cognitive-load-theory
Concept Card
What it is: Cognitive Load Theory (CLT) is a psychological framework originating with John Sweller (1988) that explains how human working memory processes new information and what design decisions help or hinder schema formation. It is the scientific backbone behind "keep it simple" intuitions — but with actionable precision about which complexity to cut and which to preserve.
Mental model: Working memory is a small workspace — only a few independent novel units at once (plan around ~4 chunks; 3–5 is the safer current range — Miller's 7±2, revised by Cowan to ~4), and it holds novel information for only seconds unless rehearsed. CLT describes the load on that workspace in terms of intrinsic load (the task itself) and extraneous load (how you presented the task); germane load is the portion of working-memory effort that gets applied to building schemas out of the intrinsic material. Total load must stay below capacity or learning and comprehension fail.
Why it exists: Without CLT, agents default to "simplify" without knowing what to cut. They might remove worked examples (germane processing of intrinsic load, valuable) while keeping verbose prose around a table (extraneous load, wasteful). CLT gives a precise vocabulary for the tradeoff. Its deeper grounding is evolutionary (Geary's biologically secondary knowledge): we did not evolve to acquire reading, mathematics, or code effortlessly, so this material runs into the working-memory bottleneck and needs deliberate instructional design — unlike biologically primary skills such as speech or face recognition, which we acquire without it.
What it is NOT: Not a general UX heuristic. Not the same as plain-language writing. Not about reducing all complexity — germane processing (building schemas) is desirable and should not be starved. Not retrieval design (see context-management). Not a token-budget model, compression algorithm, or complete instructional-design theory.
Adjacent concepts: working memory, element interactivity, chunking, schema theory, dual-channel processing (Mayer's multimedia learning), segmentation principle, split-attention effect, redundancy effect, expertise reversal effect, transient information effect, context saturation, attentional residue, prompt overflow, tool-use capability boundary.
One-line analogy: CLT is like RAM management for humans — intrinsic load is the program you must run, extraneous load is unnecessary background processes, and germane load is the OS caching data so the next run is faster.
Common misconception: "Reducing cognitive load always means making things shorter or simpler." Wrong — cutting worked examples, removing context, or over-abstracting increases intrinsic load and wastes the freed capacity that should go to schema-building. The correct target is extraneous load only.
Measurement note: Cognitive load is not just a metaphor — it is measured, classically with subjective rating scales (the Paas single-item mental-effort scale), dual-task performance, and physiological signals. This skill applies CLT as a design lens rather than running formal measurement, but the underlying loads are empirically tractable, not hand-wavy.