Human Computer Interaction

  • ACM: Interaction Journal
  • SIGCHI: around 6000 members:annual conference draws 2500 attendees
  • Italian Chapter - HCItaly (CNR, Feb. ‘99)
  • Usability Prof. Ass.
  • American Soc. for Information Science
    Human Factors of Interactive

  • present situation
  • goals of system engineering
  • goals of user-interface design
  • accommodation of human diversity
  • goals for our profession
  • references
    Present Situation

  • computer pervasiveness implies many, different users
  • which, in turn, means many, different interfaces
  • web, games, databases, simulation, business, training, education, etc. are but a few of the applications
  • impacting on: info organization, query languages, 3d representations, animation, direct manipulation, telepresence, virtual realities...(sw)
  • novel keyboards, high resolution color displays, speech i/o, gestural inputs, force-feedback devices, touchscreen & stylus...(hw)
    Goals of System Engineering

  • to serve the users
  • to design effective systems
  • in good design, the interface becomes invisible:
    US Military Standard for Human Eng. Criteria

  • allow for required performance by operator, control and maintenance personnel
  • minimize skill and personnel requirements and training time
  • achieve required reliability of personnel-equipment combinations
  • foster design standardization within and among systems
    Main issues in design

  • proper functionality (task analysis is central)
  • reliability, availability, security and data integrity (across commands)
  • standardization, integration, consistency and portability (across applications, platforms and op. systems)
  • schedules and budgets
    Goals of User-Interface Design

  • If the previous issues have been addressed then developers must focus on design and testing
  • Careful determination of the user community and benchmarks for testing
  • five measurable human factors:
    • time to learn
    • speed of performance
    • rate of errors by users
    • retention over time
    • subjective satisfaction
    Tradeoffs

  • lengthy learning favours task-performance
  • if low error rate then performance is hindered
  • subjective satisfaction may be a key point
  • design teams negotiate guidelines
  • paper prototype/mock up prototype
    Motivations for Human Factors Design

  • Life critical systems
  • Industrial and commercial uses
  • Office, home and entertainment applications
  • Exploratory, creative and cooperative systems
    • CSCW, distance learning, videoconferencing...
    • high motivation but also high expectation...
    • the computer should vanish...
    Accommodation of Human Diversity

  • Physical abilities and physical workplaces
  • American National Standard for Human Factors Engineering of Visual Display Terminal Workstations
    • Work-surface and display support height
    • Clearance under work surface for legs
    • Work-surface width and depth
    • Adjustability of heights and angles for chairs and work surfaces
    • Posture-seating depth and angle, back-rest height and lumbar support
    • Availability of armressm footrestsm and palmrests
    • Use of chair casters
    Room layout and sociology of human interaction

  • multiple workstations - encourage/hinder social interaction
  • privacy versus open space office
  • physical design of workplaces belongs to ergonomics
    Cognitive and perceptual abilities

  • Ergonomics Abstracts:
    • Short-term memory
    • Long-term memory and learning
    • Problem solving
    • Decision making
    • Attention and set (scope of concern)
    • Search and scanning
    • Time perception
    Factors affecting perceptual and motor performance

  • Arousal and vigilance
  • Fatigue
  • Perceptual (mental) load
  • Knowledge of results
  • Monotony and boredom
  • Sensory deprivation
  • Sleep deprivation
  • Anxiety and fear
  • Isolation
  • Aging
  • Drugs and alcohol
  • Circadian rhythms
    Personality Differences

  • Men/women
  • Interaction styles
  • Pace of interaction
  • Graphics versus Text
  • Dense versus sparse
  • Step-by-step versus all-at-once
    Myers-Briggs Type Indicator

  • Extroversion vs introversion
  • Sensing versus intuition
  • Perceptive versus judging
  • Feeling versus thinking
    Many other psychological scales have been suggested...
  • Risk taking versus risk avoidance
  • Internal versus external locus of control
  • Reflective versus impulsive behaviour
  • Convergent versus divergent thinking
    Cultural and international diversity

  • Cultural, ethnical, racial, linguistic background
  • User interface design concerns for internationalization include:
    • characters, numerals, special characters
    • left to right vs right to left (vertical vs horizontal)
    • date and time formats
    • numeric and currency formats
    • telephone numbers and addresses
    • names and titles (Mr., Mrs., Mme., Dr.)
    • Social security, national identification, passport number
    • capitalization and punctuation
    and...
    • sorting sequences
    • icons, buttons, colours
    • pluralization, grammar, spelling
    • etiquette, policies, tone, formality, metaphors
  • Companies should run usability studies in each country, culture and language community
    Users with disabilities

  • for low vision (even blind)
  • for hearing impairments
  • for mobility impairments
    can all be accommodated using:
  • special i/p devices
  • speech recognition
  • eye-gaze control
  • head-mounted optical mouse
    1. were pioneered for disabled users
    Computer curbcuts

    Cheaper to handle if planned (rather than added)
  • learning-disabled children (2% of school population)
  • proceduresm directions and verbal content at levels and in formats making them accessible even to poor readers
  • response requirements do not allow students to complete programs without engaging with target concepts
  • design feedback sequences that explain the reasons for sutdents’errors and that lead students through the processes necessary for responding correctly
  • incorporate reinforcement techniques that capitalize on students’ sophistication with out-of-school materials
    Elderly users

  • growing population of senior citizens
  • writing accounting, education, entertainment, social interaction, communication and challenge
  • increased access of the society
  • increased participation through networks
  • improved chances for productive employment
  • government agencies, universities, medical centers, law firms could use senior experience
  • e-mail connection enriches family life
    examples

  • larger street signs
  • brighter traffic lights
  • better nighttime lighting
  • larger fonts
  • higher display contrast
  • easier-to-use pointing devices
  • louder audio tones
  • simpler command languages
    golden age software + kidware: large opportunities
    Goals for Our Profession

  • influence academic and industrial researchers
  • provide tools, techniques and knowledge for commercial systems implementors
  • raise the computer consciousness of the general public
    Influencing academic and industrial researchers

  • early methods were based on introspection and intuition
    • lack of validity, generality, precision
  • reductionism scientific method (psychologically oriented) performs the following steps:
    1. understanding of a practical problem and related theory
    2. lucid statement of a testable hypothesis
    3. manipulation of a small number of independent variables
    4. measurement of specific dependent variables
    5. careful selection and assignment of subjects
    6. control for bias in subjects, procedures, and materials
    7. application of statistical tests
    8. interpretation of results, refinement of theory, and guidance for experimenters
    Controlled Experiments

  • have limitations:
    • difficult or expensive to find adequate subjects
    • right laboratory conditions
    • extreme performances may be overlooked
    • anecdotal evidence/individual insights may be ignored
  • yet controlled experimentation is productive and may be adapted to each situation
  • field or test experiments should be carried out
  • individual insights of researchers, designers, participants should be documented
    Human Interfaces

  • need to understand and measure human performance
  • awareness to human-factors issues
  • knowledge and techniques of traditional psychology to be used for studying human-computer interaction
  • information science, business and management, education, sociology, anthropology are all contributing and benefiting by their study of human-computer interaction
    Directions of Study

  • Reduced anxiety and fear of computer usage
  • Graceful evolution
    • methods to smooth the transition from novice to knowledgeable user to expert
    • adaptation and evolution are open topics addressed in the re-design of control panels
  • Specification and implementation of interaction: building tools reduce 10% if the tool is adapted to the task
  • Specification and implementation of interaction: building tools for interface construction
  • Direct manipulation - which is the best metaphor? - new forms: visual languages, spatial visualization, remote control telepresence virtual reality
  • Input devices - high-precision touchscreen, stylus, pen, voice, eye-gaze, gestual; mouse, dataglove, force feedback joystick
  • Online assistance - limited understanding for novices, knowledgeable and expert users - JIT: just-in-time training
  • Information exploration - navigation, browsing, searching of multimedia digital libraries - filter
    Tools, techniques and knowledge for system implementers

  • new tools (environments & prog. languages)
  • guidelines
  • iterative usability studies
  • feedback from users
  • online user consultants
    Computer consciousness of the general public

  • media boosts computer power
  • yet people feel uncomfortable about the computer
  • people are afraid of mistaking
  • people feel incompetent
  • people feel threatened
  • all these fears are generated by bad design
  • designers should be more concerned about users
    Practioner’s summary

  • thorough task analysis
  • attention to : reliability, availability, security, integrity, standardization, schedules & budgets
  • evaluation of design alternatives: short learning times, rapid task performance, low error rates, ease of retention, high user satisfaction
  • for refined design test: accomplishment of goals, expert reviews, usability tests, acceptance tests

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