Cognitive Dimensions

1
Cognitive Dimensions

• Developed by Thomas Green, Univ. of Leeds
• Used to analyze the usability of information
  artifacts
• Applied to discover useful things about usability
  problems that are not easily analyzed using
  conventional techniques
• Framework (as opposed to model or theory)

2
Cognitive Dimensions (2)

• Focused on notations, such as
• Music
• Dance
• Programming languages
• And on information handling devices, such as
• Spreadsheets
• Database query systems
• Word-processors
• VCRs and DVD players
• Cell phones

3
Cognitive Dimensions (3)

• Gives descriptions of aspects, attributes, or
  ways that a user thinks about a system, called
  dimensions
• The 14 dimensions follow

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Viscosity

• Resistance to change
• Fixed mental model
• Hard-coded structure
• Examples
• Technical literature, with cross-references and
  section headings (because introducing a new
  section requires many changes to cross-references)

5
Visibility

• Ability to view components easily
• Non-encapsulation
• Examples

6
Premature Commitment

• Constraints on order of operations
• Noun/verb
• Verb/noun
• Syntax of operations
• Examples
• Declarations required before problem analysis

7
Hidden Dependencies

• Important links between entities are not visible
• Examples
• class hierarchies
• HTML links
• spreadsheet cells

8
Role-Expressiveness

• Purpose of an entity is readily inferred (or
  obvious)
• Uniform vs. distinguishing appearance of objects
• Examples

9
Error-Proneness

• Notations (or actions) invite mistakes and the
  system gives little protection
• Examples

10
Abstraction

• Types and availability of abstraction mechanisms
• Examples

11
Secondary Notation

• Extra information in means other than formal
  syntax
• Examples
• Comments in programming languages
• Pop-up boxes for icons
• Well-designed icons

12
Closeness of Mapping

• Closeness of representation to domain
• Examples

13
Consistency

• Similar semantics are expressed in similar
  syntactic forms
• Examples

14
Diffuseness

• Verbosity of language
• Examples

15
Hard Mental Operations

• High demand on cognitive resources
• Examples

16
Provisionality

• Degree of commitment to actions or marks
• Examples

17
Progressive Evaluation

• Work to date can be checked at any time
• Examples

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Summary

• Viscosity
• Visibility
• Premature commitment
• Hidden dependencies
• Role expressiveness
• Error proneness
• Abstraction
• Secondary notation
• Closeness of mapping
• Consistency
• Diffuseness
• Hard mental operations
• Provisionality
• Progressive evaluation

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Supplementary Material

• Cognitive Dimensions of Notations website
  www.cl.cam.ac.uk/afb21/CognitiveDimensions
• 10th Anniversary CD of Notations Workshop
  www.cl.cam.ac.uk/afb21/CognitiveDimensions/worksh
  op2005/index.html

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Supplementary Material (2)

• Sally Fincher, Patterns in HCI
• Marian Petre, Expert Design Reasoning