Cognitive load is the total demand placed on working memory during learning. Cognitive Load Theory, developed by John Sweller, distinguishes intrinsic load (inherent difficulty), extraneous load (imposed by presentation) and germane load (effort that builds understanding).
What it is
Working memory is sharply limited. Once saturated, additional input does not accumulate — it displaces. The learner may still be watching while nothing is being retained.
Extraneous load is the actionable category: it is imposed by how material is presented rather than by the material itself, so it can be reduced by design.
Why it matters
Overload has a distinctive signature in engagement data — a replay spike rather than a drop-off. Learners rewind, attempt again, and only leave after the second failure. That pattern distinguishes overload from boredom, and the two need opposite interventions.
A common confusion
Replay is often read as disengagement. It is the opposite: it is effort. Only replay followed by exit indicates overload.
Related
See also microlearning, engagement index and content effectiveness. See the full glossary for the rest, or the learner engagement guide for the wider context.
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