Stress and Workload Chapter 13

Overview of Stressors Psychological Threat Threat Anxiety Anxiety Fatigue Fatigue Frustration Frustration Anger Anger Environment Noise Noise Heat Heat Cold Cold Vibration Vibration Dim lighting Dim lighting

Stressor Effects

Environmental Stressors Motion Stress Motion Stress –Vibration – VWF & precision effects –Motion Sickness – decoupling between visual & vestibular inputs Thermal Stress Thermal Stress –Normal hot & cold (between 79F & 73F in summer and between 75F & 68F in winter). Assumes 60% humidity at higher temp and 85% humidity at lower temp. –Three moderating factors – body temperature, air movement, and metabolic activity. Air Quality Air Quality

Psychological Stressors Cognitive Appraisal – Awareness of situation Cognitive Appraisal – Awareness of situation Level of Arousal – Level of concern for situation which depends on accurate appraisal and skill for dealing with situation Level of Arousal – Level of concern for situation which depends on accurate appraisal and skill for dealing with situation Performance Changes with Over-arousal – make more mistakes, unsafe actions, lower productivity, poor judgment Performance Changes with Over-arousal – make more mistakes, unsafe actions, lower productivity, poor judgment Remediation of Psychological Stress – Simplify situational elements, actions to be taken based as little as possible on working memory, specific training, & generic emergency stress management training Remediation of Psychological Stress – Simplify situational elements, actions to be taken based as little as possible on working memory, specific training, & generic emergency stress management training

Life Stress Poor working conditions, inequitable wages, personal situations such as death, illness, financial, relationships, etc. Poor working conditions, inequitable wages, personal situations such as death, illness, financial, relationships, etc. All can lead to distractions, inattention, and poor productivity. All can lead to distractions, inattention, and poor productivity.

Work Overload, Under- load, & Sleep Disruptions

Time Line Model

Task Variability

Time Stress Effects

Remediation Task redesign Task redesign Assign some tasks to co-workers Assign some tasks to co-workers Automation Automation Training Training –Training on component tasks to decrease completion times –Training on task management skills

Other Remediation

Mental Workload Measurement Primary Task Measures – speed & accuracy of performance Primary Task Measures – speed & accuracy of performance Secondary Task Measures - Measure of reserve capacity. Assumes performance of primary tasks have reserve capacity which allows concurrent performance of secondary tasks. Secondary Task Measures - Measure of reserve capacity. Assumes performance of primary tasks have reserve capacity which allows concurrent performance of secondary tasks. Psychological Measures - heart rate variability Psychological Measures - heart rate variability Subjective Measures - asking operator to rate Subjective Measures - asking operator to rate Workload Dissociations – sometimes primary task performance will improve, but other workload measures will increase Workload Dissociations – sometimes primary task performance will improve, but other workload measures will increase

Mental Workload Effects High mental workload – fatigue High mental workload – fatigue Vigilance & under-arousal Vigilance & under-arousal –Time –Event salience –Signal rate –Arousal level –Remediation – signal enhancement or generating false signals

Sleep Deprivation Not enough sleep – Not enough sleep – –Staying up to late the night before –Long work shifts –Inability to sleep well –Remediation – get more sleep or power naps Disrupted circadian rhythms Disrupted circadian rhythms –Constant shift changes –Jet lag –Remediation – make periods between shift changes longer

Performance Measures Over One 24 hr Circadian Cycle

Desynchronization Shift Work – strategies Shift Work – strategies –Assign workers permanently to a shift –Assign workers to random shifts (ship watch) –Rotate shifts on 14 – 21 day schedule (best) Jet Lag Jet Lag –Worse for east bound flights –Remediation – try to wait until local bed-time (west bound) or expose yourself to intense light until local bed-time (east bound)

Jet Lag