Human Factors Psychology

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Human Factors Psychology

• Lecture 1 Course Introduction

PSY-4340/PSY-5340, Dr. William Langston, MTSU
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Gas Pump
3
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
  performance.
• (Picture from Darnell, 2003).

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Wills Rules

• The proper way to use a device should be obvious
  from looking at it.
• 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.

5
The Infamous Ballot

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

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Wills Rules

• You have to consider every potential user, not
  just young, tech-savvy people with perfect
  vision.
• 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.

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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).

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Wills 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?

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Hubris

• 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
  om/stupid/.

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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).

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Wills Rules

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

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Fundamental Attribution Error

• When people make mistakes we tend to make an
  internal attribution. In other words, we
  perceive peoples mistakes as being their fault.
• Research shows that people generally discount
  situational pressures that might cause the
  average person to make the same mistake.
• Even though this is a difficult-to-overcome human
  propensity, its an important thing to avoid in
  design. If you create an error-likely situation,
  fix it, dont blame the victim.

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Wills Ultimate Rule

• 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.

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Human Factors

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

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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)

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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)

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Human Factors

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

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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.

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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
  transmission.
• Speed 27 m/s.
• If nervous transmission is not instantaneous,
  then we can study components, including mental
  components.

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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.

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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
  us.

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Historical Antecedents Memory

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

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Historical Antecedents Attention

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

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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
  machine/device.
• For example, a computer has input, processing,
  output just like the operator.

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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
  research.
• Find human factors research applied to
• Military technology.
• Nuclear power plants.
• Aviation.
• Automobiles.
• Consumer products.
• Human-computer interaction.

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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
  http//www.baddesigns.com.