Session 10

LBSC 690

Information Technology

Human Computer Interaction

Agenda

• Questions• Human computer interaction

– Human computer communications– User interface hardware– User interface software

• Virtual reality• Usability evaluation• Project

Design for the Application

• Office and home systems– Ease of use is an important issue

• Custom commercial systems– Complexity can be offset using training

• Support for creative tasks– User needs assessment can be challenging

• Life critical systems– Tracable design and testing needed

Human-Computer Communications

• Humans are slow but versatile devices– 120-300 words per minute– Multiple rich analog channels

• Computers are fast but limited– Around 1 billion words per minute– Single digital channel for each task

• The computer must slow down for us– We must sacrifice fidelity for the computer

User and System Models

Task System

Mental Models SightSound

HandsVoice

Task User

Software Models KeyboardMouse

DisplaySpeaker

Human

Computer

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

User Models

• Knowledge the machine has about the user– Provides a basis for making choices

• Demographic– Location, age, gender, education level, …

• Skill– Task, technology, language, spatial ability. …

• Preference– Goals, habits, interface option selections, …

User Modeling Issues• Support for learning

– Could help present new information effectively

• Locus of control– Users often prefer tools rather than “assistants”

• Privacy– Users may wish to limit dissemination– How can they understand what they are revealing?

User Characteristics

• Physical– Anthropomorphic (height, left handed, etc.)

– Age (mobility, dexterity, etc.)

• Cognitive• Perceptual

– Sight, hearing, etc.

• Personality– Including cultural factors

Common Input Devices

• Keyboards and keypads• Pointing devices

– Mouse, trackball, eraserhead, touch screen, …

• Joystick• Writing tablet

– Useful for signature verification

• Speech recognition– Particularly helpful for non-alphabetic languages

Common Output Devices

• Graphical – Cathode Ray Tube (CRT), flat panel

• Audio– Speakers, headphones, speech synthesizers

• Printers – Ink jet, laser, dot matrix, plotters, microfiche, …

Interaction Styles

• Graphical User Interfaces (GUI)– Direct manipulation

– Menus

• Language-based interfaces– Command line interfaces

– Interactive voice response systems

• Virtual Reality (VR)• Ubiquitous computing

Direct Manipulation

• Directly manipulate conceptual objects– Windows file manager, Windows explorer– Excel

• Icon are useful, but interpretation can be hard– Too small, no good metaphor, cultural differences

Menus

• Conserve screen space by hiding functions– Menu appears only when selected

• Can be logically grouped into several levels– By who’s logic?

• Tradeoff between breadth and depth– Too deep can become hard to find things

– Too broad becomes direct manipulation

Language-Based Interfaces

• Exploits a compact, flexible representation– Text retrieval interfaces– Programming languages

• Can be hard to use– Recall is harder than recognition

• What can be done may not be apparent

– Interpretation requires conceptual effort

Dynamic Queries

• What to do when menus become too deep– Cross between command language and menus

• Select menu items by typing part of a word– Requires users to know which keyword to type

• Can include several words for every topic

– After each letter, update the menu• Once the word is displayed, user can click on it

• Example: Windows help index

Visualization

• Graphical depiction of relationships– Leverages human spatial reasoning abilities

• Some applications have natural spatial layouts– Spatial analogies can be helpful in other cases

• Often based on information organization– For example, hierarchies help visualize context

• Multiple perspectives can sometimes help– For example, coordinated windows

Virtual Reality

• Creates a sensory illusion of presence– Training (Flight simulation, …)– Entertainment (Back to the Future, …)– Visualization

• Three strategies– Fish tank virtual reality– Immersive personal virtual reality– Cave Automatic Virtual Environments (CAVE)

The Five Senses

• Visual– Position/motion, color/contrast, symbols

• Auditory– Position/motion, tones/volume, speech

• Haptic– Mechanical, thermal, electrical, kinesthethic

• Olfactory– Smell, taste

• Vestibular

Types of Displays

• Image– Fixed view, movable view, projection

• Acoustic– Headphones, speakers, within-ear monitors

• Tactile– Vibrotactile, pneumatic, piezoelectric

• Force feedback– dexterous handmaster, joystick, pen

More Display Types

• Inertial– Motion-based simulators

• Olfactory– Chemical (requires resupply)

• Thermal– Object temperature

• Atmospheric– Air motion, air temperature

Wearable Visual Interfaces

• Head mounted displays– Two liquid crystal (camcorder-like) displays– Cables for video and position tracking

• Binocular omni-oriented monitor– Simpler and more comfortable– Limited range of motion

• Shuttered glasses– Used with fixed and projection displays

Modes of Expression

• Arms and hands– Aimed movement, grasp, press, tap, sign/gesture,

write/draw/paint/sculpt, crawl/swing, rub

• Legs– Walk/run/skip/hop/crawl, swim, aimed movement

• Face– Expression, speak, sing/hum, breathe

• Body– Posture, appearance/clothing

Input Devices• Position tracking

– Mechanical, magnetic, acoustic, GPS, inertial

• Data-gloves and suits– Fiber optic, flexible strip, exoskeleton

• Locomotive– Stationary bicycle, treadmill, stairs, shoes, rowing

• Conventional input devices (haptic, speech)

• Image processing (position, gesture, lipreading)

• Facial sensing, eye tracking, biosignal

Position Tracking• Magnetic

– Three fixed emitters, three movable sensors

• Acoustic– Time delay systems have variable update rates– Phase coherent systems can jump lanes

• Differential GPS– Requires unobstructed sight lines to satellites

• Inertial– Large, short term, requires initial calibration

Usability Evaluation

• What is your goal?– Formative vs. summative evaluation

• Who to ask?– Designers, experts, ordinary users, novices

• What to focus on?– System features or realistic tasks?

• What to measure”?– User satisfaction, time required, errors, …

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

• This is the central focus of LBSC 795

Specification

• Guidelines on the web site

• Contract between customer an developer– Imagine that you are one or the other

• Not cast in concrete– But the test plan must match it exactly– Any changes must be reflected in both

Test Plan

• Adopt an explicit sampling strategy– You can’t test every combination– Check broad and deep to detect systematic errors

• Pay attention to tracability– Every requirement should be tested

• Match the type of tests with your goals– White box, black box, ad hoc

Project Test Plan

• Black box assumes no design knowledge– For example, test every link on every page

• White box (or “glass box”) tests exploit design knowledge to test for likely errors– For example, run queries that exercise joins– If errors were predictable, you wouldn’t make any!

Sampling Strategies

• Systematic tests– Broad tests

• Web page example: test every link from the top page• Database example: Run each query once

– Deep tests• Web page example: follow a full sequence of links• Database example: Run a query with different data

• Ad hoc tests– Specify how users are selected, give them a task