Human Computer InteractionCSC 4730-100

User System InterfaceCSC 8570-001

Meeting 3September 11, 2012

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• Can you trust users to follow directions?

Where is Gregor?

One of the initial questions• Process vs. system• Systems (as suggested):– Google– Google Maps– Personal GPS (maybe phone-based)– Printed map

• More Systems– Google Earth– Google Maps satellite view

Where is Gregor? (2)

• But specifying a system doesn’t solve the problem.

• Need a well-defined process– Note that well-defined process has a particular

meaning: the process is unambiguously defined in terms of accepted atomic actions. These actions may vary from system to system, but they are clear to system users.

Where is Gregor? (3)The pairs of students below are matched with the system that they suggested as solving the problem, namely finding the latitude and longitude of the statue of Gregor Mendel. However, the problem asked for the process.

For the next phase of the experiment, each pair is to• Find a process based on the system matched to them that gets the

required latitude and longitude.• Run the process to get the data.• Report the data to the class.• Document the process so that others can follow it and obtain the

same answer and so that researchers measure its efficiency.

Where is Gregor? (4)

• Andrew D & James N with Google• Ken & Kristin with Google Maps• Anthony & Donald with Google Maps incorporating

the steps you outlined• Mike & Tyler with Google Maps incorporating the

steps you outlined• James B & Kevin [no clearly specified system]• Andrew L & Chris with smartphones• Shishir & John with Garmin GPS

Where is Gregor? (5)

• Process reports

Where is Gregor? (6)

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? (7)

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 02.290’ N 75 20.505’ W

Where is Gregor? (8)

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?

Where is Gregor? (6)

Questions:1. How do the 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, starting a long time ago

(What’s the date of the first computer?)• Push the Read button• Type a command at the prompt and press Enter• Click on a widget• Touch a widget• Multitouch the screen or pad

Interface Models

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

Physical Interface

• Keyboard– Hard, soft, divided

• Display (or displays)– Few lines, small, big, huge

• Graphical interface device (GID)– Mouse, track ball, joy stick

• Gesture interface device (GID)– Touch pad, touch screen, camera

Operations on Physical Interface

• Tap• Double tap (double click)• Point• Drag• Swipe• Multiswipe (parameters are direction and

number of fingers)

Buttons

• What do you do to a button?

• What do you expect the button to do?

Models of Physical Interaction

• Keystroke Level (Card & Moran): timing predictions for a task represented as a sequence of “physical” operations

• Fitts’ Law: moving a cursor to a target• Hick’s Law: time for choosing among a

number of widgets

Models of Interaction

All presume that a task is completed with a sequence of (atomic) actions. Actions are called operations, commands, or “keystrokes.”

• KLM (Keystroke Level Model)• GOMS and extensions: deals with choices of

paths to completion• PIE: deals with visible and invisible states

Models of Interaction (2)

• BNF: formal specification of an interaction grammar

• FSM: Finite State Machine or– Finite automaton– State Transition Diagram

Notations for ActionsActions 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.

Are there any others?

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: 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

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]

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.

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?

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)

Exercise: (for the interested student)Assume that you manage your email 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).

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.

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?

Research Project (2)

• Sources– 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 www.dhmo.org?

– Conference proceedings– Bibliography– Entered into EndNote

Research Project 3

• Human Subjects• 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