How to Develop Your Intelligence: 6 Research-Backed Habits

6 Smart Ways To Develop Your Intelligence

Can you actually make yourself smarter? Partly, yes. Your basic reasoning ability is fairly stable in adulthood, but the knowledge, skills and habits that let you use it well can keep growing for decades. The most reliable ways to support your intelligence are surprisingly ordinary: focus on one task at a time, sleep well, eat a brain-friendly diet, stay socially connected, read widely and keep asking questions. Expensive brain-training games, on the other hand, have a weak track record.

Below are six everyday habits, what the research says about each one, and the popular claims that do not hold up.

Can you really increase your intelligence?

Psychologists often split intelligence into two broad parts. Fluid intelligence is the ability to reason through new problems; it tends to peak in young adulthood and then slowly decline. Crystallized intelligence is your store of knowledge and learned skills; it usually keeps rising or holds steady well into later life.

There is good evidence that environment matters. Throughout much of the 20th century, average IQ scores in many countries rose by roughly three points per decade, a trend known as the Flynn effect, which researchers link to better nutrition, health and schooling. A 2018 meta-analysis estimated that each extra year of education adds about one to five IQ points. In other words, what you do with your mind and body has real effects, even if no habit turns an average thinker into a genius overnight.

A line often attributed to Albert Einstein sums up the spirit of it: "It's not that I'm so smart, it's just that I stay with problems longer." Whether or not he said it, persistence is a big part of practical intelligence.

1. Do one thing at a time

Multitasking feels efficient, but for most tasks the brain is actually switching rapidly between them. Each switch has a cost: time lost reorienting and a higher chance of mistakes. Studies of task switching have found that rapidly alternating between jobs can make the work take far longer than doing them one after another.

In a 2009 Stanford study, Eyal Ophir, Clifford Nass and Anthony Wagner found that people who habitually juggled many media streams were worse at filtering out distractions and slower to switch tasks than light multitaskers. Later reviews describe the evidence as mixed, and it is not proven that multitasking itself causes the difference, but the practical advice is sound: protect blocks of focused time.

You may have read that multitasking lowers IQ by 15 points, to the level of an eight-year-old. That claim traces back to a small 2005 London study on email and phone interruptions that was reportedly never published in a peer-reviewed journal, so it is best treated with caution.

2. Eat for long-term brain health

No single "smart food" will raise your IQ, and claims about raw eggs or specific supplements are not well supported. What does have research behind it is an overall eating pattern. The MIND diet, developed at Rush University, blends the Mediterranean and DASH diets and emphasises leafy greens, other vegetables, berries, beans, nuts, whole grains, fish and olive oil. Observational studies have linked closer adherence to slower cognitive decline, although cause and effect has not been proven.

Cutting back on heavily processed food and added sugar, including sugary drinks and fruit juice, is a sensible part of that pattern. If you are considering supplements, talk to a doctor first.

3. Rely on search engines a little less

Search engines are extraordinary tools, but there is a reasonable worry that outsourcing every fact weakens memory. In 2011, Betsy Sparrow and colleagues reported a "Google effect": people who expected information to be saved remembered where it was stored better than the information itself. A large 2018 replication project could not reproduce the effect, and later studies found it only under certain conditions, so the picture is unsettled.

The practical point still stands. Critical thinking draws on knowledge you actually hold in memory, so connections between ideas are easier when the facts are in your head. Try recalling an answer before you look it up, and take a moment afterwards to explain it to yourself. (An oft-shared statistic claiming trillions of Google searches per day is wildly inflated; estimates are in the billions.)

4. Socialise more

Conversation is a demanding mental workout: you track what others mean, read emotions, remember context and respond in real time. A 2008 University of Michigan study led by Oscar Ybarra reported that even brief social interaction improved performance on cognitive tests, comparable to doing intellectual exercises. More broadly, strong social ties are linked to better mental health and healthier ageing, while chronic loneliness is associated with a range of health risks.

You do not need a packed calendar. A regular walk with a friend, a club, volunteering or a class can all help.

5. Protect your sleep

Sleep is when the brain consolidates what you learned during the day. Studies consistently show that people who sleep after learning remember more than those who stay awake, and that sleep loss harms memory, attention and judgement. In one study, restricting sleep to about four hours a night made working memory markedly slower.

For most adults that means seven to nine hours, a consistent schedule and a dark, quiet bedroom. Short daytime naps can also help with learning. If you snore heavily, wake unrefreshed or feel exhausted despite a full night in bed, talk to a doctor.

6. Read widely and keep questioning

Socrates is often credited with "I know that I know nothing," though that exact phrase does not appear in Plato. In Plato's Apology, Socrates says only that he does not think he knows what he does not know, and that this makes him slightly wiser than someone who falsely believes he knows. The lesson is the same: noticing the gaps in your knowledge is where learning begins.

Reading builds vocabulary and background knowledge, both core parts of crystallized intelligence, and older books connect us with people who wrestled with the same human problems we face today. Reading actively, by asking questions, comparing sources and checking claims, trains the habits of careful thought.

It is also worth knowing that "intelligence" has many faces. Howard Gardner's theory of multiple intelligences proposes separate abilities such as linguistic, musical, spatial and interpersonal intelligence. Educators have embraced it, but many psychologists find little empirical support, since different mental abilities tend to correlate strongly. Still, thinking about your dominant intelligence can be a useful way to spot strengths worth developing.

What does not work as well as advertised

Brain-training apps. People get better at the specific games they practise, but a 2016 review found little evidence that this carries over to everyday thinking. The US Federal Trade Commission took action against the maker of Lumosity, which agreed to stop making unsupported claims that its games could ward off memory loss and dementia.
Quick IQ boosts. Studies on working-memory training such as the "n-back" task produced exciting early results that later studies did not reliably reproduce.
Miracle foods and supplements. Diet matters as a whole pattern, not as a single magic ingredient.

The habits that genuinely help are slower and less glamorous: attention, rest, good food, people and curiosity. A line often attributed to the Danish philosopher Søren Kierkegaard captures why they matter: "People demand freedom of speech as a compensation for the freedom of thought which they seldom use." The capacity to think is common; the habit of using it well is what you can build.

Sources: Wikipedia: Fluid and crystallized intelligence, Flynn effect, Media multitasking, Human multitasking, MIND diet, Google effect, Sleep and memory, I know that I know nothing, Theory of multiple intelligences and Brain training.