Smithsonian.com

Everybody knows about Pavlov’s dogs—the pooches who taught us about conditioning by being trained to salivate at the sound of the bell. But what kind of dog did he use? Easily trainable German Shepherds? Small, easy-to-handle Chihuahuas? Venerable Dalmations?  Turns out, Pavlov wasn’t picky about the kinds of dogs he used. He didn’t go for a specific breed, but instead seems to have used all sorts of dogs, many of them mutts. Here’s what Pavlov’s dogs looked like:

You might be wondering why making a bunch of dogs drool is so special. The Nobel Prize website explains:

Pavlov’s description on how animals (and humans) can be trained to respond in a certain way to a particular stimulus drew tremendous interest from the time he first presented his results. His work paved the way for a new, more objective method of studying behavior.

So-called Pavlovian training has been used in many fields, with anti-phobia treatment as but one example. An important principle in conditioned learning is that an established conditioned response (salivating in the case of the dogs) decreases in intensity if the conditioned stimulus (bell) is repeatedly presented without the unconditioned stimulus (food). This process is called extinction.

But while you might think of dogs when you think of Pavlov, his Nobel Prize was actually for something completely different. Here’s the prize website again:

In 1904 he received the Nobel Prize in Physiology or Medicine for his pioneering studies of how the digestive system works.

Until Pavlov started to scrutinize this field, our knowledge of how food was digested in the stomach, and what mechanisms were responsible for regulating this, were quite foggy.

In order to understand the process, Pavlov developed a new way of monitoring what was happening. He surgically made fistulas in animals’ stomachs, which enabled him to study the organs and take samples of body fluids from them while they continued to function normally.

But it’s his dogs that we remember. In fact, one of them is preserved at the Pavlov Museum, in Russia. Here’s the little guy:

Image: Rklawton

So while the pooches didn’t win him a prize, Pavlov’s legacy certainly lies in these dogs. What has your dog done for science lately?

More from Smithsonian.com:

Five Nobel Laureates Who Made Food History
Tracking America’s First Dogs