1. Human Factors, Vigilance
and Cognitive Fatigue in
24/7 Security Operations
11 Oct 2011
James C. Miller, Ph.D., CPE
millergonomics@yahoo.com
Air Force Research Laboratory (Retired),
Miller Ergonomics &
Oak Ridge National Laboratory
2. Fatigue Effects and Countermeasures in
24/7 Security Operations
Available from:
http://www.asisonline.or
g/foundation/noframe/
research/crisp.html
3. The International Ergonomics
Association (IEA)
• The federation of ergonomics and human factors societies
around the world.
• In the U.S., the Human Factors and Ergonomics Society
(HFES) is both international in membership and a member of
the IEA
3
4. Human Factors and Ergonomics
Society (HFES)
• Membership more than 4500; more than 50 active
chapters; technical groups now number 23.
4
5. Human Factors and Ergonomics
Society (HFES)
HFES publishes:
• The journal, Human Factors
• The news publication, HFES Bulletin
• The Proceedings of the HFES Annual Meeting
• Ergonomics in Design, a magazine describing applications of
human factors research
• The Journal of Cognitive Engineering and Decision Making
• Reviews of Human Factors and Ergonomics
• Monographs on selected topics
• The American National Standard for Human Factors Engineering of
Visual Display Terminal Workstations (1992), updated as Human
Factors Engineering of Computer Workstations (2002)
5
6. Human Factors in Homeland
Security
• Committee on Science and Technology for Countering
Terrorism, National Research Council. (2002). Making the
Nation Safer:The Role of Science and Technology in
Countering Terrorism. Washington, D.C.: The National
Academies Press.
• ―TSA should collaborate with the
public and private sectors to build a
strong foundation of research on
human factors and transportation
operations and to make the
evaluation of security system
concepts a central element of its
collaborative research program.‖ (p.
234) 6
7. DHS
Science & Technology Directorate, Human Factors/Behavioral
Sciences Division
TSA Human Factors/Behavioral Sciences
7
8. PNL
Pacific Northwest National Laboratory (Battelle):
• Violent Intent Modeling (VIM) system: software framework
to assist analysts in assessing the likelihood of groups to
engage in violent behavior
• Moved to the Institute for Homeland Security Systems (IHSS)
as Violent Intent Modeling and Simulation (VIMS) in 2008
(research consortium in Research Triangle Park NC)
8
10. Information Security
• Human Factors in Information Security:
http://www.humanfactorsinsecurity.com/
• Data security breaches have surfaced with increased
regularity over the past years
• Financial losses due to cybercrime continue to grow
• Simple human error, ignorance or omission are nearly
always at the root of many of these data breaches and e-
crimes; in nearly every case there was no technical defense
that would have prevented them
• IT systems at all levels and within most organizations remain
inherently vulnerable to even the most basic of security and
fraud weaknesses and vulnerabilities
10
11. Information Security
• This is because we have focused almost entirely on the
technology; we have not attended in any way to the most
fragile element – our people.
• We must ensure effective communication and understanding
of what is required of them in their everyday behavior to
handle information in all its forms in a safe and secure manner
• Unless we do this, our data security and e-crime defenses will
never be complete.
11
12. Information Security
• Gary Hinson, ―Human factors in information security,‖
http://www.noticebored.com/html/human_factors.html:
• ―Computers alone don’t implement information security
policies and standards - human beings purchase and
configure the systems, switch on the control functions, monitor
the alarms and run them. Whatever way you look at the
problem, it is just as important to invest in your people as
your technology.‖
12
13. The Human Component
Overview:
• Two main strengths: more powerful pattern recognition
capabilities and better decision-making skills than can be
provided by automation
• Main weakness: greater performance variability than one
finds in software and modern hardware
13
14. The Human Component
• Assuming adequate training and currency in system
operation, the greatest contributor to that variability is
cognitive fatigue.
• Cognitive fatigue impairs, mainly, the operator’s monitoring
of sensor displays, execution of complex system control
functions, and interactions with automation.
• The monitoring of sensor displays requires the operator to
remain ―vigilant.‖
14
16. Vigilance Performance
• Definition: A monitoring task requires sustained vigilance
over long periods under boring and tedious conditions,
awaiting signals that have a low probability of occurrence but
which, when they do occur, are extremely important to system
performance or safety (Miller & Mackie, 1980).
• In any critical monitoring environment, a slip of attention may
have dire if not fatal consequences.
• Examples follow...
16
17. Vigilance Performance
Sonar & radar operators Industrial process
TSA scanner control/quality control
Detection of suspicious Long-distance driving
behaviors embedded in Agricultural inspection
banks of video surveillance Cytological screening
monitors (radiology)
Military surveillance Electrocardiogram monitoring
Air traffic control in ICU
Cockpit instrument monitoring Anesthesia monitoring during
Seaboard navigation surgery
Ironically, while these kinds of systems are being monitored they contribute to
the cognitive decrement that is causing their own compromise. 17
18. Vigilance Research
• Norman Mackworth's Clock Test was used to establish one of
the fundamental findings in the vigilance and sustained
attention research literature: the vigilance decrement, that is,
signal detection accuracy decreases notably after 30 minutes
on task.
• Seminal paper: Mackworth, N. H. (1948). The breakdown of
vigilance durning prolonged visual search. Quarterly Journal
of Experimental Psychology, 1(1), 6.
18
19. Vigilance Research
The first depiction of the vigilance decrement (Mackworth, 1948)
19
The causes of the decrement have been debated ever since.
20. Vigilance Research
Much vigilance research in the 1970s, summarized here:
• Mackie, R. R. (1977). Vigilance:Theory, Operational
Performance, and Physiological Correlates. Springer.
• Miller, J. C., & Mackie, R. R. (1980). Vigilance Research and
Nuclear Security: Critical Review and Potential Applications
to Security Guard Performance, Goleta CA: Human Factors
Research Inc. Technical Report No. 2722. National Bureau of
Standards contract NBS-GCR-80-201 for the Defense Nuclear Agency;
available from the Electronics and Electrical Engineering Laboratory, Office
of Law Enforcement Standards, National Institute of Standards and
Technology, www.nist.gov/eeel/
20
21. Vigilance Research
• Robert Wilkinson developed a somewhat simpler test of
―arousal‖ and ―continuous, concentrated attention,‖ the
unprepared simple reaction time test (USRT).
• Seven previous studies led Wilkinson to develop a portable
testing device for the USRT: Wilkinson, R. T., & Houghton, D.
(1982). Field test of arousal: a portable reaction timer with
data storage. Human Factors, 24(4), 487-493.
• The device was based upon a cassette tape recorder. The
recommended test length was ten minutes.
21
23. Vigilance Research
• Dr. David Dinges then
introduced a solid-state
version of the USRT called
the Psychomotor Vigilance
Task (PVT)
• Dinges, D. F., & Powell, J. W.
(1985). Microcomputer
analyses of performance on a
portable simple visual RT
task during sustained
operations. Behavior
Research Methods,
Instruments & Computers,
17(6), 652-655.
• Used extensively
23
24. Vigilance Research
Both USRT devices produce similar data.
PVT Speed
Actual Sleep Times - Revised Model
Chronic Restriction Adaptation
110
95
(as a % of Baseline)
Mean Speed
9 Hr
80 7 Hr
5 Hr
3 Hr
65
SAFTE/FAST
R2 = 0.94
50
0 T1 T2 B E1 E2 E3 E4 E5 E6 E7 R1 R2 R3
Day 24
25. Vigilance Research
• However, note that the USRT/PVT has a signal probability of
1.0, much unlike many classic vigilance tests that have signal
probabilities of 0.02 to 0.03 (Miller & Mackie, 1980) or the
Clock Test that had a signal probability of 0.0067 (Mackworth,
1948).
• While the USRT/PVT is sensitive to fatigue, it is difficult to
classify it as a ―vigilance‖ task because it is such a short task
(10 min) and its signals are not embedded in a background of
high-frequency, un-meaningful events.
• Thus, though the USRT/PVT addresses some aspects of
sustained attention, and does capture errors of omission
(lapses), it fails to address the visual search component of
vigilance in security operations.
25
26. Vigilance Performance
Summary:
• Sustained attention on simple laboratory tasks wanes rapidly:
perhaps, as quickly as 20 minutes.
• Over time, error rates increase in terms of lapses:
extraordinary delays in detecting critical signals or complete
failures to detect.
• Individual vigilance performance, itself, becomes more and
more variable over time within and across subjects.
• Observers become progressively less efficient at detecting
either visual or auditory signals as the task continues.
• This is a task-specific fatigue that is caused when a console
operator is forced to remain vigilant in a task that is tedious,
detailed, and repetitive. 26
27. Vigilance Performance
Other influences on vigilance performance:
• Signal complexity, signal duration, environmental stressors,
monitoring load, social influences, personality traits, use of
drugs, sleep disruption, arousal, scheduling, health,
motivation, performance feedback (Miller & Mackie, 1980).
• Adverse environmental conditions, low motivation associated
with lack of performance feedback (Parasuraman, 1986).
• Fatigue, distraction, boredom, task environment, and outside
stressors (Mackie, 1977).
27
28. Vigilance Performance
Improving vigilance performance:
• The more involved the operator is in decision-making and the
more feedback the operator receives, the more aroused and
alert (vigilant) the operator may be (Schroeder et al., 1994)
28
29. Vigilance Performance
Recent view (Warm et al, 2008):
• Experiments comparing performance on successive vs.
simultaneous vigilance tasks support an attentional resource
theory of vigilance.
• Subjective reports also show that the workload of vigilance is
high and sensitive to factors that increase processing
demands
29
30. Vigilance Performance
Recent view (Warm et al, 2008):
• Neuroimaging studies using transcranial Doppler sonography
provide strong, independent evidence for resource changes
linked to performance decrement in vigilance tasks.
• Finally, physiological and subjective reports confirm that
vigilance tasks reduce task engagement and increase distress
and that these changes rise with increased task difficulty.
• Conclusion: converging evidence shows that vigilance
requires hard mental work and is stressful.
30
31. Vigilance Performance
Relevance:
• Vigilance is a critical component of performance efficiency in
airport baggage inspection and detection of illicit radioactive
materials at border crossings and ports.
31
32. Vigilance Performance
Relevance:
• Security guards and intelligence analysts may see but one
reportable threat in hours upon hours of search across
multiple unimportant events.
• When they report a threat, they actually may not have
witnessed a threat or they may have identified an event
incorrectly because threats and non-threatening events are
often quite similar. These are errors of commission.
32
33. Vigilance Performance
Relevance:
• The other type of error seen commonly is an error of
omission, in which a person fails to identify or notice a
threat when it is presented.
33
34. Vigilance Performance
Relevance:
• Several errors may occur simultaneously or in sequence,
a problem that, sometimes, makes the prediction of the
time course of the vigilance decrement complex
(Parasuraman, 1986).
34
35. Myths Busted
• The performance of a human operator in a system cannot be
measured objectively
• Humans are good at ―standing watch‖
• False: human vigilance performance has been measured
objectively across hundreds of investigations, and the human
operator has been found to be poor at standing watch in some
situations.
• The likelihood of errors due to changes in perceptual
threshold and/or perceptual sensitivity may be quantified in
terms of the Receiver Operating Characteristic (ROC)
35
37. Cognitive Fatigue
• In any human-machine system, the most variable
(unpredictable) component in the system is the human
operator
• After training and currency, the greatest contributor to that
variability is cognitive fatigue
• The flavors of cognitive fatigue are circadian, acute,
cumulative, and chronic
• Fatigue is ubiquitous, pervasive and insidious
• Generally, the primary source of cognitive fatigue is
inadequate sleep …
37
41. States and Stages
When we are awake, we may be in one of two different
states:
• A relaxed mental state (alpha waves), or
• An alert mental state (beta waves)
41
42. States and Stages
When we are asleep, we may enter into one of two different
states:
• Non-REM Sleep includes Stages 1 to 4; may involve
dreaming
– Stage 1: Mostly theta waves
– Stage 2: Sleep spindles and K-complex waves
– Stage 3: Mostly delta waves
– Stage 4: Delta waves; difficult to awaken
• Or…
42
43. States and Stages
• REM (Rapid Eye Movement) Sleep (= "paradoxical"
sleep)
– Brain waves somewhat similar to awake state or
Stage 1 sleep (low-voltage, mixed/fast waves)
– Rapid eye movements
– Almost complete loss of muscle control ("atonia")
– Penile erections (males) & vaginal moistening
(females)
– Easy to awaken
– Usually a time of more intensive, vivid dreams
43
45. Credit
Thanks to the web site for Psychology 340 at Le Moyne
College for all of the preceding sleep and arousal slides.
Fr. Vincent W. Hevern, SJ, Ph.D., Instructor
45
46. Sleep
• Myth busted: Sleep is a passive or vegetative state.
• In fact, sleep is a complex neurophysiological state that is
generated by the interactions of at least three extensive
systems in the brain (arousal, slow-wave, REM)
• Sleep may be prevented or disrupted easily by poor sleep
hygiene, alcohol use, caffeine abuse, energy drinks, and
prescription and OTC medications
46
48. Sleep Disorders
• Insomnia. Not sleeping enough due to (1) difficulty falling
asleep (onset insomnia), (2) frequent awakening during sleep
(maintenance insomnia), or (3) waking up too early
(termination insomnia)
• Sleep Apnea. Intermittent stopping of breathing during sleep
• Narcolepsy. Frequent, unexpected periods of sleep or
sleepiness during the day
48
49. Sleep Disorders
• Periodic Limb Movement. During non-REM sleep, individual
moves legs and sometimes arms every 20-30 seconds for
minutes or hours
• REM Behavior. During REM sleep, individual moves
vigorously or violently (kick, punch, etc.); dreams of violent
nature; occurs mostly in older men with brain diseases,
especially Parkinson’s Disease.
• Night Terrors. An intense anxiety from which one wakes up
screaming in terror
• Sleep Talking. We all do it.
• Sleepwalking. Usually in children 2-5 years old; harmless;
no danger to wake up the sleepwalking person
49
50. Sleep Disorders
Shift Work Sleep Disorder (SWSD)
• International Classification of Sleep Disorders (ICSD),
American Academy of Sleep Medicine (AASM;
www.aasmnet.org)
• Code 307.45-1, a circadian sleep disorder
• Essential features: ―symptoms of insomnia or excessive
sleepiness that occur as transient phenomena in relation to
work schedules.‖
50
51. Napping
• The research and solo-sailor practice of Dr. Claudio Stampi
indicates that ―Sleep-deprived humans are better off snoozing
like most animals—in brief, precisely timed naps.‖
(T. Zimmerman)
• ―Under less-structured environments multiple naps do occur
throughout the 24 hr, and many subjects exhibit polyphasic
sleep similar to that observed in nonhuman species. … their
striking regularity allowed speculation on the existence of an
ultradian 4-hr component of the sleep-wake cycle that may be
superimposed on the more robust circadian and midafternoon
components.‖ (Stampi & Broughton, Why We Nap, 1990)
51
52. Napping
• The structure of naps is dependent upon:
– The length of prior wakefulness for non-REM sleep
– 24-, 12- and 4-hour rhythms for REM sleep
• Because we cannot predict reliably what sleep stage will
occur in any given nap, and because all sleep stages appear
to be important for well-being, we do not prescribe limits on
nap lengths. Instead, we just advise operators with limited
sleep opportunities that
―Any sleep is good.‖
52
54. Circadian Rhythms
• Circa (about) dian (daily)
– Physiological day is slightly more than 24 hours long
• A circadian clock in the brain coordinates daily physiological
cycles (suprachiasmatic nucleus of the hypothalamus; SCN;
―body clock‖)
– Sleep-wake cycle
– Body temperature cycle
– Digestive cycle
– Hormonal cycles
54
55. Circadian Rhythms
• The SCN is synchronized daily by cues (Zeitgebers; time
givers) in the environment: mainly by daylight-darkness cycle,
weakly by social schedules and meals
• Body rhythms persist even in the absence of these external
time cues
• The SCN pacemaker cannot reset immediately to:
– Rapid time zone changes (> 1 hr/day; jet lag)
– Inverted work/rest schedules (shift lag)
• When circadian rhythms are disrupted, cognitive performance
is impaired and a feeling of malaise occurs until they are
realigned
55
56. Circadian Rhythms
• Jet/shift lag symptoms include:
– Insomnia
– Awakening too soon
– Excessive daytime sleepiness (EDS)
– Impaired physical and mental performance
– Gastro-intestinal problems
• Acclimatization rate depends upon:
– Different body rhythms adapt at different rates
– Differences between people
– Age
– Direction of travel: usually faster after westward than
eastward travel
56
57. Circasemidian Rhythm
• Circadian rhythms in many measures of performance and
physiological activity have a 2-peak daily pattern caused by
a rhythm that has two cycles per day
– Circasemidian: circa—about, semi—half, dia—day
• No evidence exists to support the presence of a circasemidian
rhythm in the rhythmic cells of the suprachiasmatic nucleus.
• Relevant behavioral and physiological observations support
the need to consider this 12-h rhythmicity in the quantification
of daily variations in physiological function and some kinds of
cognitive performance.
57
58. Circasemidian Rhythm
• Usually serves to (1) elevate the pre-dawn peak in mishaps,
• (2) create a secondary peak in the early afternoon in mishaps (the
"post-lunch dip"), and
• (3) depress the
late-morning
and early-
evening
troughs in
mishaps.
• Thus, the ―two-
peak daily
pattern of
mishaps.‖
58
61. Fatigue Symptoms
My eyes close and stay shut for too many seconds at a time.
No mental effort I exert can hold them open.
I’ve lost command over their muscles…
I’ve got to find some way to keep alert.
There’s no alternative but death and failure.
- Charles A. Lindbergh
The Spirit of St Louis
61
62. Fatigue Definitions
PHYSICAL FATIGUE
• The individual’s diminished physical capability is due to
overexertion (time or relative load).
• The effects of prolonged physical activity, or the effects of
brief but relatively extreme physical activity, either of which
taxes a person’s physical endurance or strength beyond the
individual’s normal limits.
62
63. Fatigue Definitions
TASK-SPECIFIC FATIGUE
• Repeated, demanding work causes fatigue and the need for
recovery.
• Work that is assisted by automation generally places
demands upon specific, fine-motor and visual functions. Some
of the work requires vigilance, and some requires repetitive
operations.
• Thus, we observe task-specific fine-motor muscular fatigue,
visual fatigue, vigilance failures, monotony, and repetitive-
stress injuries in the automated workplace.
• Each of these problems requires task-specific, short-term and
long-term fatigue management and recovery considerations.
63
64. Fatigue Definitions
TASK-SPECIFIC FATIGUE
• Some argue that task-specific fatigue is actually habituation;
others argue it is simply boredom.
• The fact is that task performance declines across time.
• This is the same overall pattern that we have with
wakefulness: performance declines as time awake continues.
• Task-specific fatigue and fatigue due to inadequate sleep may
be additive.
64
65. Fatigue Definitions
TASK-SPECIFIC FATIGUE
• If the individual cannot change tasks, then the effects of task-
specific fatigue may be difficult to avoid.
• The manager should provide ―a meaningful variety or mix of
tasks so as to avoid boredom and performance decrement‖
(Murphy et al., 1968).
• Some system operators do not suffer very much from task-
specific fatigue when they are in the control loop, i.e., ―hands-
on.‖ But they may suffer from sleepiness.
65
66. Fatigue Definitions
TASK-SPECIFIC FATIGUE
• Operators who monitor automated systems often fall prey to
vigilance decrements, boredom, habituation, and/or task-
specific fatigue.
• With respect to the interactions between acute fatigue and
task-specific fatigue, ―fatigue disrupts matching of effort to
task demands, such that the fatigued [operator] fails to
regulate effort effectively when the task appears easy‖
(Desmond & Matthews, 1997).
• This finding supports the practice of treating the effects of
acute or cumulative fatigue and task-specific fatigue as
additive (Murphy et al., 1968).
66
67. Fatigue Definitions
CIRCADIAN RHYTHM EFFECTS
• The individual’s normal, 24-hour, rhythmic biological cycle
degrades task performance. This is caused by one or more
nights of work or rapid movement (faster than one time zone
per day) across more than 3 time zones. These effects are
referred to as ―shift lag‖ and ―jet lag,‖ respectively.
• Continuous time spent in the new time zone will lead to
acclimation, but more acclimation time is needed for more
time zones crossed. Acclimation to night work may never
occur.
67
68. Fatigue Definitions
ACUTE MENTAL FATIGUE
• The individual’s diminished mental capability is due to
prolonged wakefulness, usually more than 16 hours, that
occurs between two major sleep periods.
• This acute, or transient, performance decrement should be
eliminated after a regular sleep period.
68
69. Fatigue Definitions
CUMULATIVE MENTAL FATIGUE
• The individual’s diminished mental capability is due to
disturbed or shortened major sleep periods between two or
more successive major waking, duty or work periods.
• One major sleep period will not eliminate cumulative fatigue.
69
70. Fatigue Definitions
CHRONIC MENTAL FATIGUE
• The individual is exposed frequently during at least one month
to multiple periods of prolonged wakefulness, excessive work
hours, disturbed or shortened major sleep periods, unresolved
conflicts, or prolonged frustration.
• It is not eliminated by any number of sleep periods without
first removing the cause.
70
71. Fatigue Definitions
CHRONIC MENTAL FATIGUE
• An individual must display, concurrently, four or more of the
following symptoms: the desire to sleep, apathy, substantial
impairment in short-term memory or concentration; muscle
pain; multi-joint pain without swelling or redness; headaches
of a new type, pattern or severity; unrefreshing sleep; and
post-exertional malaise lasting for more than 24 hours. The
symptoms must have persisted or recurred for at least one
month.
71
73. Sleep
• The most effective countermeasure for fatigue is to do as
much as possible to prevent it from occurring in the first
place.
• The primary culprit for feeling fatigued is sleep loss.
• Thus, whatever can be done to encourage regular sleep and
prevent sleep loss (cumulative fatigue, sleep debt) should be
high on the list of countermeasures.
• The principal advantage of getting enough sleep is that it will
reduce on-the-job fatigue, thereby reducing the need for other
countermeasures.
• Good-quality, nocturnal sleep is a particularly effective
control for the three hazards, length of prior wakefulness,
amount of prior sleep, and physical exertion
73
74. Sleep
How much sleep do we need?
• Eight (8) hours per 24 hours is the average sleep need.
– Half of any given group will need more than 8 hours to
prevent cumulative fatigue due to sleep debt.
National Sleep Foundation: http://www.sleepfoundation.org
74
75. Sleep Hygiene
A Healthy Mind in a Healthy Body
• Manage stress as much as possible. Keep things in perspective and focus
on what’s important. If needed, use relaxation techniques.
• Stay fit. Physical fitness tends to reduce anxiety and insomnia. Even
something as simple as brisk walking can have a positive effect, if done
regularly.
• Stimulate your mind. Chronic television viewing is associated with poor
sleeping. Spend time working, talking, doing chores and pursuing hobbies.
• Pay attention to healthy nutrition
• Stop smoking. Nicotine stimulates the brain and increases blood pressure
and heart rate, disturbing your ability to get to sleep and remain asleep.
Good Sleep Behaviors
• Use a bedtime ritual. For example, read a good book to take your mind off
the stresses of work. When you feel drowsy, turn off the light.
• Don’t watch the clock. Hide illuminated clocks from view. If needed, set a
couple of alarms and arrange for a wake-up call.
• Dress appropriately. Use loose-fitting, soft garments that breathe, in the
right weight for the temperature of the bedroom.
75
76. Sleep Hygiene
A Good Sleep Environment
• Strive for quiet. Low level and consistent sound may be useful. Use soft
earplugs.
• Strive for darkness. Use a blanket or towel to block a window or the edges
of a door. Use an eyeshade.
• Set the room temperature to 65 degrees F (20 degrees C).
• Strive for a humidity level of 60-70%. Use a humidifier or dehumidifier.
These devices may provide a soft hum of ―white noise‖ that can help mask
other noises.
• Strive for security. Lock the door.
• Design a restful-appearing bedroom. Keep It clean and free of clutter.
Good Sleep Equipment
• Use bed sheets that are clean and comfortably soft.
• Use a pillow that allows a healthy sleep posture: on your side with the spine
straight, or on your back.
Extracted from Miller JC, Controlling Pilot Error: Fatigue, McGraw-Hill, 2001.
76
77. Napping
Taking a nap can reduce fatigue effects and increase alertness
during work and non-work periods.
A nap can be very effective as a short-term countermeasure
against fatigue effects, and to compensate during a period
when workers will need to remain awake for a long time (more
than 17 hours).
Some other situations where napping would be appropriate are:
• Less than 8 hours sleep during the main sleep period
• Awake for 30 minutes or longer two or more times during the
main sleep period
• During a long and/or nighttime work period
PREACH THAT ―ANY SLEEP IS GOOD!‖
77
78. Napping
• Naps should be limited to a time, place and duration that
will not interfere with operations.
• It is important to recognize that when naps are needed
because of reduced sleep opportunities, workers are at
risk of being critically fatigued.
• Allow 30’ to 60’ for sleep inertia to clear before critical
events.
78
79. Tactical Caffeine Use
• When natural fatigue countermeasures are impossible,
caffeine is a very effective alternative.
• Studies have shown that caffeine significantly improves both
alertness (measured by MWTs) and performance (measured
by the PVT, etc.).
• Doses ranging from 200-600 mg are particularly effective in
people who do not normally use caffeine.
79
80. Tactical Caffeine Use
• OTC doses:
– 1 cup Maxwell House = 100 mg
– 1 Starbucks Tall = 250 mg
– 1 Starbucks Grande = 375 mg
– 1 Starbucks Vente = 550 mg
– 1 cup tea = 50 mg
– 1 Coke = 50 mg
– 1 Mountain Dew = 55 mg
– 2 Excedrin Xtra = 130 mg
– 1 Max NoDoze = 200 mg
Source: Dr. John Caldwell & Dr. Lynn Caldwell
80
81. Tactical Caffeine Use
• Caffeine must be used judiciously. Habituation occurs when
we take in more than about 250 mg/day!
• The best tactical approach to caffeine use is to take it only
right before you need it!
81
82. Sleep Aids
Caldwell et al, 2009:
• Temazepam (Restoril®): optimize 8-h sleep periods that are
out-of-phase with the body clock
• Zolpidem (Ambien®): optimal for sleep periods less than 8
hours
• Zaleplon (Sonata®): initiate short naps (1 to 2 h) during a
period of otherwise sustained wakefulness, or initiate early
sleep onset before very early start time the next morning
• New aids for sleep maintenance : extended-release zolpidem
(Ambien CR®) and eszopiclone (Lunesta®)
• New aid for sleep onset: Ramelteon (Rozerem®) targets
melatonin receptors
Paul et al. 2010:
• Melatonin at 4 p.m. as an aid for phase advance 82
83. Fatigue Mishap Investigation
A fatigue incident tracking method to be used across days,
weeks, and months:
• Define time blocks; e.g., 00-0:300, 03-06:00, etc.
• Record the number of the unit's operations (e.g., sorties)
per block
• Record the number of minor incidents per block; e.g.,
minor errors by maintenance, ATC, cockpit, aerial port,
weapons, etc.
• Record the number of these minor incidents caused, at
least in part, by fatigue...
83
84. Fatigue Mishap Factors
A. Length of prior wakefulness > 17 hrs
B. Amount of prior sleep for the preceding 24 h < 8 hrs
C. Time of day 0200h to 0600h
D. Sleep debt > 10 hrs
E. Time zone change - days in zone > 3
F. Estimated physical exertion across the work period of interest
Different versions of this list are being incorporated into
investigation tools by the NTSB and the FRA.
84
85. Stupid Schedules
―Stupid‖ work-rest schedules are those that that:
• Ignore the biology of the human component of the weapon
system or organization, and
• Violate the guidance given by Napoleon Bonaparte in 1796 to
his commanders: You must not needlessly fatigue the troops
These schedules are ―stupid‖ in conception and ―stupid‖ in their
effects on worker capabilities. They tend to make the worker
―stupid.‖
85
86. ―Stupid‖
American Heritage Dictionary
• Slow to learn or understand; obtuse.
• Tending to make poor decisions or careless mistakes.
• Marked by a lack of intelligence or care; foolish or careless: a
stupid mistake.
• Dazed, stunned, or stupefied.
Dictionary.com
• Lacking ordinary quickness and keenness of mind; dull.
• Characterized by or proceeding from mental dullness; foolish.
• In a state of stupor; stupefied: stupid from fatigue.
86
87. Shiftwork Scheduling
• Use a principle-based approach to shiftwork scheduling that
constrains the infinite number of possible schedules to those
schedules that are simple, practical to implement, and least
harmful to worker health, job performance, and attitude (Miller,
2006).
• There is no ―good‖ continuous, 24/7 shift work schedule:
humans are not designed to work at night, therefore night
work causes sleep loss and shift lag.
• In turn, these cause fatigue at work.
• Thus, even good-quality shift work scheduling cannot prevent
sleep loss and shift lag.
• Instead, it should be viewed as an effort to minimize the
negative consequences. This is good for the workers’ health,
safety and satisfaction, and for productivity.
87
88. Shiftwork Scheduling
• One of many components of a shiftwork schedule is the
number of crews that rotate to meet the demand for 24/7,
continuous operations.
• In regular, 24/7 operations, the number of crews used should
be greater than the number of shifts per day, so that at least
one crew is off each day, except in maritime operations
(Miller, 2006).
• In a regular schedule, it is the number of crews (not shift
length!) that defines the average yearly, weekly, and daily
amounts of time worked by an individual.
88
89. Shiftwork Scheduling
Average work demands in regular schedules for different
numbers of crews and for weekday-only workers, in hours.
89
91. Shiftwork Scheduling
• Miller, J. C. (2006). Fundamentals of Shiftwork Scheduling,
Technical Report 2006-0011. Brooks City-Base TX: Air Force
Research Laboratory.
• Available free from the Defense Technical Information Center
(www.dtic.mil) as ADA446688.
91
92. Myth Busted
• Sleepiness and fatigue always occur, and nothing can be
done about it
• False: there are many fatigue countermeasures that may be
used singly or in combination
92
93. Safety, Alertness, Fatigue, and
Task Effectiveness (SAFTE™)
Model
(PowerPoint material courtesy of Dr. Steve Hursh)
93
94. Schematic of SAFTE™ Simulation Model
Sleep, Activity, Fatigue and Task Effectiveness Model
DYNAMIC
CIRCADIAN OSCILLATORS PHASE
SLEEP
REGULATION 12
PERFORMANCE
MODULATION
SLEEP DEBT
COGNITIVE
FEEDBACK EFFECTIVENESS
LOOP
SLEEP INTENSITY
SLEEP ACCUMULATION SLEEP
(Reservoir Fill) INERTIA
RESERVOIR
SLEEP “QUALITY”
FRAGMENTATION
PERFORMANCE USE
(Reservoir Depletion)
95. Types of Fatigue Modeled
• Its homeostatic and circadian components allow SAFTE™ to
model acute fatigue, cumulative fatigue and interactive
circadian effects
– The sleep homeostat
• SAFTE™ does NOT model task-specific fatigue, chronic
fatigue or physical fatigue
95
96. Decline of Performance with Total Sleep Deprivation
SAFTE™ Model (red line) Predicts the Average Results with Precision
Sleep & Performance Model vs Angus & Heslegrave (1985)
Mean of Normalized Performance Measures
120
Serial RT
Decode
Encode
100 Vigilance
Logical
Effectiveness (Percent)
Mean Data
80 SAFTE Prediction
60
40
20 Parameters:
Acrophase: 1900
Wake up at 0700 hrs
Awakening at 0700 hrs
0 19 43
0 10 20 30 40 50 60
Hours of Sleep Deprivation 96
97. Walter Reed Restricted Sleep Study
SAFTE™ Model (red line) Predicts the Average Results
with Precision
PVT Speed
Actual Sleep Times - Revised Model
Chronic Restriction Adaptation
110
95
(as a % of Baseline)
Mean Speed
9 Hr
80 7 Hr
5 Hr
3 Hr
65
SAFTE/FAST
R2 = 0.94
50
0 T1 T2 B E1 E2 E3 E4 E5 E6 E7 R1 R2 R3
Day 97
99. FAST™
• Also, the funding has supported the development of the
Fatigue Avoidance Scheduling Tool (FAST™) software, the
Windows® implementation of SAFTE™
• FAST™ is a fatigue assessment tool based on the SAFTE™
model
• Developed for the US Air Force and US Army
• DOT/FRA has extended and enhanced the tool for
transportation applications
• DoD verification, validation and accreditation, and DOT field
validations/calibrations are underway
99
100. FAST™ I/O
• Inputs
– Work schedule data
– Sleep and naps or use AutoSleep
– Sleeping environment: Excellent, Good, Moderate, Poor
– Methods: graphic, grid, tables, import file
100
101. FAST™ I/O
• Outputs
– Graph of performance: Mean Cognitive Performance
Effectiveness
– Population Variance
– Lapse Index
– Mission Timeline – especially for aviation applications
– Dashboard
Fatigue Indicators
Performance Indicators
– BAC Equivalence Scale
– Summary Tables
– Clipboard copy of graph and tables to Excel, Power Point,
Word
101
102. Cognitive performance (%)
Cursor for I/O
―Dashboard‖
Sleep (blue; model input)
Work (red; captures data
output)
Daylight/darkness (gray)
Circadian phase (thin red
curve)
106. FAID
• Similarly, FAID® is a different software tool designed to assist
in the assessment of risks associated with workplace fatigue
due to hours of work, inadequate sleep, and fatigue-related
hazards. The underlying scientifically-based assumptions
about sleep and circadian rhythms are the same assumptions
used in SAFTE/FAST.
• A FAID® Score is in effect a relative measure of the sleep
opportunity which is afforded by the work schedule.
As the FAID® Score increases, the relative sleep opportunity
with work pattern decreases.
107.
108. Myth Busted
• The performance of a human operator in a system cannot be
measured objectively
• False: fatigue effects can be measured objectively, and many
of them can be predicted quantitatively and with good
reliability.
108
110. Fatigue and Security
Types of security-focused research from which to draw
information (Miller, CRISP report, 2011):
• Shiftwork and fatigue in police operations
• Shiftwork and fatigue in control room operations
Lessons:
• All shift and night workers tend to suffer from the same health,
sleep disturbance, and cognitive performance problems
• Thus, one may apply to security operations the results of
decades of research on night work and shift work effects in
non-police and non-security occupations to the management
and scheduling of security operations personnel.
110
111. Fatigue and Security
Fatigue Risk Management Systems (FRMS)
• DoD Operational Risk Management (ORM)
• Organizational commitment
• Systems approach
• Management-labor partnership
• Evaluation
111
112. Fatigue ORM
Use of the quantitative fatigue model, SAFTE, and well-accepted
fatigue countermeasures in the formal DoD context of
operational risk management (ORM): Miller & Eddy, 2008, DTIC
ADA501985
Identification of Fatigue Hazards
• Used the known, primary physiological and psychological
effects of fatigue.
• Aligned these effects approximately with cognitive and
physiological tests shown to be sensitive to the fatigued state
• Extrapolated the listed effects to safety-sensitive jobs through
examples
• Each effect had the potential to cause harm in military
operations and, thus, was a hazard
112
113. Fatigue ORM
Use of the quantitative fatigue model, SAFTE, and well-accepted
fatigue countermeasures in the formal DoD context of
operational risk management (ORM): Miller & Eddy, 2008, DTIC
ADA501985
Assessment of Fatigue Risks
• Using SAFTE and other data, quantified the risks associated
with the five types of fatigue:
– Physical fatigue
– Circadian effects
– Acute fatigue
– Cumulative fatigue
– Chronic fatigue
113
114. Fatigue ORM
Use of the quantitative fatigue model, SAFTE, and well-accepted
fatigue countermeasures in the formal DoD context of
operational risk management (ORM): Miller & Eddy, 2008, DTIC
ADA501985
Analysis of Fatigue Risk Control Measures
• The best fatigue countermeasure is sleep, which is the only
countermeasure that provides recovery
• It also reduces the probability that fatigue will have an effect
on mission safety and, concomitantly, reduces the exposure
to fatigue
• When adequate sleep cannot be used to counter fatigue, then
one must consider the use of ―Go‖ and ―No-go‖ adjuncts,
including schedule adjustments and pharmacological adjuncts
• These adjuncts serve to reduce the severity of fatigue effects
or the exposure to fatigue-related risk
114
115. ORM
Use of the quantitative fatigue model, SAFTE, and well-accepted
fatigue countermeasures in the formal DoD context of
operational risk management (ORM): Miller & Eddy, 2008, DTIC
ADA501985
Possible Fatigue Risk Control Decisions
• All controls except sleep should be viewed as ―band-aid‖
approaches, to be used as a last resort when other controls
are insufficient and the mission must be accomplished
• Recovery sleep will still be necessary after the other controls
have been applied to accomplish the mission.
115
116. Fatigue and Security
Fatigue Risk Management Systems (FRMS) – Organizational
Commitment
• Initiated and sustained with a top-down management
approach.
• Integrated program that addresses the requirements of all
stakeholders.
• Foundation of commitment, cooperation, knowledge,
assessment, and program refinement at all levels of the
organization (McCallum et al., 2003).
116
117. Fatigue and Security
Fatigue Risk Management Systems (FRMS) – Organizational
Commitment
• Allocation of resources sufficient for establishing and
sustaining a fatigue management program.
• Senior executives must be involved in the formulation and
support of their organization’s fatigue management policy.
• Program policy established through a joint effort by all
organizational stakeholders.
117
118. Fatigue and Security
Fatigue Risk Management Systems (FRMS) – Systems
Approach (Moore-Ede, 1994)
• Re-evaluate human asset potential and priorities; a
fundamental shift in how human assets are viewed.
• Establish management commitment and support commitment
at all levels, starting at the top.
• Define the FRMS as an integral part of organizational
philosophy and mission; institutionalize the commitment that
people requirements have priority.
118
119. Fatigue and Security
Fatigue Risk Management Systems (FRMS) – Systems
Approach (Moore-Ede, 1994)
• Assess current risks, liabilities, and hazardous exposures; get
input from the ―front-line troops.‖
• Launch appropriate change initiatives to reduce exposures
and capture performance-improvement opportunities.
• Educate and provide ongoing support and training for all
personnel.
• Report results and measure performance to plan.
• Translate into a continuous, institutionalized process for
improving overall productivity, quality, and safety
performance.
119
120. Fatigue and Security
Fatigue Risk Management Systems (FRMS) – Management-
Labor Partnership
• A challenge for CEOs and their personnel to address fatigue
management from a common perspective.
• Work-rest schedules, affect both operational efficiency and
individual well being.
• The issues are critical to both the organization and the
workers: reducing on-the-job accidents, improving employee
health, improving operational efficiency.
• May serve as a basis for establishing more productive
relationships.
• An effective FRMS will involve both CEOs and their personnel
in supporting these common objectives. 120
121. Fatigue and Security
Fatigue Risk Management Systems (FRMS) – Evaluation
• The FRMS requires periodic evaluation and refinement.
• Evaluation should be tied back to established objectives.
• Possible measures:
– Average number of sick days
– Numbers of accidents and incidents due to operator
fatigue
– Attendance at FRMS educational events
– Numbers of personnel completing confidential
fatigue-screening
– Responses to a periodic alertness management
survey 121
122. Fatigue and Security
Fatigue Risk Management Systems (FRMS) – Evaluation
• Additional information about assessment methods and tools in
Chapter 5 of Miller, 2006.
• Program refinements close the gap between objectives and
evaluation findings.
• Successful refinement requires continued oversight and
improvement of the alertness management program.
122
123. Conclusion
What we've covered:
• Myth Busting
• Human Factors and Ergonomics Research
• Vigilance Research
• Sleep Physiology and Fatigue
• Fatigue Countermeasures
• Fatigue and Security
123
124. Myths Busted
• The performance of a human operator in a system can be
measured objectively
• Humans are not good at ―standing watch‖
• Sleep is a not passive, vegetative state; ―I can sleep when I
die‖ is an inappropriate view for a person who holds a safety-
sensitive job
• Sleepiness and fatigue always occur, but many things can be
done about them in security operations
124
125. Action Items
P.A. Hancock, G.P. Kreuger (2010). Hours of Boredom,
Moments of Terror. Temporal Desynchrony in Military and
Security Force Operations. National Defense University Center
for Technology and National Security Policy, Fort Lesley J.
McNair, Washington, DC.
http://www.ndu.edu/ctnsp/publications.htm
126. Action Items
Inadequate recognition of the implications resulting from long lull
periods, work pulses, and the need to recover from stress can
lead to dysfunction and poor individual and small group
performance.
Accounting for such time-based transitions in psychological state
is important in configuring resilience training for small group
leaders, their personnel, and their organizational units.
127. Action Items
How is this done?
• Recognize rhythms in human activity
• Spread out cognitive task demands: shift some cognitive load
to periods of quiescence
• Plan for adequate rest and sleep
• Train to anticipate both hours of boredom and moments of
terror
• Anticipate future technological assists in cognitive
assessment: manager/director/commander should have
some type of on-line assessment of the cognitive and
physiological state of readiness of the individuals under his or
her direction/command [available, but not used widely]
