Pavlov's applications of his
conditioned reflex theory



The last recorded publication in Pavlov’s official Selected Works (1955) is a letter dated 7 January 1936 (a few weeks before his death) and addressed to a gathering of ‘leading miners’ in the Donetz basin in the Ukraine. These leading miners were the first Stakhanovites, heroes of Soviet labour who, leading a team of assistants, worked exceptionally hard, and thus gained official prestige and financial rewards (though not always the affection of their assistants — as Wadja’s film Man of Marble shows). In immediately preceding extracts from his speeches, Pavlov comments on the fact that around that time the Soviet government was pouring millions of roubles into his laboratories and extending his research station at Koltushi, outside Leningrad, so that it became a ‘scientific city’ (Asratian, 1953). One is obviously led to wonder whether Pavlov’s scientific psychology had any influence on contemporary methods of industrial and agricultural management or propaganda techniques in the Soviet Union. According to Gray (1979), the answer is that such influence was probably very


marginal and indirect, since Pavlov’s psychology was not endorsed by the Soviet Academy of Sciences until 1950.

It is, however, worthy of comment that Pavlov had considerable eminence in his own country, as well as internationally, following the award of his Nobel prize in 1904; and his theoretical terminology and experimental techniques spread to the applied human sciences (e.g. Luria, 1966). Pavlov himself took an interest in several areas of human psychology: types of temperament, or personality; psychiatric disturbance, especially schizophrenia; and hypnosis. He read a paper in Madrid in 1903 on ‘Experimental psychology and psychopathology in animals’, and from 1918 began attending psychiatric clinics to observe human patients. In the 19205 he took an increasing interest in psychiatric problems. Even though he was then in his seventies, he remained intellectually vigorous and productive, and he was of course still head of a very large research team, with excellent facilities. As part of the New Economic Policy in 1921 Lenin had personally signed a decree stipulating that the most favourable conditions should be established for Pavlov’s work (including double food rations for Pavlov and his wife, and maximum equipment for their apartment as well as the laboratory).

In the foreword by Popov and Rokhlin to a selection of articles under the heading of Psychopathology and Psychiatry, published in Moscow in 1962, there is the rather sinister remark that the articles are especially important for ‘problems of so-called borderline psychiatry’ (Pavlov, 1962, p. 9). Since Soviet psychiatry has become notorious in the past two decades for treating political dissidents as schizophrenics, it should be noted that Pavlov’s main suggestion to Soviet psychiatrists in 1930 was that they should not keep relatively undisturbed patients alongside the seriously ill, since the stress of this would probably make them worse:

Moreover, the violation of the patient’s rights, of which he is already conscious and which partly consists in restriction of his freedom, and partly in the fact that the attendants and medical personnel naturally and almost invariably regard him as an irresponsible person, cannot but strike further heavy blows at the weak cells. Consequently, it is necessary as quickly and as timely as possible to place such mentally diseased in the position of patients suffering from other illnesses which do not offend human dignity so manifestly. (Pavlov, 1955, p. 515)


This shows that Pavlov was not oblivious of human rights, but also that his interpretation of mental illness was always in terms of 'weak cells' or a 'weak nervous system'. As well as this idea of the nervous system being weak or strong, Pavlov believed that there were separate processes in the nervous system — of 'excitation' (causing activity) and 'inhibition' (generally suppressing bodily activity). Sleep he saw as a form of widespread inhibition; hypnotic states are also forms of inhibition and are therefore related to sleep, and 'one can hardly doubt that schizophrenia, in certain of its variations and phases, is actually a chronic hypnosis' (Pavlov, 1955, p. 514). The idea is that schizophrenics have some special weakness in cortical cells, and special states of inhibition arise as a protection against this weakness. Pavlov recommended that schizophrenics should be whispered to rather than shouted at, and generally treated gently, and this can still be regarded as a useful rule of thumb.

On the question of neurosis, rather than schizophrenia, Pavlov had more to say, since he had more data on experimentally induced neuroses. His best-known cases were accidental since they resulted from a severe flood in Leningrad in 1924. All the dogs in Pavlov's laboratory had to be made to swim from their normal quarters into the laboratory, but although at the time all of them appeared subdued by this experience, for a period after the flood some of the dogs appeared to be very disturbed, while others showed no sign of the trauma. This fitted with Pavlov's previously established view that there are pronounced individual differences between dogs' characters. Dogs 'of the inhibitable type' were put off their food by the flood more than the others. One in particular gave no salivatory reactions in its customary experimental routine, but was 'cured' if an experimenter stayed with it in the room instead of leaving it on its own, as was the usual practice. A relapse occurred two months after the flood, however, when the experimenters allowed water to trickle into the dog's experimental room and form a pool next to its stand. Not surprisingly, this reminder put the dog back into its former state of nervousness.

A second method of producing 'experimental neurosis' was to give dogs particularly difficult conditioning tasks. In most cases 'neurotic' behaviour was first observed in experiments performed for other purposes. For instance, in order to study the limits of shape perception, a dog was trained to distinguish between a circle


and an ellipse (when the circle was projected on a screen the dog was given food, but if an ellipse was projected, there was no food). This was straightforward — very soon the dog salivated when it saw the circle, but not when it saw the ellipse. But this was with a 2:1 ratio between the long and short axes of the ellipse. The discrimination was gradually made more difficult. With an ellipse of ratio 9:8, which looks very like a circle, the dog at first had some ability to tell it apart from a circle, but this obviously was difficult. After three weeks the dog barked when it was brought into the experimental room, squealed and struggled when it was put in the stand, and bit through all the tubes that connected the experimental stand to the observing room. This had previously been a quiet dog, and Pavlov attributed the changed behaviour to ‘acute neurosis’, caused by a ‘clashing of excitation with inhibition’, leading to ‘a profound disturbance of the usual balance between these two processes’.

An alternative way of upsetting dogs is to subject them to severe electrical shocks. This would be likely to produce deleterious psychological and physical effects in any case (Seligman, 1975), but the method used in Pavlov’s laboratory was to make a weak electric shock a signal for food, and then to increase its strength. Once this had been done, dogs did not perform reliably in their conditioning for several months afterwards, even for the normal stimuli of buzzers and metronomes and if given no more shocks, although in some cases bromide treatment led to a recovery (Pavlov, 1927, pp. 293—300).

Personality types

Many undergraduates become familiar with the Eysenck personality inventory — a questionnaire by which fellow students can be placed somewhere along a continuum from ‘introversion’ to ‘extraversion’. The theory behind this system of measurement, and indeed H.J. Eysenck’s theory of personality, goes back to some of Pavlov’s earliest experiments on conditioned reflexes. One of the main phenomena observable in a Pavlovian conditioning stand, and one which profoundly influenced Pavlov’s theories of inhibition, is that the dog in the stand falls asleep, or goes into various interesting states of drowsiness. This was at first a considerable problem, and Pavlov attempted to solve it by picking out


for his experiments dogs that seemed particularly wide awake and active. He recognized a type that was ‘always sniffing at everything, gazing at everything intently, and reacting quickly to the minutest sounds’. But it turned out that it was precisely this type of animal that was most likely to fall asleep in the stand, and even when let out of the stand it lay down and slept on the floor. The only way these dogs could be used in experiments was with a great variety of conditioned stimuli, with a given stimulus presented only once at a time, without long pauses when nothing happened, and with uncertainty introduced by having some negative stimuli (without food). These animals were very sociable and friendly outside the experiments and closely correspond to Eysenck’s definition of an extrovert.

On the other hand a dog that appears to be a ‘neurotic introvert’ will probably perform very well in the conditioning stand — hence Eysenck’s theory that introverts are more conditionable than extroverts. Withdrawn and ‘cowardly’ dogs, who cringe at the slightest outside noise, are certainly less likely to go to sleep in the conditioning stand. Pavlov had one animal referred to as a ‘living instrument’ and called ‘Brains’ because all her conditioned reflexes were extremely reliable and regular. Outside the experimental room, however, her tail was always between her legs, and she invariably shrank from human contact and so was described as of ‘melancholic’ temperament. Originally Pavlov assumed that the extrovert dogs were very excitable, having a predisposition to excitation in the brain — but an excess of excitation quickly brings on protective inhibition and this he supposed was why the animals tended to go to sleep. On the other hand, the introverted dogs were very ‘inhibitable’ but had a ‘special protective mechanism’ which successfully prevented this strong inhibition from spreading, and thus kept the animals awake. The reader should have no difficulty in spotting some rather tenuous stages in this reasoning: a more popular alternative is to suppose that extroverts tend to be under-aroused and thus seek maximum stimulation from the environment, whereas introverts are already over-aroused and seek to minimize external stimulation by preferring, in Pavlov’s terms, ‘extremely uniform conditions of life’ (1927, p. 287).

Pavlov himself proposed several different schemes of personality types, but not that one. His final version was in terms mainly of ‘weak’ and ‘strong’ nervous systems, qualified by the degree of


balance between the inhibitory and excitatory processes and their speed of reaction. The dog’s brain could be weak or strong, and if strong, balanced or unbalanced, and if strong and balanced, quick or slow to react. There were thus four (Hippocratic) types — weak (melancholic); strong and unbalanced (choleric); strong balanced and slow (phlegmatic); and strong balanced and quick (sanguine). Pavlov took the Hippocratic temperamental types as the last word on human personality, and claimed that ‘this coincidence of types in animals and human beings is convincing proof that such a systematization conforms to reality’ (Pavlov, 1955, p. 482). The coincidence seems extremely forced, but the Eysenck translation into stable and unbalanced introverts and extroverts has had some successes.

The second signalling system and suggestion

The underlying theme of all Pavlov’s later work was that the cerebral hemispheres function according to certain rules. These rules could be discovered, surprising as it may seem, by observing conditioned salivary reflexes in dogs, and most of the rules which apply to cerebral cortex in dogs apply also to men and women. It is because of this that Pavlov could say ‘training, education and discipline of any sort are nothing but a long chain of conditioned reflexes’ (1927, p. 395). However, the human species has a special character — a second kind of conditioned reflex, not available even to chimpanzees. Although the term ‘reflex’ implies simplicity, Pavlov’s view was that the cerebral hemispheres of dogs were the site of elaborate processes of analysis and synthesis ‘whose purpose is to decompose the complexity of the internal and external worlds into separate elements and moments, and then to connect all these with the manifold activity of the organism’ (1955, p. 300). The reason why the conditioning method can be used is that conditioned stimuli are but examples of ‘the first system of signals of reality common to men and animals’. The human species has evolved speech, which is ‘a second signalling system of reality which is peculiarly ours, being the signal of the first signals’ (1955, p. 262). Pavlov does not allow that speech makes all that much difference to his theory, since ‘the fundamental laws governing the activity of the first signalling system must also govern that of the second, because it, too, is activity of the same nervous tissue’ (1955,


p. 262). Even Gray (1979), who is very much a partisan, thinks that this is going a bit too far and that the conditioned-reflex concept is over-extended when applied to language; but the concept of a second-order signalling system for reality is better than nothing.

A curious consequence of the theory of the second signalling system is that, for Pavlov, hypnotic suggestion is more understandable than other aspects of language use since it is ‘the most simple form of a typical conditioned reflex in man’ (1927, p. 407). In other words the typical result of conditioning in man involves words, and in its simplest form speech may direct behaviour. Even the most complicated behaviour of chimpanzees can be interpreted as ‘a combination of association and analysis’, and, in Pavlov’s eyes, the processes of analysis, synthesis and association that he observed in his dog experiments applied to the most complex aspects of human psychology: ‘The same thing can be said of our thinking. Beyond association there is nothing more in it’ (1955, p.557).

Clearly there was nothing new in saying that human thinking is based on association — Pavlov’s contribution was to tie down hypothetical processes of mental association to objective measurement in scientific experiments. The idea that mental processes can be changed by objective procedures like those used in conditioning experiments is part of the background for the development of behaviour therapy, and thus an important aspect of Pavlov’s influence on psychology (Gray, 1979, chapter 7).


End of Chaper 6 | Contents | Start of Chaper 7