April 19, 2004
“Design of User-Friendly Systems”
DLC, 2004
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Design of UserFriendly Systems
Joel Clawson
Genevieve Hudak
Brock LaMeres
Kitty Turner
April 19, 2004
“Design of User-Friendly Systems”
DLC, 2004
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Introduction
•Topic:
–Design
•Objective:
–To understand good and bad design practices aspertained to the psychology of users
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Agenda
•The dysfunction of everyday things
•The psychology of everyday actions
•Knowledge in the head and in the world
•Knowing what to do
•To err is human
•User-centered design
•Overview of Things That Make Us Smart
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Characteristics of Objects
•Easy to understand
•Easy to interpret
•Contain visible cluesto operation
•Difficult to Use
•Frustrating
•No clues/False clues
•Get in the way ofnormal thoughtprocesses on operation
Well Designed
Poorly Designed
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Frustrations of Everyday Life
•Poor Visibility
•Lack of Natural Signals
•Poor Mappings
•Poor Instructions
•Poor Relations between old, knownfunctions and similarly named new ones
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Psychology of Everyday Things
•Affordances
–Plates → Pushing
–Knobs → Turning
–Slots → Inserting
•False Causality
•Conceptual Models
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Principles of Design for Understanding and Usability
•Provide a good Conceptual Model
•Make things Visible
–Provide good mappings
–Provide natural relationships
–Don’t overload a control
•Provide Feedback
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The Psychology of Everyday Actions
“Humans will try to figure it out”A user sits down at an interface with a goal. The user…1) Observes what functionality is available.2) Forms a conceptual model of how the system works.3) Takes an action to achieve the goal.4) Observes the outcome of the action, was it right or wrong? 5) Either Reinforces or Discredits his conceptual model.6) Continues until the goal is accomplished.
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The Psychology of Everyday Actions
This is good if ???- The interface understands how the user approaches the system.- Allows the user to explore the system risk free.- Provides only necessary functionality at the top level.- Handles Errors.
This is bad if ???- Inappropriate actions result in no or incorrect feedback.- There is no forgiveness for mistakes.- The model of the system varies from the conceptual model of the user.
April 19, 2004
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DLC, 2004
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The Psychology of Everyday Actions
A good system understands how users get lost….- Can the user build a conceptual model of the system from the interface? (false models, misconceptions)- Does the feedback of actions discredit the model? (Falsely Blaming yourself, Blaming the wrong cause)- Does the system reinforce misconceptions? (Learned Helplessness, Taught Helplessness)
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“Design of User-Friendly Systems”
DLC, 2004
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The Psychology of Everyday Actions
A good example:Delete Confirmation - Confirmation that an action was taken. - A correlation of the action and observation. - A way out of a dangerous situation.
A bad example:MS Word Auto Format - no relationship between action and outcome. - no consistency between the outcomes. - not always possible to reverse action and get back to where we started.
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The Psychology of Everyday Actions
-Design Aids to Compliment the User’s Thought Process…
1) VisibilityThe user will see what is available and act accordingly.2) A Good Conceptual Model The user will form a simple model, does the system allow models to be formed?3) Good MappingIs there a correlation between the action and the outcome?4) Feedback
Users reinforce/discredit their model according to the reaction they get from anaction. If there is no action, the user is lost.
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DLC, 2004
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Knowledge in the Head and In the World
“Digital Media Offers Overwhelming Information”
1)There is too much information for the user to remember.
2)Designers must Decide which information will bememorized and which will be stored in the system.
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Knowledge in the Head and In the World
What are the Tradeoff ???
Knowledge in the WorldKnowledge in the Head
Retrievability:Available when visible/audibleRequires Memory Search
Learning:Not RequiredRequired
Efficiency:SlowFast once Retrieved
First Encounter:EasyDifficult
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Knowledge in the Head and In the World
What do we do ???
- Exploit the Nature of Human Thought - Humans want to form a “conceptual model” of all things.
- Information without a model is difficult to remember.
- Try to communicate Concepts instead of Raw Information
Ex)1) Where do you find the information vs. What is the information?
2) How Features Alter the System vs. What Specifically do the features do?
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Knowledge in the Head and In the World
Mappings Can Help “Knowledge in the World”
“Stove Control Example”No Mapping Natural Mapping
This exploits the human need for a conceptual model through “mappings”
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Knowledge in the Head and In the World
Understanding Memory Can Help “Knowledge in the Head”
1) Memory for Arbitrary Things
(difficult, standardization helps)2) Memory for Meaningful Relationships(efficient)
3) Memory through Explanation
(conceptual models)
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Physical and Logical constraints
Physically constrain possible operations
•Rely upon properties of the physical world
•Examples:
–Large peg cannot fit into small hole
–Keys can have only one of two orientations when inserted into avertical slot
Logical constraints take advantage of natural mappings andrelationships
•Location and operation should follow these naturalmappings:
–Two switches to controls two lights: left switch should control leftlight and right switch should control right light
–Last piece of a jigsaw puzzle, naturally constrained to go in theempty hole
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Cultural and Semantic constraints
Cultural constraints: Knowing how to act incultural situations such as at a restaurant
•Culturally acceptable behavior frames
–Notice these when they are violated, such as standing inan elevator facing the rear
–Differ from culture to culture
Semantic constraints rely on
–the meaning of the situation
–the user’s knowledge of the situation and the world
•Example:
–How to sit in a chair with arms, sit with legs over openedge
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Visibility and Feedback
Visibility: “Making relevant parts [or the correct action] visible”– easiersaid than done
•Doors
–Unclear design of many doors as to which side of the door opens
•Switches
–Many switches controlling different things
–Natural mapping of switches often not exploited; which direction of theswitch is on/off
Feedback: “Give each action an immediate and obvious effect.”
•Use sound to make things visible
–Whistle of tea kettle when water boils
–Click when toast pops up
–Change in pitch when vacuum is clogged
•Having a good display – visual feedback
–Lets the user know what effect their actions have
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Capture and Data-Driven Errors
Capture error: When “a frequently done activity suddenlytakes charge instead of (captures) the one intended.”
•Occurs when two different action sequences have initialstages in common, where one is well practiced and theother unfamiliar
Examples:
•Going to change your clothes for dinner and findingyourself in bed
•Get in your car on Sunday to go to the store and end upgoing to work instead
Data-driven error: Occurs when sensory data interferes withthe current action sequence.
•Automatic actions are data-driven.
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Description and Mode Errors
Description error: When the intended action has a lot incommon with other actions that are possible.
•Comes from imprecise internal descriptions.
•Occurs when the wrong and right objects are physically neareach other.
Example:
•Flipping the wrong switch in a long row of switches
Mode error: When controls must perform more than oneaction, depending on the mode
•Errors occur when the mode is not made visible
•Especially prevalent on computer systems and digitalwatches
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Associative activation and Loss-of-activation Errors
Associative activation error: When internal thoughtsand associations trigger actions.
Examples:
•Thinking something you shouldn’t say and thensaying it.
•Answering your telephone ‘come in’
Loss-of-activation error: Plainly, forgetting.
•Can happen in the middle of doing something,such as walking into a room and forgetting whyyou went there.
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To Err is Human
Types of errors
Visibility of Errors
Conceptual models that lead to error
Structure of tasks:
•Wide and deep
•Shallow
•Narrow
Explaining away errors
Social Pressures
Forcing Functions
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More Info
Flanders, Vincent. “Web Pages that Suck”.http://www.webpagesthatsuck.com/dailysucker/
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User-Centered Design
•Good design
•The user says “Yes, I see” or “Of course”.A simple explanation is sufficient.
•Bad design
•The user says “How am I going toremember that?” after the explanation.
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7 principles of good designOR7 principles for transforming difficult tasks into simple ones
1. Use both knowledge in the world and knowledge in thehead.
2.Simplify the structure of the tasks.
3. Make things visible: bridge the gulfs of Execution andEvaluation.
4. Get the mappings right.
5. Exploit the power of constraints, both natural andartificial.
6. Design for error.
7. When all else fails, standardize.
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Use knowledge in the world and knowledge in the head
•Users are more comfortable and learn better when theknowledge they need to perform a task is readily available inthe world or through constraints.
•Users perform faster and more efficiently when they cansynthesize the knowledge needed for their task.
•So it should be easy to go back and forth – to combineknowledge in the head with knowledge in the world.
•The designer must develop a conceptual model for the userthat captures the important parts of the device and that isunderstandable by the user.
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Simplify the structures of tasks
•The amount of planning and problem solving for a taskshould be minimized.
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Make things visible
•On the execution side of an action:
•So that users know what actions are possible and how theactions can be done.
•On the evaluation side of an action:
•So that users know what the results of the actions are andthe current state of the system.
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Get the mappings right
•Make sure the user can understand the relationshipbetween intentions and possible actions,
•actions and their effects on the system,
•the actual system state and what is reflected in theinterface,
•and the perceived system state and the needs, intentionsand expectations of the users.
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DLC, 2004
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Exploit the power of constraints, both natural and artificial
•Use natural and artificial constraints to make users feel thatthere is only one possible action.
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Design for error
•Assume that any error is possible and plan for it.
•Allow users to recognize errors and recover from them.
•Make it easy to reverse operations and hard to doirreversible actions.
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When all else fails, standardize
•When the above principles cannot be put into place,standardize the actions, layout, display, and results.
•With standardization, users only have to learn it once butthey must be trained to the new standard.
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Knowing what to do
Constraints
Physical and Logical:
Cultural and Semantic:
Good:http://www.denver.org/index.asp
Bad: http://www.aiwa.com/flash.html
Visibility and Feedback
Visibility:
Bad: http://www.chapcap.com/main.htm
Feedback:
Good: http://www.newgrounds.com/
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Human Centered Technology
•Aimed at aiding cognition
–Often interferes and confuses
–Should be aimed at the needs of people
•Two Kinds of Cognition
–Experiential
–Reflective
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Kinds of Learning
•Accretion
–Accumulation of Facts
•Tuning
–Practice to make reflective tasks becomeexperiential
•Restructuring
–Acquiring new concepts
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Representation
•Cognitive Artifacts
–What make us smart
–Provide abstract representations
–Represent the important ideas
•Match the Artifact to the Task
•Naturalness Principle:
–Experiential cognition is aided when theproperties of the representation match theproperties of the object/idea being represented
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Fitting the Artifact to the Person
•People are better at Perception thanAbstraction and Symbolism
•Appropriateness Principle:
–The representation used by the artifact shouldprovide exactly the information acceptable tothe task: neither more nor less.
•People seek understandings, causes,purpose
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The Human Mind
•Machines use different principles thanpeople
–They complement each other
–Details vs. Representation
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Distributed Cognition
•Distributed Intelligence
–Knowledge is in the world
•Impossible means Impossible
–Properties of the world
•Accuracy is not always important
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Organizing Knowledge
•Hierarchical
•Spatial
•Temporal
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Conclusion
•User-centered design
–About the USER
–Thinking
–Interaction with world
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Questions ?