Term
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Definition
people who really disagree
with group – can enhance
group creativity |
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Term
| When dissent is not real... |
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Definition
A deliberate “devil’s advocate” in the
group can actually stifle dissent, because the majority know
the opinion is manufactured |
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Term
| Dissent is not encouraged |
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Definition
Polite or pro-forma
acceptance is not enough |
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Term
| IDEO's brainstorming rules |
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Definition
1. Sharpen the Focus
2. Playful Rules
3. Number your Ideas
4. Build and Jump
5. The Space Remembers
6. Stretch Your Mental Muscles
7. Get Physical |
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Term
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Definition
| Show a project in progress through sketches and prototypes. Solicit feedback from peers (small groups work best) |
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Term
| What is the point of a critique? |
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Definition
Get honest reactions, ask for
input on open questions. |
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Term
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Definition
Understand users’ tasks
Designers must think about …
Who are the users?
What tasks they would want to carry out?
Observe existing practices
Create scenarios of actual use |
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Term
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Definition
1. Who is going to use system?
2. What tasks do they now perform?
3. What tasks are desired?
4. How are the tasks learned?
5. Where are the tasks performed?
6. What’s the relationship between user & data?
7. What other tools does the user have?
8. How do users communicate with each other?
9. How often are the tasks performed?
10. What are the time constraints on the tasks?
11. What happens when things go wrong? |
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Term
| Task Analysis Question: Who is going to use it? |
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Definition
Identity: Need several typical users for broad product
Background/Skills: Knowledge users already have and rely on to perform task
Values, Likes/Dislikes
Personal characteristics:
-Education
-Literacy
-Physical traits, abilities/disabilities
-Age |
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Term
| Task Analysis Question: Old and New Tasks |
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Definition
Old : The way people do things now
New : The way you anticipate them doing things in future
Observe!: Pick the most important tasks |
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Term
| Task Analysis Question: How are the tasks learned? |
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Definition
What does the user need to know?
Do they need training?: Book/manual information
General knowledge / skills
Special instruction / training
Experience, level of education and literacy : 8th grade is often reasonable in broad design contexts |
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Term
| Task Analysis Question: Where is the Task Performed? |
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Definition
Office, laboratory, point of sale, home?
Effects of environment on users?:Lighting, sound, comfort, interruptions, water
Social influence of environment: Rituals, sacred places
Effects of other people (bystanders)?: Rushing, safety, privacy |
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Term
| Task Analysis Question: What’s the relationship between user & data? |
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Definition
Personal data
Privacy:
-Always accessed at same machine?
-Do users move between machines?
Common data
Handling and processing:
-Used concurrently?
-Passed sequentially between users?
Remote access required?
Access to data restricted? |
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Term
Task Analysis Question:
Tools? |
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Definition
Users work with collection of tools: -Cell phone
-Home PC
-Printed schedules
-Maps
Can we use other tools to facilitate interaction? |
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Term
| Task Analysis Question: how do users communicate? |
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Definition
Who communicates with whom?
About what?
Follow lines of the organization? Against it?:
-Example: assistant to manager
-Installation of computers changes communication
between them
-People would rather change their computer usage
than their relationship
Not so relevant in context of BART |
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Term
| Task Analysis Question: how often are tasks performed? |
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Definition
Frequent users remember more details
Infrequent users may need more help: But don’t make it tedious
Which function is performed:
-Most frequently? By which customers?
-Optimize system for these tasks will improve perception of
good performance |
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Term
| Task Analysis Question: Time Constraints |
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Definition
What functions will customers be in a hurry for?
Which can wait?
Is there a timing relationship between tasks |
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Term
| Task Analysis Question: When things go wrong |
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Definition
How do people deal with
Errors?
Practical difficulties?
Catastrophes?
Is there a backup strategy? |
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Term
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Definition
1. Write up a description of
the tasks
2. Produce scenarios
covering each task
3. Rough out an interface
design |
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Term
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Definition
Allows user to teach us what they do
– Skill knowledge is usually tacit (can’t put it in books)
– Sometimes literal apprenticeship is best |
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Term
| Principles of Contextual Inquir |
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Definition
1. Context
2. Partnership
3. Interpretation
4. Focus |
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Term
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Definition
A precise description of user in terms of:
Capabilities, inclinations, background
Goals (not tasks) |
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Term
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Definition
the term affordance refers to
the perceived and actual properties of
the thing, primarily those fundamental
properties that determine just how
the thing could possibly be used |
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Term
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Definition
| Design model----System Image====User's model |
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Term
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Definition
1. Make controls visible
2. Make sure mapping is clear
3. Provide Feedback |
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Term
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Definition
the gulf of evaluation is the degree to which the system/artifact provides representations that can be directly perceived and interpreted in terms of the expectations and intentions of the user
the gulf of evaluation is the difficulty of assessing the state of the system and how well the artifact supports the discovery and interpretation of that state
1. Perceiving the state of the world
2. Interpreting the perception
3. Evaluation of interpretations |
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Term
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Definition
Gulf of execution is a term usually used in human computer interaction to describe the gap between a user's goal for action and the means to execute that goal
1. Intention to act
2. Sequence of actions
3. Execution of actions |
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Term
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Definition
Visibility of system status
Match between system and the real world
User control and freedom
Consistency and standards
Error prevention
Recognition rather than recall
Flexibility and efficiency of use
Aesthetic and minimalist design
Help users recognize, diagnose, and recover from errors
Help and documentation |
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Term
|
Definition
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Term
|
Definition
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 |
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Term
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Definition
Purpose: Leverages knowledge of familiar, concrete objects/experiences
Transfer this knowledge to abstract tasks and concepts
Problem: Inaccurate or naive conceptual model of the system |
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Term
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Definition
Too limited: The metaphor restricts interface possibilities
Too powerful: The metaphor implies the system can do things it can’t
Too literal or cute: Makes it difficult to understand abstract concept
Mismatched: The metaphor conveys the wrong meaning |
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Term
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Definition
Capture essential elements of the event / world
Deliberately leave out / mute the irrelevant
Appropriate for user, task, and interpretatio |
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Term
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Definition
An idea/object/event about which
you are intently and actively thinking
The one entity on which you are currently concentrating
You see and hear much more
E.g., background noise |
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Term
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Definition
The same user actions have different
effects in different situations. |
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Term
| Phases of Heuristic Eval: |
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Definition
1. Pre-evaluation training
2. Evaluation
3. Severity Rating
4. Debriefing (discussion): Discuss outcome with design team, Suggest potential solutions, Assess how hard things are to fix |
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Term
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Definition
0 - don’t agree that this is a usability problem
1 - cosmetic problem
2 - minor usability problem
3 - major usability problem; important to fix
4 - usability catastrophe; imperative to fix |
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Term
Human Info. Processor
Processors: |
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Definition
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Term
Human Info. Processor
Memory: |
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Definition
Working memory
Long-term memory |
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Term
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Definition
Probably inaccurate
Predicts perf. well
Very influential |
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Term
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Definition
Physical store from our senses: sight, sound, touch, …
Selective
Capacity of visual store
Decay time for working memory: 200ms
Recoded for transfer to working memory |
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Term
Interference
Stroop Effect: |
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Definition
when the color spelled out by a word is incongruent
with the color used to show that word, naming the
word color is slower and more error prone.
Explanation: relationship between meaning and
physical form of stimulus are in conflict. |
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Term
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Definition
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Term
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Definition
| Info reproduced from memory |
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Term
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Definition
Presentation of info helps retrieve info (helps remember it
was seen before)
Easier because of cues to retrieval |
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Term
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Definition
describes the time it takes for a person to make a decision as a result of the possible choices he or she has. Given n equally probable choices, the average reaction time T required to choose among them is approximately b*log(base2)(n+1)
where b is a constant |
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Term
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Definition
Task time on the nth trial follows a power law Tn = T1*n^(-a) + c
where a = .4, c = limiting constant
You get faster the more times you do something! |
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Term
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Definition
T = a + b*log(base2) (D/S +1)
a:%start/stop%Fme%
b:%speed
a, b = constants (empirically derived)
D = distance
S = size |
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Term
| 3-State Model of Input (Buxton |
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Definition
State 0: out of range, the device is not in its physical tracking range
State 1: Tracking. Device moving the cursor
State2: Dragging |
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Term
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Definition
1. We know more than we
can tell
2. Actions in the world
outperform mental
operations
3. The value of surprise |
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Term
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Definition
purpose->understand existing experience
purpose->"inquiring actions"
purpose->communicate
"inquiring actions"->explore
"inquiring actions"->experiment
"inquiring actions"->validate
communicate->anchor discussion
communicate->persuade |
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Term
| 3 stages of prototyping (IDEO) |
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Definition
| Inspire, evolve, validate |
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Term
| What do Prototypes Prototype? |
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Definition
| Role, implementation, feel |
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Term
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Definition
| Info reproduced from memory |
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Term
|
Definition
Presentation of info helps retrieve info (helps remember it
was seen before)
Easier because of cues to retrieval |
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Term
|
Definition
describes the time it takes for a person to make a decision as a result of the possible choices he or she has. Given n equally probable choices, the average reaction time T required to choose among them is approximately b*log(base2)(n+1)
where b is a constant |
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Term
|
Definition
Task time on the nth trial follows a power law Tn = T1*n^(-a) + c
where a = .4, c = limiting constant
You get faster the more times you do something! |
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Term
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Definition
T = a + b*log(base2) (D/S +1)
a, b = constants (empirically derived)
D = distance
S = size |
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Term
| Paper Prototype contstructing steps |
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Definition
Set a deadline
Draw a window frame on large paper
Put different screen regions on cards
Ready response for any user action
Use photocopier to make many versions |
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Term
| Conducting a Test (the roles) |
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Definition
Greeter - Puts users at ease & gets data
Facilitator - only team member who speaks
Gives instructions & encourages thoughts, opinions
Computer - knows application logic & controls it
Always simulates the response, w/o explanation
Observer(s) - Take notes & recommendations |
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Term
| Preparing for a Test (steps) |
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Definition
Select your participants:
-Understand background of intended users
-Use a questionnaire to get the people you need
-Don’t use friends or family
Prepare scenarios that are:
-Typical of the product during actual use
-Make prototype support these (small, yet broad)
Practice running the computer to avoid “bugs”:
-You need every menu and dialog for the tasks
-All widgets the user might press
-Remember “help” and “cancel” buttons |
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Term
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Definition
Rehearse your actions:
-Make a flowchart which is hidden from the user
-Make list of legal words for a speech interface
Stay “in role”:
-You are a computer, and have no common sense, or ability to
understand spoken English |
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Term
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Definition
| Prototypes look like the final product |
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Term
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Definition
Artists renditions with many details missing
Paper Prototypes are low-fidelity. |
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Term
| Creating a Video Prototype |
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Definition
1) Review field data about users & work practices
2) Create use scenario in words
3) Develop storyboard of each action/event with
annotations explaining the scene. Put each element on a
card. This will save you a lot of time later.
4) Shoot a video clip for each storyboard card
Either Live action or UI Screen recording.
Hold last frame of a section/shot for 1s
5) Use titles to separate clips (keep it onscreen for 3s) |
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Term
| Advantages of Low-Fi Prototyping |
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Definition
Takes only a few hours
No expensive equipment needed
Can test multiple alternatives
Fast iterations
Number of iterations is tied to final quality
Can change the design as you test
If users are trying to use the interface in a way you didn’t design it
– go with what they think! Adapt!
Especially useful for hard to implement features:
Speech and handwriting recognition |
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Term
| Drawbacks of Lo-Fi Prototyping |
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Definition
Evolving the prototype requires redrawing
-Can be slow (but reprogramming usually slower)
Lack support for “design memory”
Force manual translation to electronic format
Do not allow real-time end-user interaction |
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Term
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Definition
A thread is a partial
virtual machine.
Each thread has its own
stack (and local variables)
but shares its heap with
other threads in the same
application.
Threads can be
independently scheduled
by the OS/VM. |
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Term
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Definition
A process is a complete virtual machine
with its own stack and heap.
Threads share memory – processes don’t.
Threads can communicate through shared memory,
processes need other mechanisms
(IPC = inter-process communication). |
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Term
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Definition
Useful model of concurrent execution, both on single
processors (time-division multiplexing) and on multi
processor/multi-core systems
Threads are relatively cheap to create, versatile because of
shared memory |
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Term
| Why wouldn’t one use threads? |
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Definition
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Term
| Why use multithreading for UIs? |
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Definition
Interactive programs need to respond quickly to
user input. Direct manipulation assumes that objects
onscreen respond to user’s touch/cursor. |
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Term
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Definition
|
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Term
| Two fundamental UI thread rules |
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Definition
1. Do not block the UI thread
2. Background threads must not modify the UI
Solution: When worker thread completes, request
update back in the UI thread. |
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Term
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Definition
Automated: Usability measures computed by software
Inspection: Based on skills, and experience of evaluators
Formal: Models and formulas to calculate measures
Empirical: Usability assessed by testing with real users |
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Term
| “Discount Usability” Technique |
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Definition
-Heuristic Eval
-Cog walkthrough
- |
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Term
| Empirical Assessment (qualitative) |
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Definition
-Qualitative: What we’ve been doing so far
Contextual Inquiry: try to understand user’s tasks and
conceptual model
-Usability Studies: look for critical incidents in interface |
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Term
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Definition
Qualitative studies:
Faster, less expensive ! esp. useful in early stages of design
cycle
Quantitative studies:
Reliable, repeatable result ! scientific method
Best studies produce generalizable results |
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Term
| Steps in Designing an experiment |
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Definition
1. State a lucid, testable hypothesis
2. Identify variables
(independent, dependent, control, random)
3. Design the experimental protocol
4. Choose user population
5. Apply for human subjects protocol review
6. Run pilot studies
7. Run the experiment
8. Perform statistical analysis
9. Draw conclusions |
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Term
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Definition
| Precise statement of expected outcome |
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Term
| Independent variables (factors) |
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Definition
Attributes we manipulate/vary in each condition
Levels – values for independent variables |
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Term
| Dependent variables (response variables) |
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Definition
Outcome of experiment (measurements)
Usually measure user performance |
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Term
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Definition
Attributes that will be fixed throughout experiment
Confound – attribute that varied and was not accounted for
Problem: Confound rather than IV could have caused change in DVs
Confounds make it difficult/impossible to draw conclusions |
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Term
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Definition
Attributes that are randomly sampled
Increases generalizability |
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Term
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Definition
| categories with labels, no order |
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Term
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Definition
| categories with rank order |
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Term
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Definition
| interval (w/o zero point), ratio (w/ zero point) |
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Term
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Definition
• Task success (binary or multi-level)
• Task completion time
• Errors (slips, mistakes) per task
• Efficiency (cognitive & physical effort)
• Learnability |
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Term
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Definition
| • Self-report on ease of use, frustration, etc. |
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Term
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Definition
Manipulation of IV is cause of change in DV
Requires eliminating confounding variables (turn them into IVs or RVs)
Requires that experiment is replicable |
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Term
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Definition
Results are generalizable to other experimental settings
Ecological validity – results generalizable to real-world settings |
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Term
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Definition
What is the task? (must reflect hypothesis!)
What are all the combinations of conditions?
How often to repeat each combination of conditions?
Between subjects or within subjects
Avoid bias (instructions, ordering, …) |
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Term
|
Definition
Each participant uses one condition
+/- Participants cannot compare conditions
+ Can collect more data for a given condition
- Need more participant |
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Term
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Definition
All participants try all conditions
+ Compare one person across conditions to isolate effects of individual diffs
+ Requires fewer participants
- Fatigue effects
- Bias due to ordering/learning effects |
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Term
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Definition
HE is much faster
1-2 hours each evaluator vs. days-weeks
HE doesn’t require interpreting user’s actions
User testing is far more accurate
Takes into account actual users and tasks
HE may miss problems & find “false positives”
Good to alternate between HE & user-based testing |
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Term
| The Three Belmont Principles |
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Definition
Respect for Persons
(Have a meaningful consent process: give information, and let
prospective subjects freely chose to participate)
Beneficience
(Minimize the risk of harm to subjects, maximize potential benefits)
Justice
(Use fair procedures to select subjects ) |
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Term
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Definition
Central tendency
(mean,median,mode)
(Dispersion)
(Range (max-min))
(Standard deviation )
Shape of distribution
(Skew, Kurtosis) |
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Term
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Definition
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