Key Dismukes, PhD

1
Lessons from Aviation Memory, Skilled Human
Performance, and All-too-human Error

• Key Dismukes, PhD
• Chief Scientist for Aerospace Human Factors
• NASA Ames Research Center
• 12 January 2002

2
Road Map of Talk

• A cognitive perspective on error
    vulnerability of skilled professionals
• Examples from one domain of error
    prospective memory
• Lapses in everyday life
• Lapses in flight operations
• Implications for professional training

3
Most Airline Accidents Attributed to Crew Error

• Society error blame
• Misrepresents nature of cognitive skill
• Undercuts safety
• Research on human factors in aviation
  safety
• Extrapolate to other professional domains?

4
Aircrew Performance

• Trained to high level of performance daily
  practice annual recurrent training
• Monitored periodically by check pilots
• Highly motivated
• NTSB accident reports reveal few examples of
  incompetence or malfeasance

5
Two Fallacies about Error

• Fallacy Error can be eliminated if pilots are
  sufficiently  vigilant, conscientious, and
  proficient.
• Truth Vigilant, conscientious experts routinely
  make errors.
• Fallacy If an accident crew made errors in tasks
  that pilots routinely handle without difficulty,
  that accident crew must have been in some way
  deficient either they lacked skill, or had a
  bad attitude, or just did not try hard enough.
• Truth The fallacy ignores sampling bias. No
  matter how many times an expert performs a
  procedure perfectly, the probability of error
  is greater than zero.

6
A Cognitive Perspective

• Simply trying hard will not prevent errors
• Unique human capabilities enabled by biological
  information-processing mechanisms
• Vulnerable to error
• Error is probabilistic, not deterministic
• Illustrate with research on memory errors

7
Prospective Memory (PM)

• Remembering to perform an action that  must be
  delayed
• Relatively new field of human memory  research
• Defining characteristics
• Delay between forming intention and opportunity
  to   execute (seconds to years)
• Delay filled with other tasks that occupy
  attention
• No explicit prompt telling us it is time to
  execute intention
• So how do we ever remember to perform
    intentions?
• A theoretical perspective

8
Attributes of the Model
Focal Attention

• Very limited capacity
• Currently attended representations
• Dynamic flow of contents
• Representations compete to enter
• attention based on level of activation

External Stimuli
More accessible
Activated representations
Activation
Memory

• Long-term memory
• very large capacity

Less accessible
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Attributes Activation and Retrieval of Memory
Representations
Focal Attention
External Stimuli
horse
horse

• Currently attended representation
• provides activation to associated item
• in memory
• Activation increases as function of
• time in attention
• Activation decays as function of time
• since last attended
• Activation is finite and divided among
• associates
• Activation is divided according to
• strength of links to associate

More accessible
More accessible
Activation
Memory
Less accessible
Long-term memory
10
Attributes Goals are Memory Representations
Focal Attention
External Stimuli
prepare vuegraph

More accessible
prepare talk
More accessible

• Deferred intentions are a form of goal
• Goals are represented as condition/action
  associates (Ifthen)
• Goals are associated in hierarchies of sub-goals
• Sub-goal in focal attention helps maintain
  activation of higher goal

Activation
schedule conference room
Memory
Less accessible
win Nobel prize
floss daily
Long-term memory
11
Einstein-McDaniel PM Paradigm

• Instruct subjects to perform cover task
    (e.g., reading a paragraph or rating
  pleasantness of   series of words)
•   Give additional (PM) task
    (e.g., Press slash key when see a name
  of an animal)
•   Subjects begin performing cover task
•   Delay between starting cover task and trial
  with   animal name
•   Must remember to perform PM task without
    prompting

12
Prospective Memory as Competing Concurrent Task
Focal Attention
External Stimuli
lion
lion
rate pleasantness
animal
More accessible
press key
More accessible

• Prospective task competes with pleasantness
  rating for retrieval
• On-going task has inherent advantage
• Outcome is probabilistic
• Depends on multiple factors

Activation
Memory
Participate in experiment
Less accessible
Long-term memory
13
Implications for Real-World Performance

• Cannot maintain delayed intentions in   focal
  attention
• Must retrieve from memory when opportunity for
    execution arises
• Retrieval requires noticing some cue associated
    with intention
• Availability of cues and noticing cues is
  haphazard
• Thus, memory lapses are commonplace

14
Strategies

• Importance of delayed intention does not
    prevent memory lapses
• Simply trying harder is ineffective
• Strategies may help to some degree
• Habitual review what do I need to do now?
• Encode environmental cues likely to be present in
  window of opportunity for execution
• Create salient cues that must be processed during
  ongoing task

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Flight Crews Manage Multiple Tasks Concurrently

• Cockpit operations are highly proceduralized
• Taxi, climb out, descent, and arrival are
  sometimes quite busy
• Each pilot is responsible for multiple concurrent
  tasks (e.g., searching for traffic and flying the
  airplane)
• Interruptions, distractions, or preoccupation
  with one task to the detriment of another found
  in nearly half of NTSB accident reports
• Issue may be management of attention rather than
  overload

17
Aviation Incident Study
Examples of Neglected Tasks

• Lapses in monitoring (2/3 of reports)
• Aircraft position taxi, altitude capture,
  navigation
• Aircraft status systems, automation
• Actions of other crew member
• Lapses in prospective memory (1/4 of reports)
• Complete interrupted procedure on checklist
• Retract speed brakes when leveling-off descent
• Reset flaps and bleed air after de-icing
• Stop fuel transfer
• Set take-off flaps when deferred
• Defer lowering landing gear in minimum fuel
  situations

18
Competing Tasks that Distracted or Preoccupied
Pilots
Aviation Incident Study

• 50 involved communication
  (e.g., conversation with other
  crewmembers/flight attendants, radio
  communication, ATIS, PAX announcements).
• 16 involved head-down tasks
  (e.g., paperwork, FMS entry, reviewing charts)
• 14 involved abnormals
• 8 involved searching for/responding to traffic
• 12 miscellaneous
  (e.g., decision-making, unstabilized
  approach)

19
Aviation Incident Study
Examples of Neglected Tasks

• Lapses in monitoring (2/3 of reports)
• Aircraft position taxi, altitude capture,
  navigation
• Aircraft status systems, automation
• Actions of other crew member
• Lapses in prospective memory (1/4 of reports)
• Complete interrupted procedure on checklist
• Retract speed brakes when leveling-off descent
• Reset flaps and bleed air after de-icing
• Stop fuel transfer
• Set take-off flaps when deferred
• Defer lowering landing gear in minimum fuel
  situations

20
Omitting a Procedural Step

• Highly practiced procedures vulnerable to
  omission when
• Interrupted
• Performed outside normal sequence or context
• Highly practiced procedures become largely
  automatic
• Allows fast, smooth execution
• Requires minimal conscious supervision
• Execution largely under control of environmental
  cues
• Most common error in maintenance omitting a step
  in re-assembly
• Example finish tightening spark plugs

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Why So Easy to Forget a Procedural Step?
Omitting a Procedural Step

• With highly practiced procedures, retrieval of
  each step triggered by
• Current state of environment
• Execution of immediately preceding step
• Interruption breaks chain of preceding steps --
  no trigger
• Environment may seem to indicate uncompleted step
  has been performed
• No episodic memory trace for habitual actions

22
Prospective Memory Countermeasures
Training Implications

• Recognize the threat
• Vulnerable even when tasks are important and
  delays are short
• Especially vulnerable Interruptions and
  performing habitual procedures out of normal
  sequence
• Explicitly note interruption and identify
  when/where intention will be executed
• In team situation, say aloud
• Create salient reminder cues
• Avoid rushing procedures
• Periodically review status and ask if anything is
  missing
• Use checklists
• Not always practical

23
Line Oriented Flight Training (LOFT)
Training Implications

• Full-mission simulation
• Normal operations and challenging situations
  (e.g., weather diversions, equipment failures)
• Should include realistic
• Concurrent task demands
• Interruptions
• Distractions
• Delays

24
Error Management Training
Training Implications

• Change in historic attitude
• Errors are inevitable
• Training should address
• Recognizing potential threats
• Detecting errors
• Managing error outcome

25
Error Data from Routine Operations
Training Implications

• What errors occur, circumstances, and how
  professionals respond
• Accident/incident reports useful but are a
  limited and biased sample
• LOSA Line Operational Safety Audits
• Large sample of daily operations
• Data on threats, errors, and how crews manage
• Comprehensive and realistic picture of challenges
• LOSA laboratory research   powerful new
  approaches to training