Skip to content
UX Atlas
Plate PSY·001 · PsychologyGrid B2 · Rev. 2026-08-14

Cognitive Load

Working memory is a narrow channel, and interfaces spend it on three kinds of work, only one of which is useful.

PsychologyEstablished researchFoundational

Definition

John Sweller's cognitive load theory divides mental effort into intrinsic load, which comes from the difficulty of the task itself, extraneous load, which comes from how the material is presented, and germane load, which is the effort that builds understanding. Design reduces extraneous load so capacity is available for the other two.

Established research. Originates in published research and has been replicated. The effect is real. Its size in your product still needs measuring.

On this plate
  1. 1Definition
  2. 2Three loads and what to do about each
  3. 3Sources of extraneous load in interfaces
  4. 4Reducing the load that is not the task
  5. 5In practice
  6. 6Commonly confused with
  7. 7Local chart
  8. 8Sources
  9. 9Continue from here

Reach for this when

  • Users report a product feels overwhelming without pointing at anything specific.
  • Designing for comparison, learning or complex domains.
  • Auditing a screen with high abandonment and no obvious error.
  • People complete a task correctly but describe it as exhausting.

Common mistakes

  • Treating all reduction of effort as improvement.
  • Removing information rather than restructuring it.
  • Adding a tour instead of reducing the load the tour is explaining.

Three loads and what to do about each

LoadSourceDesign response
IntrinsicThe inherent complexity of the taskSequence it, chunk it, provide scaffolding. It cannot be removed, only staged.
ExtraneousPresentation, layout, wording, navigationReduce relentlessly. This is where design earns its keep.
GermaneBuilding a mental model of the systemSupport it. Consistency and clear structure make this effort pay off.

Sources of extraneous load in interfaces

  • Inconsistent terminology, so the same concept has to be re-learned in each place.
  • Information split across screens when it needs to be compared, which is the split-attention effect.
  • Decorative visuals that must be scanned and discarded.
  • Ambiguous labels that require inference.
  • Layouts where visual grouping contradicts logical grouping.
  • Interruptions such as modals and tours that break an in-progress task.

Reducing the load that is not the task

Do

  • Put the instruction next to the thing it describes, not in a legend elsewhere.
  • Keep the information needed for one decision on one screen.
  • Use the reader's vocabulary, so no translation happens in working memory.
  • Let the system remember what it can: previous entries, defaults, recent items.

Do not

  • Split related content across a tooltip, a modal and a help page.
  • Require the reader to hold a value from screen one to use on screen three.
  • Animate something while asking a question.
  • Confuse difficulty that teaches with difficulty that just gets in the way.

In practice

  1. i.

    Split attention in documentation

    Help content

    Instructions on one screen and the interface on another force the reader to hold steps in memory while switching. Inline, contextual guidance removes that load entirely.

  2. ii.

    Comparison tables

    Pricing and product selection

    Putting options side by side removes the memory load of holding one option while reading the next. Sequential presentation of the same information is measurably harder.

  3. iii.

    The legend twenty rows away

    Split attention

    A table used coloured dots and explained them in a legend above the fold. Once the reader had scrolled, each dot required a scroll up, a lookup and a scroll back. Labelling the dots inline removed a loop nobody had counted.

Commonly confused with

Close neighbours that get substituted for each other. The difference is stated first, then the condition that picks one over the other.

vs.

Decision Fatigue

Psychology

The contested claim that judgement deteriorates over a sequence of decisions.

Key difference

Cognitive load is about capacity at one moment: how much a screen asks someone to hold at once. Decision fatigue is a claim about degradation across a run of choices, and its underlying research failed to replicate, so it carries less weight.

Use Cognitive Load when

  • The problem is one screen asking too much at once.
  • You can name what to remove, chunk or defer.
  • You need an argument that will survive scrutiny.

Use Decision Fatigue when

  • The problem is the length of a run of choices, not one screen.
  • You are describing an experience rather than predicting an effect size.
  • The claim is stated with the replication caveat attached.

Learn about Decision Fatigue

Local chart

PSY·001 · Region I · Grid B2

This entry and the entries it is stated to connect with. Each line is labelled with what the connection means.

Aesthetic and Minimalist DesignHEUR·008 · EXPLAINSRecognition Over RecallHEUR·006 · EXPLAINSHick's LawLAW·001 · EXPLAINSMiller's LawLAW·004 · EXPLAINSProgressive DisclosurePRIN·003 · EXPLAINSComparisonPAT·006 · APPLIED THROUGHInformation ArchitectureRES·015 · APPLIED THROUGHDensityFND·016 · APPLIED THROUGHProximityFND·004 · APPLIED THROUGHVisual HierarchyFND·001 · APPLIED THROUGHContent DesignWRT·004 · APPLIED THROUGHDecision FatiguePSY·010 · COMMONLY CONFUSED WITH

Sources

Where a source establishes something narrower than the popular reading of it, the note says so.

  1. [1]

    Cognitive load during problem solving: effects on learning

    J. Sweller, Cognitive Science, 1988

  2. [2]

    Cognitive Load Theory

    J. Sweller, P. Ayres and S. Kalyuga, Springer, 2011

Continue from here

Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.

Applies when you are designing

A DashboardA Data Table

Explains

The mechanism underneath these entries.

Applied through

Where this shows up as a concrete interface decision.

Short definition

The one-paragraph version, for when that is all you need.

Related concept

Connected closely enough to change how you apply this.