Current knowledge on the neuronal substrates of Pavlovian conditioning in animals and man is briefly reviewed. First, work on conditioning in aplysia, that has showed amplified pre-synaptic facilitation as the basic mechanism of associative learning, is summarized. Then, two exemplars of associative learning in vertebrates, fear conditioning in rodents and eyelid conditioning in rabbits, are described and research into its neuronal substrates discussed. Research showing the role of the amygdala in fear conditioning and of the cerebellum in eyelid conditioning is reviewed, both at the circuit and cellular plasticity levels. Special attention is given to the parallelism suggested by this research between the neuronal mechanisms of conditioning and the principles of formal learning theory. Finally, recent evidence showing a similar role of the amygdala and of the cerebellum in human Pavlovian conditioning is discussed.

The foundation, achievements, and proliferation of behavior therapy have largely been fueled by the movement's foundation in behavioral principles and theories. Although behavioral accounts of the genesis and treatment of psychopathology differ in the extent to which they emphasize classical or operant conditioning, the mediation of cognitive factors, and the role of biological variables, Pavlov's discovery of conditioning principles was essential to the founding of behavior therapy in the 1950s, and continues to be central to modern behavior therapy. Pavlov's reliance on a physiological model of the nervous system, sensible in the context of an early science of neurology, has had an implication for behavior therapists interested in the study of personality types. However, Pavlov's major legacy to behavior therapy was his discovery of “experimental neuroses,” shown by his students Eroféeva and Shenger-Krestovnikova, to be produced and eliminated through the principles of conditioning and counter-conditioning. This discovery laid the foundation for the first empirically-validated behavior therapy procedure, systematic desensitization, pioneered by Wolpe. The Pavlovian origins of behavior therapy are analyzed in this paper, and the relevance of conditioning principles to modern behavior therapy is demonstrated. It is shown that Pavlovian conditioning represents far more than a systematic basic learning paradigm. It is also an essential theoretical foundation for the theory and practice of behavior therapy.

The concept of conditioning as signalization proposed by Ivan P. Pavlov (1927, 1928) is studied in relation to the theory of stimulus-substitution, which is also attributed to him. In the so-called theory of stimulus-substitution a distinction must be made between an empirical principle of substitution and an actual theory of substitution, which can adopt different forms. The Pavlovian theory of substitution—which conceives substitution as a substitution of the unconditioned stimulus (US) by the conditioned stimulus (CS) in the activation of the representation of the former—can be understood as an explanation or model of signalization. Signalization and substitution are answers to different questions, and the level of analysis to which signalization corresponds, is that which concerns the nature of conditioning as an operation of the animal in the environment.

The scientific adventure of the Ivan Pavlov Department of Physiology is traced from Pavlov's and his students pioneer work on “psychic salivation” to the times of the Biological Station at Koltushi. The development of the Department after Pavlov's death is described and the research trends of the three present laboratories (Neurobiology of Integrative Brain Functions, Psychophysiology of Emotions, and Neurodynamic Correction of Psycho Neurological Pathology) are discussed.

The translation of Pavlov's lectures (Pavlov, 1927) provided English-speaking psychologists with access to the full scope of Pavlov's research and theoretical ideas. The impact this had on their study of the psychology of learning can be assessed by examining influential books in this area. This reveals that Watson (1924) had been highly effective in promoting the misleading idea that Pavlov was a fellow S-R theorist. This assumption was not questioned by Tolman (1932), Hilgard and Marquis (1940) or by Hull (1943). However, this mistake was not made by Skinner (1938), who also provided the strongest arguments against Pavlov's belief that behavioral effects required explanation in terms of physiological processes. Post-1927 most learning research in the English-speaking countries continued to use instrumental, rather than Pavlovian, conditioning procedures. Nevertheless, many of the issues addressed by this research were ones that Pavlov had been the first to raise, so that his major influence can be seen as that of defining a research program for subsequent students of learning.

The role of consciousness in Pavlovian conditioning was examined in two experiments in which visually masked neutral words were used as the conditioned stimuli (CS) and an electric shock as the unconditioned stimulus (US). The inter-stimulus interval (ISI) was established individually. A detection threshold was used in Experiment 1 and an identification threshold in Experiment 2. The primary dependent variable was the skin conductance response (SCR). Results showed that the conditioned response (CR) was acquired by 58% of participants who perceived stimuli above the identification threshold, 50% of participants who perceived stimuli below the detection threshold, and 11% of participants who perceived stimuli below the identification threshold, but above the detection threshold. These results suggest that consciousness of the CS-US contingency is not a necessary condition for acquiring a CR of the autonomous nervous system (ANS).