Exam 1 Flashcards
What are human factors?
characteristics of users that affects how they use a system
What are some goals of HF?
eliminate human error, make things easier to use, improve productivity, safety, and user satisfaction
what are affordances?
relationship b/w user’s capabilities and physical properties of object - determines how the object is used
ex. teapot - handle, top
What is the human-machine system? (6)
- perception
- cognition
- action
- controls
- operation
- displays
What are the foundations of science? (4)
empiricism, observation, self-correcting over time, scientific method
What is the scientific method?
logical approach to obtaining answers to questions
What are the 3 goals of science?
- Describe
- Predict
- Explain/understand
What is a theory?
best explanation with compelling evidence for something that can’t be proven
What is an operational definition?
describes abstract concepts in concrete terms
What is reliability?
Consistency of measurements
Ex. test-retest reliability
What are the two types of reliability?
True effects (IQ test), random error (didn’t drink coffee that morning)
What is validity?
degree to which it represents what it’s supposed to
What is construct validity?
Is the measurement relevant? ex. diabetes self-care and # veggies eaten
What is internal validity?
can you draw a conclusion?
What is external validity?
can the results be generalized?
What is ecological validity?
do observed behaviors reflect actual behaviors in a natural setting?
What is descriptive research?
want to examine a situation that can’t be replicated
What is experimental research?
test a hypothesis that makes a causal statement about relation among variables
must have manipulation and random assignment
What is knowledge in the world?
Maps, labels, signs, etc.
What is knowledge in the head?
affordances
What is a gulf of execution?
gap b/w goal of user and means to execute that goal
ex. elderly can’t figure out how to print from iPad
What is a gulf of evaluation?
not adequate feedback
ex. generic error message
What is response compatibility?
Part of mapping. Movement of control should match outcome goal
ex. turn steering wheel left, car should turn left
What is an example of exploiting the power of constraints?
Giving one option leads to fewer errors
Ex. putting a sock on v. a toga
What is front-end analysis?
before any design solutions are generated: who are the users, main functions, environment, preferences, etc.
What is a persona?
Hypothetical typical user derived from statistics
What is the difference b/w within-subject and between-subject experimental design?
Within-subjects uses same people in different conditions, between-subjects uses different people and different conditions
What is a slip?
Correct intention, carried it out incorrectly. More likely to happen when a familiar behavior must be inhibited.
Ex. putting milk in cabinet
What is a mistake?
behavior inappropriate for circumstance
ex. letting a flight leave in inclement weather
What is a lapse?
intended action is forgotten and not carried out
ex. failing to attach files to an email
What is a violation?
intentional choice to disobey rule or procedure (without intent to cause harm)
ex. not wearing hard hat in construction site
What is a mode?
action is inappropriate in one system mode, but is carried out in a different mode
ex. failing to put car into drive after backing up
What is error of commission?
User performs inappropriate action
What is error of omission?
user fails to perform required action (lapses are these)
What are the types of errors of commission?
timing error, sequence error, selection error
What is an input error?
info from sensory and perceptual processes (perception)
What is a mediation error?
Cognitive processes that translate b/w perception and action (cognition)
What is output error?
due to the selection and execution of physical responses (action)
What is operating error?
system is not used according to correct procedure
Ex. using cell phone in shower
What is design error?
system designer creates an error-likely situation by failing to consider human tendencies or limitation
ex. when you try to delete files and computer asks if you’re sure
How can one design for error?
avoid confusion, make consequences visible, lock out inappropriate behaviors, give reminders, avoid multi-mode systems, error-tolerant systems
What is a stressor?
not inherent characteristic of a system, info to be processed, usually expected to degrade performance
What is the Yerkes-Dodson Law?
deals with performance and arousal, stress moderates arousal
What is cognitive tunneling?
tunnel vision on most relevant task, attention focused
What type of memory does stress reduce?
Working memory
What is response perseveration?
rely on familiar or recently-used actions, make same response even if it isn’t working
What is cognitive narrowing?
discourages creative thinking and generation of new strategies or action plans
What is a limited resource?
attention - speed and accuracy tradeoff
How do you avoid the negative effects of stress?
design to avoid exacerbating cognitive effects (minimize working memory demands), provide knowledge and control (ex. doctors in simulation)
How does information flow in the 3 stage model?
stimulus - perception - cognition - action - response
What is the perceptual stage?
stimulation of sensory organs, can occur subconsciously, quality of stimulus is important to gain information
What is the cognitive stage?
identify/classify image, determines response, retrieval/decision-making/comparison
What is the action stage?
If a response is required
- choose response
- response (neuromuscular commands)
- execution
How does does a stimulus get to long-term memory?
(sensory info) - sensory memory - (attention) - working memory (maintenance rehearsal to keep in WM, encoding) - long-term memory.
What is used to move sensory memory into working memory?
attention
What is used to move long-term memory back into working memory?
retrieval
What is sensory memory?
buffer for stimuli, visual, auditory, haptic (touch)
ex. people swap video
What is working memory?
temporary, helps you do complicated cognitive tasks
ex. math in your head
What are the two components of working memory?
phonological loop: stores sound of language
visuo-spatial sketch pad: stores visual and spatial information
What is encoding?
Linking something new to something you already know
ex. learning Chinese, video of memory games
What is data-limited processing? (P)
info input to a stage is degraded or imperfect
ex. a number is flashed in a noisy room
What is resource-limited processing? (C)
system not powerful enough to perform the operations required for a task efficiently
ex. memory resources require to remember a phone number until it is dialed
What is structurally-limited processing? (A)
inability of a system to perform several operations at once
ex. patting head and rubbing tummy
What is sensitivity?
how much change is necessary for a person to notice
What is detectability?
absolute limits of senses to provide info that a stimulus is present
What is discriminability?
determine 2 stimuli are different
What is psychophysical scaling?
relation b/w perceived magnitude and physical magnitude
What is an absolute threshold?
smallest amount of intensity needed for a person to notice a stimulus
What is a difference threshold?
smallest amount of difference b/w 2 stimuli
What is the goal of classical methods?
measure thresholds accurately
What is the absolute method of limits?
present stimulus intensities in a succession of small increments to observer
What is difference method of limits?
present 2 stimuli at a time, one remains constant and the other changes in small increments
What is the method of constant stimuli?
different intensities in a random order. Absolute - one stimuli, difference - constant and changing intensity
What is it called when you think a signal is present but it is not?
false alarm
What is direct scaling?
ask person to rate intensity
What is indirect scaling?
derive from their performance at discriminating stimuli
What is Stevens’ Law?
Relationship b/w physical intensity and psychological magnitude
What is a reaction time?
the amount of time between the occurrence of an event and a person’s response
What is simple reaction time (SRT)?
a single response is made after the action occurs, quick response, quicker for audio than visual
ex. car horn
What is Recognition reaction time (RRT)?
a single response is made after some stimuli (the “memory set”), but not after others (the “distractor set”)
ex. dot test - patterned and solid dots
What is Choice reaction time (CRT)?
need 2 stimuli and 2 responses, adding more possible stimuli and more possible responses increases reaction time
ex. right arrow visual, press right arrow key
What is determined by wavelength of light reflected from or emitted by an object?
color perception
What are Spectral colors?
colors comprised of a single wavelength
What are Non-spectral colors?
comprised of more than one wavelength, additive mixing increases light reflection, subtraction decreases amount of light reflected
What is hue?
variations that are described by names like red, blue
What is saturation?
apparent purity, vividness, or richness
What is lightness measured in?
luminosity
What is the tri-chromatic theory?
human color vision - any hue can be matched with a combination of three primary colors
What are the three types of photoreceptors?
Short wl (blue) - cyanolabe, medium wl (green) - chlorolabe, long wl (red) - erythrolabe
What are the types of dichromatic color vision?
protanopia: can’t see red
deutanopia: can’t see green
What is the opponent process theory?
color perception is controlled by the activity of two opponent systems - blue-yellow and red-green, only one can be signaled at a time
What is visual acuity?
clearness or sharpness of vision
ex. eye chart
What is contrast sensitivity?
being able to distinguish between bright and dim, function of both contrast and spatial frequency
What are the grouping properties?
proximity, similarity, continuity, closure, common fate
what is proximity?
close together, perceived as a group
what is similarity?
similar elements grouped
what is continuity?
points connected in straight or smoothly curving lines grouped
what is closure?
open curves are seen as complete
what is common fate?
things moving at the same speed in the same direction are grouped
What are the ways to introduce artificial grouping?
common region, connectedness
What is accommodation?
automatic adjustments of the lens that maintain a focused image on the retina - good for short distances
What is vergence?
degree to which the eyes are turned inward to maintain fixation on an object
What is interposition?
nearer objects will block the view of more distant objects if they are in the same line of vision
What is motion parallax?
apparent displacement or difference in position of an object viewed along two different lines of sight
What is object motion?
external object is moving
What is induced motion?
a stationary background causes movement to be attributed to the wrong part of a scene
What is apparent motion?
discrete jumps of retinal images can produce the appearance of smooth motion
ex. tv frames
What does the vestibular system do?
allows us to feel the movement of our bodies
What does the somesthetic system do?
detects things you can physically feel
What is an absolute touch threshold?
smallest amount of touch that can be detected
What are two-point touch thresholds?
determine the distance b/w 2 stimuli
What is a passive touch?
skin is stationary, external pressure applied ex. someone pokes you
What is active touch?
skin moves ex. reading braille
Which is more sensitive: visual system or somesthetic system?
somesthetic
What sensitivity has an almost perfect temporal and spatial summation?
temperature
True or false we are good at accurately locating where hot and cold temperatures are on our skin?
False - general area
True or false: sensitivity varies across the body?
true
True or false: there are both temporal and spatial summations for pain?
false
What are the receptor cells in the nasal cavity called?
olfactory epithelium
When is it more appropriate to use auditory presentation?
short and simple message
What is a static display?
one display, does not change
What is conspicuity?
how well the display attracts attention
what is visibility?
how well the display can be seen
what is legibility?
ease with which symbols and letters can be individually distinguished
what is legibility distance?
distance at which you can read
what is readability?
larger groups of characters, meaning of the words/comprehension
what is intelligibility?
message should be unambiguous and convey warnings
What is absolute judgement?
classification of a stimulus when there are several options available - can discriminate between 5 to 7
what is relative judgement?
directly compared to one another
What is the difference between analog and digital?
analog: continuous scale, moving pointer (or other way around)
digital: present alphanumeric info
what are two ways to display arrangement?
frequency of use and sequence of use
what is a link?
the connection between a pair of items indicating a certain relation between them
