Lecture 22 Chapter 12 - Human-Computer Interaction - PowerPoint PPT Presentation


PPT – Lecture 22 Chapter 12 - Human-Computer Interaction PowerPoint presentation | free to download - id: 3d1a70-MDIyN


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

Lecture 22 Chapter 12 - Human-Computer Interaction


Lecture 22 Chapter 12 - Human-Computer Interaction A key design activity is to design the user interface Human-computer interaction (HCI) - the study of end users and ... – PowerPoint PPT presentation

Number of Views:78
Avg rating:3.0/5.0
Slides: 31
Provided by: mathYork4


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Lecture 22 Chapter 12 - Human-Computer Interaction

Lecture 22 Chapter 12 - Human-Computer
  • A key design activity is to design the user
  • Human-computer interaction (HCI) - the study of
    end users and their interaction with computers
  • For every input and output the developer must
    consider the interaction between the user and the
  • Because the interaction is much like a dialog
    between the user and the computer, user-interface
    design is often referred to as dialog design
  • The field of human computer interaction
    investigates how people use computer systems, so
    that better systems can be designed
  • One aspect is concerned with technological
    innovation (e.g. better input devices, like
    electronic pen etc.)
  • The other aspect is concerned with the human
    element (e.g. how people reason, solve problems
    and interact with computers) the most
    challenging aspect of HCI!

The User Interface
  • Many people think of the user interface as a
    component added to the system near the end of the
    development process
  • This view is changing as user interfaces become
    more important and systems become more
  • To the end user, the user interface is the system
  • The user interface is everything the end user
    comes into contact with while using the system
    physically, perceptually, and conceptually
  • Therefore, consideration of the user interface
    should come early in the development process

(No Transcript)
Physical Aspects of the User Interface
  • Physical aspects of the user interface include
    the devices the user actually touches, including
    the keyboard, mouse, touch screen, keypad
  • Other physical parts include reference manuals,
    printed documents, data-entry forms, etc. that
    the end user works with completing tasks at a
  • The desk space, the lighting, and the terminal
    hardware also make up the physical interface for
    the end user

Perceptual Aspects of the User Interface
  • Perceptual aspects of the user interface include
    everything the end user sees, hears, or touches
    (beyond the physical devices)
  • This includes
  • All the data and instructions displayed on the
    screen, including shapes, lines, numbers and
    words, sounds (like beeps etc.)
  • Recently, computer-generated speech is another
  • The user touches objects such as menus, dialog
    boxes, and buttons on the screen using a mouse
  • The user touches objects such as documents,
    drawings, or records of transactions

Conceptual Aspects of the User Interface
  • Conceptual aspects of the user interface include
    everything the user knows about using the system
    including the problem domain things in the
    system the user is manipulating, the operations
    that can be performed and the procedures followed
  • To use the system, the end user must know all
    these details
  • Users model (of the system)
  • What the user knows about using the system,
    including the problem domainthings the user is
    manipulating, the operations that can be
    performed and the procedures followed when
    carrying out tasks

  • Designers model (of the system)
  • How the designer sees and understands the system
  • Problems with user interfaces can be considered
    as resulting from mismatches between the users
    model of the system and the designers model
  • Leads to attempt to study how users view systems
    and how designers view systems can be a big

Users Model (continued)
  • Much of the users model is a logical model of
    the system
  • A logical model can be detailed so a user must
    know quite a few details to operate the system
  • A users knowledge of the requirements for the
    system becomes the determinant of what the system
    is, and if the users knowledge of the system is
    part of the interface, then the user interface
    must be much more than something added at the end

User-Centered Design
  • A collection of techniques that place the user at
    the center of the development process
  • Treat users as consultants in the design
  • Three important principles
  • Focus early on the users and their work
  • Evaluate designs to ensure usability
  • Use iterative development
  • Note that in user-centered design design and
    evaluation (testing of the design with end users)
    are considered together
  • Iterate and evaluate until a satisfactory result
    is obtained (from the perspective of the end user)

Notes on User-Centered Design
  • The early focus on users and their work is
    consistent with the approach to systems analysis
    which emphasizes the importance of understanding
    and identifying the system users and their
  • In contrast, the traditional approach focuses
    more on the requirements from the business point
    of view what needs to be done from a processing
    perspective rather than a user perspective
  • The object-oriented approach focuses more on
    users and their work
  • With focus on use cases, actors, scenarios etc.
  • Tend to be more interactive systems

Notes on User-Centered Design (cont.)
  • As discussed in ch. 7 the automation boundary
    between the user and computer is defined early
  • User-centered design goes much further in
    attempting to understand users
  • What do they know?
  • How do they prefer to work?
  • What motivates them?
  • Very important questions when trying to add
    technology to complex areas, eg. Health care
    information systems

Principles of User-Centered Design Continued
  • Second principle of user-centered design
  • To evaluate designs to ensure usability
  • Usability refers to the degree to which a system
    is easy to learn and use
  • Ensuring usability is not easy
  • There are many different types of users with
    different preferences and skills to accommodate
  • If the system is too flexible, some users may
    feel lost
  • If the system is too rigid some users will be
  • Usability engineering
  • Principled methods for ensuring usability
  • Involves continual testing of prototypes with end
    users e.g. video analysis of end user
  • A very hot area currently

Design and Evaluation Considered Together
  • In past, traditionally considered as separate
    topics. In recent years it is becoming recognized
    that interactive systems require iterative design
  • Promising approach for design of many systems
    (and user interfaces in particular)
  • Iterate and evaluate until a satisfactory result
    is obtained
  • Design principles can assist but do not help
    structure the process of design
  • Need new design methodologies
  • Rapid prototyping
  • User-centered design
  • Use of methods that go beyond to include
    continual usability testing with representative
    users doing representative tasks

Usability continued
  • Usability ease of use and learning
  • These concepts are often in conflict
  • An interface that is easy to learn is not always
    easy to use
  • Eg. Menu-based applications with multiple forms
    and dialog boxes etc. are easy to learn
  • Easy to learn interfaces are appropriate for
    systems used infrequently
  • But if system used all day by office-workers
    important to make interface fast and flexible
    with shortcuts, hot keys and information-intensive
    screens (may be harder to learn but easier to
    use once learned)

Testing for Usability
  • Developers use many techniques to evaluate
    interface designs to ensure usability
  • Some methods
  • Formal surveys
  • Focus group meetings
  • Design walkthroughs
  • Paper and pencil evaluations
  • Expert evaluations
  • Formal laboratory experiments
  • Informal observation
  • Some methods allow collection of objective data
    that can be analyzed statistically

Example video-based usability testing
  • Method Im using video record subjects
    (representative users of systems, e.g. doctors,
    nurses) as they interact with a system and
  • Record all screens on video
  • Can code the video to identify problems users
    have and suggestions for improvement
  • Can statistically compare alternative designs
  • Can provide feedback to designers to improve

Usability continued
  • Third principle of user-centered design
  • Use iterative development doing some analysis,
    then some design then some implementation (and
  • cycling through with some analysis (evaluation of
    the design) then some feedback to designers and
    improvements, followed by further evaluation etc.
  • After each iteration the project team evaluates
    the work on the system and makes changes if
  • Iterative development keeps the focus on the user
    by continually refining the system after each

Human-Computer Interaction as a Field of Study
  • User-interface design techniques and HCI as a
    field of study evolved from studies of human
    interaction with machines in general human
    factors engineering or ergonomics
  • Formal study of human factors began in World War
    II, when aerospace engineers studied the effects
    of arranging controls in cockpit
  • What the pilot does is the human factor that
    engineers realized was beyond their control

  • Example of the importance of the human factor
    involving a minor change
  • Designers switched location of the throttle and
    the release handle for the ejection seat
  • The result was a dramatic increase in the number
    of unexplained pilot ejections!
  • When under pressure, the pilots grabbed what they
    thought was the throttle and ejected from the
  • Designers dismissed the problem as need for
    better traning
  • But problem continued!
  • Became apparent that the key to the human
    factor was to change the machine to accommodate
    the human rather then trying to change the human
    to accommodate the machine
  • Computer example in avionics early Airbus
  • Too much control taken over by the computer system

Emergence of the field of Human-Computer
  • The field of human factors was associated with
    engineering, since engineers designed machines
  • But engineers often found human factors
    frustrating (different personality types)
  • Gradually specialists emerged who drew on many
    disciplines to understand people and their
  • Disciplines drawn on for HCI
  • Cognitive psychology
  • Computer science
  • Social psychology
  • Linguistics
  • Sociology
  • anthropology

(No Transcript)
Example Impact of HCI work from Xerox PARC on
  • In the 1970s an important contribution to the
    field of HCI began at Xerox Corporation
  • Xerox produced high-speed photocopy machines with
    ever increasing options
  • Recognized the importance of making these
    machines easy to use and learn
  • Xerox hired people with many backgrounds e.g.
    computers, psychology, anthropology etc.
  • Xerox started the Xerox Palo Alto Research Centre
    (Xerox PARC) to study issues that affect how
    humans operate machines

  • Xerox began offering photocopy machines with
  • Touch screens
  • Menu-driven interfaces displaying icons like
    stacks of paper, staples etc.
  • Research at Xerox PARC also included work on
  • First object-oriented language, Smalltalk was
    developed by Alan Kay at PARC
  • First laser printer
  • Basis of portable computing worked out at PARC as
  • Kay developed a portable personal computing
    platform (Dynabook)
  • Key aspects of GUI (graphical user interfaces)
    also worked out at Xerox PARC

  • In late 70s Xerox developed the first
    general-purpose personal computer with a
    graphical user interface the Xerox Star
  • Although it was ahead of its time and too
    expensive it is a landmark in computing
  • Key features of it were exploited in the early
    1980s by Apple Computers (which was located
    physically next to Xerox PARC in Silicon Valley)
  • The features from the Star became part of the
    Apple Lisa, which led to the Apple Macintosh
  • The story doesnt end there! the Microsoft
    Windows graphical user interface essentially
    evolved from the Apple Macintosh interface
    (initially was a legal battle between Apple and
    Microsoft over the rights)

Field of Human-Computer Interaction (HCI)
  • The field of HCI has evolved
  • Academic programs in it (through Computer Science
    and Psychology programs and departments)
  • Undergraduate and graduate programs
  • Major conferences, journals and books
  • In industry it is beginning to have a major
  • Usability laboratories
  • Eg. Hewlitt-Packard, Microsoft, Apple, American
    Airlines etc.
  • Hire multidisciplinary staff
  • Computer scientists
  • Psychologists
  • Graphics designers
  • Ethnographers

Metaphors for Human-Computer Interaction
  • The term metaphor describes the overall concept
    you may use to organize all the objects and
    actions in an interface into a coherent whole
  • Three major metaphors, or analogies in HCI
  • Direct manipulation metaphor
  • Desktop metaphor
  • Document metaphor
  • Direct manipulation metaphor
  • A metaphor of HCI in which the user interacts
    directly with objects on the display screen
  • Objects are made visible so the user can point at
    them and manipulate them with the mouse or arrow
  • Earliest direct manipulation interfaces were word
    processors that let users type in words directly
    into a document in a spreadsheet (which on the
    screen was conceptually similar to a paper

Direct Manipulation Metaphor (cont.)
  • Early direct manipulation applications that run
    using DOS (e.g. spreadsheets, word processors)
    led to popularity of personal computers
  • Smalltalk language developed at Xerox PARC
    extended direct manipulation to all objects on
    the screen
  • Buttons
  • Check boxes
  • Scroll bars
  • Slider controls
  • New icons appeared eg. Trash cans, which
    allowed you to directly manipulate an object
    put it in the trash

Desktop Metaphor
  • Direct manipulation coupled with object-oriented
    programming eventually evolved into the desktop
  • The display screen includes an arrangement of
    common desktop objects
  • Notepad, a calendar, a calculator, file folders
    containing documents
  • Newer ones also include a telephone, an answering
    machine, a CD player
  • Interacting with these objects is similar to
    interacting with real-world objects they represent

(No Transcript)
About PowerShow.com