Chapter 15: Human-Computer Interaction

1. Chapter 15: Human-Computer Interaction • Problems with computers and the productivity paradox • Understanding, design, and evaluation in system development • Understanding: from the artifact to the cultural context • Design: Minimizing the gulfs of evaluation and execution • Evaluation: Conducting heuristic and usability evaluations • Emerging issues in information technology and data access: Computers going beyond the desktop

2. Understanding: Users and tasks • Frequency of use • Ease of use vs learnabilty/memorability • Mandatory vs discretionary use • Satisfaction vs performance • GOMS (Goals, Operators, Methods, Selection Rules) • Explicitly identifies goals • Identifies alternate methods for achieving goals • Selection rules specify when each method should be used

3. Understanding: User characteristics and expertise • Domain knowledge vs computer/application knowledge • Novice • Knowledgeable intermittent users • Experts

4. Design: Gulfs of evaluation and execution • Gulf of Evaluation: Difficulty understanding the system state and what needs to be done • Gulf of Execution: Difficulty changing system state to desired state

5. Design: Mental models and metaphors • Mental model: Dynamic internal representation of the system that allows one to predict future system states • Mental models are often incomplete and inaccurate • Interface transparency can promote accurate mental models: • Make visible the invisible • Provide feedback • Build consistency to minimize number of concepts and rules that must be remembered • Present functionality through a metaphor

6. Design: Design heuristics and principles • Match to real world • Consistency and standards • Visibility of system status • User control and freedom • Error prevention, recognition, and recovery • Memory • Flexibility and efficiency of use • Simplicity and aesthetic integrity

7. Evaluation: Number of user tests 45 40 35 30 25 20 15 10 5 Benefit-to-Cost Ratio 10 15 20 0 5 Number of User Tests or Evaluators

8. Evaluation: Usability metrics • Learnability • Efficiency • Memorability • Errors • Satisfaction • Preference doesn’t always equal performance

9. Evaluation: Danger of usability studies Human Capabilities Usability Usefulness Understanding System Demands

10. Evaluation: Common failings in usability testing • Laboratory fixation • Failure to differentiate between inference, observation, opinion • Results presented as prescriptive instead of descriptive

11. Interface technology and pervasive computing • Navigation challenges with hypermedia • Design for information search • Multiple strategies • Diverse criteria • User backgrounds and vocabulary • Intelligent agents • Expert assistant may not be so expert • Expert may interfere with direct interaction with data • Affective computing • Information appliances

12. Chapter 15: Human-Computer Interaction • Problems with computers and the productivity paradox • Understanding, design, and evaluation in system development • Understanding: from the artifact to the cultural context • Design: Minimizing the gulfs of evaluation and execution • Evaluation: Conducting heuristic and usability evaluations • Emerging issues in information technology and data access: Computers going beyond the desktop