Human-Computer Interaction by yurtgc548


Introduction and Overview

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What is Human-Computer
A student’s incorrect answer…
    “human-computer interaction is explained
    adequately in the movie Zoolander (the
    part where Hansel and Derek realize the
    files and “in” the computer”
A little closer…
     “human-computer interaction is getting
  people to work well with machines”
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What is Human-Computer
   User     whoever is trying to get a job done
    using technology
    – Individual user
    – Group of users working together
    – Sequence of users in an organization
   Interaction   any communication between
    a user and computer
    – Direct – dialog with feedback and control
      throughout the performance of the task
    – Indirect – may involve background or batch
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What is Human-Computer
   A discipline concerned with the design,
    evaluation and implementation of interactive
    computing systems for human use and with
    the study of major phenomena surrounding
   Human-computer interaction has science,
    engineering, and design aspects.
                    (ACM SIGCHI 1992, from Preece et al, p.7)

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What is Human-Computer
   HCI is concerned with:
    – the joint performance of tasks by humans and machines
    – the structure of communication between human and
    – human capabilities to use machines (including the
      learnability of interfaces)
    – algorithms and programming of the interface itself
    – engineering concerns that arise in designing and building
    – the process of specification, design, and implementation of
    – design trade-offs

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Components of HCI
         Human Users                                Computer Systems
   Creative                                 Non-Creative (yet?)
   Inductive                                Deductive
   Flexible                                 Inflexible
   Dynamic/ Learning abilities              Static Development
   Spatial                                  Numerical
   Fast at Reasoning/Slow at                Poor at Reasoning/ fast and
    Calculation                               accurate at calculation
   Large long term memory                   Limited memory but greater
    versus limited short term                 than short term human

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   Ergonomics
    – Traditionally ergonomics is primarily concerned
      with the physical characteristics of machines,
      and how they affect user performance
    – European
   Human Factors
    – Primarily concerned with the performance of one
      or more persons in a task-oriented environment
      interacting with equipment, other people, or
    – United States

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   Human-Integrated Systems
    – A combination of one or more humans
      and one or more physical components
      interacting to bring about from given
      inputs, some desired output
   Man-Machine Interaction
   Human-Computer Interaction

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   System
    – Any organized assembly of resources and
      procedures united and regulated by
      interaction or interdependence to
      accomplish a set of specific functions
    – Can someone paraphrase?
    – A system is a collection of elements that
      function together to achieve some
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    Machines (In terms of this course)

                     Simple                        Complex
  Not Time-        Telephone              Some Information Systems
   Critical         Door                     Programmable VCR
  (Usually)     Pencil Sharpener
                 Emergency Door            Fighter Aircraft Cockpits
   Often        Basic Car Controls             Nuclear Reactor
Time-Critical   Fire Extinguisher         Other Information Systems

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History of HCI
   The term human-computer interaction has
    only been in widespread use for a little over
    a decade
   WWII started the movement towards
    studying the interaction between humans
    and machines
    – To produce more effective weapons
    – Correct accidents caused by human error in
      cockpits, following the growth of cockpit
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History of HCI
   Ergonomics research society was formed in 1949
   In the 1970s and early 1980, there was interest
    from psychologists in the information processing
    aspects of computer system design.
    – Topics such as the menu names and depth versus breadth
      in menu design were popular areas of study.
   In the early and middle 1980s, researchers became
    interested in usability issues in a single (not
    connected) computer system.
   In the late 1980s and 1990s, the powerful and
    personal computer became available.

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History of HCI
  Three systems that provide landmarks along this
evolutionary path are the Dynabook, the Star and
the Apple Lisa (Predecessor of today's Macintosh).

  In late 1990 and early 2000, the rapid growth of
Internet became a crucial field of HCI community.

 Today the field of HCI is comprised of a variety of
subfields including:
    mobile computers (i.e. cell phones, PDAs, etc.)
    smart houses (i.e. GT Aware Home)
    wearable computers
    augmented virtual reality
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    and much more!
Who Contributes to HCI?

   Psychologists
    – Gives knowledge of user’s perceptual, cognitive,
      and problem solving skills
   Sociologists
    – Helps in understanding the wider context of the
      interaction; interaction as social activity
   Computer Scientists
    – Building and creating the necessary technology

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Who Contributes to HCI?

   Systems Engineers
    – Measure system workflow and efficiency
   Graphic Designers
    – Make systems aesthetically desirable
   Ergonomists
    – Interaction is physical as well as

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Why is HCI Important?
   Computers are now widely used by people who
    may be experts in their particular field but are not
    computer experts.
    – Systems need to be much easier to learn and to use
   The cost of software is high and the competitive
    edge is more difficult to achieve.
    – The interface to a system might give it this edge.
   It is expensive to train users
    – A system which is easy and natural to use will save money
      since the training time will be kept to a minimum.
   The cost of human error can be high.
    – Systems that are transparent and easy to use ought to
      reduce the likelihood of error or at least to aid error
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General Principles of HCI
   Consistency
   Physical Analogy
   Expectations and Stereotypes
   Ease of Learning Versus Ease of Use
   Avoiding Excess Functionality and
    Using Multiple paths
   Design for Progressive Disclosure and
    Graceful Evolution
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   Lack of consistency in system design results in…
    • User must develop a new mental model of the system
    • User rely on several different models during use

   Real projects involve a group effort in
    • Graphical User Interfaces are no exception.
    • Specification is essential
    • GUI functionality should be consistent at every level

   Example
    Word processing - Deletion
    should be consistent at the letter/word/paragraph/text level.

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Physical Analogy

    Users often rely on physical analogies
    in modeling systems
    – This can be exploited
    – For example
        Users often compare word processing tools
         with type writers.
        A word processor design could exploit this by
         mimicking a typewriter

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Expectations and
   Expectations from other domains can
    be exploited to facilitate learning.
    – For example:
    Traffic Lights           User Interface
       Red                      Alarm
       Amber                    Caution
       Green                    Safe

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Ease of Learning versus
Ease of Use
   Ease of learning for novices often lowers ease of use for
     – Learning requires prompts which an expert can ignore
     – Learning limits functionality which an expert can exploit

   Steps must to taken to avoid these limitations.
     – Design for three levels of expertise: novices, intermediates,
     – Avoid & Prioritize Excess Functionality
     – Provide Multiple Paths

   Example:
     – Microsoft Paperclip “Intelligent Agent”

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Multiple Paths

   Menu Bypass
    (keyboard short cuts/Expert Menus)
   Stacking and type ahead commands to
    bypass menus
   Input device options

Multiple path choice depends on the application & task

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Progressive Disclosure
and Graceful Evolution
Progressive Disclosure:
Increased Functionality modeled by expertise of User.

Graceful Evolution:
Smooth development of User from Novice to Expert.

   Make fundamental features easy to learn.
   Make frequently used functions quick to perform
   Encourage Experimentation
    – Consistency
    – Reversibility
   Use Defaults which can be later changed by expert.

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A Conceptual
Model for HCI

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HCI & Design

Rather than the traditional design
models adopted within software
engineering. HCI has adopted a design
model which aspires to incorporate the
following premises:
  – user centered
  – multi disciplinary
  – highly iterative
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HCI & Design

   Involving Users:
    – This may range from observing users
      interacting with a system, to the use of
      psychologically based user modeling
      techniques, to the inclusion of
      representative users in the design team.
   Adopting an Iterative Design Strategy:
    – This attempts to ensure that appropriate
      knowledge has the opportunity for input at
      appropriate stages of the design cycle.
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Examples of Bad Design
Justification for learning about HCI

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Things that don’t work
the way you expect..
         The lids on oatmeal containers were
         recently redesigned. The problem is that it
         looks like you can pick up the container by
         the lid, but you can't.
         Design suggestion
         The lid on the new-style container should
         not look like it could work as a "handle" to
         pick up the container. This might be done
         by: Not making the center of the lid set
         down in the top of the container so deeply.
         Removing the "handle" from the inside of
         the lid by curving the lip outward rather
         than inward.
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Things that don’t work
the way you expect…
       How do you open the refrigerator?
       Apparently, the refrigerator door was designed so it
       could be hinged on either the left or the right side.
       Thus, handles were put on both sides. However,
       people only expect to see one handle on a
       refrigerator door. When the handle doesn't work,
       they assume the door is stuck or locked.
       Design suggestion
       It would be best to put a handle on the front of a
       refrigerator door so that it can be easily seen. On a
       reversible door with handles on both sides of the
       door, there should be a way of removing or
       concealing the handle on the hinged side. There
       should not be visible handles on both sides!

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Different things that are
too similar…
         The example shows two bottles containing different
         doses of insulin for treating diabetes. The bottle on
         the left contains Insulin R (for Regular Insulin),
         which acts relatively fast (4-6 hr period). The bottle
         on the right contains Insulin N (for NPH Insulin),
         which acts over a broader span of time and more
         slowly (12-18 hour period) The consequences of
         accidentally taking Insulin R instead of Insulin N at
         bedtime could cause a hypoglycemic reaction during
         the middle of the night and possibly cause death.
         Design suggestion
         Things that need to be distinguished from each
         other should differ by more than just a single

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Things that don’t work
well together…
Hiding the radio
  This is the center console in a
  rental car showing how the cup
  holder is blocking access to the
  radio and cassette player. Its nice
  to have a cup holder, but this isn't
  a very good spot for it. Not only is
  it hard to use the radio, but if
  your drink spills, its going into the
  cassette player!
Design suggestion
  When you design an object, you
  need to consider the environment
  that it is used in.
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Things that are hard to
Push to start
  Part of the problem is that you may look for
  a "real" button to start the pump; a 3-D
  button. Whereas the actual button is flat.
  But probably the bigger problem was that
  there were so many stickers and decals on
  the gas pump that finding the start button
  was like finding a needle in a haystack.
Design suggestion
  Here are some things that would have made
  it easier to see the "push to start" button:
  Making it larger, Using colors that
  contrasted with the background, Removing
  some of the nearby stickers and decals,
  Making it more centrally located on the gas
  pump, Using a real 3-D button

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Class Activity

   Get into groups of 4 or 5
    – Preferably people you may want to work with on
      your course project
   As a group brainstorm as many systems
    that you think could benefit from usability
    testing and redesign
    – Examples: a particular webpage, kiosk, PDA
   Pick top three to present to the class

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