Cognitive load

Definition

Cognitive load is the demand a task or a presentation places on working memory. Intrinsic cognitive load arises from the complexity of the material relative to the reader’s knowledge — the number of elements that must be processed together. Extraneous cognitive load arises from the presentation, for example when a reader must search for the label belonging to a figure. Earlier versions of the theory also named germane load, the effort devoted to building knowledge structures.

Historical development

John Sweller (1988) linked problem-solving strategies to working memory load and argued that some forms of instruction impose load that does not contribute to learning. Paul Chandler and John Sweller (1991) described the split-attention effect: learning suffers when learners must mentally integrate sources that could have been physically integrated, such as a diagram and separate explanatory text. The worked example effect (Sweller and Graham Cooper, 1985) showed that studying solved examples can be more efficient for novices than solving problems. Slava Kalyuga, Paul Ayres, Paul Chandler and John Sweller (2003) summarized the expertise reversal effect: techniques that help novices can become ineffective or detrimental for experts. Richard Mayer (2001) formulated the cognitive theory of multimedia learning, based on dual channels, limited capacity and active processing, and derived principles such as coherence, signaling, redundancy and spatial contiguity.

Main models

1. Types of load. Intrinsic and extraneous load; germane load as a third type in the 1998 formulation by Sweller, Jeroen van Merriënboer and Fred Paas.
2. Split-attention effect. Physically integrating mutually dependent sources reduces extraneous load.
3. Expertise reversal effect. The optimal amount of guidance depends on prior knowledge.
4. Worked example effect. Solved examples support novices.
5. Multimedia principles (Mayer). Coherence (omit extraneous material), signaling (highlight organization), redundancy (avoid duplicating narration with identical on-screen text), spatial contiguity (place words near the corresponding parts of a picture).

Function and purpose

The theory explains why the same content can be easy or hard to use depending on its presentation, and why material written for beginners can slow down experienced readers. It shifts attention from the amount of information to the way information has to be combined.

Applications in technical communication

Documentation practice derives several presentation rules, described in the context card Cognitive load and split attention. Labels are placed in figures next to the parts they name rather than in separate legends where possible, and the text of a step is placed next to the figure it refers to. Decorative material that carries no information is avoided on pages where readers act. Headings and consistent typographic signals show the structure of a procedure. Content is layered for different levels of expertise, for example with progressive disclosure, quick-reference job aids for experienced users and worked examples for new ones. These rules reduce extraneous load; they do not remove intrinsic complexity and never justify omitting safety-related information, which is integrated into the presentation rather than cut from it.

Limitations and evidence

Most studies of cognitive load theory were conducted in educational settings, often with students and short learning tasks, so their transfer to workplace documentation is plausible but less directly tested. Cognitive load is difficult to measure; subjective rating scales such as the one introduced by Paas (1992) are widely used but do not distinguish types of load reliably. The status of germane load has been debated, and Sweller later reformulated it as working memory resources devoted to intrinsic load rather than a separate additive type. Several multimedia principles have boundary conditions — the redundancy principle, for example, depends on pacing and on the learners — and effect sizes vary. The theory does not support adapting documentation to supposed learning styles.

Relation to other areas

Cognitive load theory rests on the limits of working memory (see Memory and instructions) and on dual coding (see Reading comprehension). Its principles meet minimalism and structured authoring (see Technical documentation models) in decisions about what a page contains and how it is arranged.

Conclusion

Cognitive load theory provides well-supported reasons to integrate related information and to adapt guidance to expertise. Its measures and some of its categories remain debated, so its principles are best applied as tested heuristics rather than exact rules.