540-310 Human Factors in Information Seeking and Use

1. 540-310Human Factors in Information Seeking and Use Wooseob Jeong

2. Notice • Class web site • http://www.sois.uwm.edu/jeong/540310 • IM communication • First assignment is due on February 18th before the class. • Review of Norman (1993) • Submission should be done via email. • Strength, Weakness, Application, Suggestion

3. Eight Golden Rules of Interface Design (0) • Shneiderman (1998) • Examples of Violation • Interface Hall of Shame • http://digilander.libero.it/chiediloapippo/Engineering/iarchitect/

4. Eight Golden Rules of Interface Design (1) • Strive for consistency • This rule is the most frequently violated one, but following it can be tricky because there are many forms of consistency. Consistent sequences of actions should be required in similar situations; identical terminology should be used in prompts, menus, and help screens. • Exceptions, such as no echoing of passwords or confirmation of the delete command, should be comprehensible and limited in numbers.

5. Eight Golden Rules of Interface Design (2) • Enable frequent users to use shortcuts • As the frequency of use increases, so do the user’s desires to reduce the number of interactions and to increase the pace of interaction. Abbreviations, special keys, hidden commands, and macro facilities are appreciated by frequent knowledgeable users.

6. Eight Golden Rules of Interface Design (3) • Offer informative feedback • For every user action, there should be system feedback. For frequent and minor actions, the response can be modest, whereas for infrequent and major actions, the response should be more substantial.

7. Eight Golden Rules of Interface Design (4) • Design dialogs to yield closure • Sequences of actions should be organized into groups with a beginning, middle, and end. The informative feedback at the completion of a group of actions gives operators the satisfaction of accomplishment, a sense of relief, the signal to drop contingency plans and options from their minds, and an indication that the ways is clear to prepare for the next group of actions.

8. Eight Golden Rules of Interface Design (5) • Offer error prevention and simple error handling • As much as possible, design the system such that users cannot make a serious error; for example, prefer menu selection to form filling and do not allow alphabetic characters in numeric entry fields. If users make an error, the system should detect the error and offer simple, constructive, and specific instructions for recovery.

9. Eight Golden Rules of Interface Design (6) • Permit easy reversal of actions • As much as possible, actions should be reversible. The feature relieves anxiety, since the user knows that errors can be undone, thus encouraging exploration of unfamiliar options.

10. Eight Golden Rules of Interface Design (7) • Support internal locus of control • Experienced operators strongly desire the sense that they are in charge of the system and that the system responds to their actions. Surprising system actions, tedious sequences of data entries, inability or difficulty in obtaining necessary information, and inability to produce the action desired all build anxiety and dissatisfaction.

11. Eight Golden Rules of Interface Design (8) • Reduce short-term memory load • The limitation of human information processing to short-term memory (7± 2) requires that displays be kept simple, multiple page displays be consolidated, window-motion frequency be reduced, and sufficient training time be allotted for codes, mnemonics, and sequences of actions.

12. Direct Manipulation • Command line system • UNIX, 80’s PC • GUI • Iconomized commands • Icon: representation, meaning • Object-Action Interface (OAI) model • Virtual Reality

13. Task-related Organization • Menu system • How can you organize menus? • How can you display menus? • Multiple ways for a menu item • Form Filling • Coded fields (mask) • Listbox, checkbox, radio buttons …

14. Command Language vs. Natural Language • grep –v ^$ file_a > file_b • Not obvious • Delete blank lines from file_a and save the result in file_b • Delete vs. rm

15. Response Time (1) • How long are you willing to wait to load a web page? • At most, 2 seconds! • Implications: few graphics, Java, Flash, … • Trade-off: not so exciting • Design vs. Contents • Productivity affected

16. Response Time (2) • Appropriate Response Time • Typing, cursor motion, mouse selection: 50-150 milliseconds • Simple frequent tasks: 1 second • Common tasks: 2-4 seconds • Complex tasks: 8-12 seconds • Users should be advised of long delays • Alternatives: elevator mirror, blinking

17. Response-time (3) • User prefer shorter response times • Longer response times (>15 secs) are disruptive • Users change usage profile with response time • Shorter response time leads to shorter user think time • A faster pace may increase productivity, but many increase error rates • Error recovery ease and time influence optimal response time

18. Humans Generally Better (1) • Sense low level stimuli • Detect stimuli in noisy background • Recognize constant patterns in varying situations • Sense unusual and unexpected events • Remember principles and strategies • Retrieve pertinent details without a priori connection • Draw on experience and adapt decisions to situation • Select alternatives if original approach fails

19. Humans Generally Better (2) • Reason inductively; generalize from observations • Act in unanticipated emergencies and novel situations • Apply principles to solve varied problems • Make subjective evaluations • Develop new solutions • Concentrate on important tasks when overload occurs • Adapt physical response to changes in situation

20. Machines Generally Better (1) • Sense stimuli outside human’s range • Count or measure physical quantities • Store quantities of coded information accurately • Monitor pre-specified events, especially infrequent ones • Make rapid and consistent responses to input signals • Recall quantities of detailed information accurately • Process quantitative data in pre-specified ways

21. Machines Generally Better (2) • Reason deductively: infer from a general principle • Perform repetitive pre-programmed actions reliably • Exert great, highly-controlled physical force. • Perform several activities simultaneously • Maintain operations under heavy information load • Maintain performance over extended periods of time

22. The Human Mind (1) • Complex, but powerful! • Stories – not logical • To err is human! • Slip vs. mistakes • Tunnel Vision • Functional fixedness, cognitive narrowing

23. The Human Mind (2) • People do err, especially when required to do things for which we are not suited. The trick is designing technology is to provide situations that minimize error, that minimize the impact of error, and that maximize the chance of discovering error once it has been committed. The human-centered way.

24. Interface Hall of Shame • http://digilander.libero.it/chiediloapippo/Engineering/iarchitect/ • Obviously, there is Interface Hall of Fame page. • http://digilander.libero.it/chiediloapippo/Engineering/iarchitect/mfame.htm • Think about this: • “Show friendly HTTP error messages” • Ex) ASP error message – http://www.sois.uwm.edu/jeong/asp.asp

25. Distributed Cognition

26. Three Mile Island Accident • http://www.libraries.psu.edu/crsweb/tmi/tmi.htm • The main control console signals overwhelmed human operators. • 18 of 22 problems identified were human factors problems • Video!

27. A place for everything, and everything in its place

28. A Technological Breakthrough

29. Other Technology Needed! • Copy Machine – coping tools • Standardized Paper Size • Is it solved really? • Post-It Notes

30. Organization of Things

31. Organization of Knowledge • Hardware Store • Hierarchical and organized by function • Coupled by expertise • Dictionary/Encyclopedia • Alphabetical – problems? • Advantage of digital format • Organization of Web? • Similar to Library Catalog? • Search engines