stories from the wilder side of science

Pavlov only rings once

The Russian medic Ivan Petrovich Pavlov is the holder of an unusual record: no set of scientific experiments has had more bands named after them than those that Pavlov conducted at the beginning of the 20th century with dogs. In the 1970s there was a rock band that went by the name of Pavlov’s Dog and the Condition Reflex Soul Revue and Concert Choir, while in the 1980s Ivan Pavlov and the Salivation Army made their debut. The 1990s saw not only the bluegrass band called Pavlov’s Dawgs, but also a rock group called Conditioned Response, while the new millennium witnessed the appearance of the English folk outfit Pavlov’s Cat. Nor were musicians the only ones who lighted on Pavlov when scouting around for a name: ‘Pavlov’s Dog’ is also the name of a communications agency in Ireland, a pub in England, a theatre group in Canada, and a drink in the One World Café in Baltimore, USA, a blend of Kahlúa, Bailey’s and milk.

Pavlov was awarded the Nobel Prize in 1904 for his researches into the digestive system. However, this is not the reason why his name is so well known nowadays. Rather, the source of his fame is the basic learning mechanism that he discovered quite by chance in the course of his studies.

While undertaking his research into digestion, Pavlov also became interested in the function of the salivary glands, and in order to observe how they worked in living dogs, he channelled the animals’ saliva directly from the gland through a hole in their cheeks into a small measuring jar. In doing so, he was trying to determine the composition of their saliva when he fed the dogs with different diets. However, a problem soon arose. After the dogs had been fed a couple of times, they began to secrete saliva as soon as they caught sight of the food. At first Pavlov regarded this effect as a disruptive element in his research and so devised ways of putting the food into the dogs’ mouths without alerting them in advance. Yet it transpired that the animals associated even quite subtle signals with feeding. The mere sight of the researcher or the sound of his footsteps were enough to stimulate the flow of saliva.

It was not long, however, before Pavlov stopped regarding this phenomenon as a flaw in his experimental method and came to look on it as a new area of research in its own right. He conducted experiments in which he controlled the signals that occurred prior to feeding. Five seconds before feeding, a metronome was set in motion or an electric bell rung. After a few such couplings – in the case of the bell, a single ring was enough – the dogs’ saliva began to flow as soon as they heard the signal. The dogs had learned that they would be fed after the bell was rung.

Because the dogs interpreted even the faintest cues from their surroundings as signals for impending feeding, Pavlov had a new building with soundproofed rooms constructed in St Petersburg, in which he could perform all the necessary operations remotely via a system of cables and levers.

The fundamental learning mechanism that Pavlov discovered through his experiments is known as ‘classical conditioning’. This involves pairing a natural combination of stimulus and response (i.e. food and salivation) with a new stimulus (i.e. a bell). In doing so, the new stimulus can only ever trigger an innate behaviour, though admittedly this can occur in almost any combination one could think of. On the other hand, the question of how new behaviours are learned was only investigated 30 years after Pavlov’s experiments by the American psychologist B.F. Skinner, using the socalled Skinner box.

During his experiments, Pavlov also discovered how conditioning can be unlearned. It was only necessary to ring the bell a couple of times without then feeding the dog for the animal to forget the connection. This was the basic principle behind the later development of behavioural therapy, which involved patients being confronted under controlled conditions with precisely those situations that usually triggered anxiety, for example. This technique was designed to break the association between certain situations and anxiety.

Today, everyone is familiar with the concept of Pavlov’s dogs. Cultural commentators have used them to symbolize the common herd in Western industrial societies, who have allowed themselves to be trained by advertising into ‘consumer animals’ and who display predictable purchasing reactions when confronted with particular stimuli.

Unlike Pavlov himself, who has gone down in history as one of the most famous scientists of all time, the bands named after him never made the breakthrough – or at least haven’t done so yet. The one that came closest was the rock group Pavlov’s Dog and the Condition Reflex Soul Revue and Concert Choir, who were rechristened simply Pavlov’s Dog in 1973 and paid $600,000 for their debut album, which at the time was the largest ever advance for a record in the USA. But three years later their record company dropped them, and the musicians found themselves broke and in dispute with one another.

from "The Mad Science Book", copyright 2010 Reto U. Schneider