A river of screens: How our digital habits are reshaping our mind

February 18th, 2025

Written by: Victoria Subrtizky Katz

How long can you focus on this article before your phone calls your attention? A notification, a newsfeed refresh, or a quick text—do they pull you away? If so, you’re far from alone.

As time spent online continues to climb, checking behaviour – the habit of quick, frequent glances at devices for incoming information – has become pervasive for many¹. A study tracking the laptop activity of undergraduate students found the median length of time spent continuously viewing a piece of content (website, application etc.) was only 19 seconds. Only 8% of continuous content interactions were longer than 4 minutes, and many of those were on video platforms like YouTube or Netflix². This phenomenon is called media multitasking: the tendency to bounce between multiple websites, tabs, and apps instead of focusing on a single application without interruption.

From Maps to Screens, Brains Adapt

You can think of your brain like a river—its pathways are carved and reshaped over time by the flow of your experiences.  For instance, before the rise of GPS, the parts of the brain involved in spatial memory were found to be larger in London taxi drivers than the general population, likely due to the mental demands of navigating the city’s complex streets³.  Our brain is influenced by the environment it is exposed to, and it is becoming increasingly exposed to the online world.

In 2024, an estimated 90% of American adults have a smartphone and 41% report they are online almost constantly⁴. Among younger generations this constant connectivity is even more pronounced with 51% of teenagers aged 15–17 and 62% of young adults aged 18–29 reporting almost constant online activity⁵. One study found the average American youth spends 7.5 hours online every day, which is more than any other waking activity⁶.

As more of our waking hours are absorbed by the online world, what might the prevalence of this digital environment mean for how our brains process information and navigate the world? One area being impacted is our ability to pay attention.

Fragmented Focus: How Heavy Media Multitasking Affects Attention

Researchers conducted a series of experiments to examine how distractions affect attention in individuals who engage in varying levels of media multitasking in their online usage, revealing that heavy media multitaskers (HMMs) struggled more with distractions than those who multitask less (light media multitaskers, LMMs)⁷. In one experiment, subjects were tested on their ability to remember the location of two red rectangles on the screen after a brief delay. When distractions were added in the form of blue rectangles on the screen (see figure 1), HMMs did worse at remembering the location of the red rectangles they were supposed to be paying attention to compared to LMMs⁷. These experimental results suggest that frequent media multitaskers are more easily distracted and less effective at maintaining focus in the presence of distractions.

Even brief exposure to an environment that facilitates media multitasking can influence attention. In one study, in the 15 minutes before performing a cognitive test some participants were instructed to shop online (which allows media multitasking) while others were instructed to shop by browsing a magazine. Subjects who shopped online had worse attention in the testing compared to those that browsed a magazine.⁸

The effects of intensive media multitasking go beyond behavior, with evidence pointing to structural changes in the brain. Individuals with higher levels of internet usageand media multitasking show reduced grey matter volume in brain areas that play a critical role in managing attention, suppressing distractions, and maintaining focus, located in a part of the brain called the prefrontal cortex^9,10. This decrease in volume suggests that the changes in behavioural performance linked to heavy media multitasking could be due to changes in brain structure.

Not all studies have found the same relationship between media multitasking and attention^11,12, but an analysis looking at the results across 41 different studies (a meta-analysis) did find higher levels of media multitasking were related to poorer performance on cognitive tasks¹. While more studies should be conducted, most of the evidence points toward a negative impact of media multitasking on attention^1,6,13,14.

The Lasting Effects of a Digital Diet

So, have you managed to read this far without the lure of a notification, message or another tab pulling your attention away?

This article touched on only one aspect of how media usage is shaping our brains. From memory capacity and reward processing to mental health and social behaviors, studies are finding that society’s new digital diet is impacting us^1,6,13,14. These effects may be even more pronounced for children and adolescents, who are not only spending more and more time online, but whose brains are still developing^6,14,15.

The existing body of scientific research on the influence of digital media on our brains is far from complete. While not all findings are conclusive and some studies have produced conflicting results, this highlights the need for deeper investigation—not the mistaken assumption that our digital habits have no neurological impact.

Much like the saying “we are what we eat,” our brains are shaped by what we consume. If we’re feeding them a constant diet of fragmented, fast-paced digital media, it will inevitably have consequences. The question is not whether media use is changing our brains and behaviour, but how—and whether we want to do anything about it.

References

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2. Leo Yeykelis, James J. Cummings, Byron Reeves, Multitasking on a Single Device: Arousal and the Frequency, Anticipation, and Prediction of Switching Between Media Content on a Computer, Journal of Communication, Volume 64, Issue 1, February 2014, Pages 167–192, https://doi.org/10.1111/jcom.12070
3. E.A. Maguire, D.G. Gadian, I.S. Johnsrude, C.D. Good, J. Ashburner, R.S.J. Frackowiak, & C.D. Frith, Navigation-related structural change in the hippocampi of taxi drivers, Proc. Natl. Acad. Sci. U.S.A. 97 (8) 4398-4403, https://doi.org/10.1073/pnas.070039597 (2000).
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5. Gelles-Watnick, Risa. “Americans’ Use of Mobile Technology and Home Broadband.” Pew Research Center, Pew Research Center, 31 Jan. 2024, http://www.pewresearch.org/internet/2024/01/31/americans-use-of-mobile-technology-and-home-broadband/.
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10.  Loh KK, Kanai R. Higher media multi‐tasking activity is associated with smaller gray‐matter density in the anterior cingulate cortex. PLoS One 2014;9:e106698. 
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15. Orben, A., Meier, A., Dalgleish, T. et al. Mechanisms linking social media use to adolescent mental health vulnerability. Nat Rev Psychol 3, 407–423 (2024).
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