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Key Dismukes, PhD Chief Scientist for Aerospace Human Factors NASA Ames Research Center 12 January 2002 Lessons from Aviation: Memory, Skilled Human Performance,

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Presentation on theme: "Key Dismukes, PhD Chief Scientist for Aerospace Human Factors NASA Ames Research Center 12 January 2002 Lessons from Aviation: Memory, Skilled Human Performance,"— Presentation transcript:

1 Key Dismukes, PhD Chief Scientist for Aerospace Human Factors NASA Ames Research Center 12 January 2002 Lessons from Aviation: Memory, Skilled Human Performance, and All-too-human Error

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 Memory More accessible Activated representations Activation Very limited capacity Currently attended representations Dynamic flow of contents Representations compete to enter attention based on level of activation External Stimuli Less accessible Long-term memory very large capacity Focal Attention

9 Attributes: Activation and Retrieval of Memory Representations Memory More accessible Activation horse External Stimuli Less accessible Long-term memory Focal Attention cowboy saddle Indian racing animal horse l Currently attended representation provides activation to associated item in memory l Activation increases as function of time in attention l Activation decays as function of time since last attended l Activation is finite and divided among associates l Activation is divided according to strength of links to associate More accessible

10 Attributes: Goals are Memory Representations Memory More accessible Activation prepare vuegraph External Stimuli Less accessible Long-term memory Focal Attention prepare talk schedule conference room floss daily win Nobel prize l Deferred intentions are a form of goal l Goals are represented as condition/action associates (If…then) l Goals are associated in hierarchies of sub- goals l Sub-goal in focal attention helps maintain activation of higher goal More accessible

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 Memory More accessible Activation lion External Stimuli Less accessible Long-term memory Focal Attention cub lion rate pleasantness Africa cat Participate in experiment animal press key l Prospective task competes with pleasantness rating for retrieval l On-going task has inherent advantage l Outcome is probabilistic Depends on multiple factors More accessible

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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16 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 Flight Crews Manage Multiple Tasks Concurrently

17 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 Examples of Neglected Tasks Aviation Incident Study

18 Competing Tasks that Distracted or Preoccupied Pilots 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) Aviation Incident Study

19 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 Examples of Neglected Tasks Aviation Incident Study

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

21 Why So Easy to Forget 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 Omitting a Procedural Step

22 Prospective Memory Countermeasures 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 Training Implications

23 Line Oriented Flight Training (LOFT) Full-mission simulation Normal operations and challenging situations (e.g., weather diversions, equipment failures) Should include realistic: – Concurrent task demands – Interruptions – Distractions – Delays Training Implications

24 Error Management Training Change in historic attitude Errors are inevitable Training should address: –Recognizing potential threats –Detecting errors –Managing error outcome Training Implications

25 Error Data from Routine Operations 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 Training Implications


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