1
Q
What does HF/E stand for?
A
Human Factors and Ergonomic OR Human Factors Engineering
2
Q
What is HF/E?
A
Understanding the interaction among humans and other elements of a system; applies thoery, principles, date, and methods to design in order to optimize human well-being and overall performance
3
Q
What are ergonomic goals?
A
1) Optimize
2) Design
(fit the task to the user)
4
Q
What are the stages in the human information processing model?
A
- Sensory Register
- Perception, Attention Resources
- Thought Decision Making
- Working Memory
- Long-Term Memory
- Response Selection
- Response Execution
5
Q
What are the main components of the HIP Model and what parts do they include?
A
1) Perceptual Encoding: sensory register & perception
2) Central Processing: attention, decision making, working memory, & long-term memory
3) Responding: response selection & execution
6
Q
What is the sensory register?
A
Your ultra-short-term memory that takes in sensory information through your five senses (sight, hearing, smell, taste and touch) and holds it for no more than a few seconds
7
Q
What is perception?
A
Mental process of transforming sensory input into meaningful information
8
Q
What is perception influenced by?
A
Prior Knowledge & What is Sensed from the World
9
Q
What is working memory?
A
Mental “Scratch Pad”
short-term store needed for certain mental tasks, defined in terms of purpose
Temporary & Effort-Demanding Store
10
Q
What is learning?
A
When working memory goes into long-term memory
11
Q
What are factors that influence working memory?
A
1) Capacity (how much we have)
2) Time (how long it takes)
3) Similarity to other things we know
4) Attentional Requirements
12
Q
What is long-term memory?
A
the mind’s capacity to store and recall information, experiences, and knowledge for extended periods, from days to years, in a relatively permanent way
13
Q
When is long-term memory always active, regardless if working memory is activated?
A
During perception to help with top-down processing
14
Q
What does ease of retrieval of information from long-term memory depend on?
A
1) Strength of memory (determined by frequency and recency)
2) Associations with other items in memory
15
Q
When is decay most rapid?
A
Within the first few days (decay is exponential)
16
Q
What are 3 reasons why decay happens?
A
1) Weakened Strength
2) Weakened Associations
3) Interfering Associations
17
Q
What is feedback?
A
reponse execution leads to new information to be sensed and perceived
feedback goes from response execution, back to sensory register
18
Q
How does short-term memory differ fundamentally from long-term memory?
A
1) Temporal decay
2) Chunk capacity limits
19
Q
What are the 2 types of decision making?
A
1) Normative: outline how rational individuals should make decisions to achieve the best possible outcomes
2) Heuristics and Biases: mental shortcuts that use information that comes to mind quickly and easily that speed up decision-making, but can lead to confirmation bias or availability heuristic
20
Q
What is top-down processing?
A
Cognitive process where prior knowledge, expectations, and context influence how we interpret and perceive sensory information
Experience -> Knowledge -> Perception
21
Q
What is bottom-up processing?
A
Cognitive process that involves analyzing sensory information from the environment to build up a perception or understanding of the world around us (data-driven)
Stimulus World -> Senses -> Perception
22
Q
What are attentional resources?
A
the mental capacity or energy available for processing information and focusing on specific stimuli in our environment
23
Q
What is the relationship between attentional resources and selective attention?
A
the resources we have to perceive, think, and execute are limited, so we much select which sensory channels we attend to
24
Q
What is selective attention?
A
the capacity for or process of reacting to certain stimuli selectively when several occur simultaneously
25
What are two aspects of attention?
1) Filter to divide between tasks
2) Mental energy
25
What are the four factors that influence selective attention?
1) Salience
2) Effort
3) Expectancy
4) Value
25
What is salience?
bottom-up process, characterized by attentional capture
a quality that makes a stimulus stand out and "jump out" to grab attention, whether due to its physical properties (like brightness, color, or novelty) or its emotional and motivational relevance to the observer
26
What is effort?
how hard it is to find information
the cognitive exertion or mental energy required to consciously focus on a specific stimulus while simultaneously filtering out other distractions
26
What is expectancy?
where we expect to find the information, based on prior information (top-down)
27
What is value?
how valuable it is to look at
the subjective importance and relevance a person assigns to a stimulus, which unconsciously guides the brain to prioritize specific information and filter out distractions
27
How does cognition occur jointly with the tools/technology we use?
It impacts the designs of the tools/technology and how we interpret them
28
What are the 6 bullet points for rods?
1) Sensitive to Light
2) Poor Spatial Resolution
3) No Color Discrimination
4) Used for Night Vision
5) Distributed Outside Fovea
6) Very Sensitive to Object Motion
28
What are the 6 bullet points for cones?
1) Low Sensitivity to Light
2) High Spatial Resolution
3) Color Vision
4) Used for Daylight Vision
5) Concentrated in the Fovea
6) Very Few at Periphery
28
What are the 3 types of cones?
1) Red
2) Green
3) Blue
29
Closer to the fovea, there are less ___ and more ___
Closer to the fovea, there are less rods and more cones
29
What are the lighting conditions and what vision does each use?
1) Photopic (bright light/day): Cone
2) Mesopic (transitional light): Rod & Cone
3) Scotopic (dark/night): Rod
29
What is luminance?
light reflected or emitted by surface
30
What is an example of luminance?
Being able to see a stop sign when driving at night from the headlights reflecting off of it
30
What is illuminance?
light falling on the surface (declines with square of distance)
30
What is an example of illuminance?
Headlights shining on a stop sign
31
What are the units of measure for luminance?
Candelas/m^2
Lamberts/ft^2
32
What are the units of measurement for illuminance?
Lumens/m^2 (lux)
Candle/ft^2 (foot-candle)
32
Why are illuminance and luminance important considerations for workplace design?
poor lighting at work can lead to eye-strain, fatigue, headaches, stress and accidents
on the other hand, too much light can also cause safety and health problems such as “glare” headaches and stress
33
What is visual acuity?
the measure of the ability of the eye to distinguish shapes and details of objects at a given distance
34
What are factors that affect visual acuity?
- brightness
- contrast
- glare
- target movement
- visual problems
34
What does 20/40 vision mean?
The observer sees at 20' what a normal observer sees at 40'
34
What is used to determine the legibility of text?
Luminance of text and luminance of background (their contrast)
35
What are factors that affect legibility?
- text contrast
- text height & width
- glare
35
What is veiling luminance?
Glare - some source causes light to scatter within the eye, causing an overall veiling brightness (Bv), which reduces contrast
36
What are the two types of eye movements?
1) Pursuit
2) Saccadic
37
What is pursuit eye movement?
a type of smooth, continuous eye motion that allows your eyes to track and maintain focus on a moving object as it travels across your field of vision
movements are smooth
37
What is saccadic eye movement?
rapid, ballistic movements of the eyes that abruptly change the point of fixation
movements are discrete from location to location
37
What are the 4 visual search strategies?
1) Serial
2) Parallel
3) Conspicuity
4) Expectancies
37
What are serial search strategies?
search top to bottom or left to right (search sequentially) to see if a defect is present
38
What are parallel search strategies?
the brain simultaneously examines every item in a visual display to find a target, rather than processing each item one by one
all items are examined at once, looking for certain patterns
38
What are 3 examples of vision problems?
1) Nearsightedness (myopia): cannot see objects far away
2) Farsightedness (hyperopia): cannot see close objects
3) Presbyopia: normal aging retreat of the near point; with age, the lens loses its elasticity and it remains too flat
38
What is brightness?
The measure of the intensity of the sensation perceived by an observer
38
What is the purpose of the outer ear?
Collects sound vibrations (sound energy)
39
What is the purpose of the middle ear?
Conduct and amplify sound waves into inner ear (mechanical energy)
39
What is the purpose of the inner ear?
Transmits sound energy information to the brain (electrical nerve energy)
40
Why is sound heard?
Because of a change in pressure sensed by the ear due to vibrations of some sort
41
What is amplitude?
Intensity or loudness (higher amplitude = louder, lower amplitude = quieter)
41
What is wavelength?
Length of sound wave
41
What is frequency?
The rate of oscillation of the sound (lower frequency = decreased pitch, higher frequency = increased pitch)
41
What is loudness?
the subjective perception of a sound's strength, varying between individuals and influenced by factors like sound intensity, frequency, and duration
42
What are important components of the equal loudness contour graph?
- noise at different frequencies have different loudness for the same pressure level
- curves show perceived loudness, everything on the same line is perceived as the same loudness
- different frequency and sound pressure level combinations where it is perceived to be equal at 10, 20, etc. phon
42
What is the unit of loudness?
phon
42
Between what frequencies is the ear most sensitive?
Between 600-4800 Hz, shown by the dip in the graph, meaning it is perceived as the same loudness at a much lower sound pressure level, so our ear must be sensitive
43
Do equal increases in sound intensity create equal increases in perceived loudness?
No, loudness is perceived to approximately double every 10 dB
43
Loudness is a ______ ________.
Loudness is a psychophysiological phenomena
43
What is the measure of sound intensity?
Decibels (dB) - ratio of a given sound to the threshold of hearing
43
What are the three sound scale weightings?
1) A scale (dBA): corresponds to 40-phon (for day-to-day) equal loudness contour
2) B scale: corresponds to 70-phon (not really used)
3) C scale: corresponds to 100-phon (for very loud sounds)
44
What is time weighting?
Weighs sounds exponentially with time (slow for most occupational assessments; fast to determine peak values)
44
What are sources of noise?
- Masking
- Startle Respone
- Hearing Loss
44
What is masking?
Noise, or unwanted sound, covers up wanted sound
Can occur due to interfering frequencies - if it has the same frequency, it'll mask
44
What are methods to reduce masking?
- increase the signal (what you want to hear)
- decrease the noise (what you don't want to hear)
44
What is startle response?
occurs when you experience an unexpected and genereally loud noise
could be bad, especially when something needs delicate movements (like surgeries)
45
What are the 2 types of hearing loss?
1) Temporary Threshold Shift (TTS)
2) Permanent Threshold Shift (PTS)
45
What is Temporary Threshold Shift?
occurs after short periods of intense sounds
a temporary reduction in hearing sensitivity caused by exposure to loud noise, where hearing returns to normal over time, often within hours or days
46
What is Permanent Threshold Shift (PTS)?
occur after being exposed to lond periods of intense sounds or extremely intense, abrupt, and often unexpected sound
permanent noise-induced hearing loss caused by prolonged or intense exposure to loud noise, which damages the inner ear's hair cells
46
What are factors affecting risk of hearing loss?
- sound intensity
- type of noise
- duration of exposure
- dose
- protections in place
- related diseases
46
How can noise affect work performance?
high concentration, complex, and high vigilance tasks are affected by noise
can cause annoyance or stress which increases musle tension and blood tension
46
Define the NIOSH recommend maximum time weighted dB level for an 8-hour shift
Weighted average of 85 dB for an 8 hour shift
47
What are the 3 Levels of Noise Control?
1) At the host (least effective)
2) Along the path
3) At the source (most effective)
47
What are examples of noise controls at the host?
- PPE
- Isolation
- Job Rotation
47
What are examples of noise control along the path?
- barriers
- increase distance
- change direction of noise
47
What are example of noise control at the source?
- equipment and tool selection
- changing design of source
- changing equipment
- stabilizing equipment
47
What are the 4 categories of display principles?
1) Perceptual - how users intially perceive material presented
2) Mental Model - users interpret displays based on their expectations (based on their past experiences) of the system being displayed
3) Attention - considers multitasking, types of attention
4) Memory - how easy it is for the user to remember
48
What are the 5 principles of Perceptual Display
1) Make Display Legible (or Audible): it has to be seen or heard
2) Avoid Absolute Judgment Limits: people are not good at attaching "labels to levels"
3) Top-Down Processing: highlight the unexpected
4) Redundancy Gain: if a signal is expressed more than once, it is more likely to be understood correctly
5) Discriminability: ratio of similar to dissimilar features; similarly appearing signals are likely to be confused at time they are perceived or delay before action occurs
48
What is a bad example of Make Display Legible?
Making a sign with really small font, making a sign with not a lot of contrast between background and text colors
48
What is a bad example of Avoid Absolute Judgment Limits?
Having a stoplight with a gradient of 10 colors that are similar
48
What is a bad example of Top-Down Processing?
A should be on
B should be on
C should be on
D should be off
48
What is a good example of Redundancy Gain?
traffic light is a good example of this principle, as the 3 states of information are coded into both positions (top, middle, bottom) and colors (red, yellow, green)
49
What is a bad example of Discriminability?
The epidural and penicillin bags looking the same, which could have deadly consequences
49
What are the 2 Principles of Mental Model Display?
1) Principle of Pictorial Realism: display should look like the variable it represents (it should look like its picture)
2) Principle of the Moving Part: match movement (spatially and direction-wise) to system/mental model
50
What is a good example of the principle of pictorial realism?
A road sign that shows the road narrowing picture that looks similar to how the road actually narrows
50
What is a good example of the principle of the moving part?
If an aircraft is moving upward, the moving element on the altimeter should also move upward
50
What are the 3 Principles of Attention Display?
1) Minimizing Information Access Cost: minimize the distance between variables and the time cost to move from one display to another to access information
2) Proximity Compatibility Principle: link related variables through common location, color, or other code
3) Principle of Multiple Resources: distribute information between different sensory channels (like between both visual and auditory instead of just one of them)
50
What is a good example of minimizing information access cost?
having the menu of a restaurant be on one page of a website instead of over multiple
50
What is a good example of proximity compatibility principle?
the design of a car's dashboard, where the speedometer, fuel gauge, and tachometer are placed near the driver in the same visual field to allow for simultaneous monitoring of related information without extensive mental effort
51
What is a good example of the principle of multiple resources?
GPS has a visual map and tells you instructions
51
What are the 3 Principles of Memory Design?
1) Replace Memory with Visual Information (Knowledge in the World): show the things a user needs to remember
2) Predictive Aiding: support proactive behavior with displays of future states since people are not good at predicting the future
3) Consistency: old habits die hard, keep design consistent
51
What is a good example of replacing memory with visual information?
Checklists, schedules
52
What is a good example of predictive aiding?
weather app showing future weather
53
What is a good example of consistency?
all road signs that are yellow are for road warnings for possible danger ahead
53
What are displays?
- represent points of exchange
- information and energy transfer
- present information and feedback
54
What are controls?
they allow workers to interact with the system
55
What are visual displays?
human-made artifacts designed to support the perception of relevant system variables and facilitate the further processing of information
55
What will effective displays consider?
Human limits and capabilities
55
What are the 3 steps to designing displays?
1) What kind of basic information do we need to know prior to getting started?
2) What are the information needs or requirements, given the task and the concept?
3) Incorporate Display Design Principles
55
What is a good representation of visual designs?
- captures essential elements and leaves out the rest (or irrelevant)
- people can make an appropriate decision/action quickly
55
What is a poor representation of a visual display?
- leads to increase difficulty
- can be misleading
- out of sight, out of mind
55
What is Signal Detection Theory?
a framework that analyzes how people make decisions when distinguishing a faint stimulus (signal) from background stimulation (noise) under conditions of uncertainty
framework to describe and study decisions that are made in uncertain or ambiguous situations
a means to quantify the ability to discern between a signal and the absense of a signal (noise)
55
What is a hit?
There was a signal and the response was yes (correct)
true positive
P[resp = YES | stim = YES]
56
What is a miss?
there was a signal and the response was no (incorrect)
false negative
P[resp = NO | stim = YES]
56
What is a correction rejection?
there was noise (no signal) and the response was no (correct)
true negative
P[resp = NO | stim = NO]
56
What is false alarm?
there was noise (no signal) and the response was yes (incorrect)
false positive
P[resp = YES | stim = NO]
56
How do you calculate the hit rate?
TP/(TP + FN)
TP = true positive
FN = false negative
56
How do you calculate false alarm rate?
FP/(FP + TN)
FP = false positive
TN = true negative
57
What are the 2 phases of perception for SDT?
- Identification
- Decision
57
How are 3 ways the decision can be based on uncertainty?
- incomplete
- ambiguous
- frequently contradictory
57
What criterion do we evaluate in SDT?
the willingness of a person to say "signal present" (YES) in response to an ambiguous stimulus
57
What are the 3 assumptions of SDT?
1) We can create a framework of 2 normal distribution curves (signal curve and nosie curve)
2) YES, NO response
3) Information is based on uncertainty
57
Describe the relationship between SDT and Display Design
We want to optimize d' to make signals more distinct from background noise
SDT helps designers create user interfaces that reduce errors like false alarms and misses by optimizing the display's ability to communicate critical information clearly
57
What is Sensitivity in SDT?
a measure of an individual's ability to discriminate between a signal and random noise, or between a signal-present stimulus and a signal-absent stimulus
d'
58
What does d' mean?
the distance between means in standard deviation units
d' = z(Hit Rate) - z(False Alarm)
58
What does low sensitivity mean?
high noise, lots of overlap
58
What does high sensitivity mean?
low noise, not much overlap
59
What does d' = 0 mean?
the two normal distributions are completely overlapped
participant was unable to discern between noise & signal
59
What is response bias in SDT?
an observer's inherent tendency to say "yes" or "no" to a stimulus, independent of their actual sensitivity
c
59
What does c mean?
The decision criterion - the judgment of decision criterion of the observer varies independantly from d', reflects the strategy of the observer, and can be changed with level of confidence
c is a measure of response bias
c = -0.5(z(Hit Rate) + z(False Alarm))
60
What does c > 0 mean?
conservative bias - a tendency to say 'absent' more than 'present'
60
What does c < 0 mean?
liberal bias - tendency to say 'present' more than 'absent'
60
What does c = 0 mean?
indicates neutral bias
60
Why was SDT developed?
To address the questions of:
1) What is the signal strength of the information?
2) What is the individual's own judgment, or "internal criterion"?
quantify ability to discern between a signal and absense of a signal (or noise)
61
What 2 values do you need to calculate c and d' values?
Hit Rate & False Alarm Rate
SYS 3023
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