Multitasking and Intelligence: Are Smart People Better at Multitasking?

People with higher intelligence are somewhat better at multitasking, but multitasking a lot is not a sign of high intelligence. In a population sample of 567 adults, fluid reasoning and performance on a multitasking test correlated about .33, while in a study of 277 students the heaviest media multitaskers scored lower on a working memory test than the lightest (a gap of about half a standard deviation).

So the ability and the habit point in different directions. This article explains what psychologists mean by multitasking, what the best studies show about multitasking ability and IQ, what happened to the famous finding that heavy media multitaskers are more distractible, and why so many people overrate their own multitasking.

"Multitasking" covers several different things, and the research findings depend on which one is measured.

• Task switching: moving back and forth between two simple tasks. In a review for Trends in Cognitive Sciences, Stephen Monsell described the "switch cost": people respond more slowly, and usually make more errors, right after changing tasks. Advance preparation shrinks the cost but does not remove it.

• Dual-tasking: doing two demanding things at the same moment, such as driving a simulator while solving a memory task. This is closest to the everyday sense of multitasking, and for most people performance on one or both tasks drops.

• Complex multitasking tests: lab simulations of office work, where people must spread limited time across several jobs. One example is the "Hotel test", in which participants have 10 minutes to make progress on five tasks that would each take at least 10 minutes to finish.

• Media multitasking: a habit, measured by questionnaire, of using several media at once (texting while watching TV, for example). It measures how often people multitask and says nothing directly about how well they do it.

The first three are abilities. The fourth is a behaviour, and the evidence below shows that the two are related in an unexpected way.

The best evidence comes from studies that give many people both intelligence tests and several multitasking tasks, then estimate the relationship between the underlying abilities.

• A population sample: Kievit and colleagues (2014) studied 567 adults aged about 18 to 89 from the Cambridge Centre for Ageing and Neuroscience. The latent correlation between fluid intelligence (measured with the Cattell Culture Fair test) and multitasking (the Hotel test) was .33. A model treating them as one ability fit the data very poorly, so the authors concluded they are related but separable. Fluid intelligence also declined much more steeply with age (r = −.67) than multitasking did (r = −.29).

• A large latent-variable study: Redick and colleagues (2016) gave 534 young adults measures of working memory, attention control, fluid intelligence and a varied set of multitasks. They found a coherent general multitasking ability, and working memory and fluid intelligence accounted for more of its variance than attention control did.

• An earlier test of preferences versus ability: König, Bühner and Mürling (2005) found that working memory, fluid intelligence and attention predicted multitasking performance, while "polychronicity" (a stated preference for doing several things at once) and extraversion did not.

A correlation of .33 means the two abilities share about 11% of their variance. Knowing someone's fluid reasoning score gives you a modest hint about how they will handle a busy multitasking test, and no more. The strongest single link runs through working memory, the ability to hold and manipulate information over a few seconds while ignoring distractions.

In 2010, Watson and Strayer tested 200 people in a high-fidelity driving simulator while they also did a demanding spoken memory task. Almost everyone got worse at one or both tasks. Five people (2.5% of the sample) showed no decline at all, and in single-task conditions these "supertaskers" scored in the top quarter on every measure. A follow-up brain-imaging study by Medeiros-Ward, Watson and Strayer (2015) compared supertaskers with controls matched on working memory capacity and found more efficient activity in frontal regions linked to attention control. Supertaskers are rare and the original sample was modest. The label describes how someone performed on a demanding test, and you cannot spot it by how busy a person looks.

The claim most people have heard comes from a 2009 PNAS study by Ophir, Nass and Wagner. They compared heavy and light media multitaskers and reported that the heavy group was more easily distracted by irrelevant information and, surprisingly, worse at task switching.

Later work was less clear-cut.

• Replications: Wiradhany and Nieuwenstein (2017) ran two replication studies with 14 tests and found that only 5 showed the expected distractibility effect, and only 2 survived a stricter Bayesian analysis.

• Meta-analysis: in the same paper, their meta-analysis of 39 effect sizes found a small association (Cohen's d = .17). After correcting for small-study effects, which are often a sign of publication bias, it fell to between .01 and .07 and was no longer significant.

• Fluid intelligence: Minear and colleagues (2013) found no task-switching or distraction deficit in heavy media multitaskers, but the heavy group did report more impulsiveness and scored lower on fluid intelligence tests.

• The overall picture: a 2018 review by Uncapher and Wagner, two of the original authors, concluded that heavier media multitaskers tend to perform worse in several cognitive areas, especially those needing sustained attention, while noting that many studies find no difference and that the direction of cause is unknown.

That last point matters. These studies are correlational, so they cannot tell us whether multitasking erodes attention, whether people with weaker attention control drift into multitasking, or both. If you are interested in how screen habits relate to IQ more broadly, our article on social media and IQ covers that evidence.

The belief that juggling several things at once marks a sharp mind is common, and self-assessment helps explain it.

Sanbonmatsu and colleagues (2013) asked 277 University of Utah students how often they multitasked and how good they thought they were at it, then measured their working memory with the Operation Span task, which itself requires doing two things at once (solving maths problems while remembering letters).

• Inflated self-ratings: on average, students placed their own multitasking ability at the 63rd percentile, and 193 of the 277 rated themselves above average.

• Self-ratings versus performance: perceived multitasking ability was essentially unrelated to actual Operation Span scores (r = .08).

• Who multitasks most: media multitasking correlated negatively with Operation Span scores (r = −.19) and positively with impulsivity and sensation seeking. Students in the top quarter for media multitasking scored about half a standard deviation lower on the working memory task than those in the bottom quarter (d = 0.52).

For scale, half a standard deviation would be about 8 points on an IQ scale with a standard deviation of 15. The Operation Span is a working memory test, not an IQ test, so that conversion is only a way to picture the size of the gap.

The authors suggested that many people multitask because they find it harder to block out distractions and stay with one task. Difficulties with attention control are also central to ADHD, and our article on ADHD and IQ explains why attention problems can lower test scores without reflecting lower reasoning ability.

Other confounds apply too. Most media multitasking studies recruit modest samples of university students, whose education and test scores are above the population average, and the studies above suggest that impulsivity and weaker attention control may explain part of the link. Age matters as well: in the Cambridge sample, multitasking scores fell with age (r = −.29), though far less steeply than fluid reasoning.

Not the habit. People who multitask the most tend to score slightly lower on working memory and fluid reasoning, although the ability to multitask well is moderately related to intelligence (about r = .33 in one large sample).

On average, somewhat. Fluid intelligence and working memory are among the best predictors of performance on lab multitasking tests, but many other factors matter.

No study has shown that multitasking causes a lasting drop in IQ. The links between heavy media multitasking and weaker attention are small, inconsistent across studies, and correlational.

In the best-known study, 5 of 200 drivers in a simulator (2.5%) showed no performance loss when doing a demanding memory task at the same time. That figure comes from one modest sample and should be treated as a rough estimate.

Most people overrate themselves. In one study of 277 students, 193 rated their multitasking as above average, yet those ratings were essentially unrelated to their measured performance (r = .08).

Multitasking ability and intelligence overlap moderately, mainly through working memory and attention control, but the urge to do many things at once is not a sign of a high IQ. If anything, the people who multitask most rate their skill highly and score a little lower on working memory and reasoning tests. If you want a measure of your reasoning ability taken one task at a time, try an online IQ test built by psychometricians.

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2. Redick, T. S., Shipstead, Z., Meier, M. E., Montroy, J. J., Hicks, K. L., Unsworth, N., Kane, M. J., Hambrick, D. Z., & Engle, R. W. (2016). Cognitive predictors of a common multitasking ability: Contributions from working memory, attention control, and fluid intelligence. Journal of Experimental Psychology: General, 145(11), 1473-1492. [doi.org/10.1037/xge0000219](. doi.org

3. König, C. J., Bühner, M., & Mürling, G. (2005). Working memory, fluid intelligence, and attention are predictors of multitasking performance, but polychronicity and extraversion are not. Human Performance, 18(3), 243-266. [doi.org/10.1207/s15327043hup1803_3](. doi.org

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5. Watson, J. M., & Strayer, D. L. (2010). Supertaskers: Profiles in extraordinary multitasking ability. Psychonomic Bulletin & Review, 17(4), 479-485. [doi.org/10.3758/PBR.17.4.479](. doi.org

6. Medeiros-Ward, N., Watson, J. M., & Strayer, D. L. (2015). On supertaskers and the neural basis of efficient multitasking. Psychonomic Bulletin & Review, 22(3), 876-883. [doi.org/10.3758/s13423-014-0713-3](. doi.org

7. Ophir, E., Nass, C., & Wagner, A. D. (2009). Cognitive control in media multitaskers. Proceedings of the National Academy of Sciences, 106(37), 15583-15587. [doi.org/10.1073/pnas.0903620106](. doi.org

8. Wiradhany, W., & Nieuwenstein, M. R. (2017). Cognitive control in media multitaskers: Two replication studies and a meta-analysis. Attention, Perception, & Psychophysics, 79(8), 2620-2641. [doi.org/10.3758/s13414-017-1408-4](. doi.org

9. Minear, M., Brasher, F., McCurdy, M., Lewis, J., & Younggren, A. (2013). Working memory, fluid intelligence, and impulsiveness in heavy media multitaskers. Psychonomic Bulletin & Review, 20(6), 1274-1281. [doi.org/10.3758/s13423-013-0456-6](. doi.org

10. Uncapher, M. R., & Wagner, A. D. (2018). Minds and brains of media multitaskers: Current findings and future directions. Proceedings of the National Academy of Sciences, 115(40), 9889-9896. [doi.org/10.1073/pnas.1611612115](. doi.org

11. Sanbonmatsu, D. M., Strayer, D. L., Medeiros-Ward, N., & Watson, J. M. (2013). Who multi-tasks and why? Multi-tasking ability, perceived multi-tasking ability, impulsivity, and sensation seeking. PLOS ONE, 8(1), e54402. [doi.org/10.1371/journal.pone.0054402](. doi.org

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