Stress and Workload

1. Stress and Workload Chapter 13

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

3. Stressor Effects

4. Environmental Stressors • Motion Stress • Vibration – VWF & precision effects • Motion Sickness – decoupling between visual & vestibular inputs • 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

6. Psychological Stressors • Cognitive Appraisal – Awareness of 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 • 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

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

8. Work Overload, Under-load, & Sleep Disruptions

9. Time Line Model

10. Task Variability

11. Time Stress Effects

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

13. Other Remediation

14. Mental Workload Measurement • 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. • Psychological Measures - heart rate variability • Subjective Measures - asking operator to rate • Workload Dissociations – sometimes primary task performance will improve, but other workload measures will increase

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

16. Sleep Deprivation • 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 • Constant shift changes • Jet lag • Remediation – make periods between shift changes longer

17. Performance Measures Over One 24 hr Circadian Cycle

18. Desynchronization • 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 • 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)

19. Jet Lag