A few weeks ago, my son’s high school hosted a derby and, for two nights, we put up two boys from the visiting school. They were polite and friendly kids but engaging them in meaningful conversation was almost impossible. They constantly had their phones in their hands: at the dinner table, in the car and in the line at the ice cream shop.
What really disturbed me was that I did not experience their behaviour as dramatically rude. I have come to accept this culture of being always connected and only partially present as the norm among adolescents.
Over the past decade, I have studied the relationship between technology and cognition through multiple research approaches and across multiple settings. In one of our recent projects, we focused on smartphone use in high schools — a topic that has become the subject of intense debate. The views of the 203 teachers and 2 264 parents who participated reveal a strikingly consistent concern. Many adults experience young people as physically present but mentally elsewhere: permanently half-available to the people and places around them. They worry about what this means for friendships, family relationships and, more broadly, the kinds of adults these children will become.
As a father, I share this concern. But as a researcher I have learnt that it is an unusually difficult concern to investigate scientifically. How do we measure the consequences of being only partially present? A strained dinner conversation is real enough to the people sitting around the table but it is difficult to convert into an outcome that allows us to say with any confidence that smartphones are harming adolescents.
Academic performance offers something much more concrete.
For parents and teachers, report cards become something like the canary in the coal mine. If the same inability to disengage from the digital world that we observe around dinner tables also prevents adolescents from engaging fully with what is happening in the classroom, we should expect it to leave a measurable academic trace. And if habitual smartphone involvement were associated with substantially poorer academic performance, the case for banning phones from schools would be significantly strengthened.
Smartphones are difficult technologies to regulate. They are small, personal, almost always carried on the body and designed to provide continuous access to communication and information. This places considerable pressure on teachers. They have to notice infringements, confront learners, confiscate devices where policies allow it, deal with arguments and exceptions, and repeat this process across lessons and school days. Many teachers experience this enforcement as difficult and draining.
Learners are also remarkably well attuned to the boundaries of their schools’ rules and to the opportunities for working around them. Our findings show that despite strict written policies, many learners use their phones throughout the school day, frequently switching their attention between academic work and online media.
But is this behaviour associated with lower academic performance?
To answer this question, my colleague Jennifer Feldman and I performed a multiple case study of five high schools that was recently published in the South African Journal of Science.
We measured something called in-school smartphone vigilance (ISSV) among 963 learners across five high schools. ISSV is a survey-based measure of learners’ cognitive involvement with their phones during the school day. It captures not only how regularly learners check their phones and respond to messages or notifications, but also how much they think about phone communication and content when they are not using their phones.
We then examined whether learners with higher levels of in-school smartphone vigilance performed worse academically, while taking into account their grade, gender and school.
They did.
But barely.
After we controlled for school, grade and gender, ISSV explained less than 1% of the remaining variation in academic performance. The learners who performed well were, for the most part, the learners who performed well regardless of how preoccupied they were with their phones during the school day.
The public conversation often treats smartphones as a powerful and primary cause of declining academic performance. Our data do not support such a strong claim. The association exists but its practical contribution to academic performance is very small.
Why?
There are several possibilities. Academic performance may simply be too blunt or too delayed an outcome to capture the daily friction caused by divided attention. Learners who perform well academically may also be better at regulating their phone use, reducing the observed relationship between smartphone vigilance and marks.
But perhaps the most interesting possibility is that the real problem is cultural and relational rather than simply academic. Smartphones may be contributing to a broader transformation in the ecology of attention and presence, a collection of small changes that are individually difficult to measure but collectively change how young people experience the world around them.
There is something strange about being with someone who is physically present but psychologically distributed across several other conversations, platforms and streams of information. That experience is sufficiently common that we barely notice it. The gap between the intensity of our concern and the modesty of the effects we can measure is therefore important in its own right.
What should schools do?
Our findings point to solutions that do not depend on teachers spending their days policing individual infringements. We have seen simple examples of teachers using phone cubbies or designated storage spaces at the front of classrooms. Learners place their phones there at the start of a lesson and collect them afterwards. Such interventions are inexpensive and uncomplicated but they do something important: by physically separating the learner from the device they remove some of the continuous negotiation about whether it may be checked.
Schools should experiment with these kinds of approaches. The objective should not only be to enforce compliance with a smartphone policy but to create cultures of disconnection: places and periods during the school day in which learners become accustomed to being unavailable to the digital world.
There is potentially an important educational lesson in this. Adolescents can learn that a message does not have to be answered immediately. They can discover that little happens when they do not check their phones for an hour. They can experience what it is like to give an academic problem, a conversation or the people around them their full attention. Perhaps schools have a role to play in creating these experiences precisely because they are becoming less common elsewhere.
The boys eventually left after the derby. They were pleasant guests and I enjoyed having them in our home. I still think about how little of the weekend they seemed to inhabit. The data from nearly a thousand South African learners tell me that this kind of partial presence may not move the academic needle very much.
They do not, however, tell me that it is harmless.
Daniel le Roux is an associate professor in the department of information science at Stellenbosch University. This article is based on his and Jennifer Feldman’s paper ‘Do school smartphone policies work? A multiple case study of five South African high schools’, published recently in the South African Journal of Science (2026).