Lying and Intelligence: Do Smart People Lie More, or Better?

Lying is not a sign of high intelligence in adults: a meta-analysis of more than 32,000 people found that honesty, measured as a personality trait, correlates only about .02 with intelligence, which is effectively zero. In young children the picture differs, because the first lies depend on new thinking skills, and children's lying correlates modestly with those skills (about r = .13 to .17).

This article explains why lying takes mental effort, what the research on children shows, whether brighter adults lie more often or more skillfully, and why the idea of the clever liar is so persistent.

A convincing lie asks a lot of the mind. You have to hold back the true answer, keep track of what the listener knows, invent something plausible and stay consistent afterwards. Psychologists link these demands to "executive functions", the mental control skills that include inhibiting automatic responses and holding information in working memory, and to "theory of mind", the understanding that other people have beliefs that can differ from your own.

Laboratory evidence backs this up. In a meta-analysis of 114 studies with 3,307 participants, Suchotzki and colleagues (2017) found that people take markedly longer to give a lying answer than a truthful one on computer tasks. The standardized difference stayed large (d = 1.05) even after correcting for publication bias.

This cognitive cost is the basis of the "cognitive approach" to lie detection, which tries to make lying harder, for example by asking people to tell their story in reverse order. In one experiment by Vrij and colleagues (2008), reverse-order interviews produced more cues to deceit, and police officers watching them detected lies more accurately. A later meta-analysis by Vrij, Fisher and Blank reported total accuracy of 71% for the cognitive approach against 56% for standard interviews, although a reanalysis by Levine, Blair and Carpenter argued that the advantage was much smaller than claimed.

Because lying draws on executive function and theory of mind, it appears as those skills develop. This is where the "lying is a sign of intelligence" idea has some truth.

• The first lies: Evans and Lee (2013) asked 65 children aged 2 to 3 not to peek at a toy while the experimenter was out of view. Of the 52 who peeked, 40% then denied it. Older children were more likely to lie, and after accounting for age, children who scored higher on a self-control task (a Shape Stroop) were 1.88 times more likely to lie for each extra point. Parent-reported verbal ability did not predict lying.

• Keeping a lie going: Talwar and Lee (2008) studied children aged 3 to 8 and found that initial false denials were linked to first-order belief understanding (knowing someone can hold a false belief) and inhibitory control, while maintaining the lie under questioning was linked to the more advanced second-order understanding.

• An experiment: Ding and colleagues (2015) recruited 58 Chinese 3-year-olds and, among those who could not yet lie, gave half six sessions of theory-of-mind training and half training on physical concepts. The groups had been matched on IQ, measured with a Stanford-Binet scale. The theory-of-mind group began to deceive consistently, more quickly than the control group, and the effect lasted more than a month.

• Working memory: Alloway and colleagues (2015) found that 6- and 7-year-olds who lied well had better verbal working memory than poor liars, with no difference in visuospatial working memory.

The best summary is a meta-analysis by Sai and colleagues (2021) covering 47 papers and 5,099 participants aged 2 to 19. Lying correlated r = .17 with theory of mind and r = .13 with executive function. Both links are real and small, which means each skill accounts for less than 3% of the differences in lying. Executive function mattered more for keeping a lie consistent than for telling the first one.

So a toddler's first fib is a normal developmental milestone. It shows that the child can now model another person's mind, and it says little about how bright that child will be compared with peers. For more on the skills involved, see our guide to what an executive function test measures.

The adult evidence points toward no relationship, or a slight lean toward honesty.

• Personality and intelligence: Anglim and colleagues (2022) meta-analysed the links between personality and intelligence. For honesty-humility, a HEXACO personality trait covering sincerity, fairness, greed avoidance and modesty, the correlation with general intelligence across 23 samples and 32,165 people was about .02, with a confidence interval spanning zero.

• A field experiment: Ruffle and Tobol (2017) had 427 Israeli soldiers roll a die in private and report the result, with each point earning an extra half hour of early release from base on Thursday afternoon. Soldiers with higher military entrance scores reported more honestly on average. In a follow-up with 156 civilians paid in cash, two measures of cognitive ability also predicted honesty, while self-reported honesty questions did not.

• Who tells most lies: in a national survey of 1,000 US adults, Serota, Levine and Boster (2010) found that 60% reported telling no lies in the previous 24 hours, and almost half of all lies came from just 5% of respondents. Lying is concentrated in a small group of prolific liars, although that survey did not measure intelligence.

Self-reported honesty is a weak guide (people present themselves well), and die-roll tasks capture small, low-stakes lies. Even so, none of these designs supports the claim that brighter adults are more dishonest.

This is the version of the claim people usually mean, and the honest answer is that it has barely been tested. I could not find a study that measured adults' IQ and then tested how convincingly they lie.

The closest evidence concerns age and self-control. Debey and colleagues (2015) tested 1,005 people aged 6 to 77 on a timed lying task and a stop-signal task of inhibitory control. Lying proficiency improved through childhood, was best in young adulthood and declined across later adulthood, tracking the rise and fall of inhibitory control. That fits the idea that the mental control skills underlying intelligence also help with lying, but it is a lifespan pattern and does not compare people of different IQ at the same age.

Self-described good liars offer another clue. In a survey of 194 adults, Verigin and colleagues (2019) found that people who rated themselves as skilled liars favoured verbal strategies, such as embedding lies in mostly truthful accounts and keeping their stories simple. The study included no cognitive ability measure.

The clever-liar image owes a lot to fiction and to con artists who make the news, which may lead people to confuse social skill with intelligence. Reading what other people believe is a theory-of-mind skill, a theme our article on sarcasm and intelligence explores from another angle.

In toddlers, the first lies show that new thinking skills are developing, and lying correlates modestly with those skills. In adults, honesty and intelligence are essentially unrelated (r ≈ .02).

The evidence says no. A meta-analysis of over 32,000 people found no meaningful link between honesty-humility and intelligence, and one field experiment found that soldiers with higher entrance scores were more honest on average.

That has not been tested directly in adults. Lying draws on inhibitory control and working memory, which relate to intelligence, so a small advantage is plausible, but no study has measured it.

Yes. In one lab study, 40% of 2- and 3-year-olds who broke a rule then denied it, and lying became more common with age. Persistent or harmful lying in an older child is worth discussing with a paediatrician or child psychologist.

Lying requires suppressing the truth and tracking what the listener believes. Across 114 studies, people answered more slowly when lying than when telling the truth.

Lying and intelligence overlap in early childhood, when the first lies mark growing self-control and an understanding of other minds. In adults the link disappears: honesty is essentially unrelated to tested intelligence, and the idea that clever people lie more, or better, rests on stories more than data. If you want an honest measure of your reasoning ability, you can take a full-length online IQ test.

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Hero image: illustration by Violet Moore Higgins from Pinocchio: The Story of a Puppet (1926), public domain. Via Wikimedia Commons.