Application of Cognitive Modeling to Fatigue Management 4 th Panhellenic Conference on Aerospace Medicine Athens, 29 February 2008 James C. Miller, Ph.D., CPE millergonomics.com [email_address] (USAF Research Lab, Retired)

4 th Panhellenic Conference on Aerospace Medicine

Athens, 29 February 2008

James C. Miller, Ph.D., CPE

millergonomics.com

[email_address]

(USAF Research Lab, Retired)

Topics Fatigue context Quantitative modeling of fatigue (SAFTE) FAST software (Windows) F/PAS Web site Modeling examples

Fatigue context

Quantitative modeling of fatigue (SAFTE)

FAST software (Windows)

F/PAS Web site

Modeling examples

The Human in the Loop The most unpredictable component in any weapon system is human cognition After training and currency, the greatest contributor to that human variability is fatigue Good human-machine system design exploits human strengths and protects the system from human weaknesses

The most unpredictable component in any weapon system is human cognition

After training and currency, the greatest contributor to that human variability is fatigue

Good human-machine system design exploits human strengths and protects the system from human weaknesses

The Human in the Loop Human Strengths : Better pattern recognition capabilities and decision-making skills than can be provided in software Human Weaknesses : Much more performance variability than one finds in software and modern hardware, primarily in attention and vigilance

Human Strengths : Better pattern recognition capabilities and decision-making skills than can be provided in software

Human Weaknesses : Much more performance variability than one finds in software and modern hardware, primarily in attention and vigilance

Sources of Fatigue Variability Large amplitude, moment-to-moment fluctuations in attentiveness associated with fatigue; average performance may be at an acceptable level Brief periods when responses are extraordinarily delayed or absent for a half-second to a minute (" lapses ")‏; often called "distractibility;" fatigued system operators are more easily distracted than non-fatigued operators Microsleeps ; i.e., falling asleep on the job for more than a minute

Large amplitude, moment-to-moment fluctuations in attentiveness associated with fatigue; average performance may be at an acceptable level

Brief periods when responses are extraordinarily delayed or absent for a half-second to a minute (" lapses ")‏; often called "distractibility;" fatigued system operators are more easily distracted than non-fatigued operators

Microsleeps ; i.e., falling asleep on the job for more than a minute

Types of Fatigue Fatigue and sleepiness are caused primarily by lack of sleep, with the exception of physical fatigue caused by brief physical work and task-specific fatigue For practical purposes, we sort the generators of fatigue into six categories: Physical Circadian Acute Cumulative Chronic Task-specific

Fatigue and sleepiness are caused primarily by lack of sleep, with the exception of physical fatigue caused by brief physical work and task-specific fatigue

For practical purposes, we sort the generators of fatigue into six categories:

Physical

Circadian

Acute

Cumulative

Chronic

Task-specific

Types of Fatigue Circadian Effects. Malaise and fatigue due to: Night Work . the pre-dawn period when sleep drive and sleepiness are highest and body temperature and alertness are lowest. Jet Lag . a time zone change that is faster than about one time zone per day and exceeds about three time zones; re-synchronization of internal circadian rhythms to new external time cues, especially the daylight-darkness cycle. Shift Lag . a change from day work to night work and vice versa. The main external time cue, the daylight-darkness and social cycles, inhibits re-synchronization. For most night workers, re-synchronization never occurs

Circadian Effects. Malaise and fatigue due to:

Night Work . the pre-dawn period when sleep drive and sleepiness are highest and body temperature and alertness are lowest.

Jet Lag . a time zone change that is faster than about one time zone per day and exceeds about three time zones; re-synchronization of internal circadian rhythms to new external time cues, especially the daylight-darkness cycle.

Shift Lag . a change from day work to night work and vice versa. The main external time cue, the daylight-darkness and social cycles, inhibits re-synchronization. For most night workers, re-synchronization never occurs

Types of Fatigue Acute Fatigue. Acute fatigue builds up normally and unavoidably within in one waking period; recovery from acute fatigue occurs as the result of one good-quality, nocturnal sleep period Cumulative Fatigue. Cumulative fatigue builds up across major waking and duty periods when there is inadequate recovery (due to inadequate sleep) between the duty periods; recovery from cumulative fatigue cannot be accomplished in one good-quality, nocturnal sleep period

Acute Fatigue. Acute fatigue builds up normally and unavoidably within in one waking period; recovery from acute fatigue occurs as the result of one good-quality, nocturnal sleep period

Cumulative Fatigue. Cumulative fatigue builds up across major waking and duty periods when there is inadequate recovery (due to inadequate sleep) between the duty periods; recovery from cumulative fatigue cannot be accomplished in one good-quality, nocturnal sleep period

Types of Fatigue The only known cure for physical fatigue, acute fatigue, cumulative fatigue, jet lag, and shift lag is good-quality nighttime sleep All other treatments, called fatigue countermeasures (including prescription drugs), are "Band-Aids" that counter the symptoms of fatigue Eventually, the individual must sleep to recover from these types of fatigue

The only known cure for physical fatigue, acute fatigue, cumulative fatigue, jet lag, and shift lag is good-quality nighttime sleep

All other treatments, called fatigue countermeasures (including prescription drugs), are "Band-Aids" that counter the symptoms of fatigue

Eventually, the individual must sleep to recover from these types of fatigue

Nature of Fatigue Ubiquitous: fatigue affects everybody Pervasive: fatigue affects everything we do, physically and cognitively Insidious: often when we are fatigued, we are quite unaware of how badly we are performing Fortunately, the biological changes and rhythms that cause fatigue-induced declines, lapses and variability in human performance are predictable ; thus, we may model them

Ubiquitous: fatigue affects everybody

Pervasive: fatigue affects everything we do, physically and cognitively

Insidious: often when we are fatigued, we are quite unaware of how badly we are performing

Fortunately, the biological changes and rhythms that cause fatigue-induced declines, lapses and variability in human performance are predictable ; thus, we may model them

Predictive Model

Quantitative Predictions of Fatigue A world-class applied model (or simulation) was developed during the 1990s, primarily with US DoD funding The Sleep, Activity, Fatigue and Task Effectiveness ( SAFTE ) is a 3-process, applied model of human cognitive performance effectiveness (Hursh et al., 2004)‏: Circadian rhythms in metabolic rate and alertness Cognitive performance recovery rates associated with sleep , and cognitive performance decay rates associated with wakefulness Cognitive performance effects associated with sleep inertia

A world-class applied model (or simulation) was developed during the 1990s, primarily with US DoD funding

The Sleep, Activity, Fatigue and Task Effectiveness ( SAFTE ) is a 3-process, applied model of human cognitive performance effectiveness (Hursh et al., 2004)‏:

Circadian rhythms in metabolic rate and alertness

Cognitive performance recovery rates associated with sleep , and cognitive performance decay rates associated with wakefulness

Cognitive performance effects associated with sleep inertia

Quantitative Predictions of Fatigue

Validation Example

Predictive Software: FAST

Quantitative Predictions of Fatigue The Fatigue Avoidance Scheduling Tool ( FAST ) was based upon the SAFTE applied model It is a Windows® program that estimates the average effects of various work-rest schedules on human cognitive performance by examining manually-entered work and sleep data in any of several formats Geophysical model allows jet lag calculations ‘ Autosleep’ function fills in best sleep estimate when needed

The Fatigue Avoidance Scheduling Tool ( FAST ) was based upon the SAFTE applied model

It is a Windows® program that estimates the average effects of various work-rest schedules on human cognitive performance by examining manually-entered work and sleep data in any of several formats

Geophysical model allows jet lag calculations

‘ Autosleep’ function fills in best sleep estimate when needed

Quantitative Predictions of Fatigue FAST was developed initially as a US Air Force product to deal specifically with R&D on Air Force mission-scheduling issues (Dr. Miller was the Government contract technical monitor) The FAST software development effort concluded in 2006 with version 1.5; FAST is available commercially

FAST was developed initially as a US Air Force product to deal specifically with R&D on Air Force mission-scheduling issues (Dr. Miller was the Government contract technical monitor)

The FAST software development effort concluded in 2006 with version 1.5; FAST is available commercially

FAST Cognitive performance (%) Cursor for I/O “ Dashboard” Sleep (blue; model input) Work (red; captures data output) Daylight/darkness (gray) Circadian phase (thin red curve)

FAST (zoom & variability) Zero suppression * Copy/Paste * -30 percentile

FAST Click and drag “grid” input function

FAST Tabular output Copy/paste work period data

Predictive Software: F/PAS

Quantitative Predictions of Fatigue A follow-on contract was awarded by the USAF in 2006 to create the "son of FAST" software (Dr. Miller was the Government contract technical monitor) Its working name was the Intelligent Scheduling Tool ( IST )‏ FAST is Windows-based; the IST is browser/Web-based This new software is now called the “ Fatigue/Performance Assessment System ( F/PAS )”

A follow-on contract was awarded by the USAF in 2006 to create the "son of FAST" software (Dr. Miller was the Government contract technical monitor)

Its working name was the Intelligent Scheduling Tool ( IST )‏

FAST is Windows-based; the IST is browser/Web-based

This new software is now called the “ Fatigue/Performance Assessment System ( F/PAS )”

Quantitative Predictions of Fatigue F/PAS uses the SAFTE model and its core software has all of the functions of FAST F/PAS gains two new functions that were unavailable in FAST: Pharmaceutical effects (caffeine, go pill, no-go pill)‏ Generalization of the Autosleep function from a single time zone to transmeridian travel

F/PAS uses the SAFTE model and its core software has all of the functions of FAST

F/PAS gains two new functions that were unavailable in FAST:

Pharmaceutical effects (caffeine, go pill, no-go pill)‏

Generalization of the Autosleep function from a single time zone to transmeridian travel

Quantitative Predictions of Fatigue F/PAS also gains three new interfaces that are being designed with a user-centered method The new interfaces replace the original, graphic interface in FAST that was designed to support fatigue scientists The interfaces include the: Mission Scheduler Interface for aircrews, mission schedulers, and flight surgeons; irregular schedules Mishap Investigation Interface for both air and ground mishaps Shiftwork Scheduling Interface ; regular, cyclic schedules

F/PAS also gains three new interfaces that are being designed with a user-centered method

The new interfaces replace the original, graphic interface in FAST that was designed to support fatigue scientists

The interfaces include the:

Mission Scheduler Interface for aircrews, mission schedulers, and flight surgeons; irregular schedules

Mishap Investigation Interface for both air and ground mishaps

Shiftwork Scheduling Interface ; regular, cyclic schedules

F/PAS Mission Scheduling Interface Under Construction. Display looks much like FAST graph. Rapid input by Outlook-style Calendar.

Under Construction.

Display looks much like FAST graph.

Rapid input by Outlook-style Calendar.

F/PAS Mishap Investigation Interface (Questions)

F/PAS Mishap Investigation Interface (Mission Log)

F/PAS Mishap Investigation Interface (Dashboard)

F/PAS Mishap Investigation Interface (Graphic Output)

F/PAS Shiftwork Scheduling Interface (Known Plans)

F/PAS Shiftwork Scheduling Interface (Plan Options)

F/PAS Shiftwork Scheduling Interface (New Plan Wizard)

F/PAS Shiftwork Scheduling Interface (Analysis)

FAST-to-F/PAS Transition Presently, the user interfaces are in early ‘alpha’ phase and usability testing; thus, too early for formal plan and schedule F/PAS will read the ‘fas’ data files created by FAST For owners of FAST, there will probably be a discounted upgrade program to F/PAS

Presently, the user interfaces are in early ‘alpha’ phase and usability testing; thus, too early for formal plan and schedule

F/PAS will read the ‘fas’ data files created by FAST

For owners of FAST, there will probably be a discounted upgrade program to F/PAS

Modeling Examples

Ground Mishap in FAST (Phase)

Ground Mishap in FAST (BAC)

Dr. Miller’s Trip to Athens

Shiftwork

Additional Information FAST (from NTI, Inc.): www.ntiinc.ms11.net Dr. Miller: www.millergonomics.com (Presently, a consultant to NTI for F/PAS development)

FAST (from NTI, Inc.): www.ntiinc.ms11.net

Dr. Miller: www.millergonomics.com

(Presently, a consultant to NTI for F/PAS development)