16422 Workload and situation Awareness Prof, r, john hansman Acknowledgements to Mica Ensley
Interface System Supervisory Control Computer Display Control Sensors Direct Observation 16.422 Workload and Situation Awareness Prof. R. John Hansman Acknowledgements to Mica Ensley
Workload What is workload? Why is it important?
Interface System Supervisory Control Computer Display Control Sensors Direct Observation Workload ü What is workload? ü Why is it important?
Driving case: B757/767 2 or 3 person crew Prior to 767 somewhat arbitrary break at 100 seats DC-9 (2 person crew-pilot, co-pilot u B-727 3 person crew-pilot, co-pilot, flight engineer) B-757/767 Designed for 2 person Crew u Use of automation and simplified systems so minimize systems management u Use of advanced Cockpit to Increase Sa and make primary flight tasks easier Safety concerns raised by air Line Pilots Association (ALPA) 口Work|oad Off Nominal and Emergency Conditions (eg manual pressurization) O Job protection issues Workload became political and requlatory issue
Interface System Supervisory Control Computer Display Control Sensors Direct Observation Driving Case: B757/767 2 or 3 person crew ? ü Prior to 767 somewhat arbitrary break at 100 seats o DC-9 (2 person crew - pilot, co-pilot) o B-727 (3 person crew - pilot, co-pilot, flight engineer) ü B-757/767 Designed for 2 person Crew o Use of automation and simplified systems so minimize systems management o Use of Advanced Cockpit to Increase SA and make primary flight tasks easier ü Safety concerns raised by Air Line Pilots Association (ALPA) o Workload o Off Nominal and Emergency Conditions (eg manual pressurization) o Job Protection issues ü Workload became political and regulatory issue
Workload definitions? Physical Workload O Traditional view of work for manual labor u Can be measured in physical terms (ergs, joules u Limited impact of skill to minimize(ie subject variability) ·“ Mental work|oad u Often not related to physical work o Internal measure difficult to observe u Varies with task difficulty and complexity u Significant subject variability o No real consensus on what it is u Workload is a" dirty"word in Experimental Psychology Activity 口 Things that are done u Physical activity easy to measure Taskload O EXternal measure of tasks which need to be done u Can be weighted for factors such as task difficulty or complexity
Interface System Supervisory Control Computer Display Control Sensors Direct Observation Workload Definitions? ü Physical Workload o Traditional view of work for manual labor o Can be measured in physical terms (ergs, joules, ..) o Limited impact of skill to minimize (ie subject variability) ü “Mental” Workload o Often not related to physical work o Internal measure difficult to observe o Varies with task difficulty and complexity o Significant subject variability o No real consensus on what it is o Workload is a “dirty” word in Experimental Psychology ü Activity o Things that are done o Physical activity easy to measure ü Taskload o External measure of tasks which need to be done o Can be weighted for factors such as task difficulty or complexity
Yerks-Dotson law 08 0.6 0.4 02 W orkload http://www.hf.faagov/ebtraining/cognition/orkload/mental3.htm
Interface Yerks-Dotson Law System Supervisory Control Computer Display Control Sensors Direct Observation http://www.hf.faa.gov/Webtraining/Cognition/Workload/Mental3.htm
l Typical Performance vs Task load Curve Task load Helicopter observation of driver Example
Interface Curve System Supervisory Control Computer Display Control Sensors Direct Observation Typical Performance vs. Task Load Performance Task Load Helicopter Observation of Driver Example
Off nominal considerations System design often driven by off-nominal conditions 口 Emergencies 日 System Failures O Failure of the automation system Secondary task considerations Cockpit Example 日 Emergency diversion 口 Depressurization
Interface System Supervisory Control Computer Display Control Sensors Direct Observation Off Nominal Considerations ü System design often driven by off-nominal conditions o Emergencies o System Failures o Failure of the Automation system ü Secondary task considerations ü Cockpit Example o Emergency diversion o Depressurization
Workload measurement Approaches Objective Performance Approaches u Primary Task(Yerks Dodson) u Secondary Task (works well to measure saturation threshold) Concept of Spare Cognitive Capacity Objective Physiological Measures(weak) 口 Heart Rate Variability 口 Pupil Diameter 口EEGP300 J Skin Galvanic Response 口 New Imaging methods Subjective Workload Assessment Techniques 口 Formal Q Direct Query
Interface System Supervisory Control Computer Display Control Sensors Direct Observation Workload Measurement Approaches ü Objective Performance Approaches o Primary Task (Yerks Dodson) o Secondary Task (works well to measure saturation threshold) u Concept of Spare Cognitive Capacity ü Objective Physiological Measures (weak) o Heart Rate Variability o Pupil Diameter o EEG P 300 o Skin Galvanic Response o New Imaging Methods ü Subjective Workload Assessment Techniques o Formal o Direct Query
Subjective Assessment Techniques Simpson-Sheridan/ Cooper-Harper · Bedford scale Rate or perceived Exertion(RPE NASA Task Load Index(TLx) Defense Research Agency Workload Scale (DRAWS) Malvern Capacity Estimate ( MCE)
Interface System Supervisory Control Computer Display Control Sensors Direct Observation Subjective Assessment Techniques ü Simpson-Sheridan/ Cooper-Harper ü Bedford Scale ü Rate or Perceived Exertion (RPE) ü NASA Task Load Index (TLX) ü Defense Research Agency Workload Scale (DRAWS) ü Malvern Capacity Estimate (MCE)
Simpson-Sheridan Scale Modified Cooper Harper Scale for Workload
Interface System Supervisory Control Computer Display Control Sensors Direct Observation Simpson-Sheridan Scale ü Modified Cooper Harper Scale for Workload
