Design Principles

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Design Principles

• Douglas M. Stewart, Ph.D.
• Anderson School of Management
• University of New Mexico

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Three Aspects of Mental Models

• Design model and user model should match

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System Image of Refrigerator
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Users Model
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Design Model
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Experience vs. Inexperience

• Use knowledge
• In the world
• In the head
• Experienced users
• Dont impede knowledge in head
• Inexperienced users
• Principles observable from system image
• Actions consistent with users conceptual model
• Manuals are part of the system image

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Will the Real Abe Lincoln Please Step Forward?

• Great precision in knowledge is not required.

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THE PAOMNNEHAL PWEOR OF THE HMUAN MNID

• Aoccdrnig to a rscheearch at Cmabrigde
  Uinervtisy, it deosn't mttaer in waht oredr the
  ltteers in a wrod are, the olny iprmoatnt tihng
  is taht the frist and lsat ltteer be in the rghit
  pclae. The rset can be a taotl mses and you can
  sitll raed it wouthit porbelm. Tihs is bcuseae
  the huamn mnid deos not raed ervey lteter by
  istlef, but the wrod as a wlohe.
• Amzanig huh?

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Simplify the Structure of Tasks

• Necessary tasks should
• Be simple in structure
• Minimize the amount of planning or problem
  solving
• Improving the task with technology
• Keep task the same but provide mental aids
• Make the invisible visible to improve feedback
• Automate but keep task the same
• Change the nature of the task

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A simple game

• Start with the nine numbers 1,2,3,4,5,6,7,8 and
  9. You and your opponent alternate turns, each
  taking a number. Each number can be taken only
  once, so if your opponent has taken it you cannot
  also take it. The first person to have any three
  numbers that total 15 wins the game.

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Make things Visible

• Bridge the gulf of Execution and Evaluation
• Give each action an immediate and obvious
  feedback
• Leitz slide projector
• Make relevant parts visible
• The remote control antenna that was really a hook
• Affordances

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Visibility
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Get the Mappings Right

• Should be able to see relations between
• Intentions and possible actions
• Actions and effects on system
• Actual system state and what is perceived
• Perceived state and needs of user
• Difficulties arise when controls deviate from
  strict
• Proximity
• Mimicry
• Analogy

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Real World Mapping
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Real World Mapping (2)
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Real World Mapping (3)
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Real World Mapping (4)
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Fantasy World Mapping
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Not even mapped with itself
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Stupid MSU Tricks
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More Stupid MSU Tricks
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Exploit the Power of Constraints

• Natural
• Extra partsfrom reassembly
• Artificial
• Lockouts and interlocks
• Im thinking of a
• Mythical being that rhymes with post
• Building material that rhymes with eel
• Unit of time that rhymes with ear
• Answers ghost, steel year

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Design for Error
From a nuclear power plant control room

• Allow for recovery
• Show what has been done and what happened
• Allow user to reverse from unwanted operations
• Make it hard to perform irreversible operations

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When all else failsstandardize

• Common Standards
• Side of road
• Clockwise to tighten
• Timing of standard
• Locking in a primitive technology
• English system
• 12 hour days of 60 minutes

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Not up to standard
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For 25,000 Id like to know what time it is
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Still More Stupid MSU Tricks
Henry Center Restrooms near class
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And just down the hall
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What is wrong here?
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Deliberately making things difficult

• Doors to keep people out
• Security systems
• Dangerous equipment
• Secret doors and cabinets
• Childproofing
• Cabinets
• Medicine
• Equipment
• Games

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Bad Design Internet Page

• http//csob.berry.edu/faculty/jgrout/pokayoke.shtm
  l
• http//www.baddesigns.com/

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Exercise

• You have been employed by a manufacturing company
  to design their new product. The company is
  considering combining the following into one
  item
• AM-FM radio
• Cassette player
• CD player
• Telephone
• Telephone answering machine
• Clock
• Alarm clock (can turn on tone, radio, cassette or
  CD)
• Desk or bed lamp

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Exercise Cont.

• The company is trying to decide whether or not to
  include a 2 TV screen and a switched electrical
  outlet that can turn on a coffee maker or toaster
• Your job is to
• Recommend what to build
• Design the control panel
• Explain how you would go about validating that
  this is what the customer wants and is easy to
  use.