1. 15. Human-Computer Interaction

2. THE TROUBLE WITH COMPUTERS AND SOFTWARE DESIGN

3. SOFTWARE DESIGN CYCLE: UNDERSTAND, DESIGN, AND EVALUATE

5. UNDERSTAND SYSTEM AND USER CHARACTERISTICS

6. Functionality -- creeping featurism
Balance between functionality and ease of use
Frequency of use
Mandatory vs. discretionary use
knowledge level of the user

7. DESIGN USING THEORIES AND MODELS

8. Foley and van Dam (1990) Conceptual level Semantic level
Provides a mental model
Semantic level
Meaning/desired function
Syntactic level
How the semantic command is formed
Lexical level
Sequence of actions

9. Seven Stages of Action (Norman, 1986)
Figure 15.2
Bridging the gulf of execution and gulf of evaluation

10. Models of User Performance for Design: GOMS
Card, Moran, & Newell (1983)
Model Human Processor

11. Keystroke Level Model (KLM) GOMS
Six execution phase operators
Physical motor: K – keystroking 0.28
P – pointing 1.1
H – homing 0.4
B – press mouse button 0.1
Mental M – mental preparation 1.35
System R – response
Times are empirically determined
Texecute = Tk + Tp + Th + Tb+ Tm+ Tr

12. Models of User Performance for Design: GOMS
Design A: drag the file into the trash can[29]
Design B: use the short cut “control + T”[30]
method encoding (operator sequence)[31]
method encoding (operator sequence)[32]
initiate the deletion (M)
find the file icon (M)
point to file icon (P)
press and hold mouse button (B)
drag file icon to trash can icon (P)
release mouse button (B)
point to original window (P)
find the icon for the to-be-deleted file (M)
press mouse button (B)
move hand to keyboard (H)
press control key (K)
press T key (K)
move hand back to mouse (H)
Total time
3P + 2B + 2M = 3*1.1 sec + 2*.1 sec+ 2*1.35 sec = 6.2 sec
P + 2B + 2H + 2K + 2M = 1.1 sec + 2*.1 sec + 2*.4 sec + 2*.2 sec + 2*1.35 sec = 5.2 sec

13. DESIGN TO SUPPORT MENTAL MODELS WITH CONCEPTUAL MODELS AND METAPHORS

15. Making invisible parts and processes visible to the user
Providing feedback
Building in consistency
Presenting functionality through a familiar metaphor

16. DESIGN USING PRINCIPLES AND GUIDELINES

17. General Usability Guidelines

18. Basic Screen Design Dialog Style Menus Fill-in forms Question-answer
Command language
Function keys
Direct manipulation
Natural language

19. DESIGN OF USER SUPPORT

20. EVALUATE WITH USABILITY HEURISTICS

21. EVALUATE WITH USABILITY TESTS AND METRICS

22. Prototypes
Usability Metrics

23. Number of Users and Data Interpretation

24. Pitfalls of Usability Testing

25. INFORMATION TECHNOLOGY

26. Hypertext, Hypermedia, and the Internet Information Database Access
Mediated retrieval
Intelligent agents
Spatially organized database
Virtual and Augmented Reality
Affective Computing