Conditioning, conditional reflex

Conditioning refers to  the elaboration of a conditional reflex (CR) by pairing a previously neutral stimulus (conditional stimulus, CS) with an unconditional stimulus (US) that triggers an unlearned response, until the CS acquires the ability to elicit the response originally elicited only by the (US). Early in the 20th century, Ivan Petrovich Pavlov, who received for his work on the physiology of the digestive glands the 1904 Nobel Prize in Physiology or Medicine, noticed “psychic salivation” in his dogs, operated with fistulas, through which the secretion of the stomach, salivary glands, pancreas and intestine could be collected. In the original “conditioning experiments”, a bell was ringing before the dog was fed, and the dog salivated when receiving the food, then the bell was ringing without presentation of food and the dog salivated in response to the ringing of the bell. Influenced by Sechenov’s concept that mental events were reflexes (Sechenov 1863), Pavlov formulated his concept of “conditional reflex”. The first communications about classical conditioning were: 1. Fillipovitch Tolochinov’s presentation at the Congress of Natural Sciences in Helsinki in 1903. (Tolochinov was the coworker of Pavlov, whose experiments were quoted by Pavlov, in 1927). 2. Pavlov’s lecture at the XIVth International Medical Congress in Madrid, in 1903. 3. Pavlov’s lecture at Charing Cross Hospital in London, England, on October 1, 1906  that  was published in Science in the same year  (Pavlov 1906).



Campos Bueno J.J., Araguz A. Neuron Doctrine and Conditional Reflexes at the XIV Inernational Medical Congress of Madrid of 1903. Psychologia Latina 2012; 3: 10-22

Pavlov I.P. The Scientific Investigation of the Psychical Faculties or Processes in the Higher Animals. Science 1906; 24: 613-19

Pavlov I.P. Conditioned Reflexes: (Translated from the Russian original into English by G.V.Anrep).Oxford Publishing Company, Oxford; 1927, p 142

Sechenov MS. Reflexy golovnogo mozga (Reflexes of the brain) Meditsinsky vestnik, 47-49 (in Russian)


Joseph Knoll
October 8, 2015