HCI

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HCI
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What is HCI?

• The role of HCI is to enhance the quality of
  interaction between humans and computer systems
• We are especially concerned with the problems
  encountered by users while interacting with
  multiple channels of communication
• HCI involves input from other disciplines

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Other disciplines which contribute

• Cognitive science
• Cognitive psychology
• Sociology, Philosophy and Anthropology
• Artificial Intelligence
• Ergonomics and Human Factors
• Design
• Computing Science
• Linguistics

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of Multimedia Systems

• User Types and capabilities
• Mental Models
• Memory
• Navigation
• Training
• Ergonomics environment
• Prototyping

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1 User types

• Four main types of user
• Novice
• Casual
• Experienced
• Professional
• The above will be included in one of the
  following
• Discretionary
• Non-Discretionary

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2 Mental Models

• Guide the user on how to structure the
  interaction task
• Are built up through interaction
• Contain structural and functional models
• how it works
• knowing how to use it
• Precise model is built up through experience

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Feedback and observation

• Feedback helps the user to build up or confirm an
  existing model by presenting information about
  itself as it is used
• Public systems are usually placed where users can
  observe before trying it out
• Prime cause of errors is disagreement with user
  model and actual model

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3 Memory

• Short-term working storage
• Transient store of temporary data
• Rapid decay of information
• Half-life of about six seconds
• Limited (but variable) capacity
• Long-term knowledge
• Retrieval of structured data
• Slower than working storage

Dont expect users to remember much for
long Dont expect users to remember things quickly
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Use of Metaphors

• Meaningless information is more difficult to
  remember.
• Concepts are more difficult than objects to
  remember.
• Analogies, metaphors and icons are therefore
  better for to help explain the workings of a
  system.
• Meaning is taken more quickly and is easier to
  maintain in memory.

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4 Navigation

• Problems of spatial disorientation
• Assessing how much information the system
  contains
• Distraction from goal directives
• Complexity in the interface

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Solutions to assist navigation

• Guided Tours
• Useful for learning specific topic
• Provide different tours for specialist interests
• Can leave tour at any point and then return later
• History Lists
• Text and Graphics
• Use graphical miniatures rather than text names
• Keep cache of last few nodes permanently visible

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Solutions to assist navigation

• Book marks
• smaller and more manageable than history lists
• depends on user to specify
• need to be able to remove as well as add
• Backtrack
• not always consistent
• should always be available
• should always be activated in same way

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Solutions to assist navigation

• Overview Diagrams
• Global and local overview
• Meta-navigation using viewports over parts of
  structure
• Different overviews
• Nutrition structured by vitamins, food source,
  disease
• Landmark nodes - Home, Topic menus

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5 Training

• Usability criteria
• how long does it take to learn
• the speed of performance
• what is the rate of errors
• how easy is the recovery
• subjective satisfaction
• how much is remembered
• how much is unused

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6 Ergonomics environment

• Health and safety requirements
• Task requirements
• Visual display
• Keyboard requirements
• Workstation layout and posture
• Lighting
• Room climate
• Noise
• Personal space

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7 Prototyping

• Interactive product design and construction is
  labour and time intensive -
• So you cannot afford many mistakes
• Prototyping as an iterative approach can be
  useful in managing blocks of work
• User centred design approach

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User Feedback Design

• Early or Late?
• Early user feedback gives you time to incorporate
  changes
• Late user feedback is more precise, since the
  product is nearly ready
• Analytic or informal?
• Analysis of user feedback may be necessary
• Informal feedback may be all that is required

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Design rules in use

• The following slides show reported principles
  for user interface design as used in industry
• The information is split into
• Input/Output Dialogue
• Conceptual model General
• Idea generation

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Input/Output

• Minimise input movements
• Maximise input channels
• Be Visually attractive
• Use language carefully
• Maintain screen key consistency
• Use a highly visual interface

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Dialogue

• Use of menus and prompts
• Context-dependent messages
• User control
• Natural response time

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Conceptual model

• Use of analogy, metaphor
• Match user expectations, minimise surprises
• Start with user model, not the developer model
• Make examples concrete
• Novice-expert path

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General

• Easy to use, "user friendly"
• Make it as simple as possible (but no simpler)
• Follow standards wherever applicable
• The key is to understand the users needs and the
  users types of conceptual models