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Dialogue Styles

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

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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

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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

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Disadvantages of Q & A Task has to be clearly defined and

quite narrow Have limited functionality Not sophisticated

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Menu Selection

Employs metaphormetaphor of restaurant menu UsersUsers read list of items; select appropriately

according to task; apply syntax to indicate selection; confirm choice; initiate action; observe effect

DesignersDesigners may need to use careful task analysis to ensure all functions supported conveniently, and that terminology is appropriate and consistent in use

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Advantages and Disadvantages of Menus Advantages

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

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Form Fill-in

Paper forms can be used as metaphormetaphor (or indeed, template)

UsersUsers see a display of related fields; move a cursor among the fields, and enter data as appropriate

DesignersDesigners 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

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Advantages and Disadvantages of Form Fill-in Advantages

simplifies data entry requires modest training makes assistance convenient permits use of form-management tools

Disadvantages consumes screen “real estate”

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Command Language

Appropriate metaphormetaphor may be military parade ground!

UsersUsers learn syntax; can express complex possibilities rapidly without reading distracting prompts

DesignersDesigners must allow for high error-rates; diversity of possibilities and complexity of mapping from task to computer syntax is hard; user training is necessary

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Advantages and Disadvantages of Command Language Advantages

flexible appeals to “power” users supports user-initiative convenient for creating user-defined macros

Disadvantages poor error handling requires substantial training and memorisation

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Natural Language

Utilises conversational metaphormetaphor Users Users enter natural language sentences;

computer often seeks clarification before beginning task

Designers Designers need to understand task domain to narrow range of interpretations to manageable level; design is extremely difficult.

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Advantages and Disadvantages of Natural Language Advantages

relieves burden of learning syntax no training!

Disadvantages requires clarification dialogue may require more keystrokes may not show context is unpredictable

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Direct Manipulation

MetaphorMetaphor is of a virtual world representing the “real world”

UsersUsers point at visual representations of objects and actions, carry out tasks rapidly and see immediate results; keyboard control replaced by cursor-motion control devices

DesignersDesigners need to choose appropriate icons and graphics to successfully “immerse” the user - minimal user training indicated

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Advantages and Disadvantages of Direct Manipulation Advantages

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

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Shneiderman’s Eight Golden Rules of Dialogue Design1. Strive for consistency2. Enable frequent users to use shortcuts3. Offer informative feedback4. Design dialogues to yield closure5. Offer simple error handling6. Permit easy reversal of actions7. Support internal locus of control8. Reduce short-term memory load

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Menu-Selection & Form Fill-in

Additional Guidelines

Menu selection design guidelines Semantic organisation

sensible, understandable, memorable menus must have logical grouping of logical grouping of options 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 multiple screens accessed

hierarchically scrollable “single” windows pull-down menuspull-down menus: lower levels invisible

until accessed from a top menu bar pop-up menuspop-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 Error correction for individual characters and

entire fields user should not be forced to “complete” data

entry before backtracking to make corrections Clear error-messageserror-messages and on-line help on-line help for

invalid entries Optional Optional and compulsory fields clearly

distinguished Clear completion signalcompletion signal

avoid making completion automatic; explicit confirmation of “finish” is preferable