On 14 September 1849, Ivan Petrovich Pavlov was the first of 11 children born on a farm. In 1870 he went to the University of St. Petersburg, where he studied law and science, from 1875 he studied medicine there. In 1890, Pavlov became Professor of Pharmacology and later Professor of Physiology in St. Petersburg. For his services to the clarification of the digestive processes he received in 1904 the Nobel Prize. Pavlov still worked in Leningrad in his laboratory every day at the age of eighty. He died on February 27, 1936.
Pavlov's famous experiment
His studies on the digestive behavior of dogs became famous. Pavlov noticed during his research that whenever he showed food to his dogs, they reacted with increased salivation. This is an automatic reaction that is innate to the dog. Such a behavior that necessarily takes place is called an unconditional reflex.
Pavlov then rearranged his experiment so that a bell rang just before feeding. Since the food was always only after a bell, the dog learned to respond to the ringtone over time.
After some time he began to drool when only the bell sounded - even before he could see or smell the food. The dog had learned during this time, that after the ringtone inevitably a reward follows. Already the sound perception was enough to cause a salivary flow in the test dog.
The result of the experiment
The ringing of the bell was initially a neutral charm and had nothing to do with the food itself. Now that Pavlov had carried out this experiment, the learned reflex reliably led to the increased secretion of saliva. The once neutral stimulus triggered a new reflex response from this time. A neutral stimulus had become a conditional stimulus. This reaction, described by Pavlov, is called conditioned or conditioned reflex. It is a learned, not natural reflex.