Lecture 4: The MultiDisciplinary Nature of Human Factors

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Lecture 4 The Multi-Disciplinary Nature of Human
Factors
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Tutorial this week

• Check out examples of bad design at
  www.bad-design.com
• Bring an example of a device of product that is
  difficult to use (from a Human Factors
  perspective) to the Friday tutorial.
• Be prepared to justify/explain why your example
  is a good one at the tutorial
• We will be allocating points for participation.
  This will count towards your final grade (10)

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Reminder

• Human Factors/Ergonomics seeks to adapt the work
  environment to the capabilities and limitations
  of the worker. The results should be increased
  productivity, user satisfaction, and reduced risk
  of injury.

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Goals

• Introduce the core disciplines that contribute to
  the multidisciplinary activity of human factors
  engineering.
• Demonstrate examples of how these disciplines
  contribute to the design of a human-machine
  system,

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Overview

• Physical sciences
• Medical sciences
• Social sciences

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Psychology

• Human sensory capacities
• Psychomotor performance
• Human error rates
• Selection tests and procedures
• Learning and training
• Individual differences and their measurement
• Team performance

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Case Study 1What is a safe stopping distance for
a car?
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Factors contributing to overall stopping distance

• The initial vehicle speed
• The weight of the vehicle
• The road conditions
• The reaction time of the driver
• The braking ability of the car

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Factors contributing to driver reaction time

• the visibility of the target
• the expectations of the driver
• how long the driver has been driving
• how fatigued the driver is

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Anthropometry

• concerned with the measurement of the physical
  features of people
• used in the design of seats, chairs, tables,
  computer consoles, automobile interiors,
  airplance cockpits, and many other work stations

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Case Study 2 Guidelines for monitor placement
and lighting

• Eye-to-screen distance at least 25", preferably
  more.
• Vertical location viewing area of the monitor
  between 158 and 508 below horizontal eye level.
• Monitor tilt top of the monitor slightly farther
  from the eyes than the bottom of the monitor.
• Lighting ceiling suspended, indirect lighting.
  Use blinds and shades to control outside light.
• Screen colors dark letters on a light
  background.

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Viewing Angles
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Exercise Gaze angle and legibility

• To see the effect of gaze angle on accommodation,
  hold a business card at arms length and at eye
  level. Slowly bring it towards you until the
  letters start to blur. Without moving your head,
  slowly lower the card in an arc, keeping it the
  same distance from your eyes. You will see the
  letters come into focus. Your eyes have improved
  their ability to accommodate simply by lowering
  their gaze angle. Presbyopes (persons over 40 who
  are losing their ability to view close objects)
  often make use of this phenomena when they
  misplace their reading glasses. They hold reading
  material at arms length and then tip their head
  back to improve their ability to accommodate.

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Exercise Gaze Angle and Convergence (Focus)

• To see the effect of gaze angle on your ability
  to converge, try this next demonstration. With
  your head erect, hold a pen at arms length and
  at belt level. Gradually bring it towards your
  nose, following it with your eyes until you can
  no longer converge accurately and you see two
  pens. Without moving your head, try the same test
  at eye level. Again, notice the distance at which
  you can no longer converge. Now bring the pen in
  from an upward gaze angle. As you can see and
  feel, your eyes converge more easily with a
  downward gaze angle.

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Applied Physiology

• concerned with metabolic processes and
• responses of these vital processes to work,
  stress, and environmental influences
• Applied physiology is used to distinguish between
  light and heavy work,
• and to figure out how long rest periods should be
  for different tasks.

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Environmental Medicine e.g., Ammonia

• Ammonia NH(3)
• CAS 7664-41-7 UN 2672 (between 12 and 44
  solution) 2073 (gt44 solution) 1005 (anhydrous
  gas or gt 50 solution)
• Synonyms include ammonia gas, anhydrous ammonia,
  liquid ammonia, aqueous ammonia, ammonia solution
  and ammonium hydroxide

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Exposure to Ammonia

• Exposure to ammonia may be fatal if it is
  inhaled.
• Contact with concentrated ammonia solutions, such
  as some industrial cleaners, can cause serious
  corrosive injury.
• Ammonia is manufactured by reacting hydrogen with
  nitrogen. It is among the five most abundantly
  produced chemicals in the world. About 80 is
  used in fertilizers

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Ammonia Properties and Standards

• Warning properties Sharp, pungent odor at 5
  ppm eye and throat irritation at 20 to 50 ppm
• OSHA STEL (Short Term Exposure Limit) 35 ppm
• NIOSH IDLH (Immediately dangerous to life or
  health ) 500 ppm

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Engineering

• provides information on electrical, mechanical,
  and chemical characteristics of elements and
  systems and principles of design, construction
  and operation of structures, equipment and
  systems

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Statistics

• used for summarizing large amounts of data on
  human measurements and human performance
• also used to design sampling schemes and
  experiments for the conduct of human studies and
  performance measurements

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Operations Research

• concerned with quantitative methods for the
  analysis of the performance of manpower,
  machinery, equipment, and policies in government,
  military, or commercial spheres
• also responsible for the development of models,
  such as queueing and allocation meodels, for
  describing operations

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Industrial Design

• concerned with design, color, arrangement,
• and packing of equipment
• to combine functionality and an aesthetically
  satisfying appearance

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Summary

• Human factors engineering requires input from
  disciplines ranging from psychology and
  environmental medicine to statistics. Each of
  these disciplines represents a huge storehouse of
  knowledge. Since it is not possible for you to
  become an expert in ALL the relevant disciplines,
  our goal in this one semester course is to give
  you an overall understanding of human systems
  design and engineering, and an awareness of the
  multidisciplinary nature of that activity.

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Reminder

• Check out discussion of usability at
  www.useit.com
• Check out latest scoop on usability of mobile
  devices at http//www.useit.com/alertbox/20000917.
  html
• Bring an example of a device of product that is
  difficult to use (from a Human Factors
  perspective) to the Friday tutorial.
• Be prepared to justify/explain why your example
  is a good one at the tutorial
• We will be allocating 1 point per tutorial for
  active participation. This will count towards
  your final grade