Military Psychology:
Human Factors
Dr. Steve Kass
Department of Psychology
University of West Florida
What is Human Factors?

The discovery and
application of information
about human behavior,
abilities, and other
characteristics to the
design of tools,
machines, systems,
tasks, jobs, and
environments for
productive, safe,
comfortable, and
effective human use.
Human Factors Psychology and
Related Disciplines
Ergonomics
 Human Factors Engineering
 Engineering Psychology
 Human-Machine Interaction
 Cognitive Engineering
 Industrial/Organizational Psychology

Scope of Human Factors
History of Human Factors

Emerged during World War II
– Need for people to effectively operate sophisticated military
systems
– Early emphasis was on productivity and physiology

After WWII the discipline continued to grow to
meet the challenge of non-military problems
– Emphasis shifted to include other objectives, such as safer
and healthier working environments and improvements in
the quality of working life
– HF boosted by space program, computers, home
technology
Role of Human Factors
User-Centered Design
– Systems designed to fit people (not vice-versa).
– Reduces training time.
– Minimizes human error.
– Improves comfort, safety, and productivity.
HF Approaches to Problem-Solving
Equipment Design – change physical
equipment
 Task Design – change how task is
accomplished
 Environmental Design – change features of
the work environment such as temperature,
lighting, sound
 Training – change worker behavior by
providing skills and teaching procedures

Human Factors Military Activities
Accident Investigation
 Simulation, Virtual Reality, & Training
 Equipment/Task Design
 Basic & Applied Research

Accident Investigation
July 1988, USS Vincennes shot down
Iranian civilian airliner killing 290 on board
February 2001, USS Greeneville accidentally sinks Japanese
fishing boat killing 9 crewmembers (4 HS students)
Simulation & Training
Submarine Training Simulators
Military Training
Intelligent Enemies (LG)

Intelligent Enemies
– Courses of action (COA) not
developed sequentially.
– COA/eCOA assessed
simultaneously by LG zones.

Hypergames
– Strategic, operational and
tactical considerations in one
game.
– Hyperlinked at different
resolutions for continuous
real-time play.
Task/Equipment Design
Displays used for Training
Joint Combat Advanced Display and Debriefing System (JCADDS)
Environment
• Heat/Cold
• G-forces/Weightlessness
• Altitude
• Lighting
• Noise/Vibration
• Stress
• Chemicals
Light & Vision
Dark Adaptation
-Takes about 30 minutes to
dark adapt, but just a few
minutes to light adapt
Human Factors application: Why use red lights in cockpits and
darkrooms?
- because rods are insensitive to longer wavelengths (red) the eyes “think”
they are in the dark already allowing user to dark adapt more quickly)
Sense of Touch:
Tactile and Haptic
Tactile – Cutaneous or somatosensory sense provided by
receptors just under the skin.
Types of Receptors:
Thermoreceptors – detect heat/cold
Mechanoreceptors – detect pressure
Nociceptors – detect noxious stimuli (caustic
substances)
Haptic – Shape information provided through manipulation of
fingers
This device provides haptic information to
aid in performing a tracking task. The
user feels the button pop out and must
move the stick in the same direction to
maintain course.
Human factors application of haptic research
Haptic Responding
Response Type by Stimulus Complexity Interaction
F(1, 28) = 4.63, p < .05
22
21
20
Error
(degrees)
Haptic
Verbal
19
18
17
16
Simple
Complex
Vestibular System
Vestibular System – detects acceleration forces, maintains
upright posture/balance and controls eye position relative to head
Semicircular Canals – detect angular acceleration (rotation) in 3 axes
- a crista embedded in a jelly-like material (cupola) is supported by hair cells
that bend and fire when the crista moves in response to head rotation.
Vestibular Sacs (Utricle & Saccule) – detect linear acceleration - hair cells
embedded in jelly-like substance lag behind when the head moves. When
motion becomes steady, otoliths catch up and hairs no longer bent.
Gz
Acceleration Gy
Gx
High G-force tolerances
• +/- 2 Gz – pressure on butt, drooping face, noticeable weight increase
• +/- 3-4 Gz – Difficult to move, loss of fine motor movements, speech affected
• + 5.5 Gz – Negative blood pressure -> GLOC or grayout (passengers may
blackout sooner)
• Higher tolerances (>10) possible in Gx plane (forward acc) – weight on chest,
difficulty breathing
Prevention/Protection
• G-suit – squeezes blood out of extremities – increases tolerance by 2 G
• Active Straining Maneuver (Blue Angels) – Pull head down, slow forceful
breathing, tensing of muscles – increase tolerance by 1.5 G
Note: force of gravity ~9.8 m/sec2 or 33 ft/sec2, therefore 5 G would be roughly equivalent to
going from 0 to 112 mph in one sec
Motion Disturbances
Spatial Disorientation – vestibular illusion which tricks the brain into
thinking body is a different position than it actually is.
Vection – the illusion of self-motion induced my visual cues
Somatogravic Illusion – acceleration creates illusion that plane is
nose-up, deceleration feels like the plane is nose-down
Motion Sickness – nausea, disorientation and fatigue attributed to
disturbance of vestibular system caused when vision and inner ear send
conflicting (decoupled) signals
Treatments –
• Medications – Antihistamines (Dramamine), Dopamine blockers or antipsychotics (Thorazine), anti-nausea (serotonin) and Scopolamine
(anticholinergic)
• Behavioral strategies – sit facing front with front window view, eat bland
foods such as bread, bananas, rice. If on a boat, stay in middle (less rocking)
and look forward at the horizon, not at the waves.
Sopite Syndrome
Sopite Syndrome – motion induced drowsiness
• Subset of motion sickness symptoms, but sometimes the
sole manifestation
• Dangerous because victims often not aware of its onset
or the likelihood of onset
• Found to affect passengers and operators of cars, trucks,
ships, helicopters, planes, and simulators
• No known prevention techniques (many motion sickness
medications increase drowsiness)
• May be a major cause of accidents and military pilot pilot
training washout
Heat Stress

Small fluctuations in body temp greatly impact
physical & cognitive performance
 Problems include:
– +/- 6° C of core body is fatal (normal ~ 37° C)
– Dehydration, heat exhaustion, heat stroke
– Effects on continuous, low arousal tasks (vigilance)
– Aggravated by sweating (slippery hands, sweat in eyes,
heated metal equipment)
– May create perceptual difficulties (e.g., mirages, visual
distortion, optical illusions)
– Carrying heavy protective gear contributes to heat stress
(gloves, boots, body armor)
Cold

Injuries associated with cold: Hypothermia,
Immersion foot, Frostbite
 Performance effects include:
– Loss of psychomotor/manual dexterity, shivering
– Reduced tactile sensitivity

Countermeasures: dry, layered clothing,
warm food/liquids, wind barriers, large muscle
activity
High Altitude

Altitude Sickness
•Acute Organic Brain Syndromes – structural &
functional defects in the CNS
7000 m
•Cyclothymic Syndrome – alternating
depression, elevated mood
•Paranoia, O-C, depression, hostility,
decreased cognitive functioning
•Neurasthenic Syndrome – fatigability,
decreased motivation, psychosomatic
symptoms + reduced visual ability
5000 m
3000 m
•Loss of aerobic capacity by 10% for every
1000m over 1500 m
Noise & Hearing Loss
Converts sound energy (outer ear) to mechanical energy (middle ear)
to electrical nerve energy (inner ear), then sends signal to the brain
Decibel Scale
Sound intensity (dB) = 20 log (P1/P2); where P2 is the threshold of hearing
Source
Intensity
# Times > TOH
Jet at take-off; ear damage likely
140 dB
1014
Threshold of pain
130 dB
1013
Front row of a rock concert
110 dB
1011
Walkman at maximum volume
100 dB
1010
Vacuum cleaner
80 dB
108
Busy street
70 dB
107
Normal conversation
60 dB
106
Quiet office
40 dB
104
Whisper
20 dB
102
Normal breathing
10 dB
101
Threshold of hearing
0 dB
100
Note: M-16 rifle ~ 160 dB, M-198 Howitzer ~ 185 dB
Hearing Loss
Dangers of excessive noise:
• Hearing loss – caused by exposure to loud noises. Some
hearing loss is expected with age (higher freqs)
• Loss of sensitivity while noise is present
• Temporary Threshold Shift (TTS) – Loss of hearing that
lingers after noise is terminated (post-rock concert)
- Tinnitus or ringing in the ears
- 100 dB for 100 min causes a 60 dB TTS
• Permanent Threshold Shift (PTS) – Occupational
Deafness caused by long term exposure (esp high freqs)
• Eardrum rupture ~ 184 dB