Old Business. -Course Syllabus -3X5 cards -Java (which version?). Good Design Comes from understanding Bad Design. Usability. Design. Implementation. Evaluation. Affordances -strong clues as to use Mappings the controls and their result in the real world
Old Business -Course Syllabus -3X5 cards -Java (which version?)
Usability Design Implementation Evaluation
Affordances-strong clues as to use • Mappings the controls and their result in the real world • Feedback- what action has taken place • Constraints- constraints the user
Affordances • Affordances provide “strong clues” to the operation of things • Push buttons, knobs, and light switches are all affordances — just by looking at them you can discern their purpose.
Visual Affordances • Appearance indicates how the object should be used • chair for sitting • table for placing things on • buttons for pushing • complex things may need explaining, but simple things (labels, instructions) should not
Mappings • Mappings refers to the relationship between two things • Eg, control and movement • Steering wheel • Door handle
Visible Constraints • Limits the actions possible perceived from object’s appearance • For example, a key into a door or “graying out” a selection from the user.
Visibility (feedback) • Allow the user to be informed • Show him the state • did I set the watch correctly? • can I see the elevator in its shaft? • Did I do this task correctly?
Transfer effects • Users will transfer their expectations of similar objects to your design • For example, the typewriter model is now the computer keyboard
Conceptual model • People have “mental models” on how things should work • Conceptual models come from: • affordances • constraints • mapping • similar devices or interfaces • interactions
Conceptual model • The user will misunderstand the interface if the attributes are misleading • Example of a bad design (digital watch) • affordances: there are 4 push buttons but since all 4 look similar, what do they do? • Constraint and mapping: no visible relation between buttons and possible actions of button presses
Guidelines for design • 1. Provide a good conceptual model • - allows users to predict the consequences of actions. Communicates the system to the user • 2. Make things visible • the user’s intentions, required actions are sensible and non-arbitrary. • Use visible affordances, mapping and constraints
Who will use your design? • Beginners - walk-up-and-use systems (internet) • casual users - help or reference guides (most software we buy) • intermediate users - knows how to quickly use the system (custom software) • experts - shortcuts are used (custom software)
Please read Chapter 2 “What Is Usability?” from Usability Engineering