Diploma in Aviation Medicine: Human Performance Revision June 11
Objectives of Aviation Psychology • to enhance flight safety • to improve effectiveness
Why is There Interest in Human Performance in Aviation? • Aviation is a safety-critical operation • Aircrew are subjected to many sources of stress • High levels of human performance must be achieved (e.g., fast jet pilots) • Human error is heavily implicated in aviation accidents
Equipment Environment & tasks Human operator Other personnel The Human in the Aviation System
General Principles • Introduction to Human Performance Module • Fundamentals of Human Performance • Individual Differences • Social Psychology and Aviation • A small amount of basic theory to help you to interpret the practical studies Content of Human Performance Module
Content of Human Performance Module New this year! • An early session on human error • …to provide a context for the module
Personal & Environmental Factors • Stress & Workload in Aviation I • Stress & Workload in Aviation II • Perceptual Issues in Aviation • Situation Awareness • Selection of Aviation Personnel Content of Human Performance Module
Training and Simulation • Simulation and Training • Fundamentals of CRM Training • Practical Aspects of CRM & LOFT Content of Human Performance Module
Systems Factors • Aviation Ergonomics I • Aviation Ergonomics II Content of Human Performance Module
The Human Factor in Aviation Accidents • Seminar: Flight Safety • Prof Peter Jorna, former head of division at NLR Amsterdam Also an accident module at Henlow, providing a context for this module See also lectures on Sleep, Fatigue and Shift-Working Content of Human Performance Module
Equipment Environment & tasks Human operator Other personnel The Human in the Aviation System: Relevance of Module Topics Individual Differences Selection
Equipment Environment & tasks Human operator Other personnel The Human in the Aviation System: Relevance of Module Topics Ergonomics Workload Technical Training
Equipment Environment & tasks Human operator Other personnel The Human in the Aviation System: Relevance of Module Topics Perception Stress
Equipment Environment & tasks Human operator Other personnel The Human in the Aviation System: Relevance of Module Topics CRM Training
Equipment Environment & tasks Human operator Other personnel The Human in the Aviation System: Relevance of Module Topics ‘Situation Awareness’ and ‘Human Error’ encompass all these interactions
Cognition Processes involved in the input, storage, transformation, and output of information by humans Main topics: • Memory • Attention • Skills
Memory Three major memory systems: • Sensory memory • Short-term memory • Long-term memory
Summary of properties of memory systems (inferred from classic experiments on memory) learn this! Sensory Short-term Long-term Capacity High 72 chunks no known limit Duration 1 sec 10-15 sec permanent? Type of storage Physical acoustic semantic characteristics Nature of retrieval parallel serial hierarchy? Nature of forgetting decay/masking interference failure of retrieval
Attention Selective attention: attend to one of several competing sources of information Divided attention: attempt to attend to more than one information source or task at the same time
Shadowing task Can detect physical changes on the unattended channel, but not semantic content Dichotic listening task Performance very poor Subjects tended to organise their recall by ear, not by recency of presentation Led Broadbent to propose Filter Theory. But, later shown that • subjects tend to hear their own name on the unattended channel • subjects tend to follow the message, even if it switches ears • hence, there is semantic processing on the unattended channel However, we can assume that recognition of unattended information is less likely than recognition of attended material Make sure that you understand this!
Divided attention Key question: Does man have a single information-processing channel (all tasks compete for the same ‘resources’ or ‘capacity’) or specialised resources for particular types of activity? (tasks performed concurrently compete only if they draw upon the same resources)
Visuo-spatial scratchpad Central Executive Articulatory loop Some support for the multiple resource theory: often, the degree of task interference depends upon the similarity of the tasks But: sometimes tasks that are dissimilar are found to interfere Baddeley’s working memory model is a compromise between extreme single-channel and multiple-resource views
Skills (obviously relevant to training lectures!) Characteristics • typically a sequence of activities • goal-directed behaviour • use of feedback Skill acquisition Three phases are sometimes distinguished: • Early or cognitive phase • Intermediate or associative phase • Final or autonomous phase In the final phase, behaviour becomes automatic; delegated to the control of ‘motor programs’ that do not require conscious attention and do not place heavy demands for mental resources Many everyday errors (actions not as planned) are associated with overlearned behaviour These errors involve well-practised behaviour, but are inappropriate Some aircrew errors are of this type
Issues in skill acquisition • Whole versus part learning • Massed versus spaced learning • Transfer of training very important aspect of simulator-based training
Two major types of individual difference covered: • Intelligence/ability/aptitude • Personality • Factor Analysis: make sure that you have a good intuitive grasp of this: you don’t need to know the underlying mathematics! • Basic psychometric criteria
Intelligence/ability/aptitude These are the key issues • Intelligence: Innate or learned? • Intelligence: How many abilities? • There is evidence for a general ability factor • However, specific abilities also appear to exist • Intelligence: The Intelligence Quotient (IQ) • Aptitudes • Test Fairness • Intelligence: Are IQ tests valid?
Personality key issues • Types of personality test: • Interview (not reliable) • Projective tests • Personality questionnaires • (discussed examples of each) • Is there a ‘pilot personality’? • Does personality influence success in flying training? • Is there an ‘accident-prone’ personality’?
Types of social influence (can use this info for CRM questions) Compliance: behaviour consistent with direct request • foot-in-the-door phenomenon • door-in-the-face phenomenon Conformity: behaviour consistent with group norms • size of group (up to about four) • attractiveness and status of group members • Informational influence (trusting others’ judgements) and normative influence (seeking group acceptance) Obedience to authority • Milgram experiment • 62.5% of the 40 subjects administered shocks to the highest level • factors affecting obedience, such as status of experimenter, proximity to ‘student’ Think about how this applies to small groups of interest to us, such as flight crew or teams of maintenance engineers
Group Decision Making: Polarisation • Was thought that group decision making was more risky than individual DM (‘risky shift’) — but became apparent that there is a shift in the direction of the pole that, on average, the group favours as individuals (polarisation) • Stoner’s experiments • Normative and informational influences produce group polarisation
Group Decision Making: Groupthink • Work of Janis. Based on real-life examples such as Bay of Pigs (or, more recently, UK MPs’ expenses!) • Desire for consensus overrides group members’ motivation to assess risk and consider alternative courses of action • Groupthink occurs under the following conditions: • High cohesiveness of the group • Uncertainty of approval • Insulation of the group • Directive leadership • High stress situations • Symptoms include • Illusion of invulnerability • Stereotypes of out-group • ‘Mindguards’ • Direct pressure on dissenters • Collective rationalisation • Effects on decision making: • Incomplete survey of alternatives • Incomplete survey of objectives • Incomplete analysis of risks associated with course of action • No contingency plans
Aeronautical Decision Making (ADM) • Work of Jensen: decision error is cause of most fatal aviation accidents; argued that decision making can be improved through training • Decisions have two components: • Rational judgement (‘Headwork’) • Motivational judgement (‘Attitudes’) • Hazardous attitudes: • Anti-authority • Resignation • Impulsivity • Invulnerability • Macho • ADM courses aim to provide: • Ability to recognise hazardous attitudes • Knowledge of effects of these attitudes • Skills to overcome the effects • Methods • Self assessment tools • Examination of case studies • Practical Exercises
Perception is the process of acquiring, selecting, and organising sensory information The most important perceptual processes for aviation are those associated with vision and hearing 1 The ear and the auditory system • balance and the vestibular system • localisation of sound and identification of source 2 The visual system • bottom-up processing • top-down processing • cues to depth perception
The ear and the auditory system The ear serves two main functions: • Balance. The vestibular system of the inner ear detects angular and linear accelerations of the head • Hearing. To detect sounds, to determine the location of their sources and to recognise the identity of these sources
Inertia force Weight force Resultant Balance and the vestibular system Practical implications With regard to the otolith, the weight force in a climbing aircraft operates similarly to the resultant force in an accelerating aircraft. Without visual feedback, pilots can mistake acceleration for pitch. Accelerating aircraft Ascending aircraft The situation is aggravated if the pilot attempts to compensate for an incorrect percept. Although feedback from the vestibular system can be compelling, a pilot needs to learn to trust instrumentation.
Auditory perception Localisation of sound Interaural differences: • Intensity. Most suited to localising high frequencies • Time/phase. Most suited to localising low frequencies. Sounds emanating from directly in front and behind the head produce the same interaural differences.
Auditory perception Practical implications • Cockpit design • The cockpit relies heavily on the presentation of visual information. Adoption of auditory signals may reduce the workload experienced by pilots in the visual domain. • Localisation of auditory warnings • Similar sounding warnings emanating from similar areas may cause confusion • Adoption of white noise bursts within ambulance sirens
Visual perception What you see is what you get? Visual modality is obviously extremely important in aviation. But can we always trust our eyes? The visual scene is captured by the eye as a poor quality, two-dimensional representation What is perceived is determined by: • ‘Bottom-up’ processes. The percept of a stimulus is determined by features of the stimulus as processed by the visual cortex • ‘Top-down’ processes. The interpretation (consciously or not) of a stimulus can be determined by our experience and knowledge Important distinction!
Visual perception Top-down processes • If the percept is generated deterministically (bottom-up processing) from the visual cortex . . . • . . . how can one distal (real world) stimulus produce two percepts? • By a mental model: Our own experience and expectations help to determine what we see (top-down processing) Thirteen or ‘B’? Necker cube Lincoln or women? Old or young women?
Visual perception Depth perception: learn this! • Convergence • of the eyes. • Stereopsis • disparity between the two images. • Accommodation • of the lens. • Retinal versus actual size • for known objects. • Overlap • a near object will occlude the view of a far object. • Position in visual field • objects nearer the horizon are farther away. • Aerial Perspective • clarity of objects is reduced at distance. • Relative motion • angular velocity greater for near objects. All require both bottom-up & top-down processing.
How we perceive depth • Position in visual field • objects nearer the horizon are farther away • Textual Gradient • Surfaces will have a finer texture with distance • Stereopsis • Binocular disparity between the two images • Convergence • of the eyes • Occlusion • a near object will occlude the view of a far object • Perceptual constancy • Retinal versus actual size • Relative motion • angular velocity greater for near objects • All require both bottom-up & top-down processing. Know this
Featureless surfaces, or those with textures of unknown sizes, can produce inaccurate judgements of size. Sea. Beehives for caravans. Can produce an inaccurate mental model of the situation which overrides the correct perception of the instruments. Top-down influences. Exacerbated by fatigue and workload. Visual perception Some perceptual problems
Pilots may have to visually judge the glide slope without any cues other than those from the surface of the world. The ‘aspect’ (retinal shape) of the runway is not very useful. However, the visual touchdown point is a constant and unchanging cue, relative to the horizon. If the horizon cannot be seen, its location must be implied, The runway’s sides meet at the horizon. The terrain’s texture gradients. The relative position of the aircraft’s canopy. Practical implications: visual approach Visual perception: know the practical implications (next few slides)
HORIZON B Visual touchdown point A Angle of Approach A = B Visual perception Practical implications: visual approach (2)
Visual impact point Actual touchdown point = angle of approach Visual perception Practical implications: visual approach (3)
Identification of a colliding aircraft is confounded by; Constant relative bearing. Unique characteristic. Periphery of retina detects sensitive to movement. Non-linear increase in retinal size. Retinal image doubles with each halving of closure distance. Uneven visual acuity across the retina. Maximal acuity at the fovea. Detection only if pilot is looking directly at it. Implications for visual scanning to acquire proximal image on the fovea. Visual perception Practical implications: mid-air collisions
Relative Bearing Aircraft B Visual perception Practical implications: mid-air collisions (2) Impact Aircraft A