By Jeff Stallings, CPDT-KA
My favorite behavior book of the past year or so is John Bradshaw’s “Dog Sense: How the New Science of Dog Behavior Can Make You a Better Friend to Your Pet”. I recommend this book to anyone wanting to better understand their dogs’ minds, especially if you’re a bit of a science geek. Which of course I am; I could hardly put this book down.
“Dog Sense” includes the best explanation I have yet read about when, how and why socialization is important. Specifically, Bradshaw used the results of many studies to determine the mechanisms that allow puppies to become familiar with—and attached to—dogs, humans and other species.

Early work in this field was conducted by Nobel Prize-winning biologist Konrad Lorenz in the 1930s. Lorenz discovered the process (now known as filial imprinting) whereby young animals learn the characteristics of their parents. Goslings, for example, will imprint onto the first moving object of about the right size that they encounter between twelve and sixteen hours after hatching.
In the wild, the chance of this first object not being the mother is remote, so imprinting is a highly-effective means for a newborn chick to become attached to its actual mother. Lorenz called this the “critical period”; we now use the term “sensitive period”, and it changes from species to species, but works the same in each.
The brief critical period
The sensitive period in puppies runs from age three weeks until about sixteen weeks. What separates puppies from the young of every other known species is that they can imprint with multiple individuals across multiple species. Thousands of years of domestication has led to the modern dog’s unique ability to bond with not only their own species, but also with humans, cats, sheep and any other species they spend time with during those crucial first months of life.
Some traditional uses of dogs exploit this flexibility. For example, sheep-guarding breeds, if raised with sheep, grow up to behave as if the flock is their family. The amazing thing is that these dogs do not at the same time lose species identity; they know they are dogs and not sheep.
To quote Bradshaw, “The domestic dog puppy’s unusual capacity for multiple socialization is the mechanism whereby we can insert ourselves into their social milieu and substitute ourselves into a role that, in the wild, would be served by their parents.” Conversely, if young pups are not familiarized with humans during this period, they will not learn to trust, love and live peacefully with humans.
Exposure to our manmade world
In addition to this sensitive period being the time in which puppies learn to not fear humans, it also is the period in which they learn to live with and not be frightened of other aspects of our man-made world, such as cars, buses, skateboards, bicycles, loud noises, etc.
Many of the behavioral problems I work with my clients to address could have been avoided with a exhaustive socialization plan to expose their puppies to many people, many dogs, and a large range of outside stimuli during those three or so months.
“The first three or four months of life”, says Bradshaw, “are arguably the most important time in a dog’s life. Born with a powerful urge to learn about the world around them, dogs adjust during this period to whatever type of environment they find themselves born into, from the back streets of a village in Punjab to a New York high-rise. As with most animals, their default reaction to the unknown is fear. But for dogs, unlike most other animals, that fearful reaction is easily nullified by the right kind of experience.”