Dialog Styles

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

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

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

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

Menu Selection metaphor n Employs metaphor of restaurant menu n Users n Users read list of items; select appropriately according to task; apply syntax to indicate selection; confirm choice; initiate action; observe effect n Designers n 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 Menu Selection n Advantages –shortens learning curve –reduces keystrokes –structures decision-making –permits use of dialogue-management tools –allows easy support of error-handling n Disadvantages –imposes danger of deep-nested menu hierarchies –may slow frequent users –consumes screen “real estate” –requires rapid display rate

Form Fill-in metaphor n Paper forms can be used as metaphor (or indeed, template) n Users n Users see a display of related fields; move a cursor among the fields, and enter data as appropriate n Designers n 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 n Advantages –simplifies data entry –requires modest training –makes assistance convenient –permits use of form-management tools n Disadvantages –consumes screen “real estate”

Command Language metaphor n Appropriate metaphor may be military parade ground! n Users n Users learn syntax; can express complex possibilities rapidly without reading distracting prompts n Designers n 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 n Advantages –flexible –appeals to “power” users –supports user-initiative –convenient for creating user-defined macros n Disadvantages –poor error handling –requires substantial training and memorisation

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

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

Direct Manipulation n Metaphor n Metaphor is of a virtual world representing the “real world” n Users n 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 n Designers n Designers need to choose appropriate icons and graphics to successfully “immerse” the user - minimal user training indicated

Advantages and Disadvantages of Direct Manipulation n Advantages –presents task concepts visually –easy to learn –easy to retain –permits error avoidance –encourages exploration –permits high subjective satisfaction n 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