Who Let the Dogs Ooze

I think many of us have heard about Ivan Pavlov. He was a Russian physiologist who won the 1904 Nobel in Physiology for his studies on digestive processes. He is most famous for his theory of classical conditioning. Today we discuss the experiment that led him to that discovery.

“Science demands from a man all his life. If you had two lives that would not be enough for you. Be passionate in your work and in your searching,” - Ivan Pavlov

Pavlov Trains the Dogs

Primary Interests

Pavlov was primarily interested in digestion. In his research, his assistants would introduce various edible and non-edible items in front of the dogs and measure the saliva production induced by the items.

Above is a setup for the digestion experiments that Pavlov carried out.

From Digestion to Conditioning

Pavlov termed salivation as a reflexive process, it occurs normally in response to a specific stimulus and is not under conscious control. However, Pavlov noted that dogs would often start salivating in the absence of food. Upon further examination, the dogs would often salivate at the sight of the lab assistants that brought them food. Pavlov quickly realized that this response was not due to an automatic, physiological process.

He set up an experiment to study this observation further.

The Experiment

The Setup

The setup of the experiment was quite similar to the previous one. The dogs tied to a post and test tubes put in their mouths to measure salivation. However, instead of providing different edible and non-edible items, Pavlov tried coupling the presentation of an edible food item with a neutral stimulus (one that doesn’t cause salivation). He termed the coupling as “conditioning”.

Stimulating the Dogs

The before conditioning part (1 and 2 in the image above) is the normal case, the dog salivates in the presence of food (unconditioned stimulus) and it doesn’t salivate in the presence of a ringing bell (neutral stimulus).
Here food is unconditioned response as the dog is never trained (or conditioned) to salivate when food is presented. Ringing bell is a neutral stimulus as it doesn’t affect salivation.

The third quarter of the image shows the conditioning. The dog is presented with food and the presentation is always accompanied by a ringing bell. The response is still an unconditioned response, as it is a response to the food mostly.

After few training cycles, simply ringing the bell leads to the dog salivating. Voila!, by coupling the action of food presentation with a ringing bell we have made the dog associate a ringing bell with food. The ringing bell is now a conditioned stimulus and the reaction to the ringing bell is a conditioned response as it was conditioned or learned by the dog.

In Pavlov’s words:

“A stimulus which was neutral in and of itself had been superimposed upon the action of the inborn alimentary reflex. We observed that, after several repetitions of the combined stimulation, the sounds of the metronome had acquired the property of stimulating salivary secretion.”

P.S. Pavlov used a metronome instead of a ringing bell, but it’s all the same in the end.

Impact of the Discovery

In addition to forming the basis of what would become behavioural psychology, the classical conditioning process remains important today for numerous applications, including behavioural modification and mental health treatment, including treating phobias, anxiety and panic disorders.

Pavlov’s work has also inspired research on how to apply classical conditioning principles to taste aversions. The principles have been used to prevent coyotes from preying on domestic livestock and to use neutral stimulus (eating some type of food) paired with an unconditioned response (negative results after eating the food) to create an aversion to a particular food.

The taste aversion is a very interesting example that we can find in the fields of ecology, buried in the concepts of aposematism. In general, this experiment contributed significantly to aspects of behavioural sciences across fields.

It has also led to the development of a paradigm where knowledge is treated as something associative. We learn by associating things and this was the beginning of the larger area of conditioning in psychology. One may be astonished to find that this significant contribution was made to the field of psychology by a non-psychologist. I guess we can contribute to distant unrelated fields if we are observing and motivated enough like Pavlov.