Download presentation
Presentation is loading. Please wait.
1
SIMS 213: User Interface Design & Development
Marti Hearst Thurs, Feb 12, 2004
2
Based on slide by Saul Greenberg
Mental Models People have mental models of how things work: how does your car start? how does an ATM machine work? how does your computer boot? Allows people to make predictions about how things will work Based on slide by Saul Greenberg
3
Based on slide by Saul Greenberg
Mental Models Mental models built from affordances constraints mappings positive transfer cultural associations/standards instructions interactions Mental models are often wrong! Based on slide by Saul Greenberg
4
Slide adapted from Saul Greenberg
Our mental models of how bicycles work can “simulate” this to know it won’t work Slide adapted from Saul Greenberg
5
People are always trying to make sense of things
Mental models often extracted from fragmentary evidence People find ways to explain things Computer terminal breaks when accessing the library catalog Certain you’re driving on the correct road
6
Norman’s Action Cycle Human action has two primary aspects
Execution: doing something Evaluation: comparison of what happened to what was desired
7
Action Cycle start here Goals Execution Evaluation The World
8
Action Cycle Goals Execution Evaluation The World Intention to act
start here Goals Execution Intention to act Sequence of actions Execution of seq uence of actions Evaluation Evaluation of interpretations Interpreting the perception Perceiving the state of the world The World
9
Norman’s Action Cycle Execution has three stages:
Start with a goal Translate into an intention Translate into a sequence of actions Now execute the actions Evaluation has three stages: Perceive world Interpret what was perceived Compare with respect to original intentions
10
Gulf of Evaluation The amount of effort a person must exert to interpret the physical state of the system how well the expectations and intentions have been met We want a small gulf!
11
Based on slide by Saul Greenberg
Example Scissors affordances: holes for insertion of fingers blades for cutting constraints big hole for several fingers, small hole for thumb mapping between holes and fingers suggested and constrained by appearance positive transfer learnt when young conceptual model implications clear of how the operating parts work Based on slide by Saul Greenberg
12
Based on slide by Saul Greenberg
Bad Example Digital Watch affordances four push buttons, not clear what they do contraints and mapping unknown no visible relation between buttons and the end-result of their actions negative transfer little association with analog watches cultural standards somewhat standardized functionality, but highly variable conceptual model must be taught; not obvious How to design a better one? Based on slide by Saul Greenberg
13
Digital Watch Redesigned for Affordances (Rachna Dhamija)
14
Digital Watch Redesigned for Affordances (Ping Yee)
15
Interface Metaphors Revisited
Definition of Metaphor application of name or descriptive term to an object to which it is not literally applicable Purpose function as natural models leverages our knowledge of familiar, concrete objects/experiences to understand abstract computer and task concepts Problem metaphor may portray inaccurate or naive conceptual model of the system A presentation tool is like a slide projector
16
The Metaphor of Direct Manipulation
Direct Engagement the feeling of working directly on the task Direct Manipulation An interface that behaves as though the interaction was with a real-world object rather than with an abstract system Central ideas visibility of the objects of interest rapid, reversible, incremental actions manipulation by pointing and moving immediate and continuous display of results Almost always based on a metaphor mapped onto some facet of the real world task semantics)
17
Object-Action vs Action-Object
Select object, then do action interface emphasizes 'nouns' (visible objects) rather than 'verbs' (actions) Advantages closer to real world modeless interaction actions always within context of object inappropriate ones can be hidden generic commands the same type of action can be performed on the object eg drag ‘n drop: my.doc move Slide adapted from Saul Greenberg
18
Slide adapted from Saul Greenberg
Direct manipulation Representation directly determines what can manipulated Slide adapted from Saul Greenberg
19
Slide adapted from Saul Greenberg
Games Slide adapted from Saul Greenberg
20
Is direct manipulation the way to go?
Some Disadvantages Ill-suited for abstract operations Spell-checker? Search database by scrolling or by query? Solution: Most systems combine direct manipulation and abstractions Word processor: WYSIWYG document (direct manipulation) buttons, menus, dialog boxes (abstractions, but direct manipulation “in the small”) Slide adapted from Saul Greenberg
21
Based on slide by Saul Greenberg
Guidelines for Design Provide a good conceptual model allows users to predict consequences of actions communicated thorugh the image of the system Make things visible relations between user’s intentions, required actions, and results should be sensible consistent meaningful (non-arbitrary) make use of visible affordances, mappings, and constraints remind person of what can be done and how to do it Based on slide by Saul Greenberg
22
Summary Good Representations Metaphors Direct manipulation
capture essential elements of the event / world deliberately leave out / mute the irrelevant appropriate for the user, their task, and their interpretation Metaphors use our knowledge of the familiar and concrete to represent abstract concepts need not be literal have limitations that must be understood Direct manipulation visibility of the objects of interest rapid, reversible, incremental actions manipulation by pointing and moving immediate and continuous display of results
23
Next Time Raskin on Cognition Modes Cooper & Norman on Errors
Similar presentations
