No. 5048

MAY 29, 1920.

Goulstonian LecturesON

THE PRINCIPLES OF MEDICAL SCIENCEAS APPLIED TO MILITARY AVIATION.

Delivered before the Royal College of Physicians ofLondon

BY J. L. BIRLEY, C.B.E., M.B., B.CH. OXON.,F.R.C.P. LOND.

LECTURE I.

Deliverecl on Many 9th, 19:20.

MR. PRESIDENT AND FELLOWS,-I am deeply consciousof, and I desire to thank you for, the honour you havedone me in offering me this lectureship; at the sametime, I am only too well aware of my limitations forfulfilling the onerous duty involved. Instead of employ-ing these past few years in making original observationsand gaining, as one had hoped to gain, some specialknowledge in a particular branch of our science, wehave been thrown into the rush of war, to be delugedby surprises, confronted with undreamt of situations,and expected at a moment’s notice to pronounce expertopinions on subjects concerning which we would some-times have preferred to confess a profound ignorance.Under these circumstances I felt myself strictly limitedin the choice of a subject, and it came therefore as arelief to discover that the subject which I was forcedto choose, scattered and diffuse as it is, would not bealtogether distasteful to some of you.

It was the fortune of war, indeed the good fortune,which during the later stages of the first great battle ofthe Somme brought me into contact with our flyingservices in France; it was similarly good fortune to beallowed to remain with them until victory had beenwon. -

The subject under discussion is, on the face of it, anew one, and I approach it with some diffidence, moreespecially since other workers in the same field havebeen tempted into making somewhat sweeping assertionswhich have failed to stand the test of subsequentinvestigation. As a matter of fact, the medical aspectsof aviation embrace no new discoveries and necessitateno revolutionary doctrines, but rather insist on theproper application of well-recognised scientific principles.The only novelty which can reasonably be claimed forthese lectures is that they deal not with the causes andresults of disease, but, on the contrary, with the effectsproduced in large numbers of healthy young men as theresult of employment -in an unnatural and dangerousoccupation. In brief, they attempt to describe thereaction of the normal individual to an abnormalenvironment.In this connexion I cannot refrain from remarking on

a difficulty which must have confronted many of us.It was an everyday experience that when dealing with isickness or injury the medical officer possessed the ’,complete confidence of his executive colleagues, but ’,when it came to a question of offering advice on matters ’,not directly connected with disease the reverse was thecase. It is both easy and popular to criticise thisconduct, but it seems to me readily comprehensible.The experienced soldier, not without reason, consideredhis credentials for knowing " what his men could ’,stand" at least as good as those of his medicalcolleague. He argued to himself that a doctor was inhis element when he had someone ill to attend to, and Iconsequently out of it when dealing with fit men. This Icriticism had a great deal of truth behind it. We were,to put it frankly, ill-equipped to answer the conundrumswith which we were confronted. Trained to con-

centrate our attention on the lesion and its treatment,we were inclined to pay insufficient attention to thefunctional disturbances which it evoked, and none at allto the bodily reactions which aim at counteractingits effects. In war, however, function is every-thing, for in terms of function one measures

efficiency. The capacity for mental and physicalendurance displayed during the war was a source

of universal pride, while to us in particular it providedin addition the stimulus for investigating the compen-satory processes by which this endurance was renderedpossible. In no field was progress more evident thanin the psychological, and it is with the psychology ofmilitary aviation that this lecture is mainly concerned.

THE MILITARY DUTIES OF THE FLYING OFFICER.

If we wish to understand the psychology of the pilotand his observer, and to gain their confidence, we musthave a clear idea of the work they have to do and theconditions under which they do it. The developmentof these activities, like the other subjects of theselectures, can best be studied historically.In the earlier days of the war the aeroplane was used

exclusively for purposes of reconnaissance-to report move-ments behind the enemy’s lines and to assist the artillery inthe location and, if possible, in the destruction of suitabletargets. As the war proceeded reconnaissance was de-veloped chiefly by the use of aerial photography andartillery cooperation by the use of wireless telegraphy.The next advance was to carry by means of bombsan offensive warfare behind the enemy’s lines with a

view to disorganising his communications, disturbing’ the productivity of his factories, and undermining hismorale. This form of activity gave birth to night-flying. As, however, enemy aircraft were employed onprecisely similar duties, retaliatory measures began todevelop on both sides. The anti-aircraft gun, thoughcapable of interfering with was powerless to put a stopto aerial activity, and it soon became apparent that thisobject could only be obtained, supposing it could be obtainedat all, by the aid of aircraft itself. In this way arose fightingin the air-i.e., the destruction of aircraft by aircraft-and itwas this aspect of, aerial warfare which naturally appealedto the public imagination to the exclusion of what alwaysremained the more essential forms of aerial activity. As thewar proceeded aerial activity, although becoming greatlyintensified owing to the increasing numbers of machinesemployed, maintained the characters alluded to. One furtherdevelopment, however, took place. This consisted in theactive cooperation of aircraft with the infantry within the-battle-zone itself. For this purpose aeroplanes were

employed at very low altitudes and within easy reach ofhostile machine-gun fire to assist bodies of infantry in main-taining contact with one another, and, further, by the use ofmachine-gun fire and small bombs to harass the enemy inevery possible way.This brief resume will serve to demonstrate the

variety and dissimilarity of tasks with which our flyingmen were confronted, a point of considerable psycho-logical importance.

ORGANISATION.

As the first Somme battle revealed the immensepossibilities of aircraft in war, so it first drew attentionto the medical requirements, or perhaps it would bemore correct to say to the medical defects, of our flyingservice. Not only were battle casualties greatly on theincrease in proportion to the numbers engaged, butlosses from sickness as a result of nervous breakdowns

began to reach alarming proportions. Moreover, officers

who had previously been sent home for a rest were notcoming back to France in the numbers that had beenexpected, or else, when they did return, exhibited lesspowers of endurance than they previously possessed.Up to this time there was practically no medical organisa-

tion in the field or at home directed to the particular needsof the flying service. The need for such was, at this time atany rate, almost entirely a psychological one, while thereason for its absence was also, in my opinion, psychological.It was realised, of course, that warfare in the air threw agreat and increasing strain on those engaged, but the beliefwas fostered, inspired partly by hope and partly by the finequalities of mental discipline engendered by military train-ing, that strain could be overcome and kept at bay by theexercise of will-power for an almost indefinite period. Itwas difficult to realise that will-power like the rest of one’smental faculties was not immune to exhaustion.After two years of war officers were still being accepted as

pilots and observers on the flimsiest medical examination oreven on none at all, while those who were systematicallyexamined were adjudged on standards which were originallylaid down from the point of view of the ability of thecandidate to march and to shoot from his right shoulder.It accordingly happened that a prospective candidate might

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be accepted with a blind left eye or be rejected ou accountof the possession of flat feet. This anomaly was correctedby the institution of a Central Board for the examination ofall candidates for the flying services. That the new standardsset up by this hard-worked body gave rise to even greatercriticism than those which they replaced will be referred toin a subsequent lecture. Suffice it here to say that such astate of affairs was, to my miud, inevitable.In the field very little organisation was necessary to meet

the requirements. The first step was to obtain suitablemedical officers for duty with groups of squadrons, with themain object of acquiring a personal knowledge of all officersunder their care ; those with previous experience of battalionwork, and therefore with knowledge of the psychology of thefighting man, were particularly sought after. It was nextnecessary to obtain at some convenient base a number of bedsreserved for the reception of flying personnel, whosedisability appeared to be directly related to the peculiarwork on which they were engaged. This hospital unitrapidly became one of the busiest in France, thanks to thetireless industry and enthusiasm displayed in its inceptionand continuation by the late Dudley Corbett and H. C.Bazett. The most important step, however, was to main-tain constant liaison with commanding officers, to makethem realise that the science of medicine had a sphere ofusefulness beyond that of dealing with the sick and wounded,to convince them that it was a necessary factor in promotingefficiency and maintaining discipline, and having excitedtheir interest to obtain what was absolutely essential for ourpurpose, their sympathetic cooperation. During the monthsfrom August, 1917, to November, 1918, inclusive, close on2000 flying officers passed through this special hospitalunit ; of these over 40 per cent. were deemed to be

suffering from the fatigue inseparable from active service.In order to interest commanding officers in the medicalaspects of aerial warfare they were encouraged not onlyto visit this unit, but also to send a confidential reporton every patient admitted. In this way the largemajority of them were stimulated into taking an intelli-gent interest in the physical and psychical welfare ofthose under their command, and many by becoming extra-ordinarily astute psychological observers afforded us

valuable assistance. Individual psychological study waspossible in the air service to a degree unknown in theinfantry; this was so not merely because of the comparativelysmall numbers involved, but also on account of the highdegree of individualism which service flying entails andencourages.

TEMPERAMENT.

A great deal has been written about ’’ the’ flyingtemperament " as if it were something sui generis,and it has been suggested, and in some quarters evenclaimed, that it is possible by medical means alone todiscover its presence and lay bare its absence. We allknow what we mean by temperament, and yet todefine the particular qualities going to make up thetemperament necessary for success in any given walkin life is not one which can be lightly undertaken.

A. The Flyin{l Temperament.It has been elsewhere pointed out that the temperament

for flying per se was of little importance in the field, sincethose devoid of it did not, as a rule, reach the active servicestage. One can hardly be surprised that a proportion ofpresumably normal individuals dislike flying, for there isafter all a certain feeling of insecurity of tenure in the airwhich becomes more pronounced during prolonged flights.I understand that the majority of those who since the warhave made flights extending over several hours have experi-enced a definite sense of relief on landing. It is, therefore,doubtful whether we are justified in classifying thisparticular distaste among those pathological phenomenaknown as phobias. A curious feature of those cases whichhave come under my notice has been a feeling of increasinginsecurity with increasing altitude. Such individualsremained comparatively comfortable up to one or twothousand feet, but above this height they were overtakenwith a consuming dread. One particularly gallant officervainly attempted to conquer this weakness by covering uphis altimeter with his flying cap. There appeared to be nocorrelation between this "altitude neurosis and the dis-comfort experienced when gazing over a precipice or lookingdown from a high building. There were, however, a fewindividuals who, greatly to their credit, in spite of an ever-present sense of insecurity in the air, not only learnt to fly,but so mastered their feelings that they became successfulmilitary pilots, gaining promotion in the service and evenwinning decorations for gallantry.The attempt to determine by physical and psychological

examination the possession, or otherwise, by an individualof the temperament for flight is one with which I mustconfess to be little in sympathy as being one beyond our

reach. Even an individual’s keenness to fly may be mis-leading owing to the lack of correspondence between antici-pation and realisation. Flying aptitude should rather becompared with any other form of activity requiring perfectcooperation between eye and hand. Such cooperation is bestexemplified, and incidentally may be greatly developed, bythe playing of games. "Flying," as Dr. Henry Head hasvery correctly said, " introduces no elements which are notin evidence in riding a motor-bicycle, game-shooting, cricket,or golf." 2 But two individuals may be equally good at thesame game or the same sport, and yet their methods mayhave nothing in common ; we say their "styles" " differ. Sotoo their temperaments may differ widely and yet the end-result be the same. At the risk of being accused of levity Iwould in all seriousness ask what possible resemblancecould be traced in the physical or temperamental qualitiespossessed respectively by Dr. W. G. Grace and PrinceRanjitsinhji ? Just as the latter could break all the rulesof batting with impunity, so can some pilots break at leastmany of the rules of flying without at the same time break-ing their necks. To postulate one temperament and one onlyfor flying, or for any other form of coürdinated activity,surely implies a too mechanical and stereotyped habit ofmind. We cannot at present identify the potential cricketeror mathematician except by watching how the formercatches a ball and how the latter does sums, and the sameprinciples would seem also to apply to the art of flying.Nevertheless, the attempt to define and isolate this elusive

quality, the flying temperament, has been productive of avast amount of pioneer work in the countries at war, more,perhaps, in France, Italy, and America than here. Largenumbers of experimental values have been obtained andcorrelated with the subsequent success or failure of thecandidate.3 For the so-called kinaesthetic ability," forexample, no less than 32 values were ascertained by theFrench authorities for each candidate, all of them con-nected with the general function of equilibration. Thesevalues, however, were not actual measurements of efficiency,but merelv determinations of certain reactions assumed tobe indicative of efficiency. It cannot be said that in thisfield, at any rate, the results were convincing ; the equilibra-tion tests employed in America, for instance, gave thesame correlation with success as a pilot as did the candi-date’s ability to drive a motor-car. Similar correlationswere sought for by statistical and routine analyses ofcharacter and intelligence, but again with indecisive results.

P.,;ycliotiieti-i(- teats.-The most promising line of approachappeared to be that afforded by the psychometric tests,which, under the direction of Camus and Nepper, achievedconsiderable fame in the French flying service. These testswere based on the assumption that aviation demands thespecial quality of rapid decision which is measurable by thecandidate’s psychomotor reactions." While not denyingthat rapidity of decision is most desirable, I would emphasisewhat has been repeatedly pointed out to me by numerousflying friends (some of whom, it is true, failed at thesereactions) that, whereas a clear judgment and correct ratherthan quick decision will make all the difference in a tightcorner, as in any other activity, flying under peaceful con-ditions in the absence of untoward events is a sedate pro-cedure, bordering at times on the monotonous. They alsopoint out that the bodily movements necessary for controllingan aeroplane are methodical and deliberate, and not to becompared in speed with those necessary for playing a gamesuch as racquets. -

Psychometric reactions are divisible into two maingroups-simple and complex or choice. In the former thestimuli are of the most elementary character, plain visual,auditory, or tactile impressions. These reactions are

recorded bv means of the D’Arsonval chronometer. Theaverage normal values are as follows : Visua119/100ths second,auditory 14/lOOths, and tactile 14/100ths. A satisfactoryreaction also entails but little variation between theindividual responses in the whole series. The responses areslowed in conditions of exhaustion and after illness, a factwhich was corr6borated on our own pilots. Although I haveno statistical evidence that these simple reaction timesare an indication of flying aptitude, I understand that theresults obtained on some of the most distinguished andsuccessful fighting pilots in the French air service stronglysupported such a view. But even so, there is still the possi-bility that these tests afford an indication not so much ofaptitude for flight as of ability to fight a gun in the air, anoperation which especially calls for great rapidity anddexterity of movement. Of the three reactions, that toauditorv stimuli would seem the most delicate.In the complex or choice reaction the subject is not

limited to one movement, but has to select between two ormore according to which stimulation occurs. Theoreticallythis would appear to give a better indication of the quality of.rapid decision, in which complex psychical processes mustnecessarily be involved. From an investigation carried outon these lines it certainly appears that the correlation with

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flying aptitude increases up to a point with the complexity Iof the reaction.4

B. 7’he ll’itlhtiiifl Temperamcllt.In war the aeroplane has to be looked upon as a device

whereby the mobility of the individual is so increased thathe is able, directly or indirectly, to inflict losses on theenemy in the enemy’s territory. The military pilot musttherefore possess the combatant spirit. This is not neces-sarily associated with the aptitude for fiight. The mostskilful pilot might be, and sometimes was, valueless as a

fighting force; while, conversely, lack of technical skill wasvery far from being equivalent to lack of military value;indeed, several of those pilots, the memory of whose con-spicuously successful gallantry will endure, could not beconsidered first-class fiiers, while one, at least, was definitelyindifferent. Hence what chiefly mattered in the field wasthe fighting temperament. This is a theme, however, whichcannot profitably be dealt with here.

PERIODS OF EFFECTIVENESS.

Confining our attention now to an officer’s effective-ness as a fighting force, and not to his skill as a pilot,from the purely technical point of view, it was foundthat the degree of effectiveness varied greatly atdifferent states of his military career. These stagesmay conveniently be compared to the seasons of theyear.

The Period of inexperience.This is the flying officer’s spring, and is chiefly occupied in

learning to fly, an aspect of which I have no personal know-ledge. Its importance is obvious, and it provides a fruitfulfield for psychological study. But this stage does not endwhen the individual reaches the fighting line as a fullyqualified pilot, for he is still without practical experience ofwar. During the next two months he passes through themost critical stage of his career, gaining experience only toooften at the cost of his life. To realise this it is onlynecessary to consider what maybe called the military ageof a flying officer, his birthday being the day of his arrival inthe fighting line. If, for example, we wish to determine theaverage military age in any squadron or group of squadronswe have to determine the total number of weeks served byeach officer since his arrival in the squadron and divide thetotal by the number of officers in the squadron or group.Similarly, we can determine the average military age of Ithose who become casualties as the result of battle, accidents,sickness, &c. The following figures are only approximate,but for our present purposes sufficiently accurate.On the Western front the average military age of casualties

due to battle and accidents combined was for the whole of1917, 2 months and 18 days; for the five winter monthsthe military age was as much as 3 months 4 days, but for thesummer (fighting) months 2 months and 11 days. Or, to putthe matter differently, of the battle casualties sustainedduring the fighting months of 1917, 35’05 per cent. occurredamong officers who had’been less than one month with theirsquadrons, 25-60 per cent. among those who had been lessthan two, and 12-32 per cent. among those who had been lessthan three. The corresponding figures for the whole of 1918up to the armistice were as follows : 26-43 per cent. underone month, 27’97 under two months, and 14-97 under threemonths. That is to say,- during 1917 and 1918 roughly 70 percent. of the casualties sustained in battle and in accidentsoccurred among officers who had completed less than threemonths of active service. These figures must not be takentoo literally. First, it must be remembered that officers didnot remain on an average much more than six months in thefield before being sent home for a rest. Secondly, there werealways larger numbers of "young" officers in a squadronthan "old" ones, and therefore the incidence of casualtiesamong the former is not as heavy as the figures quoted wouldmake it appear. Remembering, too; that casualties hadnearly always to be replaced by the inexperienced, a periodof heavy casualties by lowering the average military age ofa unit tended to increase its vulnerability.But altogether apart from figures it was the unanimous

opinion of all unit commanders that a pilot’s, especially afighting pilot’s, first two months of active service consti-tuted the critical p od, during which he was more likelyto become a casualty himself than to inflict casualties onthe enemy. The period of inexperience then corresponds tothe period of minimal military effectiveness and of maximalvulnerability, and particular stress has been laid on it, notso much because it contrasts so vividly with the ensuingperiod, but because unless it is appreciated it is impossibleto understand the psychological atmosphere of a flyingsquadron as a whole.

The Period of F’.xPe°ience.Having escaped the dangers surrounding his first twomonths, the flying officer enters upon the summer of his

career, a period of confidence and self-assurance, of initia-tive and (lash, of skill and wise discrimination, of successand achievement. His vulnerability is now relatively slightand his military effectiveness at its zenith. The length ofthis stage is naturally variable, depending on theconstitution of the individual, the amount and characterof his work, and the success he achieves in doing it.The inspiration born of success especially helps toprolong it. Nevertheless, it is absolutely certain thatit cannot last indefinitely; autumn, or the period ofreaction, must supervene sooner or later. And it will bejust here that the ability to make accurate psychologicalobservations and deductions, whether in a unit com-mander or his medical colleague, is of such vital import-ance. For if the successful officer can be spared fromexperiencing in too great a measure the mental conflictwhich characterises the period of stress, if he can berested at the crucial moment, he will in a comparativelyshort time again be fit to return to the fighting line, not toembark again on those critical two months of danger andinexperience, but to jump with one bound into a secondperiod of confidence and efficiency. The appearance of onesuch individual might even rally a broken and discouragedsquadron.

The Period of Stress.The mental strain inseparable from warfare in the air

presents the same picture, both in its development and itsend-effects, as that which occurs in other combatantbranches of the service; it is only the colouring which isdifferent. It will be worth while briefly to consider a fewpractical points peculiar to the flying service which modifiedthe development of the condition of stress. It was a curiousfeature about a fighting squadron, comprising only eighteenflying officers, that it could be made or marred by two orthree individuals, especially if they were in the position ofleaders. These few set the pace, often, it is true, to thedetriment of those who attempted to follow. If, now, one ofthese individuals were permitted to remain when the periodof stress had become definitely established, and his efficiencywas on the wane, the results might be disastrous. Hisleadership in the air became less effective, the offensivespirit dwindled, and the new arrivals in the unit obtained anentirely false impression of the standard of work expectedfrom them. A leader, therefore, whose effectiveness waslowered by fatigue could as easily mar a squadron as one inthe prime of his career could make it. Nevertheless, hiscommanding officer was often reluctant to replace one whohad served him so long and so well; often enough he hadalready acquired a reputation, to shake which somethingmore was demanded than a falling-off in achievement, toooften but generously regarded as a temporary run ofill-luck.

Secondly, the type of flying largely determined the onsetof stress. In artillery squadrons, where the mind was fullyoccupied in registering targets, signalling the progress ofoperations, &c., and pilot and observer enjoyed each other’scompanionship, complete efficiency was retained, in spite ofthe dangerous character of the work, up to eight, nine, or tenmonths, or even over a year. In fighting units, however,where the whole object was to destroy the enemy 81 the airor to take part in the infantry battle, the effective period wasmuch less.Thirdly, the irregular hours of sleep during the summer,

with the nights disturbed by the aerial activity of theenemy, were an important influence in hastening theonset of stress. The question of sleep was particularlydifficult to arrange in squadrons employed exclusively bynight.Again, all flying is in a sense fatiguing, in that it demands

attention, but the fatigue experienced is in inverse propor-tion to the skill of the pilot and the efficiency of the aero-plane. The importance of the latter factor in war is veryreal. The psychological effect of the appearance on one orthe other side of a machine superior to anything that can bepitted against it was frequently in evidence on the Westernfront. In the same way flying over enemy territory with anengine the reliability of which was open to question was anoperation peculiarly adapted to the rapid acquisition of astate of anxietv.The question of altitude will be dealt with in a subsequent

lecture. Here it is only necessary to say that flying ataltitudes over 13,000 to 15,000 feet was a factor whichdefinitely accelerated the onset of nervous fatigue.The most important psychological factor, however, peculiar

to the flying service was its individualism. Flying in forma-tion diminished but certainly never abolished this out-standing feature. A flying officer relied essentially on hisown skill, his own courage, his own resolution, and his ownsense of honour and of duty. He lacked and most certainlymissed the inspiration born of responsibility to his menand that intimate comradeship in danger which forthe infantry officer served as sources of support andencouragement.5

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THE MENTAL REACTION.* *

It is not proposed to discuss this subject in any spiritof controversy, but to regard it as a perfectly normalreaction to a very abnormal environment. That thisreaction is now comprehensible is largely due to theadvance in our psychological knowledge which wasliterally forced upon us by the war.

It will be recalled that man’s earlier interpretation of theuniverse, and therefore his attitude towards disease, wasessentially an animistic one, and all disease was ascribedto spiritual agencies. This interpretation was graduallyreplaced by explanations of a materialistic kind, so thatthe production of disease was ascribed in an increasingmajority of instances to material agents, and only where nosuch explanation seemed possible were spiritual agenciesstill invoked to account for its presence. The concept of theactivity involved by these latter agencies was, however, verydifferent from what we now understand by "mind." It wasthe impetus derived from the study of the phenomena ofhypnotism, introduced from the East, which led modernthought to the recognition of the mental factor in medicine.In the course of these studies it was found that hypnotismmight offer the means of reaching experience "which hadbeen so completelv buried that bv no effort of the will couldit be recalled." 6 It was left to Freud to demonstrate thatthese buried memories could be recalled without the aid ofhypnotism by means of what he called free association,"the necessary clues being usually provided by dreams.7 Bythe knowledge derived from his analyses he was able to putforward for the first time a definite scheme of theunconscious region of the mind and its relation to theconscious. It accordingly became possible to correlateevents in the sphere of the conscious with eventsin the sphere of the unconscious, and so to adopt inthe sphere of the mental the principle of determinismwhich had so long assisted the progress of physicalscience. It is the special value of Freud’s workthat the student of mind can now believe that everypsychical event has its psychical antecedent, and so believingwill have the patience and courage to probe deeply into thehistory of his patients.Partly independently, but partly because of Freud’s work,

the great importance of the instinctive or emotional aspectsof mind was becoming increasingly recognised before thewar, and the emotional factor in neurosis was coming to beregarded as the expression of some instinctive tendencywhich had to be repressed on account of its mcompatibilitywith social standards. It" is well known that Freud was ledto the conclusion that the mental experience which tendedto be so suppressed was nearly always connected with thesexual instinct, and the exaggerated importance attributedto this factor, more especially by his disciples, not un-naturally rendered his views unacceptable to the generalbody of medical opinion both in this country and in France.

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The war, however, while accentuating the truth of Freud’smain assumptions, has made it possible to discard thedominating importance of sex, and to substitute in its placethe stiltnore fundamental instinct of self-preservation.In dealing, therefore, with the reaction inevitable in

war we are dealing first and foremost with the defencemechanisms developed by the individual for countering hisnatural instinct of self-preservation. When these mechanismsare weakened by shock or prolonged strain, and the instinc-tive tendency comes into conflict with social standards, acondition of neurosis results. Among the instinctive oraffective aspects of mind which particularly concern us theemotion of fear naturally takes pride of place.The most frequent mode of reaction to actual danger in

man consists in an extremely complex reflex action whichso adjusts the bodily functions as to render the individualbetter fitted to meet and overcome the danger. In this,which we may call the physiological reaction, the emotionof fear takes no part and fails to appear; we say a man is" cool in the presence of danger." A second mode of reactionconsists in the replacement of the emotion of fear by theemotion belonging to the instinct of aggression-namely,the emotion of anger-and we say a man " sees red." I Inboth modes of reaction, however, although fear is not felt,we may, for many cogent reasons, confidently assume thatit is potentially present, but in a state of suppression. Itmay, however, and indeed does, appear on the surface whenthe mechanism of suppression is lowered by shock or strain,or when higher control is weakened, as, for example, in thewaking state.

* In this section I have drawn freely from two sources : (i.) twocontributions by Dr. W. H. R. Rivers-(a) Mind and Medicine, alecture delivered on April 4th, 1919, and published by Longmans,Green and Co., and (b)’ Wind Up," an article written for the use ofR.A.F. medical officers; (ii.) an unpublished paper entitled " FlyingFatigue and Efficiency," written in France in August, 1917, by mylate friend and colleague, Dudley Corbett.

These considerations lead us to the comprehension of thetwo earliest symptoms of the mental stress induced bywar, first the nightmare, and secondly the occurrence ofactual fear or of apprehension under circumstances in whichthese had not been previously experienced. These symptomsthe sufferer keeps to himself, and so begins an entirely newprocess, the conscious repression of fear and apprehension,which are regarded with shame, and as much as possibleevaded. The slang nomenclature to which the war gavebirth, especially the substitution for the word "fear" ofquasi-humorous expressions, is in itself evidence of thedesire of the individual to shun the consciousness of fear.This conscious suppression of fear only serves, however, toincrease the strain and fatigue which has led to the failureof its unconscious suppression, and a state of persistentanxiety gradually develops, characterised particularly byloss of sleep and various disturbances of physical health.

" 1T’ind U1 " : A Clinical Pictitre.

The clinical picture presented by an officer whosemechanisms of defence have given way under the strain ofwar is characteristic. In its earlier stages, however, it isusually entirely subjective, and its presence can thereforeonly be discovered by a medical officer whose personalitycompels the sufferer to come to him in confidence anddisclose his troubles. The tired pilot may under thesecircumstances complain of having lost some of his keen-ness ; he has recently been dissatisfied with his work,and for the first time has begun to wonder when it willbe his turn to go home; he has already been out over sixmonths. He has not been quite sure of himself in the airlately, and to make certain that his confidence for flying isunshaken lie has attempted to reassure himself by provinghis ability to execute various manoeuvres dangerously closeto the ground ; the result has not been a success. Perhapsit is all due to the mess having been unsatisfactory; hethinks the tone has gone down; anyhow, he has been off hisfood. He has only just recently recognised that he prefersto leave the mess after meals and lie down and read a bookin his own room. His sleep is less sound than it used to be;he takes a long time to get off and has lately been dreaming.At first the dreams were not unpleasant, merely that hewas making bad landings and getting laughed at. Then theybegan to worry him; he would dream of long-forgottenexperiences in the trenches, or that he was brought down"and taken prisoner ; and he hardly likes to mention it, butonce he was " brought down " in flames, and woke upin terror shaking all over. His administrative work 0:1

the ground has been a labour instead of a pleasant duty;he has had a row with his sergeant, and he feels the" C.O." is losing faith in him. The new pilots fromEngland are not altogether satisfactory; his responsi-bilities weigh heavily on him, and he thinks that thedeath of a member of his flight was avoidable, andperhaps was his fault. He admits that he is consciousof having to force himself into the air, and is inclinedwhen leading a patrol not to "go for" things whichhe would have done without hesitation a fortnight ago.Perhaps flying has affected his heart ; he has had palpita-tions lately, has been short of breath on exertion and easilytired. Anyhow, the whole thing is a complete mystery tohim, although he is sure it is only temporary and the doctorwill give him something to put him right. And so, seekingfor trivial causes in explanation of a fundamental change,reluctant to acknowledge what he dreads-what, moreover,he has publicly condemned in others-equivocating, pursuing

- false hopes, and evading the real issues, this eminentlybrave man will frequently conclude with the appeal, "Don’ttell me its wind up.’ "

It is at this stage that the medical officer can obtainresults of incalculable value to the individual, both as apatient and a soldier. The condition is essentially mental,and treatment must be directed to the mind. By assuringhim that there is no cause for shame or reproach but ratherthe reverse, and by inducing him to give up the process ofvoluntary repression, he can so prepare the soil that duringthe necessarv rest which he will insist on the normalmechanism of defence will be rebuilt and the individualrestored to perfect health and efficiency. Moreover, havingonce experienced the condition and made to understand itfully and frankly, the officer will in future be enabled tounderstand its appearance and recognise its onset in hiscompanions.When the condition is allowed to progress unrecognised

the state of anxiety increases. The more stout-hearted thesufferer the longer he disregards Nature’s danger signals.He becomes irritable, unsociable, morose, losing hisinspiring personality, and adopting a black outlook onthings in general. Although he feels tired, he is excitableand restless ; unable to sit down to read or write, he mustneeds always be pottering about the aerodrome looking atthe weather. To keep himself going he smokes to excess,or may even come to rely on alcohol. If he meets an enemy

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formation on patrol he either turns tail or attacks recklessly,too tired to think about manoeuvring. In the last stage thenoise of the engines on the aerodrome distresses him; hecannot bear to see a machine take off or land, and he evenhates to hear " shop talked. Sooner or later he must givein. The career as a war pilot of an individual who reachesthis extreme stage is irrevocably finished.

Prophylaxis and C1tre.It would seem at first sight an easy matter entirely to

prevent the development of the anxiety state by antici-pating it. In practice, however, such a course was well- Inigh impossible. Some of the reasons why this was so canbe inferred from what has already been said ; they were notwithin the control of any one man, but were rather theinevitable consequence of the way in which the wardeveloped. It was, however, recognised that the principle ofshort shifts was applicable here as in all other communitieswhere industrial fatigue was to be expected, and in this wayit was found possible perceptibly to reduce the permanentwastage from this cause, and materially to shorten theinterval between an officer’s admission to hospital and hisreturn to the fighting line.During the closing months of the campaign, when the

drain on the man-power of this country had become verysevere, the anxiety neurosis became a more prominent andfar more difficult problem than ever before, although in asomewhat modified form. The type of manhood that wasbeing pressed into the service inevitably deteriorated. Inthese individuals, and essentially as a result of the lack ofthat mental and bodily education which more than anythingelse assists the formation of character and the gradualdevelopment of the psychological mechanisms of defence,the powers of resistance were insufficient. The majorityof them mentally immature, many of them physically so,unaccustomed to rely on themselves, looking rather forthings to be made easy for them, lacking initiative, andnaturally apprehensive, through no fault of their own theywere ill-equipped for the duties for which they had beenhurriedly trained. Moreover, the qualities requisite for asuccessful fighting pilot are as relatively rare as they aresplendid, and it was particularly in fighting machines thatthe great numerical expansion of the air service had takenplace. These individuals, then, never having acquired thatunconscious suppression of fear which in their more fortu-nate comrades of tougher calibre had come into existence inearly boyhood, broke down early, and had to be eliminatedas’quickly as possible. For the condition of anxiety whichso rapidly developed in these misfits I have elsewhereproposed to substitute for the term "stress" that ofdistress."The line of treatment to be adopted in the states of strain

imposed by war follows closely from what has been said asto the causative factors ; mental and bodily calm have to berestored. It is first necessary to eliminate the affectivestate due to the disturbing emotion of shame, and, secondly,to persuade the sufferer to discard the process of voluntarysuppression. Two other therapeutic agencies may bementioned. The first, that of self-knowledge, by which,among other things, the sufferer is brought to understandelements of conscious experience which are being misinter-preted ; the second and more important, the agency of self-reliance, by which he is persuaded frankly to face his troublesinstead of running away from them. In other words, wehave first to assist the patient suffering from stress to under-stand his troubles, and then to appeal to his common senseand his character; it is easy to understand why, in thecondition of distress, the results of mental therapy must bedisappointing.

THE PHYSICAL REACTION.

The disturbances evoked by abnormal psychical statesin the physical sphere may be profound, and the recog-nition of this fact, forced upon us by the war, seemslikely to play a prominent part in influencing the futureprogress of medicme. There need be no difficulty inunderstanding this if we remember the profoundphysical effects invoked by emotional states, amountingin animals to complete muscular paralysis.The incidence of these disorders varied greatly. Many

onicers, after a long and arduous spell of work, thoughconscious of an altered state of mind, showed little manifestdisturbance of physical function. One of the earliest signsof stress was revealed in a loss of weight, amounting insome cases to over a stone in two or three weeks. Clearlymetabolism, as in exophthalmic goitre, was tuned to a highlevel, and it has also been shown that the oxygen consump-tion per minute was often above normal in these cases. Ina large number of individuals, however, in whom a stateof anxiety had become definitely established, all or someof the physical changes shortly to be mentioned were found toexist. These disturbances were all characterised by a loss of

central nervous control, resulting in conditions the mainfeature of which was overaction.l It was our practice inFrance, a practice originating in the supposition thatrepeated exposures to high altitudes might induce changesin the circulatory and respiratory systems, to investigatethese systems with particular care. It soon becameapparent, however, that the disturbances which were fre-quently found could not fairly be attributed to suchexposures alone, since they were common to the majorityof individuals suffering from mental strain, in many ofwhom high altitudes could not have been an setiologicalfactor.In the circulatory system a rapid pulse, throbbing cardiac

action, a pulse-rate and blood pressure both unduly sus-ceptible to changes in posture and slight exertion, and alarge pulse pressure were the rule. In such cases, even whenresting, the heart appeared to be working at full pressurewith no reserve to draw upon when an extra effort wasdemanded of it. A short walk along the road was sufficientto produce physical distress.In the respiratory system the shallow rapid breathing,

small tidal air, diminution in vital capacity, and highventilation per minute all pointed to an excessive irritabilityof the respiratory centre, and consequent diminution ofrespiratory reserve power.10In the neuro-muscular system loss of tone of the abdominal

wall, as evidenced by stomach-splashing and diminution ofexpiratory force, tremors of the hands and tongue, and dis-turbances of static equilibrium were all indicative of anescape from nervous control.The increased output of adrenalin with the production of

hyperglycaemia,l1 which has been shown to occur in variousemotional states, probably results from excessive stimulationof the sympathetic system.12 In the same way may beexplained the remarkably acute and at times alarmingdigestive disturbances, simulating the picture of duodenalulcer, which occurred so frequently, and also the abnormalaction of the vagus on the heart 13 and lungs.l4

It is impossible to escape the conviction that in a largeproportion of these cases this condition was essentiallymental (emotional) in origin. This view in no way conflictswith the theory of toxasmia favoured by Lewis to accountfor the similar condition in the foot soldier is; on thecontrary, following the influenza epidemic of 1918 numerousofficers were found to be suffering from a condition clinically

indistinguishable, save for the absence of anxiety, fromthat which has been briefly described.The emotional factor in the production of physical dis-

turbances is well illustrated by a series of pilots who hadbeen concussed as a result of a 11 ci!ash," with loss of con-sciousness. Of 24 cases one-half, several of whom couldremember nothing about the accident, seemed little affected;the response of the pulse to change of posture and toexercise was normal, there was no loss of abdominal tone, notremor, and a comparative absence of symptoms. Allreturned to duty after a short rest and did excellent work.The other half all had vivid memories of their accidents andwere definitely " on edge " ; their pulse-rates were high andunstable, abdominal tone was poor, tremors were prominent,and headache persistent. All were evacuated to Englandand none of them returned. .

SUMMARY.

The experiences which have been studied serve toemphasise the predominating influence of the highernervous centres in man. The lower centres in theirturn transmit these influences to every organ in thebody, and we realise as perhaps never before that ourbodily health and bodily activities are at the mercy, soto speak, of events taking place in our cerebral cortex.

Re.ferences.-1. Birley’ : Air Medical Invest. Com. c’2,eportsNo. 4, 1918. 2. Head: A.M.I.C. Reports, No. 7, 1919. 3. Spear-man : Report (unpublished) to A.M.I.C. on Psychol. Exam. ofFrench and American Aviators. 4. Stamm : Report (unpublished)to A.M.I.C. 5. See also Rivers: Mental Hygiene, ii., No. 4, 1918.6. Rivers: Mind and Medicine, Longnxans, Green and Co., 1919.7. Freud: Selected Papers, translated by Brill, New York, 1909.8. Rivers: "Wind Up" (unpublished). 9. Briscoe : Observations onthe Respiration of Airmen, 1918. 10. Flack: A.M.LC. Reports,No. 3, 1918. 11. Kooy: Brain, xlii., pt. 3, 214, 1919. 12. Cannon:Bodily Changes in Pain, Hunger, Fear, and Rage, New York, 1915.13. Med. Res. Com. Special Report Series, No. 8, 1919. 14. Haldaae,Meakins, and Priestley : Journ. Physiol., lii., 433,1919.

WELSH NATIONAL SCI300L OF MEDICINE: THECHAIR OF PHYSIOLOGY.-Dr. T. Graham Brown, who sincehis release from military service has been carrying on hiswork as lecturer on experimental physiology at Manchester,has been appointed Professor of Physiology in the WelshNationa! School of Medicine, to the chair which fell vacanton the resignation of Professor J. Berry Haycraft. Pro-fessor Brown will be in charge of the new physiologicallaboratories recently erected at Cardiff.

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