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)

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

Cognitive Dimensions (3)  Gives descriptions of aspects, attributes, or ways that a user thinks about a system, called dimensions  The 14 dimensions follow:

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)

Visibility  Ability to view components easily  Non-encapsulation  Examples:

Premature Commitment  Constraints on order of operations –Noun/verb –Verb/noun –Syntax of operations  Examples: –Declarations required before problem analysis

Hidden Dependencies  Important links between entities are not visible  Examples: –class hierarchies –HTML links –spreadsheet cells

Role-Expressiveness  Purpose of an entity is readily inferred (or obvious)  Uniform vs. distinguishing appearance of objects  Examples:

Error-Proneness  Notations (or actions) invite mistakes and the system gives little protection  Examples:

Abstraction  Types and availability of abstraction mechanisms  Examples:

Secondary Notation  Extra information in means other than formal syntax  Examples: –Comments in programming languages –Pop-up boxes for icons –Well-designed icons

Closeness of Mapping  Closeness of representation to domain  Examples:

Consistency  Similar semantics are expressed in similar syntactic forms  Examples:

Diffuseness  Verbosity of language  Examples:

Hard Mental Operations  High demand on cognitive resources  Examples:

Provisionality  Degree of commitment to actions or marks  Examples:

Progressive Evaluation  Work to date can be checked at any time  Examples:

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

Supplementary Material  Cognitive Dimensions of Notations website mensions mensions mensions  10 th Anniversary CD of Notations Workshop mensions/workshop2005/index.html mensions/workshop2005/index.html mensions/workshop2005/index.html

Supplementary Material (2)  Sally Fincher, Patterns in HCI Patterns in HCI Patterns in HCI  Marian Petre, Expert Design Reasoning Expert Design Reasoning Expert Design Reasoning