Environmental and Psychological stress factors (chapt. 3) Flashcards Preview

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Flashcards in Environmental and Psychological stress factors (chapt. 3) Deck (29):

motion stressor

high frequency vibration, low frequency vibration,motion sickness



whole body vibration, hand and arm vibration,vibration measurement. Vibration is simple or complex oscillatory motion. Human vibration exposure is measures by its properties magnitude of acceleration, frequency,direction, and exposure time


physiological effect of vibration

each part of the human body has its own resonance frequency, therefore, it reacts differently to different frequencies. It can manifest itself as increased pulse rate or respiratory rate or more seriously as aliments of spinal muscle, and-rectal or gastro-intestinal systems.


physiological effect of vibration

The human responses to vibration depend also on which part of the body is affected there are 2 major types of human exposure to vibration: vibration transmitted to the whole body and applied to a part of the body.
Whole-body and segmental are the two major types of human exposure to vibration.


vibration measurement

vibration is simple or complex oscillatory motion. Human vibration exposure is measured by its properties:magnitude of acceleration,frequency,direction, and exposure time


vibration and performance

performance effects on eye-hand coordination, visual tasks,reading,precision tasks, low frequency vibration and motion sickness decoupling between the visual and vestibular inputs ship, airplanes, and closed cab: military tanks


vibration reduction

source control, path control, receiver control


thermal stressors

cold, heat, air quality


comfortable heat

most people feel comfortable when the air temperature is between 20 degrees C and 27 degrees C when relative humidity ranges from 35 to 60%


Thermal balance

heat exchange between the person and the environment

storage rate-is the cumulative effect of the other factors and the indicator of risk for hyperthermia

metabolic rate- is largely driven by the amount of external work performed

convection-is the net flow of heat between the skin and air, some of which may occur through clothing

radiation-is the net rate of heat flow between the person and the solid surroundings caused by infrared radiation

conduction (k)-occurs when there is direct contact between the person and a solid surface in the workplace. The contact can occur through some clothing.

evaporative cooling-is the loss of her due to evaporation of swear from the skin.


Heat stress

is the net (overall) heat burden on the body from the combination of the body heat generated while working environmental sources (air temperature, humidity, air movement, radiation from these or hot surfaces/sources) and clothing requirements.

in door, outdoor, high humidity


cold stress

hypothermia is a condition marked by abnormally low internal body temperature. it develops when body heat is lost to a cool or cold environment faster that it can be replaced.


thermal comfort

work environment climate, work demand,clothing

Factors affecting thermal comfort air temperature, humidity,thermal radiation, air movement



indirect affecting the efficiency of information processing long term effects dehydration, heat stork and exhaustion



indirect effect disruption of coordinated motor performance coordinated by hands and fingers


psychosocial stressors

perceived threat of harm loss of esteem


cognitive appraisal

fail to perceive the circumstance of risk, fail to understand the risk, overconfidence,more in control of the situation rather than the soother agents are in control


Level of arousal

stressful circumstances of anxiety and danger produce an increase in physiological arousal such as heart rate, pupil diameter, hormonal chemistry,



the concept of arousal has been a major aspect of many learning theories and is closely related to other important concepts such as anxiety, attention, attention,a nd motivation


York's Dodson Law

predicts a reverse u-shaped function between arousal motivation and performance. Across a broad range of experimental settings, it has been shown that both low and high levels of arousal produce minimum performance whereas a moderate level of arousal results in maximum performance in a test. This suggest that too little or too much stimulation tends to be ignored by individuals.

normal distribution


Performance and over-arousal

perceptual or attentional narrowing or tunneling the tendency to restrict the range or breathe of attention, to concentrate very hard on only one things and to ignore surrounding information sources.


working memory loss

under stress people appears to be less capable using working memory to store or rehears new material or to perform computation an other attention demanding mental activities.


strategic shifts

tendency to do something now speed accuracy trade off


workload and stress

stress can be imposed by having too much to do in too little time.


Timeline model

ratio of the time required (to do task) to the time available (to do them in) time required/time available



hypothetical relationship between workload imposed by task, measured by TR/AD and workload experienced and performances


Vigilance and under arousal

cause of the vigilance decrement time longer duration greater misses, event salience: Lout Bright Intermittent, Signal rate: Relatively low rate-detection reduce. Vigilance remediation not to be too long vigil tasks. fairly frequent break, more salient signals,detecting signal through payoffs


Fatigue and Steep Disruption

sleep deprivation or sleep loss:Less than 7 to 9 hours of sleep per night


circadian rhythms

are physical, mental and behavioral changes that follow a roughly 24hr cycle, responding primarily to light and darkness in an organisms environment

What disrupt the circadian rhythms
-jet lag
-shift work