“multitasking”, this new enemy of the brain – L’Express

“If you’re trying to write a piece, but you’re checking your email every six minutes or switching back and forth between writing and your social media, that’s going to have a massive cognitive cost,” says Cal Newport, associate professor of science at Georgetown University (United States) and author of several bestsellers, including Deep Work (2017, Alisio) or Work without emails (2023, Diateino). “Constantly checking your emails or messages is not that different from drinking a shot of strong alcohol every thirty minutes: your ability to think clearly will be reduced, your thoughts may become confused and fatigue sets in more quickly.” he adds in The Economist. The reason according to him? The brain is slow to adapt to the context in which it operates, or to the task on which it must focus. Concentration requires time and calm. If the analogies and explanations of the American researcher seem simplistic, they nevertheless summarize the numerous research on the subject.

According to the wireframe cognition model, developed in a study published in 2008 in the scientific journal American Psychological Association, the brain can be compared to a processor perfectly capable of processing tasks that require resources that are compatible with each other. However, he encounters difficulties when he has to carry out operations that require the same resources. Human beings can therefore concentrate on a film without difficulty, since they use two non-competing resources: watching images and listening to sounds. On the other hand, if he checks his phone at the same time, it creates interference. “This is the principle of cognitive abilities, we have cognitive resources that we can allocate to different operations, but which are limited. And when we perform tasks that require the same input modalities – listening, seeing, etc. – , or which require a lot of operations, this enters into competition”, explains Séverine Erhel, lecturer in cognitive psychology at Rennes II University. “Multitasking”, a term widely used by French specialists and which consists of frequently interrupting one task for another, presents the same problem: either we use the same input modality, or we consume too many resources. A practice that turns out to be harmful in many respects.

“Studies show that people who practice it intensely on a daily basis are less good at listening and speaking tasks,” continues Séverine Erhel. Work published in 2016 in NeuroImage also report that children and adolescents who engage in multitasking the most are more easily distracted. Which can make them less efficient when they have to perform only one task at a time.” The researcher herself published a study in 2020, in Computers in Human Behavior, demonstrating that the more its students engage in multitasking in class – checking their SMS and social networks – the more they encounter learning difficulties, in particular in memorizing the instructions or information given orally by the teacher. Which confirms the results of another study published in 2015 in the same journal.

According to a meta analysis published in 2021 which compiles the results of 16 scientific studies, the practice of multitasking is associated with a reduction in attention regulation and an increase in mind wandering, as well as memory problems. People who juggle tasks too often also have difficulty regulating their behavior, more often have symptoms related to impulsivity and hyperactivity, and are more attracted to risk-taking or thrill-seeking. More or less marked attention deficit disorders or deficits may even appear, sometimes related to ADHD (attention deficit disorder with or without hyperactivity). Another meta analysis published in 2022 and analyzing 88 scientific studies reveals that individuals with the greatest tendency toward multitasking more often present attentional weaknesses, boredom or lack of interest in their work, reduced motivation and a low sense of self-satisfaction. “In addition to psychological vulnerability, lack of sleep and ease of access to technologies are also predictors of multitasking,” explains Séverine Erhel.

However, this work does not demonstrate causality: it does not say whether multitasking causes these disorders or whether people who suffer from it are more likely to engage in this practice. “We can hypothesize that it is bidirectional,” suggests Séverine Erhel. If certain profiles probably have predispositions pushing them towards multitasking, the fact of constantly juggling between different tasks could reinforce their difficulties. More worrying: in the long term, multitasking could disrupt inhibitory control – the cognitive process that allows you to resist temptation and concentrate on completing a specific task. The more we practice multitasking, the less we would resist it. A real vicious circle would then be set up, particularly among predisposed people. Corentin Gonthier, professor of developmental psychology at the University of Nantes, nevertheless remains cautious on this subject. “No one has really studied the brain impacts of multitasking, nor its long-term consequences on inhibitory attentional control,” he warns.

This intelligence specialist also wants to make a distinction with what he considers to be “real” multitasking, i.e. the ability to carry out several operations at the same time, as air traffic controllers do for example, and whose effects are better known. “There, we know that different networks of brain areas, linked to the processing of tasks performed, are called upon. Brain activity is overall more intense, even if these different areas are less active than if the brain had had a single operation at achieve,” he explains. Some studies also suggest that people who regularly perform several tasks at the same time – airplane pilots or professional video game players in particular – may express slightly different brain activity, with less activity in areas linked to the processing of tasks performed frequently. “These automated tasks require less effort, which in some way frees up resources to carry out other tasks in parallel,” explains Corentin Gonthier.

Scientific studies also do not provide ideal solutions to combat compulsive jumping from one activity to another. Developing attentional control is long-term training and requires discipline. In children, learning can occur through vigilant education, or even the imposition of rules, such as not having a phone while working. Adults must self-regulate. “Know how to implement metacognitive strategies [NDLR : développer une activité mentale sur ses propres processus mentaux] is one of the keys to getting out of these bad practices, believes Séverine Erhel. This requires first of all being aware of what we are doing.”

Simple rules can help, such as systematically turning the screen of your phone when working, turning off all notifications – attention hooks – or not going on social networks outside of certain times. A study published in 2021 indicates that one of the moderators of multitasking is time management skills. : people who manage to delimit distinct times to accomplish different tasks – a time to exchange, to play, to work, etc. – are less likely to engage in this practice in an unbridled manner.

Finally, there remains the world of work which very often requires, in addition to an email box, one or more professional messaging systems such as Teams or Slack, or even Signal, Telegram or WhatsApp. Here, it is companies, and in particular human resources departments, which must take measures to rationalize uses. “We need to imagine new ways of collaborating that don’t rely on constantly sending each other messages,” says Cal Newport. “As long as the hyperactive hive mind is the central driver of collaboration in companies, it “It will be difficult, if not impossible, not to constantly consult your various inboxes.” A call to reinvent shorter, less invasive and more effective methods of communication. Which will not be an easy task.