New psychology research reveals the cognitive cost of smartphone notifications

A new study published in Computers in Human Behavior suggests that receiving a smartphone notification disrupts a person’s concentration for about seven seconds. The research provides evidence that the frequency of checking a phone and the volume of notifications received are better predictors of this distraction than total daily screen time. These findings indicate that fragmented digital habits play a significant role in how technology affects human attention.

While previous experiments have shown that notifications impair task performance, these studies often used artificial alerts that did not reflect real-world conditions. Many past studies also failed to track the exact temporal duration of the distraction or isolate the underlying psychological mechanisms.

The researchers wanted to separate the different reasons a notification might capture attention. They aimed to determine if distraction is caused simply by the visual suddenness of a pop-up, a concept known as perceptual salience. They also wanted to see if distraction stems from learned habits, known as conditioning, or from the personal relevance of the message.

“People receive a very large number of smartphone notifications every day (more than 100 per day on average in our sample). While it is well established that notifications can automatically capture attention, much less is known about the cognitive mechanisms underlying this capture and why some individuals may be more vulnerable than others. Our goal was to better understand both the mechanisms involved and the individual differences that may explain this sensitivity,” said study author Hippolyte Fournier, a postdoctoral fellow at the Institute of Psychology at the University of Lausanne.

For their study, the scientists recruited 180 university students with an average age of about 21. The participants were randomly assigned to one of three experimental groups. All participants completed a Stroop task, which is a classic psychological test that measures mental processing speed and focused attention.

During a Stroop task, words representing colors are displayed on a screen, but the font color does not match the word itself. For example, the word “blue” might be printed in red ink. Participants must identify the font color while ignoring the written word, which requires intense mental effort. While the participants completed this task, the researchers presented smartphone-style notifications on the computer screen.

The scientists used a deceptive setup to make the experience feel authentic. For the first group, known as the personal-notification group, researchers used a cover story to convince the 60 participants that their own smartphones were synced to the computer. This setup made the participants believe the pop-ups appearing during the task were their actual, personal messages.

The second group of 60 participants saw clear, realistic social media notifications but knew the messages belonged to someone else. This dummy-notification group allowed the researchers to test the effect of learned habits without the element of personal relevance. The final group of 60 participants saw blurred notifications that popped up and moved like normal alerts but contained no readable information.

This blurred-notification group helped the scientists isolate the distraction caused purely by the visual movement of an unexpected object. Before the experiment, the participants completed questionnaires measuring different types of anxiety, including social anxiety and the fear of missing out. After the task, the researchers collected three weeks of objective screen time data from the participants’ smartphones to track their daily usage patterns.

The researchers found that a single notification slowed down a participant’s cognitive processing for approximately seven seconds. The delay happened across all groups but was most pronounced in the personal-notification group. This pattern suggests that distraction is driven by a combination of the visual pop-up, learned associations with the phone, and the personal meaning of the alert.

Within the personal-notification group, the magnitude of the distraction depended heavily on how relevant the participant felt the notification was. Alerts that triggered a strong emotional response or a high desire to check the content caused a longer delay in reaction time. The researchers also tracked the participants’ pupil dilation using an eye-tracking device during the task.

Pupil dilation is a physiological reaction that typically indicates a state of heightened arousal or deep mental effort. The scientists observed changes in pupil size that mirrored the behavioral delays. This provides evidence that emotionally relevant notifications trigger a measurable physical response in the body.

When analyzing daily smartphone habits, the scientists found that total screen time did not strongly predict how distracted a participant would become. Instead, the number of notifications a person typically received each day and how often they checked their phone were much stronger predictors. Participants who tended to have highly fragmented phone habits experienced the most severe attentional disruptions.

“Our findings suggest that notifications can disrupt cognitive processing for about seven seconds and that this disruption reflects multiple mechanisms, including perceptual salience, learned conditioning through repeated exposure, and their potential social relevance,” Fournier told PsyPost.

“Importantly, beyond total screen time, we found that the number of notifications received and the frequency of smartphone checks were associated with stronger disruption effects. This suggests that fragmented smartphone use, not just overall usage time, may play an important role in how digital technology affects our attention.”

“Although the delays we observed may seem small in isolation, their importance comes from how frequently notifications occur in everyday life. Even short disruptions, when repeated dozens or hundreds of times per day, may meaningfully affect concentration and productivity. The practical significance therefore lies more in their cumulative impact.”

To their surprise, anxiety levels did not show a clear link to the severity of the distraction in the main personal-notification group. The data suggests that when notifications are viewed as positive or personally engaging, general anxiety does not drastically alter the level of distraction.

The researchers note a few limitations to keep in mind when interpreting these findings. Pupil dilation can be affected by physical movements and changes in screen brightness, meaning the physiological data contains some natural variations. Because the notifications in the study tended to be viewed as pleasant, the experiment might not have fully captured how anxiety interacts with negative or threatening digital messages.

The scientists also warn against misinterpreting these findings as a sign that all social media use should be strictly banned. The goal of this research is to encourage more mindful and adaptive technology habits rather than complete avoidance.

“Given the strong public debate about social media use, our findings should not be interpreted as suggesting that social media or notifications should be avoided entirely,” Fournier explained. “Rather, they highlight the importance of better understanding the cognitive mechanisms involved in order to promote more balanced and mindful use, particularly for individuals who may be more vulnerable to attentional disruption. The goal is not prohibition, but informed and adaptive use.”

Future research will explore how notifications become so intensely attention-grabbing over time. The scientists also plan to investigate whether frequent social media use alters a person’s ability to sustain focus on long-term goals. Another planned area of study involves understanding why people engage in repetitive scrolling behaviors and how this relates to daily emotion regulation.

“One challenge in this field is that it is difficult to study the real cognitive impact of notifications (or social media use) in laboratory settings while maintaining experimental control,” Fournier said. “In this study, we used a cover story that allowed us to measure the effects of participants’ real notifications in a controlled environment. This approach opens promising avenues for future research aiming to study digital behavior in more ecologically valid ways.”

The study, “Attention hijacked: How social media notifications disrupt cognitive processing,” was authored by Hippolyte Fournier, Arnaud Fournel, François Osiurak, Olivier Koenig, Flora Pâris, Vivien Gaujoux, and Fabien Ringeval.