Knowledge, Mental Models and HCI

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Knowledge, Mental Models and HCI
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Introduction

• If we want to
• predict learning time
• identify typical errors
• relative ease of performance of tasks
• Then we need ways of discovering
• what users know about the system
• how users reason about the system

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Types of Knowledge Representation
Symbolic

• Analogical Representation
• picture-like representations
• Propositional Representations
• abstract statements that make assertions
• Distributed Representations
• networks of nodes where knowledge is implicit in
  the connections between them

Sub-symbolic
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Schools of Thought

• Imagists vs. Propositionalists
• imagists believe that images play a distinctive
  role in cognitive processes
• propositionalists believe that they are a
  by-product that plays no role, instead
  language-like propositions are key

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Imagists v Propositionalists
Which figure cannot be constructed from the
pattern?
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Connectionists

• It seems likely that people use both images and
  propositions in thinking
• Connectionists argue that the two are
  complementary and can exist together at higher
  levels of representation
• But they are emergent properties of neural
  networks of nodes at a lower (sub-symbolic) level

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Connectionist Networks
Nationality
Sex
Name
Favourite drink
Favourite Football Team
Course
Chelsea
ISYS1154
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Knowledge Organisation

• Knowledge is clearly highly organised
• But as semantic networks?
• nodes are objects (farmers, cows, sheep) and the
  links the relationship between them (farmers own
  cows etc.)
• Or as schemata ?
• repeatable patterns of experience (stereotypical
  scripts)

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Mental Models

• Developed to account for more dynamic aspects of
  cognitive activity
• ...the model people have of themselves, others,
  the environment, and the things with which they
  interact. People form mental models through
  experience, training and instruction

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Structural vs. Functional models

• Structural models are used to describe internal
  mechanics of a device in terms of its components
  (white box)
• Functional models are used to describe how a
  device should be used (black box)

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Key Points

• 3 types of mental representations analogical,
  propositional and distributed
• General knowledge is stored as schemata which,
  when activated, can be used to construct mental
  models
• Mental models enable people to generate
  descriptions and explanations about systems, and
  make predictions
• Structural models describe how systems work,
  functional models how they are used
• Most peoples understanding of systems, devices
  is Functional
• Conceptualizing users knowledge in terms of
  mental models can help designers to develop
  appropriate user interfaces