Exam 2 Flashcards
What does an HTA involve?
breaking down task into hierarchy of goals, operations, and plans (hierarchical task analysis)
Define HTA goal
the unobservable task goals associated with the task in question
Define HTA operations
observable behaviors or activities
Define HTA plan
unobservable decisions and planning
What are the 4 steps of creating an HTA
- Determine overall goal ex. boil kettle
- Sub-goals - break it down
- sub-goal decomposition - further sub-goals and operations
- Plans analysis - how the goals are achieved
What are operations?
Actions made by the operator
What are some advantages of using HTA?
starting point easy quick used extensively can depict everything that needs to be done
What are some disadvantages of using HTA?
little info can be used directly for design solutions
doesn’t cater to cognitive components of task
Time consuming
Analysts need to be well trained
No ideal software
What is a CTA?
Cognitive task analysis
Breaks down into steps of cognitive abilities required during each step
Perceptual and/or motor abilities as well
How is information collected during a CTA?
in-depth interviews
What are some advantages to CTA?
deals with cognitive aspect HTA doesn’t take care of
aids experts in articulating knowledge that is difficult to verbalize
What are two requirements of CTA?
- understanding of cognition
2. expert-level understanding of task (think-aloud protocol helpful)
What is the purpose of a secondary task?
Provide a profile of the resources used during the primary task
ex. reaction time, mental arithmetic
What is a downside to a secondary task and how can you avoid it?
artificiality - lack of external validity
ex. mental arithmetic while driving
Can use embedded secondary task - natural
ex. listening to the radio while driving a car
What is another method of gathering data other than behavior?
psychophysiological measures
What is a benefit of psychophysiological measures?
can provide online measurement, doesn’t require secondary task
What is a negative of psychophysiological measures?
equipment may interfere with primary task
What are the three psychophysiological measures used?
pupilometry - larger the pupil, greater the workload
heart rate - increased hr=increased mental workload
Brain activity - fMRI; may interrupt performance, expensive
What evaluates workload by obtaining users’ judgments about their tasks?
subjective assessment techniques - ask users to rate overall mental workload
What are the limitations of subjective workload measures?
- may not be sensitive to aspects of task environment - best to couple with primary task measure
- user may confuse difficulty with effort
- Many factors unconscious
What are the two types of subjective workload measures?
- NASA task load index
2. workload profile
What is the NASA task load index?
6 scales for users to rate workload (mean)
- mental demand
- physical demand
- temporal demand
- performance
- effort
- frustration level
What are the advantages of using NASA TLX
quick to use
easy to understand
What are disadvantages of using NASA TLX
doesn’t map very closely to existing models of how we process things
What is the workload profile?
based on Wickens’ multiple resource theory
several distinct cognitive subsystems
each subsystem has limited resources
What dimensions does the workload profile examine?
input modality (visual/auditory) processing code (spatial or verbal) processing stage (encoding and central processing or responding) output modality (manual output or speech)
What are advantages of workload profile?
based on sound theory (multiple resource theory)
Gives specifics about dimensions
What are the two main issues with subjective measurement and their interpretation?
- sensitive to only the range of conditions - only have info of the tasks they’ve done so far, not as accurate ratings as an expert
- subjective estimates
What is the difference between empirical techniques and analytical techniques?
do not require a user to interact with system
What are the 5 categories of analytical techniques?
- comparison
- expert opinion
- mathematical models
- task analysis
- simulation models
What is the comparison technique?
uses data from a predecessor system to estimate workload of a new system
often data does not exist from predecessor
What is the expert opinion?
designers of the system asked to predict workload
What is a mathematical model?
Using algorithms and mathematical models to predict the workload
what is a task analysis?
decomposes overall system goal into segments
What is a simulation model?
computerized version of reality
What are the three types of warning signals?
Advisory
caution
warning
What is an advisory?
draw attention, may or may not have to act
What is a caution?
immediate attention, relatively rapid response
What is a warning?
immediate attention, immediate action
How can you design a display to maximize detectability?
near to line of sight, large and bright
flashing stimuli
use standards (ex. red for emergency)
When are warning signals most effective?
you know consequences if it's ignored wide, colorful borders short, to the point salient and relevant to user's goals near the hazard
When are warning signals least effective?
users familiar with object warning is attached to
users do not perceive risk (don’t recognize unsafe actions, objects)
What are auditory displays best for?
simple information ex. warning signal
What is an auditory icon?
use everyday sound with stereotypical meanings
ex. police car siren -> antivirus warning sound
What is an earcon?
brief, recognizable sequences of tones to provide info (no meaning)
ex. receiving a text
What is required of a warning?
must be detectable within normal conditions (masking, should be above threshold)
info easily communicated (limit # of alarms)
What is a 3D display?
using auditory localization cues; provide spatial info by directing attention without requiring visual change
ex. surround sound
What is a dichotic display?
each ear receives different auditory info; good lateral localization, headphones can be used
What is a speech display good for?
transmit more complicated info
What are requirements of a speech display?
intelligible voice, gramatically correct
Better when paired with visual - even if both are unintelligible on their own, combining can make more intelligible (ex lip reading)
What are problems with speech display?
potential for masking
synthesized speech takes more effort to understand than natural speech
What are tactile/haptic displays?
rely on touch, good when other senses are overwhelmed, spatial info
What is tactile?
touch, useful in dark
powered - active (Braille)
or unpowered - passive
What is haptic?
apply force, vibration, or motion to the user
alerting signals
ex. vibrating car seat
What are the four rules of writing questions?
- be brief - ask one thing at a time
- be objective - word neutrality
- be simple - simple words and phrases
- be specific - precise
What is social desirability bias?
respondents give answers to make them look better to others
make surveys anonymous
What are the pros and cons of open-ended questions
good for recall, opinions, comments
bas for when people don’t know how to express their opinions, require more effort, analyzing responses can be difficult
What are the types of close-ended questions?
dichotomous: two categories (y/n)
multichotomous: multiple categories (very likely-very unlikely
What is the Likert scale?
rate level of agreement, can be positive or negative
What is a semantic differential scale?
involves opposite responses (weak to strong on a scale)
What is a prototype?
model of a new project (limited representation) , can be used in realistic settings through simulating scenarios, not designed to replicate full functionality, helps decide between alternative designs
What purposes to prototypes serve?
test technical feasibility
clarify requirements - environment
user testing and evaulation
What is a low fidelity prototype?
Doesn’t look like the final product
simple, cheap, quick to produce
What are the advantages to low fidelity prototypes?
easy and fast to modify
What is storyboarding?
type of low fidelity prototpye
sketch of how users might progress through a task
get feedback
prompt design team to consider scenario in more detail - gives you a better idea of how users interact at all stages
“sketch-like” art can help remind people they’re working with an early prototype
What is a high fidelity prototype?
looks more like finished product
may use software tools
useful for selling ideas to people, testing technical issues
What are some negatives of low fidelity prototypes?
device doesn’t work
could design something that isn’t feasible
What are downsides of high fidelity prototypes?
takes longer to build
comments on superficial aspects rather than content
developers reluctant to change
What are two compromises that must be traded against each other for prototypes?
breadth of functionality v depth of functionality
What is horizontal prototyping?
providing a wide range of functions but with little detail
What is vertical prototyping?
providing a lot of detail for only a few functions
