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:

4. 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:

18. 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

19. Supplementary Material  Cognitive Dimensions of Notations website www.cl.cam.ac.uk/~afb21/CognitiveDi mensions www.cl.cam.ac.uk/~afb21/CognitiveDi mensions www.cl.cam.ac.uk/~afb21/CognitiveDi mensions  10 th Anniversary CD of Notations Workshop www.cl.cam.ac.uk/~afb21/CognitiveDi mensions/workshop2005/index.html www.cl.cam.ac.uk/~afb21/CognitiveDi mensions/workshop2005/index.html www.cl.cam.ac.uk/~afb21/CognitiveDi mensions/workshop2005/index.html

20. 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