Pavlov demonstrated empirically the ways in which dogs develop acquired
Thorndike also used experimental methods and animal subjects, studying 'intelligence' by investigating, for example, how cats learned to escape from a puzzle box to obtain food. He too obtained pleasingly orderly behavioural data which indicated gradual changes in behaviour rather than sudden 'insightful' changes. Thorndike argued that the gradual changes occurred because the 'satisfying state of affairs' which followed the correct response made it progressively stronger or more probable. Through his law of effect Thorndike emphasized that patterns of behaviour can be selected by their consequences, rather as advantageous taxonomic form is selected by evolutionary pressures on species. In both cases, apparent purpose can be reinterpreted in terms of the effects of consequences. Thorndike originally believed that behaviour followed by an 'annoying state of affairs' became weaker, but his own research, here largely with human subjects, did not demonstrate this. Thorndike therefore retained a truncated form of his law of effect which emphasized the selective strengthening effects of what are now termed reinforcers in instrumental conditioning.
The impact of subsequent empirical studies of learning was for some time largely reflected by theories which were in effect general theories in psychology. This is illustrated in J. B. Watson's writing. He exploited his familiarity with early empirical studies which related changes in behaviour to environmental conditions in order to advocate that psychology as a whole should be reformulated as the science of behaviour rather than of mental life and experience. Watson's behaviourism has contributed to the widespread adoption of behavioural studies in psychology, but his more negative views about the relevance of mental life to the refocused discipline of psychology have been less influential. Like subsequent theorists, Watson used the empirical data of studies of learning as a platform for his approach to psychology in general. In particular, he extended the principles of classical conditioning to emotions in humans through his famous studies with 'little Albert', and emphasized environmental influences on behaviour to the neglect of inherited differences.
Edward Tolman carried out ingenious experiments on learning in animals, and demonstrated patterns of behavioural change which were not so readily interpreted in simple stimulus–response terms. For example, he showed that rats learned to run to a particular place for food rather than to make a stereotyped response such as turning right at a choice point. He also investigated latent learning, shown through savings when animals were allowed simply to explore a maze before being required to run through it to a specific goal box. Tolman used the methods of behavioural investigations, but extended the complexity of the environmental arrangements whose effects on behaviour were studied. He was drawn to use intervening concepts, such as expectancies or cognitive maps, to deal with the relationships he observed between environment and behaviour. In this regard, Tolman was a precursor of contemporary cognitive psychology.
The most detailed and systematic account of learning yet developed was that of Clark Hull. Yet again based on controlled experiments with animals, Hull's theory was presented in formal terms, with postulates giving rise to precise behavioural predictions expressed in quantitative terms through equations with intervening variables. These variables, which in Hull's theory were such concepts as drive, habit strength, and reaction potential, were more tightly tied to empirical measurements than were Tolman's more cognitive terms. Hull's theory is often cited as the best example in psychology of the hypothetico-deductive method of scientific enquiry, and in this sense it is a further example of a learning theory which has implications for psychology reaching far beyond the empirical studies of learning on which it is based. The theory also strove for a general explication of learning, emphasizing similarities between classical and instrumental conditioning and across species, though incorporating quantitative differences.
In the 30 years 1950–80 the emphasis on formal global theories of learning diminished. Empirical research on conditioning and learning has continued to flourish, however. The methods of free-operant conditioning developed by Skinner have been extremely beneficial in this respect, making it possible to study more effectively the effects of intermittent reinforcement, discriminative control, punishment, and so on. Indeed operant conditioning has become a technology for the experimental analysis of behaviour. One systematic use of the data of operant conditioning has been to support the general behaviouristic approach to psychology favoured by Skinner, with its emphasis on explanations of behaviour couched in terms of its relationships with environmental events in applied contexts with humans as well as with animals in the laboratory (functional analysis of behaviour). (See behaviourism, Skinner on.) However, the behavioural data obtained from operant conditioning may be evaluated in terms of other theories.
In recent years a number of trends have emerged from empirical studies of conditioning. First, conventional distinctions between classical and instrumental conditioning have been further challenged. One important factor here has been the suggestion that activities of the autonomic nervous system such as heart rate and blood pressure, previously thought to be affected only by classical conditioning procedures, can be modulated by instrumental reinforcement, a possibility that encouraged the use of so-called biofeedback techniques with patients in clinical practice. Secondly, greater interest has been shown in biological or phylogenetic influences on conditioning and learning. It seems that some patterns of behaviour are more readily affected by conditioning procedures than others: animals appear, for example, to be biologically prepared to associate novel tastes and nausea, no doubt because of the implications of such preparedness for survival. Similarly, species-characteristic patterns of behaviour may intrude even in the controlled environment of the conditioning laboratory. These findings have raised some doubts about the generality of the laws of learning established thus far, but they emphasize that behaviour must be interpreted in terms of interactions between inheritance and experience. Thirdly, the increasingly complex relationships between environment and behaviour studied in conditioning experiments have led some contemporary learning theorists (e.g. Mackintosh 1983) to reintroduce cognitive explanations even of animal behaviour.
The field of learning has consistently been one of the most active areas of experimental psychology. The empirical data which has been produced has consistently demonstrated the power of experimental and comparative methods in psychology. In turn it has given rise to theories which, though designed primarily to accommodate the phenomena of animal learning, have implications for psychology in general, in terms of human as well as of animal behaviour. These theories have therefore reflected (or perhaps led) changing perspectives in psychological science. Learning and learning theory can be said to offer an insight into the empirical and theoretical development of psychology as a whole.
(Published 1987)
See also memory: biological basis.
— D. E. Blackman
- Bibliography
- Mackintosh, N. J. (1983). Conditioning and Associative Learning.
- — — and Colman, A. M. (1995). Learning and Skills.
