Principles of Computing and Information Technology Lecture 8

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Principles of Computing and Information
Technology Lecture 8 Human Computer Interaction
(HCI)

• Andy Dawson
• Department of Information Studies, UCL

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What were going to look at today

• What is HCI and why is it important?
• How humans process information
• How this should affect computer interface design
• Identifying different user types
• Designing/choosing appropriate interfaces
• What the future might hold...

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A revealing quote

• The Hitch Hikers Guide to the Galaxy, in a
  moment of reasoned luciditysays of Cirius
  Cybernetics Corporation products that it is very
  easy to be blinded to the essential uselessness
  of them by the sense of achievement you get from
  getting them to work at all. In other words
  their fundamental design flaws are completely
  hidden by their superficial design flaws.
• Douglas Adams, So long and thanks for all the fish

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What is this describing?

• To stay ahead in business you have to invest in
  the latest equipment 2 Gigabyte memory, most
  advanced communications system available, high
  precision handling device, easy maneuverability
  (adjustable in over 2000 ways), highly
  sophisticated listening device, unsurpassed
  visual response mechanism, consumes no fossil
  fuels or electricity.

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One more quote

• Suddenly, computers are everywhere and, just as
  suddenly, everyone is feeling computer
  illiterate. Stop worrying. The computer
  revolution has not passed you by. In fact, quite
  the opposite is the case. The computer revolution
  hasnt caught up to where you are. If you cant
  use todays computers without pain, then just
  wait. It is the computers that will have to
  change, not you.
• Roger Schank, On language, learning and the
  cognitive computer

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So what should that tell us?

• People should be first consideration in systems
• But we have a long way to go!
• Own experience - do things work?
• The way we want them to?
• How much of the time?

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What is HCI?

• Wide-ranging discipline
• Containing elements of
• Psychology
• Physiology
• Computer science
• Ergonomics
• Designing appropriate interfaces to let people
  work with computers

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Aim of HCI

• To produce interfaces which are
• efficient
• easy to use
• do what people want
• Why is that important?
• Self evident!
• Think of your own experiences
• Increasing focus on interface development

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Human Information Processing

• Remember the basic computer process model?Add
  a store
• Also a model of how humans process information

I
P
O
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How do humans differ from machines (revisited)?

• Key differences
• Perception
• Cognition
• Motivation
• Personality

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Perception (INPUT)

• Three physical stages
• receive external stimulus
• translate to nerve impulse
• attach meaning (processing?)
• Vision predominant in computer interaction
• Sound also relevant
• Touch, smell, taste - irrelevant?

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Vision

• The nature of vision
• Physical characteristics
• Colour, intensity, contrast
• Visual pre-processing
• Perception vs physical qualities
• Image enhancement/adjustment
• Image interpretation
• Attaching meaning to what we see
• Open to misinterpretation?

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What do you see (1)?
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What do you see (2)?
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Visual acuity and sensitivity

• Ability to resolve complex shapes
• Letters, words
• Influenced by
• Complexity of image
• Intensity of light
• Colour sensitivity (or lack of it)
• Flicker
• Limitations of human vision compensated for by
  flexibility of cognitive apparatus

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Reading

• Particular application of vision
• How do we read?
• Character
• Word
• Syntax
• Semantics
• Context

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Legibility

• Size/shape of type
• Upper/Lower case, ascenders/descenders
• Length of line
• Line spacing
• Reading from screens
• Contrast (ve/-ve)
• Scrolling

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Hearing/Sound

• Importance vs vision
• Natural medium of human communication
• Similar perceptual procedure to vision
• Stimulus -gt impulse -gt meaning
• Auditory pre-processing/filtering
• Interpretation

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Language

• Speech processing
• Grammar Syntax
• Semantics Pragmatics (context)
• Impact of experience on interpretation
• Problems of computers in processing speech
• for input
• for output
• in dialogues

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Now for some audience participation

• Divide into pairs, by rows Front person faces
  the front, rear person faces the back.
• Something will appear on the screen
• The person at the front has 5 minutes to describe
  it to the person at the back, who has to draw
  it.
• Person at the front cannot look back!
• Person at the back cannot communicate in any way!
  NO Talking, giggling, crying or cheating!?
• AND NO TURNING ROUND UNTIL I SAY SO!

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Storage (Memory)

• Different types of memory
• Sensory
• Short-term
• Long-term
• Sensory memory
• Literal, easily disrupted, very brief
• Iconic (visual)
• Echoic (auditory)

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Memorise this series of numbers

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Did you get it?
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Short-term memory

• Few items (7 /- 2)
• More stable, but still disruptable
• Not purely literal
• Chunking
• Value of order and predictability
• Moral - dont overload!

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Long-term memory

• Infinite capacity?
• Requires understanding
• Not literal
• Access paths
• Reasoning, relationships, rules

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Can I have a volunteer from the audience please?

• OK, answer this simple question as quickly as you
  can.
• Whats happening here?

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How long-term memory works...

• Deconstruction/reconstruction
• Memory fails if access paths decay
• lack of use
• poor original construction
• Distraction during memorisation can cause
  recall errors
• Memory a critical limiting factor in HIP
• Affects interface design in many ways

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Memory test
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A good interface design should

• MINIMISE to reduce loading
• CUEto aid and prompt recall
• STRUCTUREto promote learning
• REPEATto reinforce models

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Output

• To complete our model
• action, e.g. spectrum from
• human computer perform task efficiently
• to
• Human throws computer out of window, followed by
  self
• Hopefully the former?

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Dont forget the ergonomics

• Impact of physical environment on human
  performance
• Particular problem in libraries?
• Old buildings
• Inappropriate equipment
• No cash
• Significant part of technostress caused by
  environment

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Ergonomic criteria
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Ergonomic factors

• Resolution
• Distance
• Angle/reflection
• Movement
• Proportion of occupied screen
• Layout (eye movement)

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Interface problems are nothing new.
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Analysing user characteristics

• HIP v. useful in identifying general terms
• BUT needs and abilities of individuals vary
• Must identify user and design accordingly
• What job to be done
• What sort of user
• Part of role of systems analysis

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Analysing user characteristics

• In terms of
• Knowledge of computers
• General levels of ability
• Other skills/domain knowledge
• To establish
• Type of interface
• Level of documentation
• Type of support/training required
• Nature of existing user model

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Categories of user

• Naive
• Novice
• Skilled
• Expert
• Learning characteristics polarised
• Categories are not static!

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Naive/Novice

• Little knowledge much ignorance
• Knowledge available in limited contexts
• Activity demands mental effort
• Low-level goals, narrow view

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Skilled/Expert

• Much knowledge, well organised
• Knowledge rapidly accessible, abstraction
• Activity becomes automatic
• Long-term goals

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Learning characteristics

• Dependent on
• Frequency of use
• Degree of commitment
• Experience
• Physical skills
• Ergonomics

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Aides to learning

• Training wheel systems
• Guided exploration
• Support the user model
• Appropriate documentation

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Interface must balance

• Ease of use
• Ease of learning
• Speed of operation
• Control
• Ease of development
• SIMPLICITY vs
• FUNCTIONALITY

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Interface design

• Dialogue control
• types
• design features
• Presentation design

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Dialogue types

• Question answer
• Menus
• Form filling
• Command languages
• Iconics
• Natural language

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Dialogue design

• Feedback
• Messages, Status
• Escape options
• Termination, Undo actions
• Minimal work approach
• Steps/Actions, Keystrokes
• Defaults
• Predictive, Security
• Help provision, consistency of format

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Presentation design

• Highlighting
• movement
• colour
• brightness
• shape
• size
• Form of messages

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Text display/Menus

• Navigation
• Classification/grouping
• Selection order
• Functional titling
• Escape routes
• Keys

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Current and future developments

• The dominance of the Windows GUI
• Webpages with everything
• Generations of interface
• CLI
• Menu-driven systems
• GUI
• The next generation?

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Thats it for today...

• Any Questions?

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This weeks practicals

• Evaluating search interfaces