Ergonomics Final Exam

Front 1

Two pure wavelengths

Back 1

Red and Blue

Front 2

Eye never sees pure wavelengths

Back 2

sees blends

Front 3

primary eye colors

Back 3

red, blue, and green

Front 4

why green?

Back 4

covers largest spectrum
Red covers shortest spectrum

Front 5

what is hue characterized by?

Back 5

saturation or lack of (greying)

Front 6

Visual range?

Back 6

400 to 700 nm (400 - ultraviolet side, 700- infrared side)

Front 7

Luminance?

Back 7

The intensity of light at given point (source) as close as you can get to it
measured in Foot Lamberts (FL)

Front 8

Illuminance?

Back 8

density of luminous flux on a surface
measured in Foot Candles (FC)

Front 9

Reflectance?

Back 9

ratio of the amount of light surfaces either reflect/absorb
Reflectance (%) = Luminance (FL)/ Illuminance (FC)

Front 10

Brightness?

Back 10

Defined as "visual intensity"
complexity due to multiple definitions of light intensity
measures luminous intensity/flux (unit: candela)
distance is key

Front 11

Eye structure

Back 11

pupil
lens
ciliary muscle - pulls lens in and out to help you see what you're trying to focus on. smooth muscle
retina
fovea - lots of color, 30 degree range
periphery - no color, highly sensitive to light changes, put flashing sensors in peripheral to move fovea range

Front 12

Visual Angles (VA)

Back 12

VA = 5.7*60*(Height/distance)

**simplified

Front 13

Factors affecting visual reception

Back 13

location on the retina
acuity - ability to resolve fine detail
sensitivity to light - too much = headaches
color sensitivity to wavelength
adaptation - too bright/dark at 1st - then you adapt (beach)
Differential wavelength sensitivity

Front 14

Myopia

Back 14

Nearsightedness
inability to flatten out lens enough to focus on distance
can't see far

Front 15

Presbyopia

Back 15

Farsightedness
inability of lens to accommodate very near stimuli
can't see near

Front 16

Protanopia

Back 16

7% males have
color blindness (1st or 2nd)
most prevalent is red-green
design rule: design in monochrome first

Front 17

Simultaneous Contrast

Back 17

colors change when placed next to each other
effects maps and multi-color displays

Front 18

color contrast doesn't produce good ____

Back 18

luminance-contrast ratio
putting a color on a white background and it bleeds

Front 19

aging reduces ____

Back 19

the amount of light passing through the cornea, perceived as poor illumination (reducing sensitivity)

Front 20

Negative Image

Back 20

phenomena to simultaneous contrast leaving prolonged after image (e.g. road glare)

Front 21

Decrease contrast

Back 21

decrease visibility
e.g. black print on gray

Front 22

decrease illumination

Back 22

decrease contrast sensitivity
e.g. reading map in poor light

Front 23

polarity

Back 23

black on white better than white on black
e.g. designing viewgraphs

Front 24

spatial frequency

Back 24

optimum CS at 3C/D
e.g. ideal size of text font given viewing distance

Front 25

visual accommodation

Back 25

CS
e.g. map reading during night driving

Front 26

motion

Back 26

decrease CS
e.g. reading a road sign while moving

Front 27

positive contrast

Back 27

light text on dark background
increase font size by 25% to gain same effect

Front 28

negative contrast

Back 28

dark test on light background

Front 29

irradiation (aka bleeding)

Back 29

white lettering spreading over dark backgrounds

Front 30

upper case lettering

Back 30

more difficult to process, less shape variation
looses curvature

Front 31

block print

Back 31

more difficult to process, less spatial separation
looses curvature

Front 32

Top down processing

Back 32

Experience --> knowledge (expectancies and desires) --> perception
MEMORIES

Front 33

bottom down processing

Back 33

stimulus world --> the senses --> perception
WHAT YOU PERCEIVE IN THAT CONTEXT

Front 34

Brain starts depth perception with three cues

Back 34

1. Accommodation - lens shapes to focus image
2. binocular conversion - "cross-eye"
3. binocular disparity - comparison on contrasting information received by each eye (Dominate eye)

Front 35

linear perspective

Back 35

conveying of parallel lines to distant point

Front 36

relative size

Back 36

cue based on two objects know to be the same size

Front 37

interposition

Back 37

near object obscures farther one

Front 38

light and shading

Back 38

shadows, reflection, illuminating lighting

Front 39

texturing gradients

Back 39

textured structure from angle WILL change texture density (spatial frequency)

Front 40

Normal eye movements

Back 40

pursuit
saccadic

Front 41

Eye movement - pursuit

Back 41

constant motion to follow moving target

Front 42

Eye movement - saccadic

Back 42

search movement, more abrupt and discrete

Front 43

Saccadic movements

Back 43

initiation latency (movement time, speed)
Destination (2 types)
Dwell (fixation) controlled by volume of information
Useful field view (fovea vision) radius of 2 degree, high accuracy, low sensitivity

Front 44

Predicting time to find objects

Back 44

time (t) = [Total # (N) * Inspection time (I)] /2

Front 45

parallel search (bottom-up thinking)

Back 45

target properties
discriminability from background elements
simplicity
automaticity

Front 46

implications to system design

Back 46

1. knowledge can lead to designer to enhance visibility of targets in dynamic displays
2. limit design clutter
3. knowledge of Top-Down processing alters display structure to make target fields apparent (utilize consistent placement)
4. knowledge will lead to models allowing for prediction of time to find targets
5. knowledge of absolute judge limits levels

Front 47

Classic error detection & prevention

Back 47

Goal - improve operator detection of signal to noise

Front 48

sensitivity vs. specificity

Back 48

sensitivity - ability to find or detect it (effectiveness)
specificity - ability not to find error (test failing)

Front 49

Auditory sound (acoustics) basics

Back 49

can be presented as a sine wave
primary components -
amplitude = loudness, expressed as ratio of sound pressure, unit - decibels (dB)
frequency - pitch

Front 50

Sound Intensity (dB)

Back 50

20*log(P1/P2)
where P2 = fixed value near threshold of hearing limit (e.g. "absolute" intensity)

Front 51

Range of pitch

Back 51

low = 80 - 250 Hz
flicker = below 80
mid = 250 - 1000Hz
high = 1000 - 20,000 Hz
ultra = 20,000 - 23,000 Hz

Front 52

Vestibular System (Ear)

Back 52

Pinnea
Cartilage
Ear Canal
Tympanic Membrane - drum portion
Malleus
Inus
Stapes
Semicircular Canals - 3 axis (x,y,z) fluid with hairs that move with dynamics of air
Cochlea
Auditory Nerve

Front 53

loudness vs. sound intensity

Back 53

loudness = perception
sound intensity = reality

Front 54

hear vs. listening

Back 54

psychological experience --> correlates but not identical
psychological scale
equal increase in sound intensity does not equate to same in loudness
scale - relates physical intensity to psychological experience
unit - sones
generally loudness doubles each 10dB increase in intensity
Critical levels (thresholds)

Front 55

lower threshold

Back 55

minimum intensity of sound that can be heard

Front 56

upper threshold

Back 56

minimum intensity of sound that damage to the ear can occur

Front 57

pain threshold

Back 57

minimum intensity of sound that physical pain occurs

Front 58

Masking Sound (complex techniques for eliminating sound)

Back 58

the minimum intensity difference necessary to ensure that a sound can be heard is around 15dB (above the mask), although this value may be larger if the pitch of the sound to be heard is unknown.
high pitch = more detrimental to low pitch
woman's voice is more likely to be masked by male voice

Front 59

Alarms design example

Back 59

- tend to be omni-directional
fact: auditory alarms induce a greater level of compliance than visual
alarm redundancy (sound, visual, tactile) has had mixed effects based on situational environments

Front 60

cognitive processing of alarms

Back 60

automation - good thing to a point
impact of false alarms - "cries wolf", "nuisance alarm", training vs conditioning

Front 61

Speech

Back 61

tone (unlike normal noise, very specific, very detailed)
time dependent changes
analysis: spectrograph
masking effect of noise

Front 62

echoic memory

Back 62

allows you to replay over and over until you capture it all (in their voice)
form of photographic memory

Front 63

sources of speech distortion

Back 63

clipping the begin/ending of words
reduce bandwidth (mumble)
echo/reverberation
poor sound quality (speaker)
dialect

Front 64

Acoustic Engineering

Back 64

product of acoustic physics
techniques include filtering and controlling bandwidth (lower/higher/ranging)
voice synthesis - recognizable speech, speech that can be heard in noise, "easy listening" --> reducing processing/extraction difficulty, individual hearing loss

Front 65

stages of hearing loss (non-natural)

Back 65

1. loss of sensitivity while noise is present - factory with ear plugs, walk out, take out plugs
2. temporary threshold shift (TTS) - concert
3. permanent threshold shift (PTS) e.g. occupational deafness

Front 66

protecting workers - Standards (ACGIH)

Back 66

time weighted average (TWA) - duration based
tradeoff of intensity of noise exposure to duration
permissible exposure limit (PEL) - exposure only (Upper limit)

Front 67

protecting workers - Enforcement (OSHA)

Back 67

Levels of action
all acceptable
TWA >85dB
PEL > 90dB

If TWA or PEL is greater, need earplugs/protection

Front 68

Actions to protect workers

Back 68

1. source - equipment or tool, high pitch more irritating than low rumble
2. environment - industrial more intense than street, controls include separation, dampening, absorption
3. individual - hearing protection - measured (NRR), 2 types, ear plugs and ear muffs

Front 69

% of people annoyed by sound

Back 69

highly annoying >70dB
% of people annoyed = 20 + 3.2*(dB-70)

Front 70

Touch (tactile and heptic senses)
referred to as feedback signals

Back 70

tactile - interpretation of pressure and texture signals, e.g. temp, rough, sharp, dull, smooth
heptic - interpretation of shape signals (cube or round)

Front 71

Historical design issues

Back 71

mechanical vs membrane keyboards
work glove design - protection vs feedback
pilot error - similar control for landing gear and flaps
designing for the blind
virtual reality - suit with inflation pockets (NASA)
over cluttered visual displays/alerts

Front 72

proprioception & kinesthesis

Back 72

sense that allow the brain to know the orientation and location of your body in space without visual stimulus

Front 73

Stimulus (3 way)

Back 73

1. muscle contraction
2. joint angle
3. epidermal

Front 74

vestibular senses

Back 74

physical structure - 2 sets of receptors (groupings of hairs) deep in the inner ear located in the semicircular canals and vestibular sacs

Front 75

Stages of human processing

Back 75

1. perceive information about environment
2. central processing
3. response to information

Front 76

Selective Attention - only pay attention to so many things at one time

Back 76

e.g. controlled flight into terrain - caused by failure of attention to sources of information

Front 77

Factors during channel/source selection

Back 77

1. salience - bottom-up - attention capture
2. expectancy (top-down)
3. value (top-down) - sampling of environment with expectations of what to find
can directly change source based on observer perceived value
4. effort - e.g. not wanting to move

Front 78

Perception is proceeded by 3 processes:

Back 78

1. bottom-up analysis
2. unitization
3. top-down analysis
(2 & 3 based on long-term memory that is no longer active)

Front 79

Associations allow for ___

Back 79

people to guess what something is based on limited sensory info

Front 80

Working memory (aka short-term)

Back 80

central executive component - is the attention control system of the body to focus on information sources

Front 81

two types of information stored

Back 81

1. verbal - "phonological loop"
2. spatial - "visuospatial sketch pad"

Front 82

time stored in working memory

Back 82

1. how long (time) -- time between being pulsed or accessed
2. how much (capacity) -- average 7 +- 2 "chunks"
3. how similar -- typical source of error due to confusion
4. attention to keep active -- a resource limited

Front 83

Human Factors issues with working memory

Back 83

1. minimize load (avoid long codes/strings of #)
2. provide visual echoes (redundancy)
3. placeholders for sequential task (feedback)
4. exploit "chunking" (lower to upper limits)
5. minimize confusability
6. avoid unnecessary zeroes
7. consider memory limits in instructions (avoid "negatives")

Front 84

Situational Awareness

Back 84

ability to process and react to dynamic environmental information (teach in military)

Front 85

Divided attention

Back 85

division of task to mental activities (lose context with divided attention)

Front 86

mental effort inversely proportional to ___

Back 86

automaticity (signing your name)

Front 87

Multi-dimensional memory - modalities

Back 87

auditory vs. visual

Front 88

multi-dimensional memory - codes

Back 88

spatial vs. verbal

Front 89

multi-dimensional memory - stages

Back 89

perceptual - working memory vs. response

Front 90

multi-dimensional memory - visual channels

Back 90

focal vs. ambient

Front 91

Interruptions are defined as:

Back 91

total interference b/w 2 ongoing tasks
e.g. mental stacking of nurses
increased separation has been linked to procedure errors

Front 92

addressing time-sharing overload

Back 92

task redesign
interface design
training
automation

Front 93

Properties of Decision Making

Back 93

when a person must make a decision from a list of alternatives
some amount of information available relative to options
time frame is relatively long
choice associated with uncertainty
in the end all about probabilities
risk adverse v risk taking behaviors
idea of willing to take risk based on uncertainty

Front 94

decision making models - normative model

Back 94

based on "utility" with outcome based on decision makers perceived "worth"

Front 95

Controlling factors when designing (3)

Back 95

1. cue reception & integration
2. Hypothesis generation & selection
3. Plan generation & active choice

Front 96

IMPROVING Human Decision Making

Back 96

1. task redesign
2. decision-support system
decision trees (simple, not modifiable)
spreadsheets (simple, modifiable)
simulation (good "what if" scenarios, more complex)
Expert systems (computer aided, variable, complex)
Displays (embedded support of feedback and cues)

Front 97

Display definition

Back 97

a human-made artifact designed to support the perception of relevant system variables and facilitate further processing of information by the user

Front 98

Graphical User Interface (GUI)

Back 98

typically graphical link that manipulates the display based on response or controls
absorbs more information more rapidly
like graphics better than text

Front 99

Display Basics

Back 99

purpose - convey task intended to support, goal of task, stimulation "information analysis" by user -- do something to move goal forward
Physical tools - color differentiation, visual objects, auditory

Front 100

13 display design principles - perceptual principles

Back 100

make displays legible (or audible)
avoid absolute judgment limits
top-down processing
redundancy
discrimination (similarity causes confusion)

Front 101

13 display design principles - Mental Model Principles

Back 101

pictorial realism -- looks like what it is (e.g. folder on computer)
moving parts -- dynamic movements should be compatible with model (spatial pattern, direction - dial running backwards)

Front 102

13 display design principles - Attention Principles

Back 102

minimize information access cost - "effort"
proximity compatibility - limit divided attention by placing compatible/complementary displays in the same region (occupy same space)
Multiple resource - divide information across two resources or stimulus

Front 103

13 display design principles - Memory principles

Back 103

replace memory (learned) with visual information: "knowledge of real world"
predictive aiding - when mental resource is completely consumed we become reactive not proactive
consistency - utilize long-term memory

Front 104

Problems with principles:

Back 104

clashing (13 contradict)
KEY - understanding importance relative to maintaining balance through tradeoffs)

Front 105

Alerts designed based on three levels of relative to consequence for failure to comply

Back 105

Warning - "most critical category"
Caution - "less critical"
Advisories - typically visual, not auditory

Front 106

Labels & Symbols (4 criteria)

Back 106

1. visibility/legibility
2. discriminability
3. meaningful - problem
4. location relative to enhance unambiguous association with displays

Front 107

Monitoring

Back 107

displays for monitoring are those supporting potential changing quantities/values
needs/functions
to be set
to be watched
to be tracked
Criteria
legibility
analog v digital
prediction/sluggishness

Front 108

Multiple displays

Back 108

"real world" can be complex
display layout -- primary visual area (PVA)

Front 109

Factors for consideration for PVA

Back 109

frequency
importance
consistency
shift process/phase-related operation
organizational grouping -- procedure
clutter avoidance

Front 110

Heads - Up Display (HUD)

Back 110

advantages - keeps eyes on environment, spatial imagery enhances, enhanced depth of display "optical infinity"
Disadvantages - clutters environment, confusion, processing difficult (changing background text)

Front 111

Head Mount Display (HMD)

Back 111

similar to HUD
projects directly to one or both eyes
problems stem from binocular rivalry

Front 112

configural displays

Back 112

allows for monitoring of multiple associated events in a single display
e.g. patient monitor

Front 113

Supervisory displays

Back 113

dynamic multiple displays allowing for monitoring of situational awareness with alerts and effective control in both normal and non-routine situations

Front 114

control vs. controls

Back 114

control is an effort to produce an optimum response constrained by a given criteria or environment
controls are rules or conditions (physical or verbal) designed to return an optimal response given difficulty, speed and needed actions
KEY - user response selection

Front 115

5 design principles of response selection

Back 115

decision complexity (hick-hyman law)
response expectancy - expectancy only works if we correctly perceive the stimulus
compatibility - location and movement
speed-accuracy tradeoff
feedback - stimulate, monitor, confirmation, instantaneous vs delayed

Front 116

discrete control activation

Back 116

physical feel
size (relative)
confusion and labeling

Front 117

positioning control devices

Back 117

movement time (Fitt's law) - sensitivity (move mouse 1in and on screen moves 6cm)
device characteristics - indirect vs direct, movement, gain
task performance dependence
work space environment

Front 118

device characteristics - indirect vs direct position control

Back 118

direct - something directly attached or you move directly
indirect - move mouse on pad to move mouse on screen

Front 119

device characteristics - movement

Back 119

isotonic - free moving
isometric - resistance on levels
spring loaded - offers resistance

Front 120

device characteristics - gain

Back 120

G = change of cursor/change of control position

Front 121

Verbal and Symbolic devices

Back 121

numerical data entry - verbal vs manual
linguistic data entry - verbal vs. manual
other
character/symbol data entry

Front 122

voice input

Back 122

disadvantages - cost, confusion & limited vocab, training personnel, training software, speed/reaction/processing time, acoustic quality, noise, stress & tone change, compatibility

Front 123

software design cycle

Back 123

constant feedback loop - understanding, design, evaluation

Front 124

Understanding the System

Back 124

frequency of task performed using a particular application
mandatory vs discretionary use
knowledge of the level of the user

Front 125

Design to support mental models (4 categories)

Back 125

making invisible parts and processes visible to the users
providing feedback
building in consistency
presenting functionality through a familiar metaphor

Front 126

Dialog styles (variables with impact)

Back 126

menus - provides users with a list of items from which to choose one of many
fill-in forms - provides blank spaces for users to enter information
question - answer - provides one question at a time and user types answer in field provided
command languages
restricted natural languages
function key
direct manipulation

Front 127

design of user support

Back 127

manuals
online help systems

Front 128

usability test (reliability engineering, warranty)

Back 128

basic elements - systems engineering approach
process - inputs, controls
time delays & transport logs - calculate gain, estimate stability
metrics - effectiveness, efficiency, user satisfaction
testing, cost, interpretation

Front 129

pitfalls of usability testing

Back 129

prototypes - don't want to have to recall for more than a region. looking for free usability testing
lab based testing

Front 130

Job stress def

Back 130

the harmful physical and emotional responses that occur when the requirements of a job do not match the capabilities, resources, or needs of the worker

Front 131

Influences of job stress:

Back 131

noise
vibration
heat
light

Front 132

causes of stress

Back 132

environmental stress
psychological stress
life stress
workload overload
fatigue and sleep disruption

Front 133

environmental stressors

Back 133

motion (vibration)
thermal stress
air quality

Front 134

psychological stressors

Back 134

cognitive appraisal - say something in a positive way
ethical issues - avoid
level of arousal - level of interest

Front 135

life stress

Back 135

strategies for addressing:
keep it simple and focused
provided outlets and programs
provide counselors

Front 136

workload overload

Back 136

timelines - ID task, schedule and assign priority, task demand and resource, multiple resource
hypothetical breaking point - overload consequences
mental workload measurement - ID primary and secondary task, psychological measures (objective), subjective measures

Front 137

fatigue and sleep disorders

Back 137

vigilance & under arousal
causes of decrement - time, event salience, signal rate, arousal level
sleep disorders & disruption - circadian rhythm

Front 138

safety legislation for accidents in the workplace (6)

Back 138

1. employer negligence
2. company's argument (normal defense)
3. product liability
4. enforcement agency
5. research and recommendations
6. workman's compensation

Front 139

employer negligence

Back 139

failure to exercise a reasonable amount of care, or to carry out a legal duty so that the injury or property damage occurs to another

Front 140

Company's argument (normal defense)

Back 140

contributory negligence
fellow employee negligence
injured employee was aware and assumed risk

Front 141

product liability

Back 141

basic position - designed unsafe (inherently unsafe)
manufacturing defect
warning defect (not standardized)

Front 142

enforcement agency

Back 142

OSHA

Front 143

research and recommendations

Back 143

NIOSH, ACGIH

Front 144

Workman's Comp (Criteria)

Back 144

injury from accident/incident
incident occurred due to employment
incident occurred during employment

Front 145

Problem - Employees and Risk Taking

Back 145

basic - individuals evaluate risk by the event likelihood vs severity of injury - play on recent memory
product use - perceived risk of injury, novelty of hazard and whether exposure voluntary, familiarity of product, cost of compliance

Front 146

2 systems to support healthy behavior

Back 146

1. use performance - support systems on job
2. use training systems before job