Dialogue Styles

The Primary Styles of Interaction Q & A Menu selection Form fill-in Command language Natural language Direct manipulation

Q & A Simple interaction style Users respond to series of questions Input is usually Y/N or a particular single input Print whole document? No of pages to print? No of copies

Advantages of Q & A Easy to learn Good for novice or casual users Errors can be trapped User is led step by step through the task

Disadvantages of Q & A Task has to be clearly defined and quite narrow Have limited functionality Not sophisticated

Menu Selection Employs metaphor of restaurant menu Users read list of items; select appropriately according to task; apply syntax to indicate selection; confirm choice; initiate action; observe effect Designers may need to use careful task analysis to ensure all functions supported conveniently, and that terminology is appropriate and consistent in use

Advantages and Disadvantages of Menus shortens learning curve reduces keystrokes structures decision-making permits use of dialogue-management tools allows easy support of error-handling Disadvantages imposes danger of deep-nested menu hierarchies may slow frequent users consumes screen “real estate” requires rapid display rate

Form Fill-in Paper forms can be used as metaphor (or indeed, template) Users see a display of related fields; move a cursor among the fields, and enter data as appropriate Designers need to ensure that users understand field labels, appropriate values and the data-entry method, and are capable of responding to error messages - some user training may be necessary

Advantages and Disadvantages of Form Fill-in simplifies data entry requires modest training makes assistance convenient permits use of form-management tools Disadvantages consumes screen “real estate”

Command Language Appropriate metaphor may be military parade ground! Users learn syntax; can express complex possibilities rapidly without reading distracting prompts Designers must allow for high error-rates; diversity of possibilities and complexity of mapping from task to computer syntax is hard; user training is necessary

Advantages and Disadvantages of Command Language flexible appeals to “power” users supports user-initiative convenient for creating user-defined macros Disadvantages poor error handling requires substantial training and memorisation

Natural Language Utilises conversational metaphor Users enter natural language sentences; computer often seeks clarification before beginning task Designers need to understand task domain to narrow range of interpretations to manageable level; design is extremely difficult.

Advantages and Disadvantages of Natural Language relieves burden of learning syntax no training! Disadvantages requires clarification dialogue may require more keystrokes may not show context is unpredictable

Direct Manipulation Metaphor is of a virtual world representing the “real world” Users point at visual representations of objects and actions, carry out tasks rapidly and see immediate results; keyboard control replaced by cursor-motion control devices Designers need to choose appropriate icons and graphics to successfully “immerse” the user - minimal user training indicated

Advantages and Disadvantages of Direct Manipulation presents task concepts visually easy to learn easy to retain permits error avoidance encourages exploration permits high subjective satisfaction Disadvantages may be hard to code may require graphics displays and pointing devices

Shneiderman’s Eight Golden Rules of Dialogue Design 1. Strive for consistency 2. Enable frequent users to use shortcuts 3. Offer informative feedback 4. Design dialogues to yield closure 5. Offer simple error handling 6. Permit easy reversal of actions 7. Support internal locus of control 8. Reduce short-term memory load

Menu-Selection & Form Fill-in Additional Guidelines

Menu selection design guidelines Semantic organisation sensible, understandable, memorable menus must have logical grouping of options based on user’s task single menu is simplest, but options are few (in GUIs radio buttons or check boxes can be used) binary (Yes/No) menus are a possibility extended menus (multiple pages are more normal)

Extended menus Strategies for extended menus include multiple screens accessed hierarchically scrollable “single” windows pull-down menus: lower levels invisible until accessed from a top menu bar pop-up menus: context-sensitive availability of option lists

Menu selection guidelines Use task semantics to group menu options Use “broad and shallow” options rather than “narrow and deep” Make items brief; show position by numbers, graphics or titles Use meaningful sequences of items Use consistent grammar, layout, terminology Provide short-cuts (e.g., “hot-key combinations) Allow jumps to previous menus

Form fill-in design Meaningful titles - dictated by task, not computer, semantics Comprehensible instructions brief, jargon-free instructions preferred Logical grouping and sequencing of fields close as possible to paper form “template” Visually appealing layout uniform spacing is better than crowded areas Familiar field-label names and order of entry left-to-right, top-to-bottom but with task logic in mind

Form fill-in: Error handling and feedback Error correction for individual characters and entire fields user should not be forced to “complete” data entry before backtracking to make corrections Clear error-messages and on-line help for invalid entries Optional and compulsory fields clearly distinguished Clear completion signal avoid making completion automatic; explicit confirmation of “finish” is preferable