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Human Factors


Human Factors Lecture 1: Introduction How Do I Open This? Some human factors issues to consider: The goal of human factors is to optimize system performance (operator ... – PowerPoint PPT presentation

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Title: Human Factors

Human Factors
  • Lecture 1 Introduction

How Do I Open This?
  • Some human factors issues to consider
  • The goal of human factors is to optimize system
    performance (operator machine environment).
    A 50 failure rate is hardly optimizing system
  • (Picture from Darnell, 2003).

General Rules
  1. The proper way to use a device should be obvious
    from looking at it.
  2. Even in a reasonably trivial situation like this,
    wasted time and effort are frustrating and
    unnecessary. If it really mattered (like in a
    car), serious disaster could result.

The Infamous Ballot
  • Some human factors issues to consider
  • The side-by-side presentation is confusing.
  • No consideration of even minimal visual
  • No consideration of even minimal motor
  • Why is it possible to punch two if you can only
    vote for one?
  • It presents extraneous information (e.g., the

General Rules
  • You have to consider every potential user, not
    just young, tech-savvy people with perfect
  • You have to anticipate common mistakes the user
    might make and prevent those mistakes.
  • Nothing the user does should result in a
    catastrophic error. Ever.

Popping the Trunk
  • Some human factors issues to consider
  • Physical limitations also need to be considered
    in design. When hiding controls, keep in mind
    that fingers have less visual acuity than eyes.
  • (Picture from Darnell, 2003).

General Rules
  • You have to consider the everyday use of an
    object when planning its design. Will it work as
    intended in the heat of the moment?

  • Some human factors issues to consider
  • How do I get it to present one bullet at a time?

PowerPoint 2
  • Some human factors issues to consider
  • Why wont it allow me to center the picture this

General Rules
  1. The labels/options should say what things are and
    what they do.
  2. In general, if you need a label or a tool-tip,
    its not clear enough. Think some more.
  3. In general, KISS. You can always make increased
    complexity an option for more experienced users.
  4. Turning something gray when it isnt an option is
    a good start, but some sense of when an option
    applies is better.

  • Customer "I'm looking at the back of the
    system, and I don't know where to plug in the
    mouse. There are two holes that are the same size
    as the mouse."
  • Tech Support "Ok, what color is the tip of
    the mouse plug?"
  • Customer "Orange."
  • Tech Support "Do you see the orange 'hole'
    on the back of the computer?"
  • Customer "Yes."
  • Tech Support "That is where the mouse
    plugs into."
  • Customer "Oh. How about the keyboard?"
  • Tech Support "What color is the plug on
    the keyboard?"
  • Customer "Purple."
  • Tech Support "And do you see the purple
    'hole' on the back of the computer?"
  • Etc.
  • From Stoddard, S., RinkWorks Productions.
    (2003). Computer stupidities Calls from Hell.
    Retrieved May 10, 2003 from http//www.rinkworks.c

You try
  • Does the green label go with the top or the
    bottom hole? (Ignore the arrows, theyre not
    intended to be giving the answer.)
  • (Picture from Darnell, 2003).

General Rules
  1. Blaming the user is not the same thing as proper
    human factors design.
  2. Its important to step back and think like a
    novice user, not a developer/designer. Of course
    you know how it works.

The Ultimate Rule
  1. Theres a big difference between being a grumpy
    old man and making a legitimate point. The goal
    of human factors is to improve human/machine
    interaction. Most of the time, if you make a
    mistake using a product, its a design flaw, not
    a human flaw.

Human Factors
  • Systems approach
  • Operator machine/device environment.
  • Any failure system failure. Thats to be
  • Theres a lot more flexibility in manipulating
    the machine/device than in manipulating the
  • Consequences of failure
  • Bad press (Microsoft).
  • Lost productivity.
  • Lost profit.
  • Serious injury/death.

Human Factors
  • Definition
  • The study of those variables that influence the
    efficiency with which the human performer can
    interact with the inanimate components of a
    system to accomplish the system goals. (Proctor
    van Zandt, 1994, p.2)

Human Factors
  • Or
  • Human factors is that branch of science and
    technology that includes what is known and
    theorized about human behavioral and biological
    characteristics that can be validly applied to
    the specification, design, evaluation, operation,
    and maintenance of products and systems to
    enhance safe, effective, and satisfying use by
    individuals, groups, and organizations.
    (Christensen, Topmiller, Gill, 1988, p.7, as
    cited in Proctor van Zandt, 1994, p.2)

Human Factors
  • Basic human capabilities
  • Perceptual
  • Attention span
  • Memory span
  • Physical limitations
  • Etc.

Course Outline
  • Introduction.
  • Perceptual factors.
  • Cognitive factors.
  • Movement factors.
  • Environmental factors.

Historical Antecedents Psychophysics
  • Weber (1846)
  • How can we tell that two stimuli differ?
  • Webers Law D I/I k.
  • Application Recognizing that an indicator light
    has come on.
  • Fechner (1860)
  • Attempt to produce a scale to relate a physical
    stimulus to the sensation produced.
  • Fechners Law S k log(I).
  • Demonstrate the use of empirical methods to
    understand human performance.

Historical Antecedents Physiology
  • Helmholtz
  • Nervous transmission is not instantaneous.
  • Attach electrodes at two points on a frog leg,
    stimulate, look for effect. Difference in time
    can be used to compute speed of nervous
  • Speed 27 m/s.
  • If nervous transmission is not instantaneous,
    then we can study components, including mental

Historical Antecedents Timing
  • Donders (1868)
  • Analyze components of speeded tasks
  • Detect.
  • Identify.
  • Discriminate target from other stimuli.
  • Select a response.
  • Subtractive method Create tasks that vary by
    only one component, compare times in the various
    tasks to compute how long each component takes.
  • We can actually break mental activity into its
    component parts. Response time is the handle on
    doing this.

Historical Antecedents Role of Mental Activity
  • Wundt (1879)
  • First psychology laboratory.
  • Believed that mental events play a causal role in
    human behavior.
  • Understand mental by decomposing sensory and
    perceptual experience into basic elements.
  • Introspection.
  • The method had problems, the ideas are still with

Historical Antecedents Memory
  • Ebbinghaus (1885)
  • Created lists of nonsense syllables, memorized
    them, studied properties of memory (e.g.,
  • Demonstrated empirically that mental constructs
    like memory could be studied in the laboratory.

Historical Antecedents Attention
  • James (1890)
  • Outlined the basic components of attention.

Historical Antecedents Information Processing
  • We have the basic foundation for a human
    information processing approach
  • Cognition is a series of operations performed on
    information originating from the senses.
  • Human factors implication The human operator
    can be analyzed in the same way as the
  • For example, a computer has input, processing,
    output just like the operator.

Human Factors
  • World War II was a major force in bringing all of
    this together. New technologies, many untrained
    users, and profound consequences of failure
    highlighted the critical need for human factors
  • Find human factors research applied to
  • Military technology.
  • Nuclear power plants.
  • Aviation.
  • Automobiles.
  • Consumer products.
  • Human-computer interaction.

Human Factors Psychology
  • Lecture 1 Course Introduction
  • End
  • References
  • The notes are based on Proctor, R. W., van
    Zandt, T. (1994). Human factors in simple and
    complex systems. Boston Allyn and Bacon.
  • Most pictures and bad design examples are from
    Darnell, M. J. (2003). Bad human factors
    designs. Retrieved May 10, 2003 from