Workload and Performance Yerkes-Dobson law Low arousal  ________________ Moderate arousal  ____________ Overarousal  _______________ ISE

Workload OverloadUnderload Measures Time req’d / Time avail. (TR/TA) Primary task measure Secondary task measures Physiological Measures Subjective Measures TR/TA signal detection task performance Effects Fatigue Performance decrement Workload disassociation Future performance Fatigue Vigilance decrement Future performance Remediation Automation Task sharing Training (performance, task management) Reduce length of vigil, increase rest breaks Signal enhancement Increase level of arousal ISE

Workload Measures Time required / Time available (TR/TA) ratio Based on task analysis Percentage computed per time unit on task timeline Useful predictor, but difficult to construct Primary task measures measure the influence of mental workload Secondary task methods measure the reserve capacity Physiological measures allow non-intrusive measures Subjective measures SWAT, TLX, etc. ISE FUNCTIONAL MENTAL

An example using NASA TLX Form two teams. Each team will follow the instructions given to you. You have 1 minute to complete the task. The team that comes closest to completing their task with the fewest errors will “win.” ISE

Relative workload scores: Enter your workload scores below: What does this say about the relative workload of the two tasks? What does this say about the subjective nature of the workload scores? ISE

Dynamic Decisions Flow of dependent situations Also applicable to emergency response Each decision shapes the options and utilities for the next decision ISE From: Gonzalez, C. (2014) Dynamic Decision Making: Implications for Recommender System Design.

Situation Awareness Having a complete and accurate mental model of the situation. Knowing what to do next. Anticipating the responses to the control actions. Afforded by the right controls & displays. ISE

SA includes three processes: The perception of what is happening (Level 1) The understanding of what has been perceived (Level 2) The use of what is understood to think ahead (Level 3). ISE PERCEIVE (gather data) UNDERSTAND (create mental model) THINK AHEAD (update the model) Understanding the situation triggers decision making, action, and review

Principles Organize around the operator’s major goals Present information directly (smart display) Assistance for system projections (predictive) Display global system status Support global-local trade-offs Support perception-action schemata Take advantage of parallel processing ISE