slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33 PowerPoint Presentation
Download Presentation
IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33

play fullscreen
1 / 17
Download Presentation

IE 553 Engineering of Human Work Dr. Andris Freivalds Class #33 - PowerPoint PPT Presentation

pravat
93 Views
Download Presentation

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

- - - - - - - - - - - - - - - - - - - - - - - - - - - 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