Week 11

1
Human Computer Interaction

• Week 11
• LBSC 690
• Information Technology

2
What is HCI

• Human-computer interaction is a discipline
  concerned with
• the design,
• evaluation and
• implementation
• of interactive computing systems for human use
  and with the study of major phenomena surrounding
  them.

From ACM SIGCHI Curricula for Human-Computer
Interaction
3
Why is HCI important?

• Computer technology is pervasive
• Issues of
• Effeciency
• Frustration
• Economy
• Health
• Safety

4
Goals of HCI

• 5 measures
• Time to learn
• Speed of performance
• Error rate
• Retention over time
• Subjective satisfaction

5
The Discipline of HCI
From ACM SIGCHI Curricula for Human-Computer
Interaction
6
What are humans good at?

• Sense low level stimuli
• Recognize patterns
• Reason inductively
• Communicate with multiple channels
• Apply multiple strategies
• Adapt to changes or unexpected events

From Ben Shneidermans designing user
interfaces
7
What are computers good at?

• Sense stimuli outside humans range
• Calculate fast and mechanical
• Store large quantities and recall accurately
• Response rapidly and consistently
• Perform repetitive actions reliably
• Maintain performance under heavy load and
  extended time

From Ben Shneidermans designing user
interfaces
8
What should Interaction be?

• Synergic
• Humans do things that human are good at
• Computers do things that computers are good at
• the strength of one covers the weakness of the
  other

9
User Characteristics

• Physical
• Anthropomorphic (height, left handed, etc.)
• Age (mobility, dexterity, etc.)
• Cognitive
• Perceptual
• Sight, hearing, etc.
• Personality
• Including cultural factors

10
Human Factors in Systems

• Life critical
• Low error rate first and foremost
• Justifies an enormous design and testing effort
• Custom Commercial
• Speed and error rate
• Office and Home
• Easy learning, high user satisfaction, low cost
• Creative
• User needs assessment is very challenging

11
The GOMS Perspective

• Goals
• What the user is trying to achieve
• Operators
• What capabilities the system provides
• Methods
• How those capabilities can be used
• Selection strategies
• Which method to choose in a specific case

12
User and System Models
Human
Mental Models
Sight Sound
System
Task
Hands Voice
Software Models
Keyboard Mouse
Task
User
Display Speaker
Computer
13
Discussion Point Mental Models

• As a user, what do you want to know about a
  machine for your interaction?

14
Interactive Systems

• Input Devices
• Computer Output Devices
• Interfaces

15
Input Devices

• Text
• Keyboard, optical character recognition
• Speech recognition, handwriting recognition
• Direct manipulation
• 2-D mouse, trackball, touch pad, touch panel
• 3-D wand, data glove
• Remote sensing
• Camera, speaker ID, head tracker, eye tracker

16
Keyboard

• Produces character codes
• ASCII American English
• Latin-1 European languages
• UNICODE Any language
• Pictographic languages need entry conventions
• Keyboard shortcuts are important for data entry
• VT-100 standard functions are common
• But differing layouts can inhibit usability
• And different conventions for standard tasks
  abound

17
Interesting Design Example QWERTY keyboard
From http//home.earthlink.net/dcrehr/whyqwert.ht
ml
18
Dvorak Keyboard
From http//www.mwbrooks.com/dvorak/
19
2-D Direct Manipulation

• Match control actions with on-screen behavior
• Use a cursor for visual feedback if needed
• Rotary devices
• Mouse, trackball
• Linear devices
• Touch pad, touch panel, touch screen, joystick
• Rate devices
• Laptop eraserhead

20
Human Senses

• Visual
• Position/motion, color/contrast, symbols
• Auditory
• Position/motion, tones/colume, speech
• Haptic
• Mechanical, thermal, electrical, kinesthethic
• Olfactory
• Smell, taste
• Vestibular

21
Computer Output

• Image display
• Fixed view, movable view, projection
• Acoustic display
• Headphones, speakers, within-ear monitors
• Tactile display
• vibrotactile, pneumatic, piezoelectric
• Force feedback
• dexterous handmaster, joystick, pen

22
Computer Output

• Inertial Display
• Motion-based simulators
• Olfactory Display
• Chemical (requires resupply)
• Locomotive display
• Stationary bicycle, treadmill, ...
• Temperature Display

23
Interesting Design Example Virtual Wall
Picture is from viz-tek.com
24
Virtual Walls
Picture is from viz-tek.com
25
Interaction Styles

• Graphical User Interfaces (GUI)
• Direct manipulation
• Menus
• Language-based interfaces
• Command line interfaces
• Interactive voice response systems
• Virtual Reality (VR)
• Direct manipulation
• Ubiquitous computing

26
WIMP Interfaces

• Windows
• Spatial context
• Icons
• Direct manipulation
• Menus
• Hierarchy
• Pointing devices
• Spatial interaction

27
GUI Components

• Windows (and panels)
• Resize, drag, iconify, scroll, destroy
• Selectors
• Menu bars, pulldown lists
• Buttons
• Labeled buttons, radio buttons, checkboxes
• Icons (images)
• Select, open, drag, group

28
Direct Manipulation

• Select a metaphor
• Desktop, CD player, map,
• Use icons to represent conceptual objects
• Watch out for cultural differences
• Manipulate those objects with feedback
• Select (left/right/double click), move (drag/drop)

29
Limitations of Direct Manipulation

• Understand the metaphor first
• Not all tasks can be described as concrete
  objects
• For example clipboard
• Visual representation may be misleading
• Draw incorrect conclusions
• Culture difference

30
Menus

• Conserve screen space by hiding functions
• Menu bar, pop-up
• Can hierarchically structured
• By applications logic
• By convention (e.g., where is the print
  function?)

31
Limitations of Menus

• Some functions are hidden
• Need exploration
• Need careful organization of menus
• Bad organization really increase time and errors
• Tradeoff between breadth and depth
• Too deep ? can become hard to find things
• Too broad ? becomes direct manipulation

32
Dynamic Queries

• What to do when menus become too deep
• Merges keyboard and direct manipulation
• Select menu items by typing part of a word
• After each letter, update the menu
• Once the word is displayed, user can click on it
• Example Windows help index

33
Language-Based Interfaces

• Command Entry
• Compact, flexible representation
• Precise meanings
• Powerful in the hands of expert users
• Natural Language
• Intuitive to use
• Powerful expressiveness

34
Limitations to Language-Based Interfaces

• What can be done may not be apparent
• Easy to over or underestimate, thus cause
  frustration
• NL could be vague, ambiguous, and ungrammatical,
  context dependent
• High demand on systems ability
• Commands are difficult for naïve users
• Push away new users

35
Text Retrieval Interfaces

• A practical, compromised NL interface
• NL input, but only keywords
• Not try to understand, just shallow processing
• Example MIRACLE system at
• http//tides.umiacs.umd.edu/CLIR_interface

36
Aural Perception

• We respond to sounds without prior focus
• Lack of focus limits simultaneous stimuli
• Absolute amplitude pitch hard to interpret
• But changes stand out clearly
• Stereo effect provides a sense of direction
• Relative amplitude, phase difference

37
Speech Output

• Replay of digitized speech clips
• High fidelity, but limited vocabulary
• Speech Synthesis
• Generate spoken output from unrestricted input
• Based on pronunciation rules and lists of
  exceptions
• Sounds unnatural due to misplaced emphasis
• Prosody-guided speech synthesis
• Use pronunciation of similar words as a guide

38
Auditory Display

• Nonspeech audio output for user interfaces
• Same objectives as graphical output
• Alert the user to exceptional conditions
• Provide ubiquitous feedback
• Present information
• But different characteristics
• Effective even without focus
• Fairly low resolution

39
Auditory Display Design

• Need a metaphor
• Clock ticking, alarm bells, keyboard clicks, etc.
• Channel is easily overloaded
• Focus helps manage cognative load
• Changes are more useful than values
• Pitch, amplitude, position, harmonics, etc.

40
An Auditory Image Display

• Display 2-D images using only sound
• Sweep from left to right every second
• Audible pause and click between sweeps
• Top pixels are high frequency, bottom are low
• Blind users can detect objects and motion
• Time indicates horizontal position
• Pitch indicates vertical position
• Sweep-to-sweep differences indicate motion

http//www.visualprosthesis.com/voice.htm
41
Interactive Voice Response Systems

• Operate without graphical interfaces
• Hands-free operation (e.g., driving)
• Telephone access
• Built on three technologies
• Speech recognition (input)
• Text-to-speech (output)
• Dialog management (control)
• Example TellMe (1-800-555-TELL)

42
Dialogue Management

• Turn-taking
• User initiative
• System initiative (allows smaller vocabulary)
• Mixed initiative (e.g., barge in)
• Interaction style
• Direct answers
• Achieving conversational goals

43
System Initiative

• Finite state control automates scripts
• Restaurant, airline reservation,
• A state encodes everything you know
• What prompt to offer
• What to do for each possible answer
• Loops allow for compact representations

44
Interaction Design
San Francisco Oakland San Jose
Baltimore National Dulles
Anywhere else
Not a day
Where do you want to go?
What day do you want to travel?
Where are you departing from?
Another day
Anywhere else
Day when there are flights
Sorry
Wrong
Verification
Goodbye
Confirmed
45
Cooperative Responses

• I want to fly to Tysons Corner on Friday
• Completion
• All of the flights are sold out
• Correction
• There is no airport in Tysons Corner
• Suggestion
• Dulles is the closest airport
• Conditional answer
• The only flight is on Tuesday
• Summary answer
• I have flights on US carriers or KLM

46
Summary

• HCI design starts with user needs abilities
• Users have a wide range of both
• Users must understand their tools
• And these tools can learn about their user!
• Many techniques are available
• Direct manipulation, languages, menus, etc.
• Choosing the right technique is important
• LBSC 790 in Fall 2004 has this focus

47
Mental Models

• How the user thinks the machine works
• What actions can be taken?
• What results are expected from an action?
• How should system output be interpreted?
• Mental models exist at many levels
• Hardware, operating system, and network
• Application programs
• Information resources