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PSY205s: The psychology of aviation -
Situational Awareness
Dave Nunez, MPhil
Department of PsychologyUniversity of Cape Town
2PSY205s – The psychology of aviation: Situational Awareness
Admin info
I am in room 4.22 (650 4606)
Paper: Endsley 1999 from Work Return Room
Slides for the time being:http://www.cs.uct.ac.za/~dnunez/teaching(on the course web page later)
3PSY205s – The psychology of aviation: Situational Awareness
Why study aviation in psychology?
Airplanes get more complex….
Bleriot Model XI - 1909 Aerospatiale-BAC Concorde - 1969
….but the people who fly them remain the same.
4PSY205s – The psychology of aviation: Situational Awareness
Why study aviation in psychology?
Goal: Increase safety (purely applied)
Aviation is a potentially dangerous activity
Increase safety by engineering (better engines, etc)What about the people doing the flying?
How safe is flying?
Deaths per year by cause(USA 1981-1994)
Commercial flight: 100Electrical current: 850Bicycle riding: 1000Pedestrian: 8000Falling: 12000Auto accidents: 46000
So flying to Joburg should be about 460 times safer than driving there.
5PSY205s – The psychology of aviation: Situational Awareness
A little history
During the ‘psychometrics boom’ (1920s-1930s), psychologists get involved
Pilot selection tests
During WW2, psychologists begin to look at aviation loses
More aircraft lost to accidents than the enemy!Bartlett, Chapanis, Craik, Gibson and other ‘big names’ got involved
6PSY205s – The psychology of aviation: Situational Awareness
Pilot error vs. Human error
General rule was: If the plane didn’t fail, it was “pilot error”
Pejorative phrase; laid blameImplication – ‘not good enough’
Evidence from Chapanis and others showed it was actually “human error”
Acknowledge limits of human beingsCertain system features create situations where an error is more likelyProblem becomes worse under certain environmental conditions
Alphonse Chapanis (1917-2002), was a leading figure in the
psychology of aviation safety since the 1940s
7PSY205s – The psychology of aviation: Situational Awareness
Example: Human error (and a solution)
Problem: Pilots shut down engines in flight by pulling the wrong lever
Chapanis’ solution: shape coding the lever handles (also color coded by function)
Dou
glas
DC
-4 (
early
194
0s)
Bee
chcr
aft
Duc
hess
(la
te 1
970s
)
8PSY205s – The psychology of aviation: Situational Awareness
Human Factors (Ergonomics)
Understand patterns of errorsMany errors can occur regardless of experienceWhat about being human makes us likely to commit errors?Examine cognitive processes to identify ‘danger spots’
Goal: To create systems which reduce the probability of errors
‘Pilot friendly’ aircraft which reduces errors and creates a better working environment
9PSY205s – The psychology of aviation: Situational Awareness
A major contribution: SA
A recent important contribution: Situational awareness
Combination of mental models, working memory and situated cognition theoryTries to predict how and when errors can happenApplied to operation of complex systems (nuclear powerplants, ships, aircraft, cars)
Much research, and is taught to pilotsIncrease their awareness of when things can go wrong
10PSY205s – The psychology of aviation: Situational Awareness
A quick recap of the info-processing model
[Herbert Simon’s model]Attention, WM (STM), LTM.Attention filters irrelevant (unexpected) stimuli outStimuli are transformed in WM according to active rules and schema (from LTM)Contents of WM in turn activate rules and schema as required by the dataBehaviour/consciousness is based on the contents of WM and active scripts
11PSY205s – The psychology of aviation: Situational Awareness
SA: definition
“the perception of the elements in the environment within a volume of time and space, the comprehension of their meaning and the projection of their status in the near future” (Endsley 1998)
Cognitive task (probably expertise bound)Dynamic (over time and space)Several levels of processing (perception, comprehension, prediction)
12PSY205s – The psychology of aviation: Situational Awareness
Levels of SA (1)
Level 1: Perception of the environment
Other aircraft, terrain, own aircraft systems, navigation, radiosDeals with the present – loads perceptual buffers, attention and working memory
Mica Endsley (of SA Technologies,
previously of MIT) is one of the leading
experts on situational awareness in aviation
13PSY205s – The psychology of aviation: Situational Awareness
Levels of SA (2)
Level 2: ComprehensionSynthesis of disjoint level 1 elements (‘big picture’)Assign importance to each element (goal-directed)Forms a holistic understanding of what is happening nowReaching this level requires experienceIt is mostly a top-down task; loads working memory, and requires LTM
14PSY205s – The psychology of aviation: Situational Awareness
Levels of SA (3)
Level 3: Projection (predicting)
Requires both Level 1 and Level 2 SAAlso expertise bound – More experienced pilots spend more time predicting what will occurEffectively gives the pilot more time for decision making
The heavier an aircraft, the longer it takes to respond to a pilot’s input. In
such situations, Level 3 SA is essential. This is partly why airlines pick their most experienced pilots to
fly such aircraft.
15PSY205s – The psychology of aviation: Situational Awareness
Cognition and SA levels
All three levels require some WM and attentionLevel 1: Speech comprehension, decoding system interfaces; attentional filtering (mostly bottom-up)Level 2: Activating mental models and schemata (mostly top-down)Level 3: Take LTM information and apply it to active models (mostly top-down)
So WM and attention loads can be high during SA
But: Experts will use less (better chunking strategies, better at filtering out irrelevant elements)
16PSY205s – The psychology of aviation: Situational Awareness
Information load: ExampleData Sources:
Outside (terrain)Outside (weather)Outside (aircraft)Inside (gauges)Inside (maps)Inside (checklists)Inside (crew)Aural (crew)Aural (control)Aural (aircraft)Aural (alarms)Haptic (controls)Haptic (buffets, etc)
17PSY205s – The psychology of aviation: Situational Awareness
Individual factors in SA (1)
Limits of attentionNovices or experts in novel situations require more attention to be placed on the environmentInformation overload can exceed the capacity – ‘miss’ important relevant information
Giving more attention to one SA task reduces it on another
Serious problem: NTSB review – 31% of human errors due to problems acquiring relevant data
18PSY205s – The psychology of aviation: Situational Awareness
Individual factors in SA (2)
Can be overcome by ‘sampling’ informationLearn a way to ‘scan’ the world (avoids fixation)Strongly trained patterns become habitual
Sampling can fail:Non-optimal strategy (focus on the wrong things)Visual dominance (forget other inputs)Memory failures (forget relative importance of elements)In overload, ‘leave out’ certain elements
19PSY205s – The psychology of aviation: Situational Awareness
Individual factors in SA (3)
Attention limits can be helped by expertiseTop-down knowledge creates expectations, which can increase processing speedBUT: if unexpected information occurs, more likely to make an error (‘superiority’ effects)
WM is used mostly for integration and projection (Levels 2 & 3)
If much new info is being processed, little WM will be left for integration (and vice-versa!)Projection places a particularly heavy load on WM (need to store multiple states)
20PSY205s – The psychology of aviation: Situational Awareness
Coping mechanisms (1)
All is not lost – cognitive strategies/structures exist to deal with this
‘coping mechanisms’ (not really)Normal info sorting/learning structures
Generally: use previous knowledge to order the world
Some trained (automaticity); some developed (mental models)Generally automatic, subconcious processes
21PSY205s – The psychology of aviation: Situational Awareness
Coping mechanisms (2)
Structured knowledge from experience (LTM)
Schemata, scripts & mental models‘fill in’ missing info (default values)Help with structuring & comprehension (reduce WM & attention used)Increase accuracy of predicting the futureCan be a ‘fuzzy fit’Almost essential for higher levels of SA
22PSY205s – The psychology of aviation: Situational Awareness
Coping mechanisms (3)
Goal-driven processingGoals determine how resources are allocated alsoGoals provide a structure in which to process (allows higher levels of SA)
Automaticity (habitual responses) – ‘scripted’Allows processing with minimal attentionCan miss novel stimuliSafe for routine situations (is there such a thing?)
23PSY205s – The psychology of aviation: Situational Awareness
Pu
ttin
g it
all
tog
eth
er
(En
dsl
ey
19
95
)
24PSY205s – The psychology of aviation: Situational Awareness
Wh
ere
th
e p
rob
lem
s ca
n o
ccu
r
25PSY205s – The psychology of aviation: Situational Awareness
Factors which reduce SA – Stress (1)
Physical stressorsNoise, vibration, lighting, temperature, fatigue, ‘jet lag’
Social/psychological stressors
Anxiety/fear, uncertainty, self-esteem, career advancement, time pressure
Stress effects are complex – a little can help (yerkes-dodson law)
Stress produces many physical and psychological effects which can reduce SA and undermine a
pilot’s ability to act correctly.
26PSY205s – The psychology of aviation: Situational Awareness
Factors which reduce SA – Stress (2)
Why does stress affect SA?Attentional narrowing (high arousal/anxiety)Oversampling of dominant cuesScan patterns disruptedPremature closure (hasty decisions)Reduction in WM capacity / LTM retrieval (affects Level 2 & 3 most)
Training reduces these effectsAutomaticity reduces attention and WM requirementsMore cues, better associations improve retrieval
27PSY205s – The psychology of aviation: Situational Awareness
Factors which reduce SA – under/overload
Mental overloadWM and attention limits reachedIncomplete/erroneous perceptionStressor (being ‘behind the plane’)
Mental underloadNo active search for infoLow vigilance/motivation
Air traffic controllers (ATCs) also require high levels of SA. In busy sectors (such as London, Atlanta or Tokyo) the volume
of traffic can lead to mental overload.
28PSY205s – The psychology of aviation: Situational Awareness
Factors which reduce SA – bad systems
The aircraft’s interface can present information poorly
Presenting too much can lead to overloadHiding too much can lead to unawarenessThe layout of information can interfere with the scan
Recently: ‘Smart’ planes (‘glass cockpit’)Aware of the information required in a flight phaseShow what is necessary, but watch for problems in the backgroundAlert the crew if a problem exists (speech, icons, etc)
29PSY205s – The psychology of aviation: Situational Awareness
Improvements in interfacesB
oein
g 73
7-20
0Adv
(la
te 1
960s
)
Boe
ing
737-
800
(Ear
ly 2
000s
)
30PSY205s – The psychology of aviation: Situational Awareness
Factors which reduce SA - Complexity
Aircraft keep getting more complexTechnology demandsIncreases workload – more system components, more interactionsEffectively increases number of goals and tasks
An expert in these systems will be protected (a little)
Pilots vary widely on their self-reported understanding of the systemsA difficult road to becoming an expert!
31PSY205s – The psychology of aviation: Situational Awareness
Factors which reduce SA – Automation (1)
Habitual procedures can take crews ‘out of the loop’
Reduce vigilance, increase complacencyBecome a passive recipient of information
Automatic states have bad cognitive consequences
Pilots are slower to detect problemsSlower to re-orient after realizing the problem (schemata de-activation/re-activation)
32PSY205s – The psychology of aviation: Situational Awareness
Factors which reduce SA – Automation (2)
But: automation can help SA also
Computers can monitor many variablesRemove unnecessary manual work (navigation)Can present many variables already integrated (for Level 2)
The trick is: create systems which aid but do not promote complacency
33PSY205s – The psychology of aviation: Situational Awareness
How serious is a failure in SA?
Jones & Endsley looked at accidents in the USA over a 4 year period (major carriers)
77% had a substantial human error componentOf those, 88% due to a failure of SA
SA failures not even distributed among levels
Level 1: 72%Level 2: 22%Level 3: 6%
34PSY205s – The psychology of aviation: Situational Awareness
Further: specific cause
35PSY205s – The psychology of aviation: Situational Awareness
Teamwork: SA in CRM
Most aircraft are flown by a team
Do other people increase or decrease SA?Spread the work: Effectively have more WM and attentionBut: Is that enough for collaboration?
Can too many cooks spoil this broth?
36PSY205s – The psychology of aviation: Situational Awareness
Sharing data
To work together, people must share infoKeep mental models etc. alignedEach must know what information the other needsMust also share higher level understanding, and projection (level 2 and 3)
Essential: shared mental modelsHigh functioning crews communicate less than low functioning crews