Schneiderman Interaction styles Human error Norman

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SchneidermanInteraction stylesHuman error
(Norman)

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Direct manipulation design principles

• Visually represent the world of action
• Objects of interest shown on screen
• Actions of interest shown on screen
• Rapid execution of actions
• Actions s/b reversible
• Interaction accomplished through
• Pointing
• Selecting
• Dragging

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Direct manipulationWhy does it work?

• According to Schneiderman
• It engages human perceptual recognition
• Human vision is an effective way to learn and
  understand the world

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Visualization Tree maps

• A way to visually explore data
• In this case it is a visual representation of
  3200 files
• Rectangle size reflects the file size
• Works well if your goal is to identify which file
  (or files) are the biggest disk hogs
• Pointing at a rectangle uncovers more information
  about that particular file
• Question What do the colors represent?

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Skipped Chapters 11 12

• Interesting stuff but most of you guys know about
  this stuff
• I will briefly cover Sound Output starting on
  page 247...

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Sound Output

• Kinds of sounds
• Speech
• Music
• Natural
• Synthetic or sampled
• The ears tell the eyes where to look
• Excellent for monitoring the status of some
  process not being directly attended to

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Natural soundsAudio Icons

• Human hearing has evolved to allow the extraction
  of a great deal of information from the nature of
  the sounds heard
• The sounds generated tell us about the properties
  of those things making the sounds
• But then there is the Foley artist recording a
  sound that generated by the real thing isnt
  necessarily sufficient. Example gunshot sounds
  like a cracked whip when recorded...

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Natural soundsExample of use with email

• Scott Hudson paper on doing exactly this
• http//www.acm.org/sigchi/chi96/proceedings/shortp
  ap/Hudson/hs_txt.htm

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Musical sounds

• Earcons
• Distinctive musical sounds that are associated
  with particular operations
• Examples
• http//www.dcs.gla.ac.uk/stephen/earconexperiment
  1/earcon_expts_1.shtml

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Speech

• Speech synthesis technology
• Concatenation (Less flexible vocabulary)
• Uses recorded sounds that are concatenated
• Synthesis by rule (More flexible)
• Rules control the concatenation of phonemes
• Phonemes can be recorded
• Phonemes can be generated by a model of the human
  vocal tract (Show Dude)

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Chapter 13 Interaction styles

• Interaction styles include
• Turn-taking dialogs
• Take the general form
• User specifies instructions
• System executes the instructions
• System provides feedback
• Command line entry
• Manipulation of objects and tools
• Gesturing

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Interaction styles

• Command line entry (nuf said)
• Form filling and spreadsheet (nuf said)
• Menus and navigation (more to come--gt )
• Natural language (more to come--gt )
• Direct manipulation (more to come--gt )

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Menus

• Types
• Pull down, pop up, pie menu
• Take advantage of recognition rather than memory
• Menu organization
• Alphabetical
• Chronological
• Categorical

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Menus (cont)

• Provide a major real-estate savings
• Pull down menus
• Location is permanently set ()
• Location is permanently set (-)
• Pop up menus
• Appear at various places on the screen
• User needs to be given an indication of their
  availability
• Pie menus
• Typically appear around the cursor
• Can obscure some of the screen

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Natural language dialogue

• Spoken vs keyboard entry
• Reduces ambiguity by removing recognition from
  the picture
• Ambiguity is a real problem
• Limits implementation to some subset of natural
  language
• Subsets have been used to build expert systems
  and intelligent tutors

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Direct manipulation

• (lt-- See Schneiderman discussion earlier)
• Novices gain basic functionality quickly
• Users feel in control of the system
• Users experience less anxiety because the system
  is comprehensible and reversible
• Users see the results of their actions and can
  determine if they are furthering their goals

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The gulfs (Norman)

• The gulf of execution
• The distance between the users goals and the
  means of achieving them using the system
• The gulf of evaluation
• The distance between what the system presents as
  feedback and the users expectations of that
  feedback

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Bridging the gulfs

• The user can change
• Adapt to the system (faulty design?)
• The designers can change the system
• To better match the expectations of the user
• Create a means of input that better matches the
  users expectations of how to use the system
• Create displays of system feedback to better
  match the users expectations of that feedback

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The notion of directness expanded Semantic
directness

• Does the interface support what the user wants to
  say in a concise way?
• If the user wants to send a document that
  includes text, pictures, audio and video can he
  do it directly or must he create 4 different
  documents?

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The notion of directness expanded Articulatory
directness

• Similar to the idea of mapping
• Example The turn signal that pushes forward and
  pulls back, when mapped to the idea of pushing
  and pulling on the handlebar, gets a high rating
  in articulatory directness

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Affordances and constraints

• Affordances of an object suggest the range of
  possibilities for use of that object
• Constraints limit the range of possibilities
• Physical constraints shape is an example
• Semantic constraints meaning constrains choice
• Cultural constraints ingrained, well-learned
  meanings, schemata
• Logical constraints only one place left

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DOET 5 Human error

• Mistakes and slips (recap)
• reference the notes from Preece, chapter 8
• Mistakes are the result of conscious deliberation
• Slips result from automatic behavior
• Capture, description, data-driven, associative
  activation, loss-of-activation and mode errors

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More on Slips

• Easy to detect discrepancy between intended
  result and the actual result
• Only if results of the action are visible
• Actions are specified at different levels at
  which level did the error occur?

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How can you handle slips?

• Prevent slips from happening by designing
  appropriately
• For example, if you have modes, reduce the number
  or eliminate them by redesign
• Make things deliberately different
• Detect and correct them when they do
• Confirmation only handles part of the problem,
  with deletion of a file the user is confirming
  the action (delete) not the filename (which is in
  error)
• Provide for recovery
• Trash can does not delete, rather stores for
  deletion

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One small problem

• When you design an error-tolerant system, people
  come to rely on that system! (It had better be
  RELIABLE!)
• Anti-skid brakes
• Blade guard on circular saw

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Human thought

• Is dependent on the underlying memory
• Is not like logic, it is much messier
• Memory
• Not like a photo album, not that neat and orderly
• Filing cabinet models of memory
• Schema, frames, semantic networks, propositional
  encoding,
• Connectionist
• Represented as patterns of activation and
  inhibition
• Much is hidden, inaccessible, beneath the
  surface, with only the end states available for
  conscious inspection

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Task structure

• Descriptions of even simple tasks result in wide
  AND deep structures
• Consider the game of tic-tac-toe
• Shallow
• Many, simple choices, few steps
• Narrow
• Few choices, many steps

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Everyday tasks

• Not frequently studied by psychologists
• Generally routine, requiring little conscious
  thought or planning
• Much of human behavior is subconscious
• Conscious thought
• Is slow and serial
• Is limited by the small capacity of STM
• The nature of explanations
• Easier to predict result AFTER it happens!
• Obvious only happens after the fact

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To increase errors, add a little

• Social pressure
• Time pressure
• Economic pressures

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Designing for error

• Design to minimize error by understanding the
  causes of errors
• Make actions reversible
• Make error discovery easier
• Make error correction easier
• Change the attitude toward error from stupid
  user to stupid design

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Dealing with error

• Warning signals should not occur frequently to
  attract attention (key in ignition buzzer)
• Warning signals dont work when there is the
  possibility that there will be many at the same
  time

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Forcing functions

• Physical constraint
• Three flavors
• Interlocks force a particular sequence
• Lockins prevent premature stops (word editor)
• Lockouts prevents entrance (stairs to basement)

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Resultant design philosophy

• Put knowledge in the world
• Use natural and artificial constraints
• Make stuff VISIBLE!
• Narrow the gulf of execution
• Make options visible
• Narrow the gulf of evaluation
• Make the results of actions visible

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The End!