CS789, Spring 2005, Lecture notes, Week 9

CS789, Spring 2005

Lecture notes, Week 9

UI Metaphors

Why do they exist?

How do they function?

Fundamental to user experience

Icons and Direct Manipulation

Separate dialogue styles exist along a continuum: linguistic-->graphical, menus and forms in the middle. Linguistic is based on words, talking:

Graphical is based on symbols, looking: E.g. contrast "rm myfile", with moving myfile icon to the trash, with selecting icon and choosing "delete" from a menu. This is a contrast between
  1. commands with names as objects
  2. commands with icons as objects
  3. icons as commands and as objects.

General organization of graphical dialogue styles:

In the end these interaction techniques show


What is an icon?

  1. graphical name
  2. names an object known to the interface
  3. its internal structure is not directly accessible, but is often indirectly accessible through a form
  4. identity, location
  5. subject to a limited set of operations

Why use icons instead of words?

  1. help the user to remember: icons can even be animated. This points out the interesting double existence of icons.
  2. visual distinctiveness: a richer set of perceptions related to finding, arranging, grouping.

What factors make icons visually distinctive? Distinctiveness is a property of a set of icons!

  1. colour
  2. some aspects of shape: angles, lines, curves
  3. usually not conjunction or disjunction
  4. your eye will make a good decision
  5. you can always do simple tests

    but it's likely that you care about peripheral distinctions, not foveal ones.


How are selection actions carried out by the user?

  1. single
  2. multiple: indicate space containing several icons
  3. expand or contract It's interesting to note that discontinuous selection, which seems to be a hard interface to produce for linear structures, is a fact of life for unstructured collections. Why?
  4. differentiated selection

Why do users change the placement of icons?

How do users change the placement of icons? Two methods for supporting grouping of icons


How do we indicate commands to be carried out?

There are some unexploited possibilities in current interfaces

Direct Manipulation

Differentiate interface operations (with pointer) from the actions they entail (create). Typical operations

  1. position: where or what
  2. click: trigger
  3. down-drag-up: what-what; what-where; where-where
Note that there aren't very many of them. How do we make more?
  1. multiple triggers with differentiated meanings: multiple buttons or keyboard modifiers
  2. chorded clicking: only order matters
  3. rhythmic clicking: real-time interface
These parse into what and where, from which actions must be selected. Typical actions associated with click-and-drag
  1. Operate, works fine as long as there is a single obvious operation that you want to do
  2. Create, applies to anything: need to know what to create, and where to create it
  3. Other operations
  4. Joining

Graphical Interaction

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