CSC USI Class Meeting 3 January 23, 2009
Course Textbook Carroll, HCI Models, Theories, and Frameworks is no longer readily available for reasonable cost. Copies of relevant chapters will be provided.
Homework for Today Research team membership –Finished Research areas –Comments sent
Creating Tables Concerns: 6 of 12 tables didn’t follow specifications and example row Several examples of header row (not required by specs) poorly formatted or with less helpful labels
Where is Gregor? One of the initial questions Process vs. system Systems: –Google Maps (maybe Satellite View) –Google Earth –Personal GPS (maybe phone-based)
Where is Gregor? (2) Process: –Use GPS, read off coordinates –Read from map –Read from mapping software
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: –4002’15.92”N 7520’29.53”W
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
Where is Gregor? (5) Questions: 1. How do the two answers compare? 2. How big is one hundredth of a second? 3. How big is one thousandth of a minute?
Generalizing How do users interact with the interface? Historically, Push the Read button Type a command at the prompt and press Enter Work with a widget
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 Quasimodes Others?
Interface Examples Focus on battery operated devices on our first week’s list and other small interfaces –Remote car lock control –Watch –Cell phone –IPod –Laptop computer –PDA –Programmable thermostat –Simple calculator
Interface Examples (2)
Notation How should we describe interactions with (or actions taken with) the interface devices? Time for some discovery groups
Group Work Pair up by threes Create a list of simple (atomic?) widgets that appear in interfaces. Consult the list of examples, generalize, then synthesize. For each item on the list, state the actions that can be performed on it. Suggest a notation for each action expressed in a way that it is easy to form a sequence of actions.
Group Work (2) Notes: Distinguish between physical devices and actions on them and interface widgets and actions on them. Both types should be on your list.
Group Work Summary Construct the union table of widgets and actions on them. Invent the formal notation for describing the actions. Create some examples of performing tasks using these widgets, expressing the method in the formal notation.
Interface Widgets Physical devices –Keyboard –Graphical Interface Device (GID) Point, buttons –Touch pad Gestures, point, tap Virtual devices –Programmed as objects and methods –Summary Syntax vs. semantics
Interface Widgets (2) The linked chart shows the summary of the group work. linked The chart will be revised as –new widgets are created or discovered –new actions are needed –new notation is invented
Interface Models Look at: Physical interface Operations of physical interface Task set Error cost
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.
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
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?
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.
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
Notations for Action (3) What does the description To create a right justified paragraph, use Control +. ask you to do?
Notations for Action (4) More actions: Press and hold a key Release a key –But on what signal or input?
Notations and Actions (5) Raskin/Beck –Press and hold: b –Release: b –Tap: b b , shortened to b or just b –Release on signal: b [ ] –Note that key names are italicized Examples: –Create an upper case M: Shift m m Shift , shortened to Shift m
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 E n t e r –b [20] gives a string of bs –Ctrl Alt Del brings up the Task Manager –Drag is the same as LMB ↓ LMB↑[on target]
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
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}
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)
GOMS (4) 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).
Research Project Teams (done) Areas (should be narrowed, can be revised) Hypothesis Independent variables Dependent variables
Research Project (2) Sources –ACM Digital Library –Science Citation Index –Web, but be careful –Conference proceedings, MSC 159 Bibliography –Entered into EndNote
Research Project (3) IRB Form IRB Form IRB Form –Consent form –Data gathering process
Research Project (4) Experimental design –Between subjects –Within subjects Sources of bias Sources of subjects Logic of conclusions
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.
Next Time (2) Research project –Submit hypothesis, independent variables, dependent variables –Submit draft of IRB form –Submit bibliography as printed from EndNote
Handouts Reprint of Chapter 3, Carroll, HCI Theories, Models, Frameworks. The chapter, written by Scott MacKenzie, deals with motor behavior models.