HCI121 III Understanding Users

• Core cognitive aspects

  • Attention

  • Perception and recognition

  • Memory

  • Reading, speaking and listening

  • Problem-solving, planning, reasoning and decision-making, learning

  • Here we focus on attention, perception & recognition, & memory
• ATTENTION

  • Selecting things to concentrate on from the mass around us, at a point in time.

  • Focused and divided attention enables us to be selective in terms of the mass of competing stimuli but limits our ability to keep track of all events.

  • Information at the interface should be structured to capture users’ attention, e.g. use perceptual boundaries (windows), color, reverse video, sound and flashing lights.
• DESIGN IMPLICATIONS FOR ATTENTION

  • Make information salient when it needs attending to

  • Use techniques that make things stand out like color,

  ordering, spacing, underlining, sequencing and animation. • Avoid cluttering the interface - follow the google.com

  example of crisp, simple design.

  • Avoid using too much because the software allows it.

  o An example of overuse of graphics
• PERCEPTION AND RECOGNITION

  • How information is acquired from the world and transformed into experiences

  • Obvious implication is to design representations that are readily perceivable, e.g.

  o Text should be legible.

  o Icons should be easy to distinguish and read.
• MEMORY

  • Involves encoding and recalling knowledge and acting appropriately.
  • We don’t remember everything - involves filtering and processing.
  • Context is important in affecting our memory.
  • We recognize things much better than being able to recallthings.

  o The rise of the GUI over command-based interfaces

  o The use of icons rather than names

  o Better at remembering images than words.
• FILE MANAGEMENT

  • Facilitate existing memory strategies and try to assist users when they get stuck.

  • Help users encode files in richer ways.

  o Provide them with ways of saving files using color,

  flagging, image, flexible text, time stamping, etc.
• Mental models


  Users' understanding of a system through learning & using it
• Mental models


  • How to use the system (what to do next)
  • What to do with unfamiliar systems or unexpected situations (how the system works)
  • People make inferences using mental models of how to carry out tasks
• Craik (1943)


  Described mental models as internal constructions of some aspect of the external world enabling predictions to be made
• Mental models


  • Involve unconscious and conscious processes, where images and analogies are activated
• Deep versus shallow models


  e.g. how to drive a car and how it works
• THE DESIGN PRINCIPLE OF TRANSPARENCY

  • NOT to be understood as literal

  • Useful feedback

  • Easy to understand.

  • Intuitive to use.

  • Clear & easy to follow instructions.

  • Appropriate online help

  • Context sensitive guidance of how to proceed when stuck.
• WHY DO WE NEED TO UNDERSTAND USERS?

  • Interacting with technology is cognitive.

  • We need to take into account cognitive processes involved

  and cognitive limitations of users.

  • We can provide knowledge about what users can and

  cannot be expected to do.

  • Identify and explain the nature and causes of problems

  users encounter.

  • Supply theories, modelling tools, guidance and methods

  that can lead to the design of better interactive products.