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Notational Systems. Fall 2003 IST 331 Lecture 4. Cognitive Dimensions. Tool to aid non-HCI specialists evaluate usability of information-based artifacts Broad-brush evaluation Use terms easy to understand Not just applicable to interactive devices, but also to paper-based notations
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Notational Systems Fall 2003 IST 331 Lecture 4
Cognitive Dimensions • Tool to aid non-HCI specialists evaluate usability of information-based artifacts • Broad-brush evaluation • Use terms easy to understand • Not just applicable to interactive devices, but also to paper-based notations • Distinguish between different types of user needs
Cognitive Dimensions • Provides a common set of terms for discussion of the issues • Provides a kind of reminder of issues to be considered and discussed
Notational Systems • Four components: • An interaction language or notation • What the user sees • An environment for editing the notation • A medium of interaction • Paper, visual displays, auditory displays • Two kinds of subdevices • Helper devices – post-it note • Redefinition devices – keyboard shortcut on telephone
Notational Systems • www.ndirect.co.uk/~thomas.green/workStuff/devices/controllers/HeatingA2.html
Notational Dimensions • Viscosity: resistance to change • Visibility: ability to view components easily • Premature Commitment: constraints on the order of doing things • Hidden Dependencies: important links between entities are not visible
Notational Dimensions • Role-Expressiveness: the purpose of an entity is readily inferred • Error-Proneness: the notation invites mistakes and the system gives little protection • Abstraction: types and availability of abstraction mechanisms • Secondary Notation: extra information in means other than formal syntax
Notational Dimensions • Closeness of Mapping: closeness of representation to domain • Consistency: similar semantics are expressed in similar syntactic forms • Diffuseness: verbosity of language • Hard Mental Operations: high demand on cognitive resources
Notational Dimensions • Provisionality: degree of commitment to actions or marks • Progressive Evaluation: work-to-date can be check at any time