- The effects of flying upon human performance - article ; n°1 ; vol.50, pg 629-638

Bartlett

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L'année psychologique - Année 1949 - Volume 50 - Numéro 1 - Pages 629-638
10 pages
Source : Persée ; Ministère de la jeunesse, de l’éducation nationale et de la recherche, Direction de l’enseignement supérieur, Sous-direction des bibliothèques et de la documentation.

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• Publié par: L-annee-psychologique
• Publié le: 01 janvier 1949
• Nombre de lectures: 23
• Langue: Français

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F. Bartlett
XI. - The effects of flying upon human performance
In: L'année psychologique. 1949 vol. 50. pp. 629-638.
Citer ce document / Cite this document :
Bartlett F. XI. - The effects of flying upon human performance. In: L'année psychologique. 1949 vol. 50. pp. 629-638.
doi : 10.3406/psy.1949.8479
http://www.persee.fr/web/revues/home/prescript/article/psy_0003-5033_1949_hos_50_1_8479XI
THE EFFECTS OF FLYING UPON
HUMAN PERFORMANCE *
by Sir Frederic Bartlett, F. R. S.
Cambridge Psychological Laboratory.
In considering what I could contribute to this Volume it
seemed to me that I should choose some topic having a definite
experimental basis, fundamental in its interests and yet at the
same time alive to current movements of thought and method.
For it is fair to say that these have been leading characteristics
of the long series of important contributions with which Pro
fessor Piéron has enriched the records of psychological science.
Especially during the late War, it became necessary for many
of the workers in this Laboratory to turn their attention to a
study of the changes in the performance of a variety of skills
when that performance must continue without interruption for
relatively long periods, often under stress. The types of activity
most involved rarely required excessive physical or muscular
effort at any stage. But they did require accuracy and usually
considerable speed in manipulation. They all, that is to say,
had their expression in co-ordinated bodily movements, and the
changes accompanying prolonged exercise could all be best stu
died as measurable changes in, or directly in relation to, these
1. I consider it an honour to have this opportunity to pay my tribute,
and that of many generations of students at the Cambridge Psychological
Laboratory, to the outstanding achievements of Professor Henri Piéron.
His work has been to us a persisting stimulus and a guide, for theincisiveness
and clarity of his ideas, for his strict adherence to the demands of scientific
method, and for the great breadth of his interests. We wish for him now a
long period of active leisure, during which his genius may move freely
wheresoever it desires. 630 PSYCHOLOGIE APPLIQUÉE
movements. At the same time the movements themselves were a
serial response to successive signals, or " displays", which made
up the working environment. The operations were in the form
of a continuous interplay between information and action, each
of which largely determined the next step in succession of the
other. The essential problems conformed in general to the
'familiar fatigue problem. But it very soon appeared from obser
vation that the results did not agree very well with any familiar
fatigue picture. Indeed it became speedily apparent that what
is often called «• fatigue » in the case of skill cannot be well
investigated in any experimental situation which calls for
the prolonged repetition of a relatively simple operation, and
attempts a measure in terms of a curve representing the course
throughout the whole active period of some simple character
of overall output. Skill " fatigue " — if we are to continue to
-use this word — has characteristics of its own. Its experimental
study demands special methods and the measures needed are
special measures.
One of the particular cases selected for special study was
the case of changes of human activity accompanying prolonged
air flights. Very broadly speaking there are two sets of problems :
fatigue in aircrew, and fatigue in the passenger. A little is
beginning to be known about the first, though far more remains
yet to be discovered. The second is still practically all a matter
for anecdote and speculation. I shall therefore limit this commun
ication to some remarks about fatigue in aircrew.
I. — Characteristics
AND CONDITIONS OF FATIGUE IN AIRCREW.
There is so far no compelling evidence that any single process,
or any single group of processes, underlies all the many manif
estations of what is commonly called fatigue. For working
purposes fatigue must be held to include all those changes of
performance which appear to be due to the continued exercise
•of the activities involved; and in practice it is desirable to di
stinguish between continued exercise under what may be regarded
as the normal range of performance conditions, and continued
exercise when the normal conditions are exaggerated in some
special direction, or unaccustomed environmental circumstances
are present. Flying fatigue, for example, covers the possible F. BARTLETT, F. R. S. THE EFFECTS OF FLYING 631
effects of noise, of vibration, of a certain range of temperature
changes and of a number of other environmental circumstances
to the extent to which they are commonly present in flight,
and of course it covers also all possible direct effects of the
duration of the. activity up to the customary limits of continued
exercise. In addition there are special effects with marked oxygen
lack, or with abnormal acceleration, or at extreme altitude, or
with great excess of heat or cold, or with many other unusual
accompaniments. The present paper will be concerned only
with conditions that lie within the normal range.
All members of air crew have special duties to perform and
it is reasonable to seek a measure of fatigue in terms of the
recordable changes in the ways in which they carry out their
particular technical tasks. Although these operations differ from
one member of aircrew to another, they all have important
broad likenesses. None normally involves long continued heavy
muscular effort. All are of the nature of skilled adjustment to
environmental signals which to an increasing extent are given
by a variety of instrument readings, the instruments being a
part of the normal aircraft equipment. The operations are the
refore correctly to be regarded as requiring a continued process
of interplay between receptor interpretations of environmental
signals and groups of signals, and timed and co-ordinated effector
response. When an instrument record is perceived to have
changed by a certain amount, it initiates an effector response,
and this itself brings about a further change of instrumental
record which in due course leads to a further bodily adjustment.
An important and never-to-be-forgotten part of the significance
of this is that, within limits, whenever any trained and efficient
aircrew operator does something, he is able to some degree to
anticipate and prepare for the probable next adjustment in the
series. This is one of several reasons which make it impossible
ever to express change of activity as a measure of efficiency
in the execution of any single item of the performance alone,
or as a measure of the overall final product of the total number
what' is regarded as the finished task, or in any of items in
single cycle of operations of that task.
In a general sense the extraordinary feature of any series of
receptor-effector interchange of this type, if both the display
— the signals for action — and the control — the bodily move
ments - — are well designed, with a due consideration of what
the human body and mind are adapted to do, is the very long PSYCHOLOGIE APPLIQUEE 632
period of continuous exercise that is possible for any fit man
before notable changes in performance become manifest, either
during or after exercise. It is safe to say that if significant dete
rioration can be shown in any bodily fit and mentally interested
member of aircrew within the limits of a flight of -ordinary dura
tion, or of any continuations of such flights from day-to-day,
either the operation has been badly designed, or factors are at
work which lie outside those involved in the continued exercise
itself.
Changes of activity leading to actual or potential deterioration
of efficiency do however commonly occur, even, say, in the
course of an ordinary trans-Atlantic flight. They indicate that
there is still very much to be learned about the correct design
and matching of display and control in the case of aircrew
operations. This is of course well known and widely recognised,
and it dictates what is at present an over-riding group of pro
blems in research into the psychological conditions affecting
human activity in flying operations. What is the optimum design
and positioning for instrument dials and scales and their recorder
devices? How may direction of control most naturally fit corre
sponding directional change of signals? What are the normal
human tolerance limits for " speed " and " load " when linked
interpretation and action have to be prolonged? Perhaps most
important and least known of all, how can the tempo and other
features of serially arranged signals and controls be so planned
as best to fit the inevitable anticipatory pattern of human
performance?
The answers to these and other questions of the same basic
rationale which are now being actively investigated all over the
world, vary in detail according to the particular function concer
ned, and also probably, as Russell Davis (1948) h