1. Class Meeting 3 September 7, 2010
CSC USI
Class Meeting 3
September 7, 2010

2. Homework for Today Research team membership Research areas Finished
Comments sent

3. Creating Tables Concerns:
3 of 7 tables didn’t follow specifications and example row

4. Where is Gregor? One of the initial questions Process vs. system
Systems:
Google Maps (maybe Satellite View)
Google Earth
Personal GPS (maybe phone-based)
Printed map

5. Where is Gregor? (2) Process: Use GPS, read off coordinates
Read from map
Read from mapping software

6. Where is Gregor? (3) Example: Google Earth Start Google Earth
Enter “Villanova University” in search dialog box
Drag map to center on statue
Zoom to highest resolution
Point to statue
Read coordinates:
4002’15.92”N 7520’29.53”W

7. Where is Gregor? (4) Example: Garmin GPS
Push “on” button, label with light icon
Wait for satellite acquisition
Push “Page” button
Place GPS at Gregor’s feet and read location
40 ’ N 75 ’ W

8. Where is Gregor? (5) Example: Google Maps Start Google Maps
Enter “Villanova University” in search dialog box
Switch to satellite view
Drag map to center on statue
Zoom to highest resolution
Point to statue (oops, no coordinates show)
Now what?

9. Where is Gregor? (6) Questions: How do the answers compare?
How big is one hundredth of a second?
How big is one thousandth of a minute?

10. Generalizing
How do users interact with the interface? Historically, starting a long time ago
Push the Read button
Type a command at the prompt and press Enter
Click on a widget
Touch a widget
Multitouch the screen

11. Interacting with the Interface
Issues are:
Types of interface widgets
Methods of interaction
Formal notation for interactions
Extensions to the Keystroke Level Model
Timings for each simple interaction
Interactions for control vs. for content
Modes and quasimodes
Others?

12. Interface Models Look at: Physical interface
Operations of physical interface
Models of the physical interactions
Task set (of possible interactions)
Error cost

13. Error Cost
Definition: The cost, measured in time or keystroke level actions, needed to recover from an erroneous action with a widget.
Example: Mistyping “the” as “teh”. Error cost is four keystrokes: 2 backspace and 2 for the correct keys.

14. Models of Physical Action
Fitts’ Law: moving a cursor to a target
Keystroke Level (Card & Moran): timing predictions for a task represented as a sequence of “physical” operations
Hick’s Law: time for choosing among a number of widgets

15. Models of Interaction
All presume that a task is completed with a sequence of (atomic) actions.
KLM (seen before)
GOMS and extensions: deals with choices of paths to completion
PIE: deals with visible and invisible states

16. Models of Interaction (2)
BNF: formal specification of an interaction grammar
FSM: Finite State Machine or
Finite automaton
STN: State Transition Network

17. Actions on Keys From your slip of paper Action Hard Keys Soft Keys Hit2
Press 5
Stroke 1
Tap
Touch

18. Descriptions of Actions
Report on phrase grammar
Number of phrases generated?
96 or 88 (w/o push) or 84
Number of meaningful phrases?
52, 34, 59, 65, 75, 69, 24
Mapping of phrases to actions?

19. Notations for Actions
Actions for a keyboard and graphical input device (GID) include:
Tap: pressing and immediately releasing a key. Implemented with a momentary contact (spring-loaded) switch.
Click: Position the GID and tap the GID button.
Double click: Position the GID and tap the GID button twice quickly, without repositioning.

20. Notation for Actions (2)
Keystroke Level Model
K[ ], a keystroke. E.g. K[b] means tapping lower case b
P, pointing. E.g. positioning the GID
H, homing. E.g. moving from keyboard to GID or GID to keyboard
M, mental processing
R, responding

21. Notations for Action (3)
What does the description
To create a right justified paragraph, use
Control + .
ask you to do?

22. Notations for Action (4)
More actions:
Press and hold a key
Release a key
But on what signal or input?

23. Notations and Actions (5)
Raskin/Beck
Press and hold: bi
Release: bh
Tap: bibh, shortened to bih or just b
Release on signal: bh[ ]
Note that key names are italicized
Examples:
Create an upper case M: ShiftimimhShifth, shortened to Shiftimihh
Down arrow = Wingding 3, lower case i
Up arrow = Wingding 3, lower case h

24. Notations for Action (6)
Examples (continued)
Distinguish between Enter and E n t e r Enter is the name of a key and E n t e r is short for
Shiftieihhnihtiheihrih
bih[20] gives a string of bs
CtrliAltiDelihhh brings up the Task Manager
Drag is the same as LMBiLMBh[on target]

25. Fitts’ Law
The time to move a cursor to an object is given by T = A log (D/S) + B where A, B are constants, D is distance, S is size Think about interpretations and limiting cases.

26. Fitts’ Law Questions
How does Fitts’ Law generalize to 2-dimensional targets?
Where does the user aim?
Where does the user land?
What path is followed?
What happens with partially hidden targets?

27. GOMS Model for user interaction Goal: task to be accomplished
Operators: set of atomic actions provided by system
Methods: set of sequences of operators. Each sequence accomplishes the goal
Selection rule: Governs which method the user chooses to use

28. GOMS (2)
Example:
Goal: Unlocking the rear doors on a car using a three-button remote control.
Operators: {Lock, Unlock, Panic}
Methods: {Double click Unlock}
Selection Rule: {Only method available}

29. GOMS (3) Example: Goal: Selecting an item from a menu Method:
Find menu heading
Point cursor at menu heading
Click “mouse” button (displaying menu entries)
Find desired entry
Point cursor at menu entry
Click “mouse” button (choosing menu option)

30. GOMS (4) Exercise: (for the interested student)
Assume that you manage your messages using a hierarchy of folders that is at least five levels deep. Develop a GOMS analysis for deleting a message in a level three folder when you currently are reading messages in your inbox (a level one folder).

31. Research Project Teams (done)
Areas (should be narrowed, can be revised)
Hypothesis
Independent variables
Dependent variables
Theoretical foundation
Which models from this evening’s discussion apply?

32. Research Project (2) Sources Bibliography ACM Digital Library
Look carefully at entries; follow up on citations
Science Citation Index
Web, but be careful
Have you edited a Wikipedia entry?
Have you checked
Conference proceedings, MSC 159
Bibliography
Entered into EndNote

33. Research Project (3)
IRB Form
Consent form
Data gathering process

34. Research Project (4) Experimental design Sources of bias
Between subjects
Within subjects
Sources of bias
Sources of subjects
Logic of conclusions

35. Next Time Carry out research project activities
Create a GOMS model for constructing the table of sums of powers of 2. The methods must be at the keystroke level and include the 45 keystrokes necessary to enter the data.

36. Next Time (2) Research project
Submit hypothesis, independent variables, dependent variables
Submit draft of IRB form
Submit bibliography as printed from EndNote