Ivan Petrovich Pavlov (1849-1936) was a pioneering Russian physiologist credited with developing the scientific study of Behaviorism.
Rather than spend time rewriting what every psychology 101 student learns, I’ll just copy and paste Wikipedia’s version of Pavlov’s remarkable contribution to the history of ideas:
The concept for which Pavlov is famous is the “conditioned reflex” (or in his own words the conditional reflex) he developed jointly with his assistant Ivan Filippovitch Tolochinov in 1901. He had come to learn this concept of conditioned reflex when examining the rates of salivations among dogs. Pavlov had learned that when a buzzer or metronome was sounded in subsequent time with food being presented to the dog in consecutive sequences, the dog would initially salivate when the food was presented. The dog would later come to associate the sound with the presentation of the food and salivate upon the presentation of that stimulus. Tolochinov, whose own term for the phenomenon had been “reflex at a distance”, communicated the results at the Congress of Natural Sciences in Helsinki in 1903. Later the same year Pavlov more fully explained the findings, at the 14th International Medical Congress in Madrid, where he read a paper titled The Experimental Psychology and Psychopathology of Animals.
As Pavlov’s work became known in the West, particularly through the writings of John B. Watson and B. F. Skinner, the idea of “conditioning” as an automatic form of learning became a key concept in the developing specialism of comparative psychology, and the general approach to psychology that underlay it, behaviorism. Pavlov’s work with classical conditioning was of huge influence to how humans perceive themselves, their behavior and learning processes and his studies of classical conditioning continue to be central to modern behavior therapy. The British philosopher Bertrand Russell was an enthusiastic advocate of the importance of Pavlov’s work for philosophy of mind.
Pavlov’s research on conditional reflexes greatly influenced not only science, but also popular culture. Pavlovian conditioning was a major theme in Aldous Huxley‘s dystopian novel, Brave New World, and also to a large degree in Thomas Pynchon‘s Gravity’s Rainbow.
It is popularly believed that Pavlov always signaled the occurrence of food by ringing a bell. However, his writings record the use of a wide variety of stimuli, including electric shocks, whistles, metronomes, tuning forks, and a range of visual stimuli, in addition to the ring of a bell.†
† Follow this link for more https://en.wikipedia.org/wiki/Ivan_Pavlov