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CognitionandFlightPerformanceinOlderPilots

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DOI:10.1037/1076-898X.3.4.313

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Journal of Experimental Psychology: Applied1997. Vol. 3, No. 4.313-348

Copyright 1997 by the American Psychological Association, Inc.1076-898»97/$3.00

Cognition and Flight Performance in Older Pilots

David J. Hardy and Raja ParasuramanThe Catholic University of America

The authors reviewed studies of cognitive proficiency and flight perfor-mance. Age-group differences were found in pilots in perceptual-motorskills and memory and, to a lesser extent, in attention and problem solving.Flight experience does not alter this age-related decline, with the possibleexception of the metacognitive skill of time sharing. Age-group differencesin flight performance are most evident in the secondary task of air trafficcontrol communications. Age-related differences in current measures ofpilot cognition are minimally predictive of primary measures of flightperformance (flight simulation and accident rates). A model of cognitionand flight performance is proposed involving higher order factors that tapinto pilot knowledge structure, including mental workload and workloadmanagement, mental models, and situation awareness.

The cognitive changes that accompany adultaging have been extensively examined in studiescomparing the performance of young and olderadults on laboratory psychological tasks (e.g.,Craik & Salthouse, 1992). Older participants inthese studies typically are retired adult volunteersin the general population. Given the continuedaging of the adult population (U.S. Bureau of theCensus, 1995), however, there is a renewedimpetus, for safety and practical reasons, toexamine the older adult in a variety of typical lifesituations including job performance. The rela-

David J. Hardy and Raja Parasuraman, CognitiveScience Laboratory, The Catholic University ofAmerica. David J. Hardy is now at the Neuropsychol-ogy Program, University of California, Los Angeles.

This study was supported in part by NationalResearch Service Award MH-11361 from the NationalInstitute of Mental Health, by the National Institute onAging Grant AG-07569, and by the National Aeronau-tics and Space Administration Grant NAG-1-1296. Wethank Evan Byrne, Alan Hartley, and Mustapha Moul-oua for helpful comments on earlier drafts of thisarticle.

Correspondence concerning this article should beaddressed to Raja Parasuraman, Cognitive ScienceLaboratory, The Catholic University of America, 250O'Boyle Hall, 620 Michigan Avenue, Washington, DC20064. Electronic mail may be sent via Internet toparasuraman@cua.edu.

tion between cognition and everyday activitiesand work has been investigated in such areas asmedication adherence (Park, Morrell, Frieske,Blackburn, & Birchmore, 1991), use of automaticteller machines (Rogers, Fisk, Mead, Walker, &Cabrera, 1996) and other technologies (Czaja,1997), driving (Parasuraman & Nestor, 1991),and commercial flight operations (Morrow, 1996).The focus of this review is on the flight perfor-mance of older pilots.

When aviators first took to the air followingthe Wright brothers' successful powered flight atthe beginning of this century, piloting demandedconsiderable physical and perceptual-motor skills.In contrast, pilots today must rely primarily onhigh-level cognitive skills such as decision mak-ing, planning, and appropriate management oftheir workload. For example, modern commer-cial aircraft have been designed to be highlyautomated. This has resulted in significantchanges, both quantitative and qualitative, in thecognitive demands that flying imposes on pilots(Bainbridge, 1983; Parasuraman & Mouloua,1996; Sarter & Woods, 1994; Wiener, 1988).Such changes have created opportunities fordifferent kinds of human error and, in fact, 50%to 75% of fatal aircraft accidents (both civilianand military) are due to human error1 (Baker,

1 We include in the term "human error" not just

313

https://www.researchgate.net/profile/Raja_Parasuraman?el=1_x_100&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/profile/David_Hardy?el=1_x_100&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

314 HARDY AND PARASURAMAN

Lamb, Li, & Dodd, 1993; Billings & Reynard,1984; Vyrnwy-Jones, 1985). Perceptual-motorskills—for example, maintaining the flight pathin turbulence, or split-second responding to avoidcollision—are still important, particularly in mili-tary aviators, but the physical demands of flyinghave decreased, whereas the cognitive demandshave concomitantly increased.

Because cognition plays an increasingly largerrole in the piloting of modem aircraft, understand-ing the impact of age-related changes in cogni-tion on pilot performance becomes correspond-ingly more important. It is well documented thatsome (but not all) cognitive abilities decline withage in adults (Craik & Salthouse, 1992). Informa-tion-processing speed, for example, slows, andthe capacity to hold information in workingmemory may also decline with age (Birren &Schaie, 1990; Cerella, 1994; Salthouse, 1991a).Could age-related cognitive decline result in aloss of flying proficiency in older pilots? Thequestion is important for at least two reasons: (a)there are more older pilots than before, particu-larly in general aviation (Bruckart, 1992), reflect-ing the aging of the adult population (U.S.Bureau of the Census, 1995); and (b) the FederalAviation Administration (FAA) has a regulationcommonly called the "Age 60 rule" that man-dates the retirement of commercial airline pilotswhen they turn 60 years old (Federal Register,1978).

Understanding the Cognition-PerformanceLink in Older Pilots

Although seemingly straightforward, the ques-tion of age-related cognitive decline and flightperformance in older pilots involves some intrica-cies. To begin with, the relationship betweenage-related cognitive decline and job perfor-mance is complex (Czaja, 1990). Cognitive abil-ity (including perceptual-motor skills) is moder-ately associated with job proficiency (see Hunter& Hunter, 1984, for a review). This is also true

errors made by pilots, but also those potentiallyattributable to human designers of Might equipmentand software, as well as to managers, supervisors, andregulators who define and enforce procedures concern-ing operator use of automation technology (see Para-suraman & Riley, 1997).

for pilot performance, at least during training(Martinussen, 1996). But many studies havefailed to find a negative relationship between ageand job performance (Davies & Sparrow, 1985;McEvoy & Cascio, 1989; Van Zelst, 1954).Perhaps the job-related experience or occupation-specific knowledge of older workers compen-sates for any age-related cognitive decline(Salthouse, 1994a).

This raises the question of how expertise andage interact, an issue that has been examinedextensively in the cognitive aging literature.Expertise sometimes ameliorates the effects ofaging, but not always (Ericsson & Charness,1994; Salthouse, 1994a). In studies of pilots,flight expertise or experience and pilot age areoften confounded, making comparisons betweenyounger and older pilot performance potentiallydifficult to interpret.

Another reason for a lack of a relationshipbetween age-related cognitive decline and jobperformance could be that the simple, staticmeasures of cognitive functioning typically ob-tained in laboratory tests may not be representa-tive of the more complex and dynamic cognitiveprocesses required in real-world tasks. We iden-tify this as a major limiting factor in drawinggeneralizations about older pilot cognition andflight performance. A model discussing howthese higher order processes are linked to flightperformance is proposed.

Finally, although cognitive ability can be rela-tively easily evaluated, assessing flying profi-ciency in pilots is not so simple. Should onemeasure simulator performance, observe actualflights, analyze incidents, or investigate acci-dents? Is a single index of pilot performanceuseful? Or is it more likely that a complexaggregate of flight performance measures is re-quired? For example, in an early study, 21"critical requirements" for the job of a commer-cial airline pilot were determined on the basis ofaccident and incident reports and flight-checkrecords (see Table 1; Gordon, 1949). Each criticalrequirement or component was named for agroup of related pilot acts. It is instructive toexamine these requirements or component abili-ties—despite the datedness of the study—because they were based not a priori on just face

https://www.researchgate.net/publication/232593473_The_Effect_of_Age_and_Experience_upon_Accident_Rate?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232519120_Expert_Performance_Its_Structure_and_Acquisition?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232519120_Expert_Performance_Its_Structure_and_Acquisition?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232504500_Cumulative_Evidence_of_the_Relationship_between_Employee_Age_and_Job_Performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232476443_Validity_and_Utility_of_Alternate_Predictors_of_Job_Performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232476443_Validity_and_Utility_of_Alternate_Predictors_of_Job_Performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/220457578_Humans_and_Automation_Use_Misuse_Disuse_Abuse?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/220457578_Humans_and_Automation_Use_Misuse_Disuse_Abuse?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

COGNITION AND FLIGHT IN OLDER PILOTS 315

Table 1Component Abilities of Commercial Airline Pilot Performance Determined by Frequency of ErrorsExtracted From Accident Reports, Critical Incidents, and Flight Checks

Frequency of errors

Component ability Accidents Incidents Flight checks Total

Establishing and maintaining angle of glide, rate of descent,and gliding speed on approach to landing

Operating controls and switchesNavigating and orientingMaintaining safe airspeed and attitude, recovering from

stalls and spinsFollowing instrument flight procedures and observing

instrument flight regulationsCarrying out cockpit procedures and routinesEstablishing and maintaining alignment with runway on

approach or takeoff climbAttending, remaining alert, maintaining lookoutUtilizing and applying essential pilot informationReading, checking, and observing instruments, dials, and

gaugesPreparing and planning of flightJudging type of landing or recovering from missed or poor

landingBreaking angle of glide on landingObtaining and utilizing instructions and information from

control personnelReacting in an organized manner to unusual or emergency

situationsOperating plane safely on groundHying with precision and accuracyOperating and attending to radioHandling of controls smoothly and with coordinationPreventing plane from undue stressTaking safety precautions

47154

11

57

3140

12

11

3

0700002

414439

28

2731

312319

2627

2325

21

171577655

113319

18

134

51

18

73

85

0

71

1510874

999262

57

4542

393837

3432

3231

24

24232217141211

Note. Based on "The Airline Pilot's Job," (Gordon, 1949).

value (which is sometimes done) but on factorsfound relevant to actual flight performance. AsTable 1 shows, the component skills vary consid-erably in scope and complexity. An importantpoint is that some of the more complex compo-

' nent abilities are difficult to examine in thelaboratory, but they are still ultimately crucial inthe assessment and prediction of pilot profi-ciency. One of the conclusions in this article isthat examining potential age-related differencesin these more complex skills is necessary tobetter understand the experience, proficiency, andlimits of older pilots.

These complexities notwithstanding, to under-stand whether age-related cognitive decline isassociated with poorer flight performance in

older pilots is of both theoretical and practicalimportance. In this review, we examine severaldifferent aspects of age-related changes in cogni-tion and flight performance among pilots. Al-though we refer to studies of cognitive aging ingeneral, studies that examined pilots are empha-sized. The scope of this review is framed in threequestions. First, what are the age-related differ-ences in pilot cognition? Second, what are theage-related differences in pilot flight perfor-mance? And third, what is the relationship be-tween age-related differences in pilot cognitionand age-related differences in flight perfor-mance? The first question was the primary topicof a previous review (Tsang, 1992). We reviewstudies conducted since that time (and studies

https://www.researchgate.net/publication/247502735_A_Reappraisal_of_Aging_and_Pilot_Performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

316 HARDY AND PARASURAMAN

that were not included in that review), and weexamine the influence of expertise, includingflying experience, on age-related differences incognition. We also review studies of flight perfor-mance in pilots.

Pilot Cognition and Aging

What are the age-related changes in pilotcognition? Although cognitive ability (includingperceptual-motor skills) has been extensivelyexamined in relation to military pilot selectionand flight performance (Callister, King, & Ret-zlaff, 1996; Koonce, 1996; Olea & Ree, 1994)and will probably become more important in theroutine medical assessment of civilian pilots(Mohler, 1993), it is surprising that few studieshave actually compared basic cognitive ability inyounger and older pilots. Age-related differencesin cognitive task performance have been exam-ined in relation to aviation-relevant factors (e.g.,altitude, drugs, workload demands, etc.), but inmany of these studies, the participant samplesincluded nonpilots (e.g., Braune & Wickens,1985; Fox, Eggemeier, & Biers, 1995) or partici-pants that were merely the health equivalent (bypassing the equivalent of a pilot's physical exami-nation) of pilots (e.g., Collins & Mertens, 1988;Mertens & Collins, 1986; Mertens, Higgins, &McKenzie, 1983). These studies could not assessthe impact of task-related experience or expertiseon cognitive functioning. Because all pilots haveflight experience and varying degrees of exper-tise, the applicability of performance data fromnonpilots is limited. In addition, age, flight classi-fication, pilot health, and task demands are allimportant factors in the interpretation and gener-alization of experimental results. This is particu-larly true with respect to the Age 60 rule, whichhas stimulated much aviation aging research (andfueled the angst of many older pilots). The Age60 rule is discussed in a later section of thisarticle.

Theories of Cognitive Aging

Many theories that account for age-relateddifferences in cognition have been proposed.Although critical examination of all theories isbeyond the scope of this article, five prominenttheories of cognitive aging are briefly discussed,with their suggested implications for older pilot

cognition and flight performance. It should bekept in mind that these theories are based on thecognitive performance of nonpilot young andolder adults (and sometimes individuals withneurological deficits, e.g., due to dementia orfrontal-lobe damage). Furthermore, some of thesetheories do not explicitly address the potentialameliorating effects of extended experience orpractice in relevant skills (that a pilot might have)on the cognitive performance of the older adult.

Fluid versus crystallized intelligence. Onetheory of cognitive aging proposes that olderadults decline in fluid intelligence but that crystal-lized intelligence remains stable or even im-proves (Horn & Cattell, 1966). Fluid intelligenceis required for processing of relatively newinformation or information in a context of mini-mal meaningfulness, such as in many simplelaboratory perceptual-motor and memory tasks.Crystallized intelligence refers to stored knowl-edge or to those processes that tap into theaccumulated products of previous processing thatare often overlearned or embedded in a meaning-ful context. A typical measure of crystallizedintelligence is vocabulary. Much research evi-dence supports this distinction in the cognitivedevelopment of the elderly (for reviews seeSalthouse, 1991b; for a critical assessment seeRabbitt, 1993).

According to this theory, older pilots, likeother older adults, should experience a decline influid but not crystallized intelligence. If fluid andcrystallized intelligence are represented by DigitSymbol (a standard measure of cognitive process-ing efficiency) and vocabulary performance onthe Wechsler Adult Intelligence Scale—Revised(WAIS-R), then the prediction holds (see Table2). The resulting effect on flight performancewould depend on whether piloting makes greaterdemands on fluid or crystallized intelligence. Thetask of flying an aircraft includes components ofboth fluid and crystallized intelligence, but therelative proportion of these components necessar-ily changes according to situational demands. Forinstance, cruising at high altitude imposes mini-mal demands on fluid intelligence (e.g., theoccasional monitoring of altitude or heading) andonly routine demands on crystallized intelligence(e.g., having to know the schedule of a flight planand the procedures of flying the aircraft). Duringan emergency situation, however, the demands onfluid intelligence could be extremely high, such

https://www.researchgate.net/publication/278511402_Special_issue_Aviator_selection_-_Preface?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/235094063_Age_Altitude_and_Workload_Effects_on_Complex_Performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/235094063_Age_Altitude_and_Workload_Effects_on_Complex_Performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232510721_Predicting_Pilot_and_Navigator_Criteria_Not_Much_More_Than_g?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232505382_Crystal_quest_A_search_for_the_basis_of_maintenance_of_practised_skills_into_old_age?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/19953080_Age_alcohol_and_simulated_altitude_Effects_on_performance_and_breathalyzer_scores?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/19603381_The_effects_of_age_sleep_deprivation_and_altitude_on_complex_performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

COGNITION AND FLIGHT IN OLDER PILOTS 317

Table 2Mean Scores on Digit Symbol and Vocabularyfor Younger and Older Pilots

Digit Symbol" Vocabulary15

Study Young Old Young Old

Tsang et al. (1995) 68.3 50.9* — —Taylor, Dolhert, et al.

(1994) 65.0 53.6* 62.4 65.6Taylor, Yesavage, et al.

(1994) 63.7 53.4* 62.8 65.5Yesavage etal. (1994) 63.9 53.5* 62.6 65.6

Note. Digit Symbol and Vocabulary tests are from theWechsler Adult Intelligence Scale—Revised (Wechsler,1981). Dashes indicate that pilots in the Tsang et al. studywere not given the Vocabulary test."Digit Symbol scores = the number of test items completedwithin 90 s; maximum score = 93. 'Vocabulary scores =the number of correctly identified words; maximumscore = 70.*p < .05.

as when novel information (that does not neces-sarily fit into the pilot's mental model or schemaof flying) must be quickly integrated and decidedupon. The potential vulnerability of an older pilotshould increase with an increase in the demandson fluid intelligence. However, if crystallizedintelligence is called upon, the theory predictslittle age-related decline. Furthermore, to theextent that crystallized intelligence develops as aresult of experience, the fluid-crystallized intelli-gence theory includes the role of flight experi-ence in potentially mitigating age-related decline.

Decline in inhibition. A prominent explana-tion for age-related differences in cognition isthat inhibitory cognitive processes decline inolder adults (Hasher & Zacks, 1988; Layton,1975). Inhibition is proposed to be a mechanismthat facilitates selective attention, and that adecline in inhibition results in the inclusion ofirrelevant information into working memory, in-terfering with a variety of cognitive processes.The evidence for an age-related decline in cogni-tive inhibition includes a variety of interference-sensitive tasks showing performance deficits inolder adults, such as the Stroop test, the stopparadigm, and negative priming (Dempster, 1992).

A possible cause for inhibitory decline in olderadults is a normal age-related decline in frontalcortex functioning (Dempster, 1992; Rafal &Henik, 1994). Because this is considered a nor-mal physiological decline, older pilots would beexpected to experience the same age-related

decline in inhibition (and frontal cortex function-ing) as other older adults. There are seriousimplications if this kind of inhibitory declineexists at higher order cognitive processing levelssuch as strategy or procedure use. For example,developments in aviation technology, such asadvanced automated systems, can producechanges in pilot routines, procedures, and flyingstrategies. Older pilots could have more difficultyadapting to a new system or inhibiting responseprocedures appropriate for an older system, whichcould be risky in an unusual, time constrained, oremergency situation. At the same time, olderpilots are typically more experienced than youn-ger pilots. However, theories of cognitive inhibi-tion do not explicitly address the idea of extendedexperience or expertise protecting against inhibi-tory decline.

Reduction in processing resources. A popu-lar concept in cognitive psychology is that ofprocessing resources (see Navon, 1984). As theterm implies, these resources are fundamentaland necessary for cognitive processing, like thefuel for a working engine. Processing resourcesare also in limited supply. An explanation forage-related differences in cognition is that olderadults experience a reduction in the requisiteprocessing resources (Salthouse, 1985, 1988).Processing resources can be characterized asspeed of processing, working-memory capacity,or attentional capacity. Speed of processing istreated separately in the next section.

Age-group differences in working-memory ca-pacity have been found on a variety of measures,including digit span (Salthouse, 1988), the moredifficult sentence span (Gick, Craik, & Morris,1988; Light & Anderson, 1985), and other typesof computation spans (Dobbs & Rule, 1989;Salthouse, 1990b, 1994b). Evidence of an age-group difference in attentional capacity includesthe finding of older adults having more difficulty,or greater divided attention costs, when perform-ing two difficult tasks simultaneously (Green-wood & Parasuraman, 1997; Hartley, 1992).

According to processing resource theories,pilots, like other older adults, should experiencean age-related reduction in processing resources.Therefore, whether due to a reduction in working-memory capacity or attentional capacity, olderpilots would be expected to exceed their process-ing capacity limit sooner than would youngerpilots. Simplistically speaking, this means that if

https://www.researchgate.net/publication/232521837_Resources_-_A_theoretical_soup_stone?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232504870_The_Aging_of_Working_Memory?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/222993152_Working_memory_as_a_processing_resource_in_cognitive_aging_1?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/222302763_The_Rise_and_Fall_of_the_Inhibitory_Mechanism_toward_a_unified_theory_of_cognitive_development_and_aging?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/222302763_The_Rise_and_Fall_of_the_Inhibitory_Mechanism_toward_a_unified_theory_of_cognitive_development_and_aging?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/21967560_Perceptual_noise_and_aging?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/21967560_Perceptual_noise_and_aging?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/20536172_Adult_Age_Differences_in_Working_Memory?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/20079603_Initiating_the_formalization_of_theories_of_cognitive_aging?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/20079603_Initiating_the_formalization_of_theories_of_cognitive_aging?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/19945274_Task_complexity_and_age_differences_in_working_memory?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/19945274_Task_complexity_and_age_differences_in_working_memory?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

318 HARDY AND PARASURAMAN

the processing demands of flying are relativelylow or moderate, older pilots should be fine andperhaps perform no differently than youngerpilots. However, if processing demands are unusu-ally high, as during an in-flight emergency, thenolder pilots may be vulnerable.

A disadvantage of the processing resourcetheory is that independent measurement of re-sources has proven difficult, although the use ofworking memory capacity (Salthouse, 1985,1988)and psy chophy siological measures (Kramer, 1991)has been explored. As a result, processing re-source theory has been criticized for circularity ofreasoning (Navon, 1984). In contrast to thispotential limitation, an advantage of resourcetheory is that it explicitly incorporates the impactof expertise, particularly as derived through prac-tice. Extended practice is thought to reduce theprocessing resource demands of tasks through thedevelopment of automaticity (Schneider & Shif-frin, 1977). Kramer, Larish, and Strayer (1995)found that training with a variable priority tech-nique led to automaticity of single task compo-nents during dual-task performance, with olderadults benefitting more than younger adults incertain dual-task conditions.

Cognitive slowing. Slowing of all cognitiveoperations has been proposed as a general charac-teristic of adult aging (Birren, 1970; Cerella,1994; Salthouse, 1985). Generalized cognitiveslowing proposes that all cognitive operations areslowed by the same proportional amount. Thisaccount of age-related cognitive slowing is some-times known as the complexity hypothesis or theBirren hypothesis. The evidence for this theoryusually takes the form of a regression plot, whereit is shown that across tasks of differing complex-ity, mean reaction time (RT) for older adults canbe expressed as a linear function of young RT,with slope of between 1.3 and 1.7. Other theoristsargue for selective slowing, for example, thatcognitive slowing in older adults is more pro-nounced for response-related processes (Bashore,1990; Hartley, 1992).

What does this mean for older pilots? Accord-ing to the theory of generalized cognitive slow-ing, older pilots, like adults in general, willexhibit slowing of RT. Thus, proportional age-group differences in a variety of cognitive process-ing speed measures should be evident in pilots.The selective slowing theory predicts that olderpilots should be differentially slower in response-

related processes. Both theories predict that olderpilots will have more difficulty under time pres-sure. According to the selective slowing version,older pilots will have the most difficulty reactingin an emergency only when having to make manyovert (motor) responses.

Disuse. One theory proposes that cognitivedecline in older age is due not to aging per se, butto unexercised cognitive abilities (Denney, 1984).The idea of cognition as a skill, where cognitiveability develops and is maintained with frequentuse but withers away with disuse, is an ancientone and a traditional conceptualization in psychol-ogy (Pax, 1937). As an explanation for cognitiveaging, evidence for this theory includes thedifferentiation of age-group differences on perfor-mance (or fluid) versus verbal (or crystallized)measures of intelligence. This is similar to thefluid versus crystallized intelligence theory ofcognitive aging. However, a significant differ-ence is that in the disuse theory, the processes thatshow decline are unexercised ones and not neces-sarily fluid intelligence processes. Thus olderadults experience a decline in performance mea-sures of intelligence because they do not fre-quently use them. Regular training or exercise inthese skills, it is proposed, prevents their decline.

Therefore, the degree to which older pilotsexperience a cognitive decline depends on whichcognitive skills they frequently use and whichones they ignore. This in turn would depend onthe type of flying or the type of pilot. Forexample, active military pilots are more likelythan general aviation (GA) pilots to routinely andintensely use verbal and performance (such asperceptual-motor) types of processing when fly-ing. Military pilots should therefore show lessdecline in performance or fluid processing mea-sures than nonpilots and GA pilots. Commercialairline pilots would be expected to preservecognitive skills at a level somewhere betweenmilitary and GA pilots. This is an optimistictheory in the sense that flying performance wouldnot be expected to decline in older pilots, at leastnot until their performance potential is seriouslycompromised by physiological decline. There-fore, flight performance, and cognitive profi-ciency, would be related less to age and more topilot experience (such as recent and total flyinghours).

Summary of cognitive aging theories. Thedisuse theory is the only theory that predicts little

https://www.researchgate.net/publication/238705249_Controlled_and_automatic_human_information_processing_i?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/238705249_Controlled_and_automatic_human_information_processing_i?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232521837_Resources_-_A_theoretical_soup_stone?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232518722_Age-related_changes_in_mental_processing_revealed_by_analyses_of_event-related_brain_potentials?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232518722_Age-related_changes_in_mental_processing_revealed_by_analyses_of_event-related_brain_potentials?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232426089_Training_for_Attentional_Control_in_Dual_Task_Settings_A_Comparison_of_Young_and_Old_Adults?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/222369787_A_model_of_cognitive_development_across_the_life_Span?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/35062013_A_critical_study_of_Thorndike's_theory_and_laws_of_learning_microform?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/24381792_Physiological_metrics_of_mental_workload_A_review_of_recent_progress?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/20079603_Initiating_the_formalization_of_theories_of_cognitive_aging?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/17754149_Toward_an_experimental_psychology_of_aging?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

COGNITION AND FLIGHT IN OLDER PILOTS 319

or no change in cognitive ability in active olderpilots. Four other cognitive aging theories predictthat older pilots will experience age-related de-cline in cognitive ability, which could potentiallynegatively impact on flight performance. Olderpilots would be expected to have deficits inprocesses of fluid intelligence, a decline in cogni-tive inhibition, a reduction in processing re-sources (working-memory or attentional capac-ity), and a slowing of cognitive processing speed.Some of these declines are relatively specific,such as inhibition. Other declines are more glo-bal, such as cognitive slowing, and they would beexpected to have a more inclusive impact on pilotcognitive functioning. According to these fourtheories, age-group differences or age correla-tions in pilot performance would be expected ona variety of cognitive tasks. Two of the theories,however, fluid-crystallized intelligence and pro-cessing resource theory, provide for the possibil-ity of extended flight experience amerlioratingage-related cognitive decline. We now examineto what extent the empirical evidence supportsthe predictions of these theories.

Studies of Older Pilot Cognition

As can be seen in Table 3, the number ofstudies that have examined age-related differ-

ences in basic cognitive processes in pilots isrelatively small. This is surprising given thenumber of articles that have discussed aging andaviation (Birren & Fisher, 1995; Dille, 1985;Halaby, 1962; Hyland, Kay, Deimler, & Gurman,1994; McFarland, 1953; Mohler, 1961, 1963,1985; Salive, 1994; Tsang, 1992). Among the fewstudies that did examine cognition in older pilots,a variety of pilots was examined including com-mercial, military, and GA pilots. As might beexpected given the Age 60 rule, the upper agelimit for older pilots was greater in the samplesthat included GA pilots. Several cognitive pro-cesses were examined, particularly in a fewcomprehensive studies (e.g., Glanzer & Glaser,1959; Tsang, Shaner, & Schnopp-Wyatt, 1995;Szafran, 1969). Cognitive processes, especiallyas they pertain to aviation performance, can becategorized in a variety of ways (Braune &Wickens, 1985; Gopher, 1982; Hyland et al.,1994; Tsang, 1992; Wickens & Flach, 1988). Wesummarize the results of the cognitive agingstudies in pilots around four cognitive processingdomains: perceptual-motor skills, memory, atten-tion, and problem solving-decision making (seeTable 4).

Perceptual-motor skills. Perceptual-motorskills are fundamentally important to basic flighttasks such as take-off and climb, maintaining the

Table 3Summary of Age and Pilot Type in Cognitive Aging Studies

Study

Age group mean

Pilot type Age range Young Older All

McFailand et al. (1939)Glanzer & Glaser (1959)Birren & Spieth (1962)Spieth (1964)Szafran (e.g., 1969)Morrow et al. (1992)Hyland (1993)Morrow, Leirer, et al. (1994)Taylor, Dolhert, et al. (1994)Taylor, Yesavage, et al. (1994)Yesavage et al. (1994)Tsang et al. (1995)Callisteretal. (1996)Lassiter et al. (1996)

CC,MGGC,MVCVG"G'G>VC,MG

20-4720-5023-6023-5920-60

—41-70

——

21-7421-6920-80

—21-75

—————30

—29272727312432

—————66

—66606160704455

——40———53

———

——

——

Note. Dashes indicate that data were not available. For pilot type, C = commercial (airline,transport, etc.); M = military (Navy, Air Force, etc.); G = general aviation; V = various(typically including commercial and general aviation pilots)."We assume the pilots were general aviation; most pilots were instrument rated, but it ispossible that some pilots had more advanced rating.

https://www.researchgate.net/publication/247724463_Cross-Sectional_and_Longitudinal_Results_in_a_Study_of_Age-Related_Changes1?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/247724463_Cross-Sectional_and_Longitudinal_Results_in_a_Study_of_Age-Related_Changes1?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/247502735_A_Reappraisal_of_Aging_and_Pilot_Performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/247502735_A_Reappraisal_of_Aging_and_Pilot_Performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232550640_Aging_and_pilot_performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/40961655_Rules_and_reason_in_the_forced_retirement_of_commercial_airline_pilots_at_age_60?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/23917980_Information_Processing?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/17414777_Psychological_studies_of_aging_in_pilots?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

320 HARDY AND PARASURAMAN

Table 4Summary of Age Effects on Pilot Cognition

Study Task/process

Age-relateddifference/

relationship?

Perceptual-motor skills

McFarlandetal.(1939)

Glanzer&Glaser(1959)

Birren & Spieth (1962)Spieth (1964)

Szafran (e.g., 1969)

Morrow etal. (1992)

Morrow, Leirer, et al. (1994)Taylor, Dolhert, et al. (1994)Taylor, Yesavage, et al. (1994)Yesavage et al. (1994)Tsang et al. (1995)

Glanzer&Glaser(1959)Spieth (1964)Morrow et al. (1992)

Morrow, Leirer, et al. (1994)

Taylor, Dolhert, et al. (1994)Taylor, Yesavage, et al. (1994)Yesavage et al. (1994)Tsang etal. (1995)

Callister etal. (1996)Lassiter et al. (1996)

Serial RT testDomino testObject IdentificationSpatial OrientationInstrument ComprehensionReoriented Reading — ClocksReoriented Reading — WordsContinuous Serial RTContinuous Serial RTDigit SymbolBlock DesignTactual Performance testVisual AccommodationDark AdaptationPulsed Tone ThresholdContinuous Tone ThresholdCritical flicker fusion frequencyMinimum perceptible interflash

intervalVisual Recognition ThresholdsChoice RTObject RotationBlock DesignBlock DesignDigit SymbolDigit SymbolDigit SymbolDigit SymbolHorizontal TrackingVertical TrackingMental Rotation

Memory

Code MemoryTactual Performance TestAviation Scenario RecallSentence SpanATC (visual) ReadbackATC (auditory) ReadbackDigit SpanDigit SpanDigit SpanDigit SpanSteinberg V-V manualStemberg V-V verbalDigit SpanSternberg Memory Search —

Manual

YesNoYesYesYesYesYesYesYesYesYesYesYesYesYesYesNoNo

NoNoUnclear"Unclear"YesYesYesYesYesYesYesYes

NoYesYesUnclear"NoYesNoNoNoYesYesYesYesYes

https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

COGNITION AND FLIGHT IN OLDER PILOTS 321

Table 4 (continued)

Study Task/process

Age-relateddifference/

relationship?

Szafran (e.g., 1969)

Tsang et al. (1995)

Callisteretal. (1996)

Attention

Effect of noise on tone detection NoEffect of noise on visual detection NoChoice RT/memory load YesChoice RT/memory load, flicker NoChoice RT/verbal response NoChoice RT/verbal response with Yes

delayed speech monitoringVertical tracking/Horizontal Yes

trackingMental rotation/Horizontal tracking YesStemberg V-V manual/Horizontal No

trackingStemberg V-V verbal/Horizontal No

trackingDivided attention test YesDual task test Yes

Problem solving/decision making

Glanzer&Glaser(1959)

Birren & Spieth (1962)Spieth (1964)Morrow et al. (1992)Morrow, Leirer, et al. (1994)Taylor, Dolhert, et al. (1994)Taylor, Yesavage, et al. (1994)Yesavage et al. (1994)Tsang etal. (1995)

Code learningFinding relationshipsMechanical principlesOrientation to new equipmentMathematical reasoningNumerical operationsReading comprehensionNumerical approximationTrail Making testTrail Making testVocabularyVocabularyVocabularyVocabularyVocabularyRaven advanced Progressive

matrices

YesYesYesYesNoNoNoNoYesYesUnclear"YesNoNoNoNo

Note. RT = reaction time; ATC = air traffic control; for Steinberg memory search tasks:V-V = visual presentation, verbal stimuli; manual = manual response; verbal = verbalresponse.Test was mentioned, but results were not provided.

flight path, final approach, and landing. Misper-ceptions while flying, such as altitude and atti-tude illusions, due to sloping cloud formationswithout a ground reference for example, alsohighlight the importance of perceptual skills inflying (Edwards, 1990). Accordingly, tests ofperceptual-motor skills have historically played acentral role in the selection and training of

military pilots (Pitts, 1946; Fleishman & Hempel,1956; Marquis, 1944; Office of the Air Surgeon,1943) and to a lesser extent civilian pilots (Vrte-les, 1945). An early example of this special role isthe examination, at the Army Aviation Groundschool in 1917, of cadets on tests of simpleauditory and visual RT, continuous choice RT,maze tracing, eye saccades and smooth pursuit,

https://www.researchgate.net/publication/232603015_Factorial_analysis_of_complex_psychomotor_performance_and_related_skills?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232603015_Factorial_analysis_of_complex_psychomotor_performance_and_related_skills?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/42293155_German_applied_psychology_during_World_War_II?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

322 HARDY AND PARASURAMAN

finger tapping, auditory difference threshold, andsimple reaction learning (Yerkes, 1919). As men-tioned previously, although modern cockpit auto-mation has shifted the balance of requisite pilotskills to more cognitive and strategical tasks,tactical perceptual-motor skills are still impor-tant. Perceptual-motor skills remain central to thepilot selection research of the U.S. military(Griffin & Koonce, 1996). Sometimes a singleperceptual dimension has been shown to bepredictive (at least in a controlled environment)of pilot performance. For example, in a flightsimulation study with experienced jet pilots,those with the most sensitive ability to detectvisual spatial frequencies under different con-trasts (a contrast sensitivity function; CSF) wereable to spot the furthest away an obstructingairplane on the runway and abort a landing(Ginsburg, Evans, Sekuler, & Harp, 1982). Re-lated to this CSF-related difference and perhapsimportant to flight performance is the finding ofan age-related decline in CSF beginning after age30 (Owsley, Sekuler, & Siemsen, 1983; Sekuler& Blake, 1994).

For many perceptual-motor skills across alltypes of pilots, younger pilots performed betterthan older pilots. Processing speed was a factor inmany of the age-related differences reported.Older pilots have been shown to be reliablyslower than younger pilots on the Digit Symboltest (of the WAIS, Wechsler, 1955, and theWAIS-R), a standardized test of mental profi-ciency. Age-group differences have been reportedboth for GA pilots (Birren & Spieth, 1962;Spieth, 1964; Taylor, Dolhert, Morrow, Fried-man, & Yesavage, 1994; Taylor, Yesavage, Mor-row, Dolhert, Brooks, & Poon, 1994; Yesavage,Dolhert, & Taylor, 1994) and for a mixed sampleof pilots (Tsang et al., 1995; see Table 2).

Older pilots were also found to be slower thanyounger pilots in serial choice RT. In an extensivestudy of commercial airline pilots (N = 200),McFarland, Graybiel, Liljencrantz, and Turtle(1939) reported a significant age-group differ-ence in commercial airline pilots on the Mash-bum Serial Action Test (Mashburn, 1934). Thistask, which required the coordination of stick andrudder movements in response to different pat-terns of lights on a panel, was considered a crudesimulation of pilot psychomotor and decision-making performance. Task performance for each

pilot was measured as the time to complete aseries of 40 different pattern settings. Mean taskcompletion time was found to increase fromyounger to older pilot groups (see Figure 1). Twoother early and adjoining studies (Birren &Spieth, 1962; Spieth, 1964) examined a largesample of participants (age range = 23 to 60years) who were either GA pilots or air trafficcontrollers (ATCs), or both (N = 161 andN = 560). Age significantly correlated (.59) witha composite response latency score from a batteryof choice RT tasks (Psychomet, WAIS DigitSymbol, Trail Making test, etc.) (Birren, Riegel,& Morrison, 1962). Factor analysis of all themeasures obtained revealed that age was mostclosely associated with a psychomotor speedfactor (Birren & Spieth, 1962). Age-group differ-ences were also found with young participants(age 23 to 39 years) faster than older participants(age 50 to 59 years; Spieth, 1964). An exceptionto these findings is the result of a study (reportedin several overlapping articles) on a mixed sam-ple of commercial and military pilots (Szafran,1963, 1965a, 1965b, 1966b, 1966a, 1969). Sza-fran (1965a) reported that there was no signifi-cant difference in mean RT on a choice RT taskbetween younger (253 ms) and older (262 ms)pilot groups. Notwithstanding this exception, thebulk of the evidence indicates that older pilots are

20-24 25-29 30-34 35-39 40-47

Pilot Age Group (years)

Figure 1. Mean completion time for commercialairline pilots on the Mashburn Serial Action Test(based on data from McFarland et al., 1939). Verticallines represent standard errors of the means.

https://www.researchgate.net/publication/286368118_An_analysis_of_the_physiological_and_psychological_characteristics_of_two_hundred_civil_air_line_pilots?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/286368118_An_analysis_of_the_physiological_and_psychological_characteristics_of_two_hundred_civil_air_line_pilots?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232442086_Report_of_the_Psychology_Committee_of_the_National_Research_Council?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/17414777_Psychological_studies_of_aging_in_pilots?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/17277927_Limitations_and_reliability_of_the_human_operator_of_control_systems_to_process_information?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

COGNITION AND FLIGHT IN OLDER PILOTS 323

slower in perceptual-motor processing speed thanyounger pilots.

Age-related differences or relationships havealso been reported for other perceptual-motortasks. For example, in the Szafran (1969) study,age correlated with visual accommodation atshort viewing distances (—.75) and with visualdetection thresholds as a function of dark adapta-tion (.25 and .20 for alpha and terminal points).Auditory thresholds for pulsed and continuoustones were also higher for older pilots comparedwith younger pilots. However, in the Szafranstudy there were also no significant age-relatedchanges in detection threshold of critical flickerfusion frequency and minimum perceptible inter-flash interval and recognition thresholds for tachis-toscopic displays for simple stimuli such asshapes, numbers, letters, and words. For morecomplex perceptual-motor tasks, in a heteroge-neous sample of pilots, older pilots performedworse (had larger deviations) than younger pilotson a horizontal tracking task and a verticaltracking task (Tsang & Shaner, 1995; Tsang et al.,1995). In a large sample of commercial airlineand military pilots (N = 90 and N = 454, respec-tively), there were significant correlations be-tween pilot age and several aviation-related tasksincluding object identification (-.29), spatialorientation (—.14), instrument comprehension(-.33), and reoriented reading clocks (—.09;Glanzer and Glaser, 1959).

In summary, age-related differences in percep-tual-motor skills are apparent in a variety of pilottypes. These differences appear to be less reliablein commercial airline and military than in GApilots. For example, in the Szafran (1969) study,there was no significant age-group difference invarious visual detection thresholds and in achoice RT task, and in the Glanzer and Glaser(1959) study, age correlations with task perfor-mance were at best of modest magnitude. Per-haps the expertise produced by the unusuallyhigh demands on commercial airline and militarypilots compensates for the detrimental effects ofaging on some aspects of perceptual processingspeed and skill (this issue is examined in moredetail later). On the other hand, the commercialairline pilots and certainly the military pilots inthese samples were younger in general comparedwith other types of pilot samples (such as GApilots), and at least in the Glanzer and Glaser

study, the age range in the pilot sample wasrelatively restricted (20 to 50 years) comparedwith other aviation aging studies.

Memory. The many tasks of flying a planeoften place demands on memory. It is importantfor the pilot not only to remember incominginformation, such as ATC messages and instru-ment readings (involving short-term or workingmemory) but also to remember when to do thingsin the face of many competing distractions and todevelop appropriate mental schemata or modelsabout procedures and systems (memories thatwould be considered more long-term or prospec-tive). Age-related differences have been reportedfor both working memory and long-term memoryin pilots. For example, in a mixed sample ofpilots, younger pilots had better scores on theDigit Span test, a standard measure of workingmemory, compared with older pilots (Tsang et al.,1995; see Table 5). In another study (Callister,King, & Retzlaff, 1996) where cognitive perfor-mance in a large sample of U.S. Air Force(USAF) pilot candidates (n = 512) was com-pared with that of commercial pilots (n = 584),digit recall accuracy was significantly higher inthe younger USAF pilot candidates (89%) com-pared with the older commercial pilots (84%).However, in GA pilots, no such difference inDigit Span was found (Taylor, Dolhert, et al.,1994; Taylor, Yesavage, et al., 1994; Yesavage etal., 1994). These results may reflect the fact thatage-group differences in digit span in the generalpopulation are typically small, as they are forolder pilots (see Table 5). Short-term recall of

Table 5Mean Scores on Digit Span for Youngerand Older Pilots

Digit Span'

Study

Tsang etal. (1995)Taylor, Dolhert, et al. (1994)Taylor, Yesavage, et al. (1994)Yesavage et al. (1994)

Young

8.99.29.49.4

Old

8.0*8.58.68.8

Note. Digit Span tests are from the Wechsler Adult Intelli-gence Scale—Revised; (Wechsler, 1981).'Digit Span scores reflect the longest sequence of digits thatwere recalled. Scores were averaged over the forward andbackward versions of the test. Maximum score = 14. A scoreof 2 means that three digits were reliably recalled. A score of14 means that nine digits were reliably recalled.*p < .05.

https://www.researchgate.net/publication/247724463_Cross-Sectional_and_Longitudinal_Results_in_a_Study_of_Age-Related_Changes1?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

324 HARDY AND PARASURAMAN

sentences, which imposes a greater load onworking memory, shows greater age-related de-cline in both pilots and nonpilots (Morrow,Leirer, & Altieri, 1992). Age-group differences inspeed of access to working memory also exist. Aswith measures of processing speed in perceptual-motor tasks, older pilots have been reported to beslower than younger pilots on a variety of Stem-berg memory-search tasks (Lassiter, Morrow,Hinson, Miller, & Hambrick, 1996; Tsang et al.,1995).

Pilot age-group differences in working memoryare also dependent on stimulus modality. Mor-row, Leirer, Altieri, and Fitzsimmons (1994)found that for an ATC communications task inwhich pilots had to read back a series of messages(concerning position, heading, altitude, and flightspeed), there were fewer age-group differenceswith visual messages compared with the moreconventional auditory messages. In the near fu-ture, aircraft will be equipped with data link(Kerns, 1991), in which clearances from control-lers will be communicated digitally to the cockpitand displayed visually. The results of Morrow,Leirer, et al. (1994) suggest that this will tend toreduce any negative impact of aging on immedi-ate memory for ATC messages, although datalink will also affect other aspects of cognitiveprocessing, some of which may be age sensitive.For example, the multimodal environment pro-duced by the integration of data link with existingvoice ATC communication, which would requirethe quick switching of attention between visualand auditory modalities, may prove more disrup-tive to older pilots than younger pilots (Morrow,1996).

Age-related differences have also been re-ported in pilot long-term memory. For example,in the recall of block shapes (Tactual Perfor-mance Test, Halstead, 1947), older GA pilotswere found to be less accurate than youngerpilots (Birren & Spieth, 1962; Spieth, 1964).Older pilots (retired commercial airline pilots)were also found to be less accurate than youngerpilots (a heterogeneous sample of pilots) in theinterpretation (e.g., choosing a referent of apronoun) and recall of visually presented textsdescribing aviation scenarios (Morrow et al.,1992). Glanzer and Glaser's (1959) study is anexception. Even with an exceptionally large sam-ple of commercial airline and military pilots

(N = 544), there was a nonsignificant correlation(.08) between pilot age and memory for simpleletter-number codes. The simplicity of the task,the restricted age range (with younger olderparticipants), and the inclusion of military pilotsprobably account for the lack of an age associa-tion with memory for codes.

Attention. Attention is necessary for basicflight proficiency and for avoidance of accidents.In a study of USAF accidents of F-16 fighteraircraft from 1975 through 1993, approximately20% of pilot errors were attributed to attentionfactors (channelized attention, distraction, inatten-tion; Knapp & Johnson, 1996). In addition,absence of flying appears to result in the decay ofattention, monitoring, and procedure-related flightskills (Childs & Spears, 1986). Attentional abili-ties have also been shown to be a salient factor inthe prediction of successful flight performance, atleast at the level of flight training. For example,performance on a divided attention test wasround to substantially correlate (.42) with thepass-fail rate of airline pilots hi training (Trankell,1959). Similarly, the correlation between dividedattention performance and flight check rating inprivate student pilots increased as flight trainingprogressed (Damos, 1978). Individual differencesin dual-task performance (but not single-taskperformance) were also found between pilots ofvarying experience (e.g., flight instructors vs.student pilots) and were predictive of flighttraining success (Gopher, 1982; Gopher & Kahne-man, 1971; North & Gopher, 1976).

Time-sharing ability, which can be considereda metacognitive skill, is thus clearly necessary forflight proficiency. Nevertheless, age-related differ-ences in this ability have not always been found(Braune & Wickens, 1983a). Older pilots had agreater time-sharing decrement in processingspeed than younger pilots in some dual-taskconditions but not in others (e.g., Szafran, 1965a,1969; see Table 4). In a mixed sample of pilots,time-sharing efficiency decreased in older pilots,particularly when the dual-tasks had similar pro-cessing demands (such as mental rotation-horizontal tracking; Tsang et al., 1995; Tsang &Voss, 1996). CaUister et al. (1996) also foundgreater divided attention costs in a sample ofUSAF pilot candidates and older commercialpilots. It should be noted, however, that indi-vidual differences in time-sharing performance

https://www.researchgate.net/publication/279649289_Residual_attention_as_a_predictor_of_pilot_performance?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232565306_The_Psychologist_As_An_Instrument_of_Prediction?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232565306_The_Psychologist_As_An_Instrument_of_Prediction?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/19200606_Flight-skill_decay_and_recurrent_training?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/18008911_Individual_differences_in_attention_and_the_prediction_of_flight_criteria?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/18008911_Individual_differences_in_attention_and_the_prediction_of_flight_criteria?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

COGNITION AND FLIGHT IN OLDER PILOTS 325

were large, with some older pilots performing aswell as some younger pilots (Tsang & Voss,1996).

Attention is also a factor in monitoring, whichis an important aspect of flying, particularly inmodern aircraft that are highly automated. Recentstudies have shown that both pilots and nonpilotsare inefficient at monitoring automated systemsin the cockpit when they are simultaneouslyengaged in other manual flight tasks (Molloy &Parasuraman, 1996; Parasuraman, Molloy, &Singh, 1993). Because monitoring is efficientwhen it is the only task or when it is carried outfully manually, this "automation complacency"effect has been attributed to insufficient attentionallocation (Molloy & Parasuraman, 1994). Thereare individual differences in the extent of thiseffect (Singh, Molloy, & Parasuraman, 1993),including age-group differences in nonpilots whentask demands are high (Hardy, Mouloua, Molloy,Dwivedi, & Parasuraman, 1995; Vincenzi, Mul-doon, & Mouloua, 1997). Given that the pace ofautomation in aircraft shows no sign of slowing,the importance of monitoring skills in the cockpitwarrants further studies to examine whether theseskills decline in older pilots (see Madigan &Tsang, 1990; Singh, Deaton, & Parasuraman,1993, October).

Problem solving-decision making. Becausemodern piloting is less perceptual-motor andmore cognitive, studies have examined problemsolving, decision making, and related highercognitive functions in pilots (e.g., Buch & Diehl,1984; Jensen, 1982; Lester & Bombaci, 1984;McKinney, 1993; Wiggins & O'Hare, 1995; seeTelfer, 1989, for a review). In a study of GAaccidents between 1970 and 1974, Jensen andBenel (cited in Tsang & Vidulich, 1989) foundthat 35% of nonfatal and 52% of fatal accidentswere associated with poor pilot judgment. In acognitive analysis of accident reports, pilot goalselection errors were the most frequent kind ofoperator error in fatal accidents (O'Hare, Wig-gins, Batt, & Morrison, 1994). More than everbefore, the modern commercial aviation pilot is a"manager" (not just of other crew members butof on-board automation) who is often called uponto exercise high-level cognitive skills. Unfortu-nately, little research has examined individual orage-related differences in these skills in pilots.Additional studies are urgently needed to rectify

this need. The evidence that does exist is for verysimple, artificial tasks. For example, older GApilots have been reported to be slower thanyounger pilots on the Trail Making test (Reitan,1958), taking longer to serially connect a se-quence of numbers and letters (Birren & Speith,1962; Spieth, 1964). In the Glanzer and Glaser(1959) study, older pilots were associated, to avarying degree, with worse performance whenhaving to remember and specify principles andrelationships of new aviation-related material(e.g., code learning, —.11; finding relationships,-.28; mechanical principles, —.12; and orienta-tion to new equipment, -.20). However, in thesame study, there were no significant correlationsbetween pilot age and quantitative problem solv-ing tasks (e.g., mathematical reasoning, —.04;numerical operations, .08; and numerical approxi-mation, —.01) or simple verbal processing (e.g.,reading comprehension, —.10). There was alsono significant age-group difference in a mixedsample of pilots in performance on the RavenAdvanced Progressive Matrices, a test that re-quires visuospatial reasoning (Tsang et al., 1995).

The Role of Expertise

Given that pilots are a highly trained group ofindividuals, the relationship between expertiseand basic cognitive functioning also needs exami-nation. Expert performance is characterized bythe acquisition and automatization of skills (Erics-son & Chamess, 1994). These skills include aqualitative change in skilled memory where infor-mation is stored and indexed in long-term memoryin a way that enables quick access into workingmemory (Ericsson & Kintsch, 1995; Woltz, 1988).Experts also show an enhanced ability to antici-pate relevant future events. These skills aredomain specific and may allow the expert tocircumvent normal limits in basic cognitive pro-cessing, facilitating performance in their domainof expertise.

Outside the domain of expertise, such automa-tized expert skills may not improve performanceon basic cognitive tasks and are not alwaysavailable to declarative memory. For example,when comparing younger and older pilots andnonpilots on an ATC communication type of task,Morrow, Leirer, et al. (1994) found that expertise(pilot experience) eliminated age-group differ-

https://www.researchgate.net/publication/284240376_The_validity_of_the_Trail_Making_Test_as_an_indicator_of_organic_brain_damage?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/284240376_The_validity_of_the_Trail_Making_Test_as_an_indicator_of_organic_brain_damage?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/279934362_An_Investigation_of_the_Role_of_Working_Memory_in_Procedural_Skill_Acquisition?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/258138479_The_Relationship_between_Personality_and_Irrational_Judgment_in_Civil_Pilots?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/258138478_An_Investigation_of_the_Effectiveness_of_Pilot_Judgment_Training?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/258138478_An_Investigation_of_the_Effectiveness_of_Pilot_Judgment_Training?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/246866207_Monitoring_of_automation_failures_by_young_and_old_adults?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/246866207_Monitoring_of_automation_failures_by_young_and_old_adults?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/232483120_Cognitive_demands_of_automation_in_aviation?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/220457777_Monitoring_an_Automated_System_for_a_Single_Failure_Vigilance_and_Task_Complexity_Effects?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/220457777_Monitoring_an_Automated_System_for_a_Single_Failure_Vigilance_and_Task_Complexity_Effects?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/34311164_Monitoring_of_automated_systems_the_role_of_display_integration_and_redundant_color_coding?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/null?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==

326 HARDY AND PARASURAMAN

ences in reading back heading commands but didnot reduce age-group differences in less aviation-related tasks such as a word test and the WAIS-RBlock Design test. Wiggins and O'Hare (1995)found that in GA pilots, general problem-solvingability was predictive of weather-related decision-making ability in novice flyers but not in moreexperienced pilots. This finding suggests thatmore experienced pilots go beyond general prob-lem-solving skills when making decisions inspecific flight situations.

Research examining the moderating effect ofexperience in older adults (e.g., Salthouse, 199la;Salthouse & Mitchell, 1990) has shown that workexperience does not prevent age-related declinein basic cognitive processing ability (Salthouse,1990a, 1994a). Given that there are significantdifferences in basic cognitive abilities betweenyounger and older adults in the general popula-tion, particularly in processing speed and inworking memory, one would predict that suchdifferences should also be found between youn-ger and older pilots. The studies reviewed in theprevious four sections generally support thisproposition, a conclusion that was also reached inprevious reviews (Hyland et al., 1994; Tsang,1992).

We further tested this prediction with an analy-sis of RT data reported in previous studies. Asshown in Figure 2, mean RT for older pilots in anexperimental condition was plotted as a functionof mean RT for younger pilots in that samecondition in a so-called Brinley plot (Cerella,1994). There were 53 conditions across a varietyof tasks, pilot types, and ages from all the studiesreviewed in this article that provided mean RTdata (Callister et al., 1996; Lassiter et al., 1996;McFarland et al., 1939; Spieth, 1964; Szafran,1965a, 1966a; Taylor, Dolhert, et al., 1994;Taylor, Yesavage, et al., 1994; Tsang et al., 1995;Yesavage et al., 1994). As Figure 2 shows, theresulting plot is highly linear (r = .99), with aslope greater than one (b = 1.46). This functionis similar to old-young Brinley plots with nonpi-lots (e.g., Hartley, 1992). At a global level,therefore, older pilots exhibit cognitive slowingto the same extent as older adults in general.

The experience or expertise of pilots does notappear to prevent or alter the pattern of age-related slowing in cognitive processing speedthat is typically observed in older nonpilots. The

Old RT = - 1.27 -f 1.46(Yng RT), r = 0.99

.1 1 10 100 1000

Younger Pilot Reaction Time (sec)

Figure 2. Older pilot mean response latencies plot-ted as a function of younger (Yng) pilot meanresponse latencies (in seconds). Digit Symbol scores(Tsang et al., 1995; Taylor, Dolhert, et al., 1994;Taylor, Yesavage, et al., 1994; Yesavage et al., 1994),which are the mean number of test items completed in90 s, were converted to response latency scores: themean time to complete each item (90 s per meannumber of completed items). In studies with more thanone age group (e.g., McFarland et al., 1939; Tsang etal., 1995), the youngest and oldest groups were usedfor the plot. Data used from the Lassiter et al. (1996)study included the younger, less experienced pilotsand the older, more experienced pilots (to morestrongly test the effects of expertise). RT = reactiontime.

same appears to be true for other basic cognitivefunctions, although Tsang et al. (1995) and Las-siter et al. (1996) found that pilot experience didattenuate some of the age-related decline in ametacognitive skill, time-sharing proficiency. Theimplications of these studies are considered later,but for now the general conclusion is that flightexperience does not greatly affect age-relateddecline in basic cognitive abilities.

This conclusion holds even though age andflight experience were confounded in most ofthese studies (an exception being Lassiter et al.,1996). Such a confound primarily affects theinterpretation of the finding of equivalent levelsof cognitive ability in young and older pilots. Inthis case, it could be argued that the lack of anormal age effect could be attributed to thegreater experience of older pilots. The confoundis less problematic if older pilots are found to

https://www.researchgate.net/publication/286368118_An_analysis_of_the_physiological_and_psychological_characteristics_of_two_hundred_civil_air_line_pilots?el=1_x_8&enrichId=rgreq-7e9ea846aee1bc182bb13b96441cc458-XXX&enrichSource=Y292ZXJQYWdlOzIzMjU2MjQ2NTtBUzoxMDEwMjc2MzQyMjEwNzFAMTQwMTA5ODI3MzIzOQ==https://www.researchgate.net/publication/286368118_An_ana