When we talk about what makes online learning work, we usually talk about teaching quality, course design or the platform itself. A new study in Nature Human Behaviour points to something far more mundane: the second or two a learner spends waiting for the next page to load.
In short: loading delays of around one to two seconds were linked to less engagement and lower achievement, across two very different groups of online learners.
What the researchers looked at
The team, led by Asaf Mazar and including Angela Duckworth, analysed two large datasets:
- 26,707 primary and secondary school students in the United States completing online maths assignments.
- 55,184 aspiring coders, mostly in Latin America, using an online learning platform.
Rather than simply comparing learners with fast connections to learners with slow ones, who might differ in many other ways, the researchers used two longitudinal, quasi-experimental field studies. They looked at how the same learner behaved and performed when their pages happened to load more slowly than usual. That within-person comparison helps rule out explanations such as household income or prior attainment.
What they found
Even short “microdelays” of about one to two seconds were associated with worse outcomes. When school students experienced longer loading times, they:
- completed fewer maths assignments;
- took longer to finish the ones they did;
- were more likely to get distracted mid-task; and
- scored lower.
The coders showed a similar pattern. With more delay, they spent less time actively engaged, multitasked more, completed fewer lessons and were less likely to reach a key course milestone.
Why it matters
It is tempting to assume that if the learning material is good, small technical hiccups do not matter much. This study suggests they may matter a great deal. Learning depends on sustained attention, and every pause is an invitation for the mind, or the phone, to wander. A few seconds lost here and there can add up to fewer tasks attempted and less practice completed.
There is also an equity issue. Learners on slow connections or older devices meet more of these delays, which could put them at a disadvantage that has nothing to do with their ability or motivation.
For schools, tutors and EdTech designers, some practical implications follow:
- Treat page speed as part of learning design, not just an IT concern.
- Test platforms on the slower devices and connections that students actually use at home.
- Where possible, choose tools that pre-load the next question or work well offline.
A note of caution
These were quasi-experimental field studies, not randomised trials in which students were deliberately assigned different internet speeds. The within-person design strengthens the case that delays play a causal role, and the authors report that the results held across several analyses. Even so, the findings are not proof that each extra second of loading costs a fixed amount of learning. The two settings, US school maths and adult coding courses, also differ, so we should be careful about assuming the effects carry over unchanged to every classroom or platform.
Source
Mazar, A., Tomaino, G., Siedahmed, A., Abdolsaheb, A., Heffernan, N. T., Carmon, Z., Duckworth, A. L. et al. (2026). Microdelays disrupt online learning. Nature Human Behaviour. Published 8 October 2026. The abstract is free to read; the full text may require a subscription. The research data and code are available through OSF.
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