16.5 Users and Their Tasks

Components of Objects/Actions Interface Model:

• Task
• Structured information objects (e.g. hierarchies, networks)
• Information actions (e.g. searching, linking)
• Interface
• Metaphors for information objects (e.g. bookshelf, encyclopedia)
• Handles for actions (e.g. querying, zooming)

Designing task objects and actions

Strategies for aggregating information:

• Short unstructured lists
• City guide highlights, organizational divisions, current projects (and this list)
• Linear structures
• Calendar of events, alphabetic list, human body slice images from head to toe,
• Orbital swath
• Arrays or tables
• Departure city/arrival city/date, latitude/longitude/time
• Hierarchies, trees
• Continent - country - city (e.g. Africa, Nigeria, Lagos)
• Concepts (e.g. sciences - physics - semiconductors - gallium arsenide)
• Multi-trees, faceted retrieval
• Photos indexed by date, photographer, location, topic, film type
• Networks
• Journal citations, genealogies, World Wide Web

Atomic information actions include:

• Looking for Hemingway's name in an alphabetical list
• Scanning a list of scientific article titles
• Reading a paragraph
• Following a reference link

Aggregate information actions are composed of atomic actions:

• Browsing an almanac table of contents, jumping to a chapter on sports and scanning for skiing topics
• Locating a scientific term in an alphabetic index and reading articles containing the term
• Using a keyword search in a catalog to obtain a list of candidate book titles
• Following cross reference from one legal precedent to another, repeatedly, until no new relevant precedents appear
• Scanning a music catalog to locate classical symphonies by eighteenth century French composers