1 / 17

IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33

IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33. IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33. Cognitive Workload & Physiological Strain. Overload causes: Arousal Physiological strain ↑ accident rates ↑ absenteeism ↑ stress. Yerkes-Dodson Law.

pravat
Download Presentation

IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33 IE 553

  2. IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33 IE 553

  3. Cognitive Workload & Physiological Strain • Overload causes: • Arousal • Physiological strain • ↑ accident rates • ↑ absenteeism • ↑ stress Yerkes-Dodson Law • Sympathetic stimulation (“flight or fight”) • Physiological strain ≈ cognitive performance IE 553

  4. Physiological Strain Indices • Adrenaline (↑) – blood tests? • Heart rate (↑, ↓ variability) • Blood pressure (↑) • Sweating (↑) • Galvanic skin response (↑) • Respiration rate (↑rate but shallower) • Tremor amplitude (↑) and frequency (↓) • Electroencephalogram (EEG) IE 553

  5. Heart Rate • Direct recording of EKG • Use QRS complexes for instantaneous rate • Which ↑ with stress • Or examine variability (sinus arrhythmia) • Which ↓ with stress IE 553

  6. Sinus Arrhythmia • Simple variance (σ2 or σ) • SABS (Sum of absolute differences) = ∑|xi – xi-1| • # Reversal points (NR) • S/N Index = SABS/NR • Blood Pressure – Cumbersome, measuring ↑ IE 553

  7. Galvanic Skin Response (GSR) • (Electrodermal response) • (Skin conductance response) • Related to sweating (insensible, hard to measure) • Depends on humidity • Basal skin resistance • Sudden changes due: • Stress - Arousal • Fear - Emotions • Workload IE 553

  8. GSR – Wheatstone Bridge • By C. Wheatstone in 1843 • Bridge circuit, when balanced • Current through Rg = 0, or V=0 • Then R2/R1 = Rx/R3 • Find unknown Rx by • Adjusting R2 so that V=0 • Very high precision IE 553

  9. GSR – Galvanometer • Instrument for measuring electrical current • Current in transducer produces rotary deflection IE 553

  10. Respiration Rate & Depth • Strain gauge pneumograph • Elastic belt • Stiff leaf spring • Strain gauges • Wheatstone bridge • Analog voltage output • ↓ tidal volume • ↑ frequency IE 553

  11. Physiological Tremor • Forearm pointing task • Potentiometer at elbow 1) Move to lighted target 2) Point & hold • Record & analyze 1) Analog amplitude 2)FFT of digitized signal to get mean frequency IE 553

  12. Electroencephalography (EEG) • Electrical activity of brain (≈ EMG) • Electrodes on scalp (number?, hair?) • Spontaneous activity • Evoked potentials – response to stimuli • Spurious Kappa waves from eyelids IE 553

  13. Types of EEG Waves IE 553

  14. Levels of Consciousness IE 553

  15. EEG Waves and States • Delta (4 Hz) = young, sleep • Theta (4-8 Hz) = drowsiness, hypnosis • Alpha (8-12 Hz) = relaxed but alert state, but eyes closed • Beta (12-30 Hz) = active concentration, thinking, busy, eyes open • Gamma (>30 Hz) = higher mental activity, problem solving, IE 553

  16. Delta Alpha EEG Analysis • Frequency spectrum • Amplitude analysis • Problems: • Source? • EEG vs. EMG • # Electrodes • Complexity IE 553

  17. Conclusions • Applications • Biofeedback • Polygraph testing • Scientology, E-meter = GSR • Poor reputation and problems? • Extraneous influences and artifacts • What are you really measuring? • Voluntary control? IE 553

More Related