Knowledge and Mental Models

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Knowledge and Mental Models
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Knowledge is represented in memory

• Analogical picture-like images
• Propositional abstract and language-like
  statements that make assertion.
• Distributed are networks of nodes of knowledge.
• schema

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What is a mental model?

• is most commonly used to refer to a
  representation (in the head) of a physical system
  or software being run on a computer, with some
  plausible cascade of causal associations
  connecting the input to the output.John
  Carroll and Judith Olson

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How do you learn a new piece of software?
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How do you learn a new piece of software?

• install it and use it
• read all the manuals first
• go through a tutorial
• trial and error and HELP
• take a course or workshop in it
• one on one training

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Mental Models

• During the learning process, users build mental
  models of how the system behaves.
• May not be correct or may not be the designers
  model.
• Mental models do guide the users experience with
  the software.

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Pre Heat Oven to 350 degrees

• Does it get hotter sooner if you turn the oven up
  to 450 ?
• What is the mental model?

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Why are mental models important to HCI?

• It may be possible to predict
• learning time
• likely errors
• relative ease with which users can perform their
  tasks.

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Styles of Mental Models

• Metaphors are considered a type of mental model
• used to explain the way a program works.
• Networks
• users knowledge of the system in terms of the
  states in which a program might be and actions
  that change the current state to another state.

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Principles of user-interface design which allow
users to build better mental models

• Consistency
• internal consistency - behavior of the software
• external consistency-extent to which the software
  behavior matches other things the user already
  knows from other contexts.
• Providing the user with appropriate metaphors is
  one way to increase external consistency.

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Completeness

• must gain experience with system to add to the
  completeness of mental model
• switching from one system to complete a task,
  complicates mental models.
• stay within one window for a task when possible.

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Layering of functionality

• provide access to functionality in a layered
  fashion.
• second level of menus
• deactivating the more complex functions during
  the learning phase.
• disable functions

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Useful feedback

• explanatory error feedback
• help messages

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Metaphors

• convey an abstract concept in a more familiar and
  accessible form.
• desktops
• more examples
• visual metaphors (icons)

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More examples of metaphors.

• icons
• menus
• windows
• cutting
• pasting
• copying

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Conceptual models

• the way users conceptualize and understand the
  system
• the way designers conceptualize and view the
  system

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Metaphor problems

• metaphors are hard to find
• printer (easy)
• buying a ticket (hard)
• setting a format
• they constrict our thinking
• tie our interfaces to mechanical age artifacts
• calendar -- Allan Cooper