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### Fax: Ariel:idnet muze získat udinal), POSilující (Discriminating L.muže jako postojoišení nebo úzkosi. ,tu, napr. zvyšovatnuto podnetu predrozlišující vliv na kci priblížení nebo á navozování zmen Vlo dosaženo zmen'. muži zmenit ponegatívní k pozitiminaHvní hodnotu bude vyvolávat pri-:vence se bude zvyijící hodnoty ženyD systému ve vztastaci, má-li mužriího chování (zmeá automaticky chonaucil), muže však ho chování, .pro~ože takovému chovánízpracovaným pren popisem behaviopodaných kazuistilcování koncepti¡álTní a diferencovanýLpii sexuálních abeS. Kratochvil posium of the Inter-:;ongress of Electrothe Eleventh World ': School and Work, anism of Action of ncluding Diagnostic

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# ACTIVITAS NERVOSA SUPERIOR

I~~-L. 18 DECEMBER 1976 F ASe. 4 Avicenum, zdravotnické nakladatelství, n. p., 1975



# PSYCHOLOGICAL AND P S Y C HOP H Y S I 0 LOG IC A LAS PEe T S 

## o F W 0 R K AND FAT I G U E 1) 

# (A rev i e W 0 f pap e r s pre s e n t e d a t P C - I AOH 

# Sub-Committee meeting on Higher Nervous Fun c t ion s, P rag u e, J u i y, 1 9 7 5 )
P. Colquhoun2) 

### INTRODUCTION As defined by one of the speakers at the Prague meeting, the general aim of this area of research is the assessment of the consequences for the worker of 

### the mental demands arising from his work, by quantifying changes in those physiological variables that are influenced by psychological stimuli. The problems posed by this statement of aim are numerous and complex,

### and most of them were ilustrated in one way or another by the Prague contributions. Perhaps the most pervasive problem is that of individual differences. 

### Patterns of physiological response to a given work situation vary widely indiferent people; on the other hand, there is encouraging evidence that anyparti

### cular person is relatively consistent in his response pattern when presented with the same work situation on different occasions. If, then, we could identify those variables which would give us, as it were, a "baseline" for a particular 

### individual, we would have gone a fair way towards a solution to the problem. 

### There is growing evidence that per son a lit yfactors, particularly those of iritroversion on the one hand, and anxiety-level on the othér, are of considerable 

### relevance to individual diferences. These personality factors may influence the 

### relationship between "tonic" and "phasic" psysiological activation levels, and, 

### in turn, this relationship is likely to affect the way in which a person actually performs a particular task during a period of observation. 

### Successful identification of personality type, however, may not provide the whole answer. Physiological response patterns to a particular task, or to changes 

### in performance demands within that task, occur against a background of overall

I) A report at the 18 th International Congresl' of Occupational Health, Brighton, England, September 1975. Session No. 32: Environmental and Psychological Stress. 2) MRC Applied Psychology Unit, University. of Sussex, Brighton, England.

257response to the t0'tal w0'rk situation which is partly the result of the individual's past experience. Although it may well be true that the nature of this "long-term" 

### reaction wil itself be dependent to a substantial extent on intrinsic personality factors, it is also the case that the O'verall characteristics of the job, the social 

### structure of the workf0'rce in the factory, and even the way the worker views his work in be c0'ntex of his general life-pattern wil all have affected the 

### individual's basic physi0'logical response by a 'process of extended conditioning 

### over a period of perhaps many years. Whilst acknowledging the importance of these long-term underlying response patterns, we should not be deterred by the magnitude of the problem invO'lved 

### in defining them from continuing to search for physiological correlates of objectively measureable changes in work demand, or of clearly different types 

### of performance; because success in identifying such correlates at a predictive level would at least enable us to' make a practical start towards the improvement of working conditions. Demonstration of the occurrence of critical physiological response patterns in a group of workers engaged in a particular form of work would point clearly to the need for changing the way their tasks were organised. 

### This would provide a strong argument for a thorough appraisal of the jobs 

### involved in terms of their ergonomic and social characteristics. Hopefully, this would then lead to a scientific redesign of the work-system as a wh0'le.



### THE CONTRIBUTIONS "p s Y c h 010 g i c a 1" s t u die s. Broadly speaking, one c0'uld distinguishtwo kinds of w0'rk situatiO'n which had been experimentally studied by the con

### tributors to the Prague symposium, These were designed to investigate, on the one hand, the psysi0'logical changes that occur simply as a function of t i me in a particular work situati0'n - perhaps involving a task of the "vigilance" 

### il "monitoring" type, in which in one sense it could be said the subject is consistently un d e r 1 0' ad e d - and, on the other hand, changes resulÜng from v a r y i n g the d e g r e e of load within a particular task, sometimes up' to 

### the point of 0 v e r loa d. Several diferent tasks were used in these studies. Besides these task diferences, there were even greater differences in the 

### physiological variables measured. Again, these fell into two broad categories -measures of central nervous function on the one hand, and 0'f autonomic function on the other. Sometimes both were studied together. In some cases the choice 

### of variables gave the appearance of having been 20mewhat haphazard - depending, perhaps, on the investigators' own theory, or (possibly) on the 

### equipment available in his laboratory. But perhaps this is a little unfair; at this stage, in the area we are discussing, almost a 11 information is potentially 

### usefuL. The problem comes when one tries to interpret it, particularly in the absence 0'f an adequate model which attempts, to relate actual performance to concurrent changes in both central and autonomic variables which are themselves 

### related, and makes specific hypotheses about such multiple relationships. An 

### associated difficulty is "what is the best method0'logy to apply to the analysis of the mass 0'f data that can be collected even when only 0 n e variable is being 

### measured?" There are many diferent ways of analysing, for example, data on "sinus arrhythmia" - but happily one crf the ~peakers suggested a technique 

### for solving this question 0'f "h0'w to analyse" 51ch data, which may turn out

to

### be of considerable value for general use. To turn now to details of particular contributions, we might start with two 

### related papers from the Laboratory for Ergonomic Psychology of The Netherlands
258 I

I i

J

1Organization f( 

### 13. W. Hyndm binary choice 

### pace of work j 1 minute 'with( to a neon flas: 

### made before a of the visual e, to information 

### variability, the increase. in am recovery perioi to be compose 

### electrical, and The authors f( 

# intra-ind were highly s( -acting factors 

### During t 

### Acting on th, cardiac event converging on 

### of the 7 - i 0 with blood-pn after completi that 0'1 Wave nism 0'f this of endocrine 

### central and a Simultán
nerv0'us func1 colleagues fre 

### at changes in by varying tl perf0'rmed. Tl included two 

### amount of ii patterning wI 

### to demonstrai also. There v 

### EEG pattern and again as changes in re 

### of the compc also, t0' some the changes i hO:wever the Uonship. In cont Institute of ta~k in conj eye-blinking. 

### Jthe individual's :his "lang-term" 

### n~ic persanality
: Jab, the social ie worker views le affected the led conditioning

erlying response roblem involved ll correlates of different types at a predictive he improvement al physiological r form of work were organised. :al of the jobs 

### Hopefully, this a whole.

Juld distinguishied by the COIestigate, on the 

### iction of t i il e the "vigilance" the subject is s resulting from ometimes up. to iese studies. ferences in the id categories -IUtonomic funccases the choice haphazard - ssibly) on the 

### little unfair; at n is potentially ticularly in the performance to i are themselves lationships. An the analysis of i-riable is being ample, data on ed a technique . i may turn out

start with two 'he Netherlands 

### Organization for Health Research in Amsterdam, presented by J. L. Blom and



### B. W. Hyndman. Their technique is to use what they describe as a "100 %" binary choice task of paced pitch discrimination. "100 %" means setting the 

### pace af work for the subject at the rate at which he can perform the task for 1 minute 'without error. While performing the task, the visual evaked response to a neon flash repeated at 2 second intervals is recorded; recordings are also 

### made before and after the task period. Selection Wave iv as the component 

### of the visual evoked response that they had previously found to be most sensitive to information processing, they observed that, despite large inter-individual 

### variability, the a v era g e d Wave iv from a group of subjects sho.ws a marked 

### increase in amplitude during the task, and also, very interestingly, a prolanged recavery period lasting approximately 35 minutes. This recovery curve appears 

### to be composed af a primary rapid phase, which the authors hypothesise to be electrical, and a secondary, much slower phase, presumed to be biochemicaL. 

### The authors fonnd that the reactians to the task, and the recovery curve, were 

### i n t r a - i n d i v i d u a 11 y quite stable, but (significantly) admit that they 

### were highly sensitive to what they describe as "emotional and extraneous long- -acting factors". 

### During their experiments Blom and Hyndman also recorded heart rate. 

### Acting on their theory that the signal produced by low-pass filtering af the cardiac event sequence is the physialagical counterpart of autonomic activity converging on the sin0'-atrial no.de, they showed that the relative spectral po.wer of the 7 -10 sec0'nd period band (which corresp0'nds to. the range associated 

### with blood-pressure homeostasis) was significantly depressed up to 35 minutes after completion 0'f the task. They n0'te the similarity 0'f the recovery pattern 10

### that o.f Wave iv 0'f the visual evoked response, and conclude that the mechanism 0'f this persisting post-task effect is probably associated with the activity 

### of endocrine processes, which (in their words) "in turn affects the activity of central and autonomic nervous systems alike". 

### Simultaneously recording, in this case, two measures af c e n t r a I 

### nervous fnnction (EEG and the auditory evoked response), E. Ott0' and his colleagues from the Central Institute for Occupational Health in Berlin looked
at changes in these measures when responding to different mental loads produced 

### by varying the speed with which a 6minute mental arithmetic task had to be performed. They examined time-dependent changes over a one-hour period which 

### included two cantrol conditions and showed that both time period, and the 

### amount of information load, produced significaut differences in the EEG patterning which were indicative of changes in activation leveL. They were able 

### to demonstrate that these differences showed up wit h i n each 6-minute period also.. There was a significant mono.tonic trend towards desynchronisation of the 

### EEG patterning as load increased from resting up to fast, paced, performance,. and again as time on task increased. In the case of the auditory eVo.ked response, 

### changes in respo.nse to the task requirements were found only in the peak latency 

### of the component P2, which shortened monotonically with increasing load, and also, to some extent, whith time on task. Thus a parallelism was shown between the changes in the EEG and in particular aspect of the auditory evoked response;

### hawever the authors do nat comment on the significance of this apparent relaÜonship. In contrast to the papers just described, N.Roth (of the Paul-Flechsig Institute of Brain Research in Leipzig) used a mat or , rather than a mental 

### task in conjunction with recordings of EEG, heart and respiratory rates, and eye-blinking. The ta~k was one of tracking the deflections of an osciloscope
259beam; this task was alternated with a visual reaction-time task in which feedback of performance was given to the subjects. A particular aim of this experiment was to examine, under strictly controlled laboratory c0'nditions, the relationship between individuals' resp0'nse patterns and factors intrinsic to the pers0'n such as extraversion, anxiety, m0'tivati0'n and risk-taking levels. In the tracking task, it was found that the extraverts performed the task better than the introverts, and were less variable. Adaptation to the sequenceof trials as shown by a decrease in heart rate just before the expected deflec

### tion of the osciloscope beam, and by the occurrence of alpha activity in the inter-trial intervals, was more distinct in highly-motivated extraverts. By contrast, 

### subjects with high anxiety and with what the auth0'r describes as "undirected expectancy" showed increased heart, respiratory, and blinking rates without adaptation to the sequence of trials, and also less EEG alpha activity.

In the reaction-time task with feedback, the adaptation to the sequence of 

### trials was again more pronounced in extraverts. Risk-taking scores were also

found to be related to performance, in this case to the probability of responding to a non-signal stimulus (a "click" occasionally inserted 0.3 seconds before the 

### visual stimulus). Anxious subjects again showed higher levels of activation throughout the experiment. 

### M. Horváth, E. Frantík, K. Kopriva and J. Meissner (from the Institute of Hygiene and Epidemiology in Prague) have concentrated on a laboratory 

### situation which models practical tasks requiring only infrequent, small, and rapidcontrol- actions by the operator - in other words, a vigilance-type task. Some

### times a secondary tracking task is added. Typical of the main vigilance-type 

### task was one in which maintained attention was required to auditory stimuli presehted at irregular intervals and at varying intensities through each of two 

### earphones in such a way that the signals were perceived as emanating at diferent 

### spatial locations away fr0'm the mid-line. The subject had to respond to those signals which did not appear to be in the mid-line, while performing a secondary visual tracking task, ina testing situation which was deliberately arranged to be maximally m0'n0'ton0'us, and which c0'ntinued for about one hour. 

### The performance of over 80 % of subjects deteriorated in these conditions, 

### mainly in respect 0'f an increase in failures to detect signals with time on task,and a slowing of response-time. This is the typical "vigilance decrement func

### tion", and in this experiment this decrement was shown to be accompanied by an increase in the amplitude 0'f EEG theta waves, indicative of a sleep-like 

### state. A test-retest correlation 0'f 0.69 was found for this task - which shows its reliability, and a correlation of 0.60 with subjects' reported ability to maintaih 

### vigilance in a reallife situations - which demonstrates its validity. A meth0'd of detecting the effects of fatigue and stress (and also, incidentally, of chronic intoxication with various neurotropic drugs) using the electrodermal reflex, was described by i. Dumitrescu of the Centre for Protection and Hygiene 

### of Work of the Ministry 0'f Industrial Chemistry in Bucharest. The technique used enables separate calculations to be made of the various components 0'f :the reflex. These comp0'nents are considered to make up the time required for 

### crossing a multisynaptic circuit and represent (i) the afferent time, (ii) the central efferent time (iii) the peripheral efferent time and (iv) the peripheral effector or "glandular" time. The prop0'rtions of the total reflex time accounted 

### for by these diferent components .was shown to. vary in different states, the central efferent time, for example, increasing relative to the 0'thercomponents in fatigue states, and acc0'unting for m0'st of the overall increase in hitency 

### observed in this situation. 26Ó 

## Method0'lo: have already seen , The quantification 0 problem in some cas( in Amsterdam, sugg
would 

### be to retrievi 

### possible, and in the only do different em cular physi0'logical v physi0'l0'gical reactio those aspects 0'f the 

### kinds of stimuli pn be identified it woul The first 0'f the üf a correlation mat the single variable variance could be ei The second aim. wa üf change in each ~ 

### opposed to' resting. j 

### each üf these scores, scores for this partÜ 

### v a ria t i 0' n 0'f thi seem to have gener 

### besides sinus arrythi 

## S t u die s of The papers mention( 

### siological" , and as responses. Other c0'r or intrinsic states 0 üther. One of the mo 

### C. Teiger and A. L Ergonomics in Paris through a particular 

### latter with a stationa as well as younger 

### are clear! y diferent Thus 0'lder subjects which are themselve larger and more var 

### and more variable i age changes reflect tion into kinaesthetii 

### in which their spatia keep these frames of remain accurate. Cle task studied, but of 

### of work is faster, ( adjustments is neces A different fac1 by V. Brichácek anc261

Met hod 0 log i c a I Pro b I ems. In the papers mentioned so far we have already seen a variety of different physiological measures being used. The quantification af some of these variables presents a major methodological problem in some cases. C. Opmeer, of the Laboratory for Ergonomic Psychology 

### in Amsterdam, suggested a two-way approach to this problem. The first aim

would be to retrieve as much of the information present in the variable as 

### possible, and in the most economical way. This is very important, since notonly do. different environmental situations influence different aspects of a particular physiological variable, but individual peaple also often show idiosynchratic physiO'logical reactions. Opmeer's second aim would be the determinatian of thO'se aspects of the variable in question that are mO'st sensitive to the different 

### kinds O'f stimuli present in the working environment. If these aspects could be identified it would then unnecessary to use the remaining scores. The first of these aims was ilustrated by the results of a factm analysis of a correlation matrix of 25 scores calculated by a computer programme fO'r 

### the single variable sinus arrythmia. It was found that about 80 % of the variance could be explained by 5 factors which were deccribed by the author. The second aim was ilustrated by using the same 25 scores and a criterion 

### of change in each score when performing an auditory binary chaice task, as oppased to resting. A rank order was abtained for the diferentiating power of 

### each of these scores, and by this method it was found that the most sensitive scores for this particular task were the ran g e an the c 0 e f f i c i e n t 0 f v a ria t ion of the interval times. This two-way approach of Opmeer would seem to. have general value for application to other physiological measures besides sinus arrythmia. 

# Studies of "long-term" and "psychological" factors.The papers mentioned up till now could be generally described as "psychophy

### siolagical", and as being concerned primarily with relatively short-term responses. Other contributions at Prague were concerned with more long-term, or intrinsic states on the one hand, and with "psychological" aspects on the other. 

### One of the more. obvious of these "long-term" factors is of course, age.

C. Teiger and 

### A. Lavile, O'f the CNAM Laboratory of Work Physiology and Ergonomics in Paris showed that, in a learning task involving punching holes 

### through a particular pattern of circles on a moving target by comparing the latter with a stationary model, subjects aged between 35 and 45 actually perform
as well as younger subjects between 18 and 25. However, the twO' age groups are clearly differentiated in the way in which this performance is effected. Thus older subjects are slawer in making the necessary postural adjustments, which are themselves smaller and made less frequently. They also make fewer, 

### larger and more variable ocular fixations af the model, and have much longer and more variable inter-fixation time intervals. The authors suggest that these

### age changes reflect increasing diffculty in rapidly translating visual information into kinaesthetic information, which leads older people to modify the ways in which their spatial frames of reference are constructed. They wil tend to try to keep these frames of reference stable in order to ensure that their motor responSes 

### remain accurate. Clearly this change O'f strategy was successful in the particular 

### task studied, but of course it may not work in other situations where the pace of work is faster, or a more complex pattern of eyemovements and postural 

### adjustments is necessary. A different factor, this time in the "psychological" area, was investigated 

### by V. Brichácek and colleagues at the Charles University in Prague. They wereconcerned with the behavioural, physiological, and subjective components of what they term "negatively oriented tension", which may of course be a chronic 

### condition in some individuals. However, since they considered that reliable methods for detecting this state "in the field" are not at present available they induced this tension experimentally by aversive conditioning techniques: using expectation of electric shocks. As might perhaps be predicted, activation 

### levels (measured by pulse rate and GSR) were increased under this induced 

### negative tension. However, of a number of different psychological tests given, some were not affected at all by the tension, whereas others were. Thus reaction

time was shortened but, in accordance with a hypothesis of the authors, in a projective test more photographs of people were classified as producing feelings of antipathy in the subjects. The general idea behind these experiments was 

### that the more test (or work situation) is unstructured, the greater the probability that aversive reactions to the task wil occur in people with negative emotional 

### tension. Since it was found that there was a "carry-over" effect from the

tension condition to the control condition, the authors suggest that the past 

### stress experience of an individual wil affect the way he responds to any work situation with which he may be confronted, and that aversive reactions may 

### be expected if the situation is relatively unstructured. A similar conception follows from a pilot study described by M. Horvath, O. Kovalik and E. Frantik from the Institute of Hygiene and Epidemiology, Prague. This study forms the basis of a longitudinal survey of occupational mental hygiene in technical resarch and development workers. Although the
work of research workers does not usually involve occupational hazards in the 

### traditional sense. nevertheless their mental performance is affected by a number

### of factors. An analysis of the influence of these factors was based on the hypothesis that the creative effciency of this kind of worker depends on an intensive 

### activation of higher nervous functions, which may easily switch into negative 

### emotional tension. This tension affects primarily the creative rather than the routine components of the working activity, it increases the risk of exceeding the person's adaptability, and may give rise to states of maladjustment and psychosomatic disturbance in predisposed individuals. 

### A correlative longitudinal study is about to be initiated, involving on the one hand the determination of those external factors adversely affecting work 

### comfort and mental condition, life style, personality traits, and habitual behavioural patterns; and, on 'the other, measurement of subjective pressuresand tensions, somatic and psychic sPate, physical fitness and autonomic reac### tions. The aims are to elucidate (a) which of the factors do not form an indispensable part of the actual job and whether their removal could improve working conditions, and (b) the best best ways (preventive measures, counselling, etc.) to 

### counteract the negative effect of the remaining factors in order to maintain an optimal mental condition.D. A. Vasilescu and i. P. Vasilescu of the Ministry of Transport in Bucharest also talked about "stress". The purpose of their paper was to introduce 

### the concept of "interpersonal" stress, which describes the action of any stressing agent on a group of people, as opposed to its action on an individuaL. The effect of this stress can be measured using sociometric techniques; thus the authors consider that it could also be called "sociometric" stress. They see it as a type 

### of "superindividual" stress, which is not necessarily dependent on the stress effects occurring in a particular person (the sort of situation most frequently 

### studied up til now). In the groups that had been studied in stress situations almost all the classical sociometric indicators seemed to be sensitive to the
262 

### action of t relations v tion of or! nient of s " aggressOl in a secOl tion at a the socior

It Sf 

### particular of physic range of extremel) recording 

### handling advance demonstJ records i 

### tions. T 

## which fully fo 

### of perfo autonorr logies. ' in dang defy dii have h~ 

### is held

I

\ \n, m in gs is ty al le st
~k iy 

### CONCLUSIONS

I t should be evident from the foregoing account of the Prague papers that, particularly in the "psychophysiological" area, an almost bewildering variety of physiological measures are being investigated, along with a considerable 

### range of work tasks. Some of the technical aspects of the research indicated an 

### extremely high level of sophistication, which the use of automatic devices for recording both digital and analogue data, associated computer facilities for 

### handling this data, and complex programming for subjecting the results to 

### advance forms of statistical analysis. All this is very encouraging, in that it demonstrates that we are now in a position to make very accurate and detailed

### records of a large number of highly specifc variables in many different situations. The questions one is left with, however, are: w h i c h variables? - in

### w h i c h situations? It would seem that there is now a pressing need for care

### fully formulated hypotheses about the relationships between selected aspects of performance at specific types of task, and changes in particular central and

### autonomic variables - hypothese that can now be tested with the new techno

### logies. Without models on which such hypotheses can be based, we may bp in danger of being overwhelmed by a feast of information which could easily 

### defy digestion, let alone interpretation. It wil be interesting to see, when wp have heard the other contributions to this present meeting, whether this view 

### is held generally by the participants here. of iie iIe Ie, ~S, )U ~d 

### action of this sociometric stress, and indices based on perception of interpersonal

### relations were found to be particularly sensitive, The three phases in the evolution of organic stress described by Selye could also be identified in the develop

### ment of sociometric stress, induced by, for example, what the authors call an 

### "aggressor factor". This could act in a primary way to produce the stress, orin a secondary way in the sense that the aggression first causes a stress reaction at a level other than the sociometric one, and this reaction in turn produces the sociometric stress.

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