Design of Everyday Things

(Norman, 2013)

1. Affordances and Signifiers

• affordance: the action the object physically allows (button wants to be clicked)
• signifiers: implicitly communicated action (plate suggest pushing, handle suggests pulling)
• users must guess when affordances are unclear

2. Conceptual Models

• user builds internal mental model. good products make this easy.

3. Mapping

• relationship between controls and their effects
• natural mappings rely on spatial or logical correspondence
• poor mappings force users to rely on memory instead of perception

4. Feedback

• every action should produce an observable reaction

5. Constraints

• Design can prevent incorrect actions through constraints.

6. Slips vs. Mistakes

• slips: intention correct, execution fails (pressing wrong button) → reduce through constraints and feedback
• mistakes: intention itself is wrong → mental model fails → reduce through clear conceptual models

7. Visibility

• important parts of the system should be visible. hidden controls foce useres again to rely on memory instead.

→ externalize knowledge into the environment. effective design uses perception instead of memory by making structure, mapping and feedback visible

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