# Shared Flashcard Set

## Details

Human Factors Final
Final
97
Engineering
05/09/2010

Term
 The 3 Types MMH Measurements and Assessments
Definition
 Biomechanical Physiological Psycophysical
Term
 Factors Affecting Lifting Ability
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 techniquePersonal: Strength; body size; experience and knowledge of task; attitudeEnvironmental: Floor conditions (traction; plant); vibration; illumination; heat and coldManagement: frequency and length of rest breaks; variability of tasks= job rotation or enrichment; overtimePsychosocial: attitude to work; interaction with co-workers
Term
 Most efficient lift range and weight
Definition
 40-60 inches off floor40 lbs
Term
 What are some scientific guides for protection from injury?
Definition
 NIOSH EquationThe Job Severity Index (Texas Tech)
Term
 What are the Biomechanical limitations for lifting?
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
Term
 What are the Psychophysical limitations for lifting?
Definition
 MAL- Maximum acceptable lifting weight a worker is willing to lift and is capable of lifting for a shit, at work
Term
 What are the Metabolic limitations for lifting?
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
Term
 What is the NIOSH equation?
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.
Term
 What variables are used in the NIOSH equation?
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
Term
 Compute the Lifting Index (LI)?
Definition
 LI = L/RWL (Load of weight)(Recommended Weight Limit)LI > 3.0 the work is at great risk
Term
 What position should be maintained for the wrist in hand tool use?
Definition
 Neutral
Term
 What hand disorders can result from unnatural wrist and forearm positions?
Definition
 Tendinitis; tenosynovitis; CTS; epicondylitis
Term
 What are some precautions of Hand-Tool use?
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
Term
 What is Thrombosis?
Definition
 the formation of a blood clot (thrombus) inside a blood vessel, obstructing the flow of blood through the circulatory system
Term
 Causes of Injury
Definition
 FrequencyDurationIntensity
Term
 What are the major factors of workplace design?
Definition
 *Work equipment and muscular effort*Work Posture -work height, workspace, work surface area*Work task design*Environmental variables
Term
 What are the 4 principles of work area design?
Definition
 *Importance*Frequency of Use*Sequence of Use*Function
Term
 Importance Principle of Work Area
Definition
 Put most important and work items in most visible and accessible areas
Term
 Sequence of Use Principle of Work Area
Definition
 The sequential arrangement of equipment should correspond to the sequence of use
Term
 Functional principle of work area?
Definition
 Equipment that are functionally related should be placed near to each other
Term
 Frequency of use principle of work area
Definition
 Equipment that are most frequently used should be placed in most accessible areas
Term
 What are the different Work Postures
Definition
 SitStandSit-standKneelLying downVariable
Term
 When and why would you use sitting posture?
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
Term
 When and why would you use Standing posture?
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
Term
 What is information?
Definition
 The reduction of uncertainty
Term
 What is a Bit?
Definition
 The amount of information uncertainty required to decide between two equally likely alternatives
Term
 What is the principle of Hick-Hyman's Law?
Definition
 The choice reaction time is a linear function of the number of bits of information in the stimulus
Term
 What's the difference between Direct and Indirect sensing?
Definition
 Direct- such as by direct observation of an airplaneIndirect - through some intervening mechanism such as radar or telescope
Term
 What is the difference between coded and reproduced stimuli?
Definition
 Coded stimuli- visual or auditory displaysReproduced stimuli- such as those presented by TV, radio, or photographs or through such devices as microscopes, microfilm viewers, binoculars, and hearing aids
Term
 Define Display
Definition
 Any indirect method (stimuli) of presenting information
Term
 Types of Displays
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.
Term
 Under what conditions are auditory display better than visual display?
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
Term
 How do you identify a display?
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.
Term
 What is the difference between absolute and relative judgments?
Definition
 Absolute judgments along single dimension: ex: Identifying without actually comparing, except in memory- identifying an aircraft as a military oneRelative judgments: compare stimuli and judge positions along a dimension: compare two sounds to determine the louder one
Term
 How many single-dimension identifications can be made on an absolute basis?
Definition
 People can make about 7+_2 identifications on absolute basis
Term
 How many pairs of sounds differing in tone pitches can people discriminate (relatively)?
Definition
 1800
Term
 How many pairs of sounds can be identified (absolute basis)?
Definition
 5
Term
 When do we display information?
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
Term
 What is the difference between orthogonal and redundant coding?
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 circleRedundant 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.
Term
 What are the 5 main display modalities?
Definition
 VisualAuditoryTactualOlefactoryTaste
Term
 What is visual acuity?
Definition
 Th ability of the eyes to differentiate between the detailed features of what we see
Term
 What is convergence?
Definition
 The ability of the 2 eyes to position the object (being viewed) at corresponding positions so that the 2 images are fused
Term
 What is color discrimination?
Definition
 cone cells in retina are responsible
Term
 What is visual accommodation?
Definition
 the adjustment of the lens of the eyes to focus images sharply on the retina
Term
 What is visual myopia?
Definition
 (short-sightedness) Difficulty in seeing sharply at far distances but not close up
Term
 What is Hyperopia?
Definition
 (Farsightedness) Difficulty in seeing close up but not at far distances
Term
 What is visual angle?
Definition
 measures the detail that can be seen as the angle the target makes with the eye.
Term
 Which pairs of colors get confused?
Definition
 Red and GreenBlue and yellow
Term
 What cells are responsible for daytime vision?
Definition
 Cones
Term
 What cells are responsible for color discrimination?
Definition
 Cones
Term
 What are some conditions that affect visual discrimination or acuity?
Definition
 Luminance contrastTime: discrimination increases with viewing timeGlare:Discomfort glare; disability glare; blinding glareMovement: decreases the threshold of visual acuity (dynamic visual acuity). Acuity decreases rapidly beyond 60deg/secPersonal factors:AgePerceptionAdaptationColor Discrimination
Term
 What is reflectance?
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
Term
 What is luminance?
Definition
 the amount of light reflected by a surface
Term
 What is Illuminance?
Definition
 the amount of light striking a surface
Term
 What is the effect of age on contrast or color discrimination?
Definition
 Presbyopia occurs. Lens becomes discolored and less flexible, so light intensity must increase and more time must be allowed for refocusing
Term
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
Term
 How do you calculate visual acuity using visual angle?
Definition
 1/VA
Term
 Explain glare
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
Term
 What is the difference between direct glare and reflected glare?
Definition
 Direct glare is caused by light sources in the field of viewReflected glare is caused by light being reflected by a surface in the field of view.(Specular)-from a smooth polished, mirror-like surface
Term
 What are glares effects on the observer?
Definition
 Discomfort glare produces discomfort, but does not necessarily interfere with visual performance or visibilityDisability glare reduces visual performance and visibility and oftern is accompanied by discomfortBlinding glare is so intense that for a appreciable length of time after it has been removed no object can be seen
Term
 Explain the difference between visibility, readability, and legibility
Definition
 Visibility: Targets detectable from surroundingsEX-You can see a plane in the skyLegibility: targets identifiable from othersEX- You can tell if one plane is military and the other isn'tReadability: recognition and meaningfulness EX- You can tell the model of the plane
Term
 HF criteria for good visual displays
Definition
Term
 Conditions that affect visual discrimination
Definition
 Luminance ContrastAmount of IlluminationTimeLuminance RatioGlareCombinations of variablesMovementAge and VisionPerception
Term
 What factors affect visibility, readability and legibility of text?
Definition
 This refers to TYPOGRAPHY *Stroke width-ratio of stroke thickness to character height*Width to height ratio*Styles of type (font)
Term
 Important Principles of symbolic design
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
Term
 What does HF research say about the use of aircraft, geometric, military and color coding? Compare their usefulness
Definition
 1-Colors2-Military Symbols3-Geometric Shapes4-Aircraft Shapes
Term
 What are the 4 main uses of dynamic displays?
Definition
 To present:QuantitativeQualitativeStatusand Representational information
Term
 What are the 3 types of quantitative displays?
Definition
 Fixed scale with moving pointerMoving scale with fixed pointerDigital display
Term
 Important features of quantitative displays
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
Term
 Compare digital and analog scales
Definition
 Digital advantages: 1)a precise numeric value is required2)the values presented remain visible long enough to be readDisadvantages: 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.
Term
 What do qualitative displays depict?
Definition
 Approximate valuesTrendsRates of Change
Term
 What are the quantitative bases for qualitative data?
Definition
 1) Determine status or condition of a variableEX: such as determining if the temperature gauge of an automobile is col, normal, or hot2) Maintain Desired Range EX: such as maintaining a driving speed between 50 and 55mi/h3) Observing trends/rates of changeEX: such as noting the rate of change in altitude of an airplane)
Term
 What factors influence detectability of signal and warning lights?
Definition
 *Size*Luminance*Exposure Time*Color-consider background color *Flash rate*Background lights
Term
 Recommendations regarding signal and warning lights
Definition
 When to use?--To warn of dangerous conditionsHow many to use?--One ideallySteady state or Flashing?--Flashing for extreme emergency since it is distractingFlash Rate?--3-10/sec (4 best) at equal intervals of light and darkWarning light intensity?--Light should be at least twice as bright as the immediate surroundingsLocation?--Within 30 deg of the normal line of sightColor?--Red
Term
 What are the 4 different decisions that are made according to the signal detection theory?
Definition
 HitFalse AlarmMissCorrect Rejection
Term
 When a decision is made b a conservative decision maker according to SDT what happens?
Definition
 The miss rate is minimizedThe hits are maximizedFalse Alarms are increased
Term
 Human Error Classification according to IE
Definition
 1. Engineering Classifications - assumes that errors are from discrete action*Error of omission*Error of commission*Sequence error*Timing Error*Extraneous act
Term
 Human Error Classification according to the stimulus-organism-response (S-O-R)
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
Term
 What is the difference between iconic and echoic storage?
Definition
 Iconic storage is the visual system (1 sec)Echoic storage is the auditory system (a few sec)
Term
 How is information in working memory coded?
Definition
 1. Visual2. Phonetic3. 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
Term
 Memory Subsystems
Definition
 Sensory StorageWorking (short term)Long Term
Term
 Explain the difference between selective, focused, and divided attention
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 othersDivided A- pay attention to 2 or more tasks, performed simultaneously (multi-tasking; time sharing)
Term
 Selective Attention
Definition
 Ex: A person monitoring a switch boardEx: Someone doing air traffic controlling1) Use as few channels as possible2)Train Subject to scan optimally3)Place visual channel close Together
Term
 Focused Attention
Definition
 Ex: When a male and female are speaking you focus on one or the otherEx: When two people are talking at different volumes you focus on the louder one1) Have distinction in competing channels2) Separate competing channels
Term
 Divided Attention
Definition
 Ex: Talking on the phone and playing video gamesEx: Listening to music and watching tv1) Minimize the number of potential tasks2) Let the subject know relative priorities of tasks3)Lower the difficulty levels of the tasks
Term
 We give more weight to early information
Definition
 T/F
Term
 We do not extract enough information as we should
Definition
 T/F
Term
 Odds are not assessed as extreme, as they should be
Definition
 T/F
Term
 We increase our confidence, but not necessarily our accuracy, with more information
Definition
 T/F
Term
Definition
 T/F
Term
 WE treat all information equally reliably
Definition
 T/F
Term
 We cannot entertain more than 3 or 4 hypotheses at a time
Definition
 T/F
Term
 We consider only a few attributes at a time
Definition
 T/F
Term
 We choose information supporting a chosen course of action
Definition
 T/F
Term
 A potential loss is viewed with greater influence than a gain of similar amount
Definition
 T/F
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
Definition
 T/F
Term
 Computer aided decision making can help eliminate biases
Definition
 T/F
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