Engineering Psychology

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Engineering Psychology

• The design of machines and equipment for human
  use, and the determination of the appropriate
  human behaviors for the efficient operation of
  the machines
• Synonyms include human factors engineering and
  ergonomics

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History of Engineering Psychology

• Until the 1940s the design of machines was the
  sole province of engineers. Human needs and
  comfort were ignored
• Workers were adapted to the needs of the
  machine through time and motion studies
• WWII and high rate of failure of well designed
  machines brought about engineering psychology
• For example, airplane controls were not
  standardized

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Current Examples of the Field

• Brake light in rear windows of cars
• Car safety research on window tinting and
  cellular phones
• Design of cameras and toothbrushes
• Working with US Postal system to change design of
  mailbags to reduce back pain in carriers

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Time and Motion Studies

• An early attempt to redesign tools and to reshape
  the way workers performed routine and repetitive
  jobs
• 1898 Frederick Taylor of Bethlehem Steel.
  Studied optimal shovel use.
• Saved company 78,000 a year

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Time and Motion Continued

• Frank and Lillian Gilbreath their goal was to
  eliminate all unnecessary motion. Made workers
  more productive within having them work harder.
  Applied ideas to own lives
• Today, this type of work is done by efficiency
  experts. Truly only useful for routine manual
  jobs

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Person-Machine Systems

• A system in which human and mechanical components
  operate together to accomplish a task
• Neither part is of value without the other
• These systems involve a wide range of human input
• Even automated equipment needs to be designed and
  maintained by humans

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Allocation of Functions

• Machines are superior to humans at
• Detection of stimuli beyond human sensory
  capacities
• Monitoring reliably for lengthy periods
• Making large s of rapid and accurate
  calculations
• Storing and retrieving huge amounts of info
• Applying greater physical force continuously and
  rapidly
• Engaging in repetitive activities w/ no
  deterioration

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Shortcomings of Machines

• Not flexible. Are controlled by programming
• Can not learn from errors or previous experience
• Can not improvise. Can not reason

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Workspace Design

• Effective design of the human operators
  workspace follows 3 principles
• All materials should be placed in the order that
  they will be used. Reduces searching, allows
  continuous movement
• Tools should be pre-positioned so that they can
  be picked up ready for use
• All parts and tools should be within a
  comfortable reaching distance (approx. 28
  inches). Otherwise, too fatiguing

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Workspace Design

• Issue of accommodating workspaces to workers
  special needs (e.g., pregnancy)
• Researchers have spent tremendous effort reducing
  the design of tools in order to reduce injury
• Human anthropometry concerned with the
  measurement of the physical structure of the
  body. Provide averages used to design work areas
  (e.g., normal and maximum working distances,
  viewing angles for display terminals)

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Displays Presentation of Information

• What is the most effective means of
  communication?
• Visual media are better when
• Message is long, difficult, and/or abstract
• The environment is noisy
• Auditory channels are overloaded
• Message consists of many different kinds of
  information that must be presented simultaneously

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Auditory Displays are Better When

• Information is short, simple, and straightforward
• Message is urgent
• Environment is not optimal for vision (e.g., too
  dark)
• Work requires movement to different locations

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Visual Displays

• Common error is presenting more information than
  is needed
• Quantitative Displays present a precise
  numerical value (e.g., speed, altitude). Can be
  digital
• Qualitative Displays less precise. Show ranges,
  often are color coded (e.g., engine temperature)
• Check Reading Displays binary. On-off,
  safe-unsafe (e.g., warning light)
• Heads-up Display projected on windshield

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Auditory Displays

• Advantages include
• Our ears are always open
• Our ears can receive information from all
  directions
• Our visual sense is often taxed to capacity

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Controls

• How do humans communicate with machines?
  Questions include how much force is needed to
  use, frequency of adjustment, can it be used
  while wearing gloves?
• Control-task Compatability a control action
  should imitate the movement it produces (e.g.,
  what happens when a steering wheel is turned to
  the right?

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More Control Issues

• Combining related controls for example on-off
  and volume
• Clear identification of controls
• Placement of controls issue of standardization.
  A non-example, kitchen ranges and arrangement of
  dials

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Computers

• A wide variety of issues to be considered when
  designing workspace area
• Table and keyboard height should be designed to
  maintain a 90 degree elbow angle
• Viewing angle and viewing distance
• Document holders
• Height and position of footrest
• Seat height and angles

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Checklist for Computer Stations

• Adjust your chair height so your feet are flat on
  the floor.
• Position you keyboard so your elbows are at the
  same height as the keyboard and your wrists have
  little or no tilt.
• Position your mouse at the same height as your
  keyboard.
• Set up your display so the top of the screen is
  at or slightly below eye level.
• Position the screen so it doesn't reflect glare
  into your eyes.
• Keep your screen clean
• Make sure your display's brightness and contrast
  controls are properly adjusted.
• Place your laser printer in a well-ventilated
  area and make sure it receives regular
  maintenance.
• Alternate working at the computer with tasks that
  use different muscles.
• Take frequent breaks to rest your eyes and move
  your body.

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Industrial Robots

• Very useful when hazardous chemicals are used
  (e.g., spray painting)
• ¼ of all industrial robots are used in the
  automotive industry
• Almost all benefits of robot use go to management
  in particular,