself and the press that has written about it.

Course LibraryBite-sized courses, grouped by topic. General KnowledgeFill the gaps in what you should know. Pub Quiz500 free questions, ready for quiz night. Free Learning ToolsQuizzes, timers, and fact generators. Rabbit HolesImmersive science, history, and nature journeys. World EventsEclipses, Oktoberfest, and Nobel week, explained. Mind-Blowing FactsFacts worth repeating out loud. Brain Rot RecoveryTrade doomscrolling for short learning loops. Replace Social MediaSwap the endless feed for real progress. BrainmaxingFocus, recall, and daily brain training. Leverage MicrolearningTurn spare minutes into steady progress. Build Good HabitsStacking, triggers, and routines that stick. Never Run Out of Things to SaySmall talk, listening, conversation fuel. Become InterestingCuriosity, taste, stories, a wider library. Exam PrepRecall, spacing, AI, and audio review. Learning for SeniorsBrain training and habits to stay sharp. Learning with ADHDShort, dopamine-friendly ways to focus. App FeaturesSwipe-to-learn deck, fact-checking, podcast mode. Press and MediaNewspaper coverage of NerdSip, plus our own videos.

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