1 Ch. 3: Interaction Introduction – 3.1 (Reading Assignment – RA) Introduction – 3.1 (Reading Assignment – RA) Models – 3.2, 3.3 (RA) Models – 3.2, 3.3 (RA) Ergonomics or Human Factors – 3.4 (RA) Ergonomics or Human Factors – 3.4 (RA) Interaction Styles – 3.5,3.6,3.7,3.8 Interaction Styles – 3.5,3.6,3.7,3.8 Context – 3.9 (RA) Context – 3.9 (RA) Conclusion – 3.10 (RA) Conclusion – 3.10 (RA)

2 Interaction Models Why use models Why use models Models and frameworks provide a theoretical basis for design, analysis and evaluation Models and frameworks provide a theoretical basis for design, analysis and evaluation We will discuss two models We will discuss two models Some terminology Some terminology Domain, tasks, goals, intentions, actions Domain, tasks, goals, intentions, actions System and user: state and language System and user: state and language

3 Norman’s Model Execution-evaluation cycle Execution-evaluation cycle Execution Execution Establishing a goal Establishing a goal Formulating intentions Formulating intentions Specifying actions Specifying actions Executing actions Executing actions Evaluation Evaluation Perceiving the system state Perceiving the system state Interpreting the system state Interpreting the system state Evaluating the system state Evaluating the system state

4 Two Gulfs Gulf of execution Gulf of execution Difference between actions formulated by the user and actions allowed by the system. The lesser this difference, the more effective the interaction. Difference between actions formulated by the user and actions allowed by the system. The lesser this difference, the more effective the interaction. Gulf of evaluation Gulf of evaluation Difference between user’s expectation of state changes and the system’s presentation of its changed state. The more effort user has to expend to interpret this presentation, the less effective the interaction. Difference between user’s expectation of state changes and the system’s presentation of its changed state. The more effort user has to expend to interpret this presentation, the less effective the interaction. Very important when designing error messages. Very important when designing error messages.

5 Good Design Minimize both gulfs Thinking assignment: come up with examples of each gulf from any interactive system that you are familiar with, and explain the gulfs

6 The Interaction Framework S U I O Presentation Observation Articulation Performance

7 The Interaction Framework Interaction requires translation between the 4 languages of user, input, system and output Interaction requires translation between the 4 languages of user, input, system and output Language of thought: intentions, comprehension Language of thought: intentions, comprehension System’s interface command language System’s interface command language System’s underlying computations System’s underlying computations System’s interface presentation language System’s interface presentation language Articulation: intentions > commands Articulation: intentions > commands Performance: syntax > execution Performance: syntax > execution Presentation: execution > presentation Presentation: execution > presentation Observation: presentation > comprehension Observation: presentation > comprehension

8 The Interaction Framework Articulation Articulation Larger the gulf of execution, the more difficulty user will face in translating intentions to actions Larger the gulf of execution, the more difficulty user will face in translating intentions to actions Conversely, if articulation is easy, gulf of execution will be small Conversely, if articulation is easy, gulf of execution will be small Example: GUIs vs. Command-line interfaces for file operations Example: GUIs vs. Command-line interfaces for file operations Performance Performance A system design issue: implementation cost A system design issue: implementation cost Example: immersive VR vs. Command-line Example: immersive VR vs. Command-line

9 The Interaction Framework Presentation Presentation An interface design issue: interface must be sufficiently expressive to show all relevant system changes An interface design issue: interface must be sufficiently expressive to show all relevant system changes Important in minimizing the gulf of evaluation Important in minimizing the gulf of evaluation Observation Observation Problems: incompleteness of the presentation and misinterpretation by user Problems: incompleteness of the presentation and misinterpretation by user Examples: stove controls, progress meters Examples: stove controls, progress meters

10 The Interaction Framework Interaction difficulties arise when presentation, observation and/or articulation are incomplete or difficult to accomplish. Interaction difficulties arise when presentation, observation and/or articulation are incomplete or difficult to accomplish. System inefficiencies arise when performance and presentation are poorly designed. System inefficiencies arise when performance and presentation are poorly designed. Thinking assignments: Thinking assignments: Come up with examples of articulation and observation problems from any interactive system that you are familiar with. Come up with examples of articulation and observation problems from any interactive system that you are familiar with. Understand how these two models are related. Understand how these two models are related.

11 Human Factors Study of the physical characteristics of interaction Study of the physical characteristics of interaction Issues: Issues: Physical layout of controls and displays Physical layout of controls and displays Design of work environment Design of work environment Health issues Health issues Aspects of presentations: color, sound etc Aspects of presentations: color, sound etc Reading assignment: 3.4, especially the design focus, p.112 Reading assignment: 3.4, especially the design focus, p.112 If you are interested in pursuing a HF topic for the report/presentation project, see proceedings of the annual meetings of human factors and ergonomics society and the journal Human Factors. If you are interested in pursuing a HF topic for the report/presentation project, see proceedings of the annual meetings of human factors and ergonomics society and the journal Human Factors.

12 Next Topic Interaction Objects & Styles Interaction Objects & Styles Read 3.5 and 3.6 from the text Read 3.5 and 3.6 from the textAND All of Ch. 3 in Reference All of Ch. 3 in Reference