Applying cognitive theory

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Applying cognitive theory

• We have a lot of models and concepts now
• What good are they?
• Cognitive theory can be useful for things other
  than psychology
• Used in engineering to improve designs
• Two large fields of interest
• Human Computer Interaction (HCI)
• Human Factors (cognitive ergonomics)

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Human Computer Interaction

• Three main aims
• Improve access to computing devices
• Reduce complexity of using computing devices
• Reduce likelihood of error in using computing
  devices
• This is done in various ways
• Mathematical models of computer use
• Direct observation of computer use
• Application of cognitive models

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Example WIMP vs. CLI

• Before 1970s, computers controlled by command
  line interface (CLI)

• Single line of text input
• Needed to know each commands keyword
• Needed to know the syntax for each command
• Eg. Copy source filename destination filename

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Problems With CLI

• People found it hard to use
• Forgot command names
• Would transpose command parameters
• Novices would be overwhelmed (blank screen)
• Cognitive analysis
• Many of the problems can be traced to recall vs.
  recognition memory
• Commands and syntax had to be recalled (quite
  hard)
• Almost no recall cues are provided
• Can expect even experts to make mistakes

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Solution WIMP

• Xerox invented the Windows Icons Mouse and
  Pointer (WIMP) interface

• Very few commands (mouse buttons), bring up
  options
• Visual metaphor
• Contextually appropriate commands are brought up
• Drag Drop removes parameters

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Why WIMP works

• Uses recognition rather than recall
• Icons show available commands
• Menus give complete list of available commands
• Visual metaphor removes abstract syntax
• No longer remember order of commands or positions
  in path trees
• Can see where things are, move them from place
  to place
• Reduced likelyhood of making syntax errors

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Mental Models

• How do we understand how the world works?
• More than simple memory
• Includes expectations of behaviour
• I throw a ball at my friend, and she catches it
• How did I know how hard to throw it?
• How did she know where to stand to catch it?
• We have an understanding of the mechanics of the
  world
• How objects interact, the relationships between
  them

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What is a mental model?

• A cognitive structure that encodes how an aspect
  of the world operates
• Includes information about which object classes
  interact with which other classes
• Also includes information about how objects
  interact, and how interactions change properties
• Malleable structures which are strengthened by
  successful application

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Mental model example

• The circle is above and to the right of the
  square
• We can ask questions about this situation
• Which object is to the left?
• Which object is at the bottom?
• Would the circle balance on the square?
• By creating a mental model, these questions are
  simple to answer
• Add in knowledge we already have
• You can simply see the answer

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How we use mental models

• We use mental models to generate predictions
• Predict where the ball will land
• Expertise is generally associated with mental
  models closer to reality
• An expert cricket player understands ball physics
  better
• But mental models are always unconscious
  (knowing doesnt help)
• Mental models are not based on accurate physics
• Can lead to incorrect predictions
• Based on experience, etc
• Change as they are used

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Expanding mental models

• HCI researchers have expanded the idea
• Includes a users understanding of the workings
  of a computing device
• Expectations of menu structures, where files are
  stored, etc.
• In HCI understanding users mental models is
  important
• Understand how learning a system works
• Reduce stress/workload by supporting users
  mental models
• Tailor systems to fit how users perceive the
  system

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Mental models and user-interfaces

• Any interface requires a mental model to use
• What to expect when typing, clicking, etc
• How to interpret the consequences of actions
  (e.g. link new window with clicking of the icon)
• Mental models are important when interface has
  little feedback
• Difficult to recognize results
• Few cues to evaluate the new state of the system
• Particular problem with impoverished devices

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Impoverished devices

• Small screen
• Little space for feedback
• User will have to remember what state the
  device is in
• Few input points (buttons, etc)
• Each button has many functions, depending on the
  state of the device
• User will have to remember buttons functions in
  this state

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Interface modes

• One way to get around small display problem use
  modes
• phone call mode
• speaking mode
• address book mode
• text message mode
• In each mode, the buttons/display take on a new
  meaning
• Blue line button in phone call mode answers
  a ring, in speaking mode hangs up, in address
  book mode selects the menu option
• Requires fewer buttons

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Modes cognitive analysis

• Effectively require a mental model for each mode
  of the interface
• Each mode, the input/display has different
  meaning
• Can have difficulty selecting the mental model to
  use
• Wrong model means errors
• Confusion about interface behaviour
• Problems can be reduced
• Few modes
• Clearly indicate which modes are present

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Problems in changing modes

• The most common modes tend to dominate
• Well practiced mental models are more easily
  activated
• Can lead to confusion
• Problems can arise from mode confusion
• Thought you were in one mode, note the other
• Can be reduced by clearly indicating modes (eg.
  Colour change)
• Difficult in small, monochrome displays

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Example Showing mode context
Active mode
Actions under this mode
Active mode shown by layout
Sony Ericsson P800
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Navigating modes

• Phones change modes by menus
• Each menu option set s a new mode
• Finding your way around a menu is called
  navigating the menu
• Menu design has a large impact on phone usability
• Bad menu presentation
• Confusing grouping of items

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Bad menus

• Menu encode trees of options
• Based on the grouping of functions and modes
• People experience menus as lists of options

Search Service Nos. Add Entry Erase Edit Assign
Tone Send Entry Options Speed Dials
Phone Book Messages Call Register Settings Cal
l Divert Games Calculator Clock Tones
Inbox Outbox Write Messages Picture
Messages Message Settings Info Service Voice
mailbox no
Nokia 3210 menu
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Bad menus

• Spatial position of the item in the list becomes
  a retrieval cue
• its near the top
• Simple to communicate
• To exploit this, need to show context on the
  display
• Avoid circular lists

Single option no spatial context
Several options spatial context
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Bad menus

• Context is also required to going back
• Correct errors find place later
• Deep menus are easy to get lost in (Nokia limits
  to 2 levels)
• hard to consider it as a list
• difficult to chunk a tree
• Context can be displayed on the screen

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Confusing menus

• Menus group items together
• Based on what?
• Some make sense, some not
• Eg. Nokia 3210 (assign tone in Phone Book, not
  Tones)
• Menu groupings are based on some structure
• If its not shared with your users, problem!
• The grouping can become a mental model if the
  structure makes sense (deep processing)

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Confusing menus

• Menu structure confusion can be overcome
• Memorize how to access functions
• Allow menu customization (not with phones!)
• flatten the tree (can browse more easily)
• Having no sub-menus can help
• Simple mental model (line)
• Browse each time
• Having no sub menus can hinder
• No structure to organize
• Forced to browse each function

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Alternative No menus at all!

• Nokia experimental interface
• No menus simply type what you want
• Uses a T9 text-prediction to reduce the
  keystrokes required
• Uses recall rather than recognition!!
• But not a severe problem
• Number of frequently used functions tiny (phone
  book, SMS, missed calls)
• How to overcome weird technical terms?
• Use multiple phrases for the same function
• Eg. Address book, Numbers, Phone Book, My Numbers
  List, People
• Possibility of adding terms to the dictionary

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Summary Using mental models to make a better
phone

• Provide context on the display
• Reduces mental workload
• Allows people to keep track of where they are in
  the model
• Structure the information the way your users
  understand it
• Support the models they have
• Prevent them from having to replace current
  models
• Keep structures simple
• Lists, shallow trees
• Avoid removing spatial information