Term
| The 3 Types MMH Measurements and Assessments |
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Definition
Biomechanical
Physiological
Psycophysical |
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Term
| Factors Affecting Lifting Ability |
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Definition
Task: weight, height of lift; frequency of lift; load distance from body; load distance from floor (bending); load position relative to sagittal plane (twisting); C.M. of load; load dimension and characteristics; handles; lifting technique
Personal: Strength; body size; experience and knowledge of task; attitude
Environmental: Floor conditions (traction; plant); vibration; illumination; heat and cold
Management: frequency and length of rest breaks; variability of tasks= job rotation or enrichment; overtime
Psychosocial: attitude to work; interaction with co-workers |
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Term
| Most efficient lift range and weight |
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Definition
40-60 inches off floor
40 lbs |
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Term
| What are some scientific guides for protection from injury? |
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Definition
NIOSH Equation
The Job Severity Index (Texas Tech) |
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Term
| What are the Biomechanical limitations for lifting? |
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Definition
*Below 3400 N is safe
*3400-6400 N compression is considered a range within which injury is likely
*6400 N of compressive forces on the L5/S1 is considered dangerous |
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Term
| What are the Psychophysical limitations for lifting? |
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Definition
| MAL- Maximum acceptable lifting weight a worker is willing to lift and is capable of lifting for a shit, at work |
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Term
| What are the Metabolic limitations for lifting? |
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Definition
*9.5 kcal/min for 8-hr job
*50% of the persons PWC for 1-hr
*40% for 1-2 hours
* 33% for 2-8 hours |
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Term
| What is the NIOSH equation? |
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Definition
| The equation gives the recommended weight limit for lifting based on the task conditions based on 6 variables and a constant based on perfect conditions. |
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Term
| What variables are used in the NIOSH equation? |
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Definition
*The distance of the person from the load
*The height of the object at the start of the lift
*The vertical range of the lift
*The amount the upper body is twisted (rotated)
*The frequency-duration-range of lift combination
*How good the hand-handle coupling is |
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Term
| Compute the Lifting Index (LI)? |
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Definition
LI = L/RWL
(Load of weight)
(Recommended Weight Limit)
LI > 3.0 the work is at great risk |
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Term
| What position should be maintained for the wrist in hand tool use? |
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Definition
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Term
| What hand disorders can result from unnatural wrist and forearm positions? |
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Definition
| Tendinitis; tenosynovitis; CTS; epicondylitis |
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Term
| What are some precautions of Hand-Tool use? |
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Definition
*Muscular Force: Avoid large hand grip or finger forces to activate tool
*Wrist bending: Design handle angle such that a person minimizes bending of the wrist
*Repetition: Design for mechanical/electrical power instead of muscular power.
*Avoid vibration as much as possible, especially in the range 5-140Hz
*Tissue compression from sharp edges should be avoided |
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Term
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Definition
| the formation of a blood clot (thrombus) inside a blood vessel, obstructing the flow of blood through the circulatory system |
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Term
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Definition
Frequency
Duration
Intensity |
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Term
| What are the major factors of workplace design? |
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Definition
*Work equipment and muscular effort
*Work Posture -work height, workspace, work surface area
*Work task design
*Environmental variables |
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Term
| What are the 4 principles of work area design? |
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Definition
*Importance
*Frequency of Use
*Sequence of Use
*Function |
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Term
| Importance Principle of Work Area |
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Definition
| Put most important and work items in most visible and accessible areas |
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Term
| Sequence of Use Principle of Work Area |
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Definition
| The sequential arrangement of equipment should correspond to the sequence of use |
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Term
| Functional principle of work area? |
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Definition
| Equipment that are functionally related should be placed near to each other |
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Term
| Frequency of use principle of work area |
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Definition
| Equipment that are most frequently used should be placed in most accessible areas |
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Term
| What are the different Work Postures |
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Definition
Sit
Stand
Sit-stand
Kneel
Lying down
Variable |
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Term
| When and why would you use sitting posture? |
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Definition
*To prevent muscle fatigue
*To maintain body stability/arm positions
*When worker must use foot controls
*When fine assembly, writing and precision hand work are required
*When the hands will not work at more than 6 in above work surface
*When work period is long |
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Term
| When and why would you use Standing posture? |
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Definition
*Work periods are not lengthy and muscular fatigue is not a problem
*Mobility of the body is required
*Great manual forces are required and objects above 10lb are handles frequently
*When fine assembly, writing and precision hand work are required
*High, low or extended reaching is frequent |
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Term
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Definition
| The reduction of uncertainty |
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Term
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Definition
| The amount of information uncertainty required to decide between two equally likely alternatives |
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Term
| What is the principle of Hick-Hyman's Law? |
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Definition
| The choice reaction time is a linear function of the number of bits of information in the stimulus |
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Term
| What's the difference between Direct and Indirect sensing? |
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Definition
Direct- such as by direct observation of an airplane
Indirect - through some intervening mechanism such as radar or telescope |
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Term
| What is the difference between coded and reproduced stimuli? |
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Definition
Coded stimuli- visual or auditory displays
Reproduced stimuli- such as those presented by TV, radio, or photographs or through such devices as microscopes, microfilm viewers, binoculars, and hearing aids |
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Term
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Definition
| Any indirect method (stimuli) of presenting information |
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Term
|
Definition
*Static or Dynamic
*Quantitative or Qualitative
*Status Information- speeding zone on a speedometer; closed/open sign; etc
*Warnings and signals
*Representational Information-photos; maps; graphs; etc.
*Identification displays-color-codes pipes; slippery road sign; etc.
*Alphanumeric and symbolic - textbook material; braille; etc.
*Time-phased-Morse code; blinker light; etc. |
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Term
| Under what conditions are auditory display better than visual display? |
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Definition
When the message is:
*Simple
*Short
*Not to be referred to later
*Time sequenced
*Of emergency type
*Vision is overburdened
*Brightness and glare present visual problems
*Movement (of person) is necessary |
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Term
| How do you identify a display? |
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Definition
Identification of code depends on identification of its position along a dimension
* a dimension of sound is frequency and a position is HZ value
*a dimension of a visual display is color and positions are red, blue, etc. |
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Term
| What is the difference between absolute and relative judgments? |
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Definition
Absolute judgments along single dimension: ex: Identifying without actually comparing, except in memory- identifying an aircraft as a military one
Relative judgments: compare stimuli and judge positions along a dimension: compare two sounds to determine the louder one |
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Term
| How many single-dimension identifications can be made on an absolute basis? |
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Definition
| People can make about 7+_2 identifications on absolute basis |
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Term
| How many pairs of sounds differing in tone pitches can people discriminate (relatively)? |
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Definition
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Term
| How many pairs of sounds can be identified (absolute basis)? |
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Definition
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Term
| When do we display information? |
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Definition
When sensing is inadequate, because stimulus is:
*Blow threshold
*Too large
*Embedded in excessive noise
*Removed or obstructed
*Sensed with low precision
*To be stored
*Convertible |
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Term
| What is the difference between orthogonal and redundant coding? |
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Definition
Orthogonal coding-Value of one dimension independent of another; eg. if color and shape are combined orthogonally then a red square would signify something different from a green square or red circle
Redundant coding- Knowing the value of one dimension helps predict the value of the other dimension; eg. we may have shapes such that all circles are red, all squares are green, all triangles are amber, etc. |
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Term
| What are the 5 main display modalities? |
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Definition
Visual
Auditory
Tactual
Olefactory
Taste |
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Term
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Definition
| Th ability of the eyes to differentiate between the detailed features of what we see |
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Term
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Definition
| The ability of the 2 eyes to position the object (being viewed) at corresponding positions so that the 2 images are fused |
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Term
| What is color discrimination? |
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Definition
| cone cells in retina are responsible |
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Term
| What is visual accommodation? |
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Definition
| the adjustment of the lens of the eyes to focus images sharply on the retina |
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Term
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Definition
(short-sightedness)
Difficulty in seeing sharply at far distances but not close up |
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Term
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Definition
(Farsightedness)
Difficulty in seeing close up but not at far distances |
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Term
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Definition
| measures the detail that can be seen as the angle the target makes with the eye. |
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Term
| Which pairs of colors get confused? |
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Definition
Red and Green
Blue and yellow |
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Term
| What cells are responsible for daytime vision? |
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Definition
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Term
| What cells are responsible for color discrimination? |
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Definition
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Term
| What are some conditions that affect visual discrimination or acuity? |
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Definition
Luminance contrast
Time: discrimination increases with viewing time
Glare:Discomfort glare; disability glare; blinding glare
Movement: decreases the threshold of visual acuity (dynamic visual acuity). Acuity decreases rapidly beyond 60deg/sec
Personal factors:Age
Perception
Adaptation
Color Discrimination |
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Term
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Definition
| The ratio of the amount of light reflected (luminance) by a surface to the amount striking the surface (illuminance) is called the reflectance of the surface |
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Term
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Definition
| the amount of light reflected by a surface |
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Term
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Definition
| the amount of light striking a surface |
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Term
| What is the effect of age on contrast or color discrimination? |
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Definition
| Presbyopia occurs. Lens becomes discolored and less flexible, so light intensity must increase and more time must be allowed for refocusing |
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Term
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Definition
Ability to adapt to different levels of light intensity so the eye retina is not overexposed or underexposed.
Time for adapting from light to dark is abut 30 minutes or more. Time for dark to light varies from a few seconds to about 2 minutes |
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Term
| How do you calculate visual acuity using visual angle? |
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Definition
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Term
|
Definition
| Glare is produced by brightness within the field of vision that is sufficiently greater than the luminance to which the eyes are adapted so as to cause annoyance, discomfort or loss in visual performance and visibility |
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Term
| What is the difference between direct glare and reflected glare? |
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Definition
Direct glare is caused by light sources in the field of view
Reflected glare is caused by light being reflected by a surface in the field of view.
(Specular)-from a smooth polished, mirror-like surface |
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Term
| What are glares effects on the observer? |
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Definition
Discomfort glare produces discomfort, but does not necessarily interfere with visual performance or visibility
Disability glare reduces visual performance and visibility and oftern is accompanied by discomfort
Blinding glare is so intense that for a appreciable length of time after it has been removed no object can be seen |
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Term
| Explain the difference between visibility, readability, and legibility |
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Definition
Visibility: Targets detectable from surroundings
EX-You can see a plane in the sky
Legibility: targets identifiable from others
EX- You can tell if one plane is military and the other isn't
Readability: recognition and meaningfulness
EX- You can tell the model of the plane |
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Term
| HF criteria for good visual displays |
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Definition
Visibility
Legibility
Readability
Conspicuous
Emphasis
Maintainability
Standardization |
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Term
| Conditions that affect visual discrimination |
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Definition
Luminance Contrast
Amount of Illumination
Time
Luminance Ratio
Glare
Combinations of variables
Movement
Age and Vision
Perception |
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Term
| What factors affect visibility, readability and legibility of text? |
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Definition
This refers to TYPOGRAPHY
*Stroke width-ratio of stroke thickness to character height
*Width to height ratio
*Styles of type (font) |
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Term
| Important Principles of symbolic design |
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Definition
*Figure/Ground - clear and stable
*Figure boundaries - solids often better than outlines
*Closure-enhances perceptual processes relative to discontinuous outlines
*Simplicity
*Unity- Symbols should be unified; e.g. a solid figure should be within an outline, and not outside it |
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Term
| What does HF research say about the use of aircraft, geometric, military and color coding? Compare their usefulness |
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Definition
1-Colors
2-Military Symbols
3-Geometric Shapes
4-Aircraft Shapes |
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Term
| What are the 4 main uses of dynamic displays? |
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Definition
To present:
Quantitative
Qualitative
Status
and Representational information |
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Term
| What are the 3 types of quantitative displays? |
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Definition
Fixed scale with moving pointer
Moving scale with fixed pointer
Digital display |
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Term
| Important features of quantitative displays |
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Definition
*Numeric Progressions of Scales (1s and 5s most common)
*Length of Scale Unit
*Design of Scale Markers
*Scale Markers and Interpolation
*Design of Pointers
*Combining Scale Features
*Scale Size and Viewing Distance |
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Term
| Compare digital and analog scales |
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Definition
Digital advantages:
1)a precise numeric value is required
2)the values presented remain visible long enough to be read
Disadvantages:
1)When the values are subject to frequent or continual change
2)when important to observe the direction or rat of the change of the values presented. |
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Term
| What do qualitative displays depict? |
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Definition
Approximate values
Trends
Rates of Change |
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Term
| What are the quantitative bases for qualitative data? |
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Definition
1) Determine status or condition of a variable
EX: such as determining if the temperature gauge of an automobile is col, normal, or hot
2) Maintain Desired Range
EX: such as maintaining a driving speed between 50 and 55mi/h
3) Observing trends/rates of change
EX: such as noting the rate of change in altitude of an airplane) |
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Term
| What factors influence detectability of signal and warning lights? |
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Definition
*Size
*Luminance
*Exposure Time
*Color-consider background color
*Flash rate
*Background lights |
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Term
| Recommendations regarding signal and warning lights |
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Definition
When to use?--To warn of dangerous conditions
How many to use?--One ideally
Steady state or Flashing?--Flashing for extreme emergency since it is distracting
Flash Rate?--3-10/sec (4 best) at equal intervals of light and dark
Warning light intensity?--Light should be at least twice as bright as the immediate surroundings
Location?--Within 30 deg of the normal line of sight
Color?--Red |
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Term
| What are the 4 different decisions that are made according to the signal detection theory? |
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Definition
Hit
False Alarm
Miss
Correct Rejection |
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Term
| When a decision is made b a conservative decision maker according to SDT what happens? |
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Definition
The miss rate is minimized
The hits are maximized
False Alarms are increased |
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Term
| Human Error Classification according to IE |
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Definition
1. Engineering Classifications - assumes that errors are from discrete action
*Error of omission
*Error of commission
*Sequence error
*Timing Error
*Extraneous act |
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Term
| Human Error Classification according to the stimulus-organism-response (S-O-R) |
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Definition
2. Information processing classification
*Human error may be viewed as a break in the (S-O-R) chain (as input, mediation, or output error)
*Failure to perceive stimulus
*Inability to discriminate among various stimuli
*Misinterpretation of meaning of stimulus
*Not knowing correct response to stimulus
*Physical inability to make response
*Responding out of sequence |
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Term
| What is the difference between iconic and echoic storage? |
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Definition
Iconic storage is the visual system (1 sec)
Echoic storage is the auditory system (a few sec) |
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Term
| How is information in working memory coded? |
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Definition
1. Visual
2. Phonetic
3. Semantic
*Visual word DOG is phonetically coded as sound
*Hearing the word DOG you could generate visual code (picture)
*Semantic codes are abstract representations of the meaning of a stimulus rather than the sight or sound generated by the stimulus |
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Term
|
Definition
Sensory Storage
Working (short term)
Long Term |
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Term
| Explain the difference between selective, focused, and divided attention |
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Definition
Selective A- Monitor several sources of information and determine whether the even has occurred
Focused A- Attend to one source of information and exclude all others
Divided A- pay attention to 2 or more tasks, performed simultaneously (multi-tasking; time sharing) |
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Term
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Definition
Ex: A person monitoring a switch board
Ex: Someone doing air traffic controlling
1) Use as few channels as possible
2)Train Subject to scan optimally
3)Place visual channel close Together |
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Term
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Definition
Ex: When a male and female are speaking you focus on one or the other
Ex: When two people are talking at different volumes you focus on the louder one
1) Have distinction in competing channels
2) Separate competing channels |
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Term
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Definition
Ex: Talking on the phone and playing video games
Ex: Listening to music and watching tv
1) Minimize the number of potential tasks
2) Let the subject know relative priorities of tasks
3)Lower the difficulty levels of the tasks |
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Term
| We give more weight to early information |
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Definition
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Term
| We do not extract enough information as we should |
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Definition
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Term
| Odds are not assessed as extreme, as they should be |
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Definition
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Term
| We increase our confidence, but not necessarily our accuracy, with more information |
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Definition
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Term
| We seek more information than we can absorb |
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Definition
|
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Term
| WE treat all information equally reliably |
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Definition
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Term
| We cannot entertain more than 3 or 4 hypotheses at a time |
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Definition
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Term
| We consider only a few attributes at a time |
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Definition
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Term
| We choose information supporting a chosen course of action |
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Definition
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Term
| A potential loss is viewed with greater influence than a gain of similar amount |
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Definition
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Term
| We believe that mildly positive outcomes are more likely than mildly negative ones; highly positive outcomes are more likely than mildly positive ones; and highly negative ones are less likely than mildly negative ones |
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Definition
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Term
| Computer aided decision making can help eliminate biases |
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Definition
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