Cognitive Load & Usability
The extent to which a system places a load on working memory has a decisive influence on its usability. Cognitive Load Theory provides a useful framework model for this.
Definition: Cognitive Load & Usability
Cognitive load describes the mental effort required to process information and perform tasks - especially in working memory.
Three Types of Cognitive Load
The Cognitive Load Theory (CLT) according to Sweller distinguishes between three types of mental stress:
1. Intrinsic load This results from the complexity of the content itself. A simple form for changing an address generates a low intrinsic load - a complex control module, on the other hand, generates a high intrinsic load. UX design cannot reduce it, but it can support it through good structuring.
2. Extrinsic load This is caused by poor design. Illogical navigation, unnecessary pop-ups or incomprehensible wording lead to unnecessary mental effort. UX goal: minimize this burden.
3. Load conducive to learning It arises when information is prepared in such a way that it promotes deeper understanding - for example through interactive assistance or clear visual structures. UX goal: activate this in a targeted manner.
Design Goal
Good interfaces reduce extrinsic stress - without devaluing the cognitive content.
Principles for cognitively relieved UX design
A usable design helps users to use their cognitive energy efficiently. Here are some key strategies:
- Chunking: Organize complex content into meaningful sections - for example by creating groups in forms.
- Progressive Disclosure: Only show the information that is currently relevant, e.g. through step-by-step navigation or accordions.
- Consistency: Recognizable symbols, layouts and interactions promote quick comprehension.
- Visual feedback: After an input, for example, a button should react so that no uncertainty arises.
- Use white space in a targeted manner: It improves visual legibility and reduces sensory overload.
- Limited choices: Fewer options lead to faster decisions (→ Hick’s Law).
Practical Example: Form Design
An insurance form with 20 mandatory fields on one page seems overwhelming.
Better: It is divided into three manageable sections, each of which is supplemented by a progress bar. Help texts appear depending on the context - only when they are needed. This significantly reduces extrinsic stress.
Measurement of Cognitive Load
UX research can capture cognitive load using various methods:
- Subjective methods such as NASA-TLX questionnaires
- behavioral data such as time-on-task or error frequency
- Physiological methods such as pupillometry or eye tracking
These indicators help to identify critical points in the interface - and to make targeted improvements.
Conclusion
A good UX design is not just visually appealing or functional. It also takes into account the __MARKBOLD_cognitive resources of the user.
Design decisions that consciously control cognitive load enable more effective use, more satisfaction - and ultimately better usability.
Take Home Message
Good usability takes the pressure off thinking - not the users.
Last modified: 17 June 2025