Discover how canine cognitive abilities compare to those of a human toddler. Learn about the intelligence of dogs and what research reveals about their mental skills.

How smart are our dogs? If you base your opinion on YouTube videos, it’s easy to conclude they’re extremely intelligent. They do everything from surfing and skateboarding, to punching sound-producing buttons to answer questions. They seem to be the equivalent of four-footed humans in fur coats — at least sometimes. Let’s take a closer look at canine cognitive abilities, and find out just how smart our dogs are!

How research into canine cognition has evolved

The scientific study of higher mental abilities in dogs is a relatively recent phenomenon. In the early 1900s, Ivan Pavlov extensively studied the dog’s ability to learn simple reflexes. However, researchers lagged well behind in studying more complex canine cognitive skills. As recently as the late 1980s, there were virtually no psychological laboratories specifically dedicated to studying canine cognition. Despite the sparse level of scientific research, people continued to wonder how smart their dogs were. They questioned what dogs could understand and the limits of their ability to learn and solve problems.

Fast fact: Researchers eventually changed the scientific climate around canine cognitive research. Today, approximately three dozen laboratories worldwide study the mental abilities of dogs.

These include university labs at Duke, Emory, Arizona, Yale, and Texas Tech in the US, as well as labs throughout Europe, including Max Planck, Eötvös Loránd, Padua, Milan, and Vienna, to name but a few.

With all this research dedicated to studying the minds of dogs, have we achieved any major breakthroughs in our understanding of how our best friends think?

Studies show dogs are as smart as human toddlers

Perhaps one breakthrough, when it comes to our ability to assess the cognitive capacity of dogs, came about in the early 1990s. At the time, it dawned on me that one way to learn about the limits of canine mental abilities was to use tests that researchers had already developed to assess human infants and toddlers, and modify them for dogs.

The idea was simple: if a dog could pass the test, he clearly demonstrated that mental ability. In addition, many of these tests are scored in terms of human mental age, which permits researchers to compare the cognitive abilities of dogs to that of young humans.

This led some investigators to start thinking that canine cognitive abilities might truly mimic those in human children, which has led to some interesting new research.

My own initial studies using this technique began when I was looking at canine language learning ability. I began by modifying the MacArthur Communicative Development Inventory. It contains several tests to assess language and communication ability in very young children, including word use and gestures.

Using only family dogs, which were not explicitly trained to understand language and gestures, I concluded that the mental ability of dogs roughly equates to that of a 2 to 2½-year-old human child. This means the average dog can understand about 165 words, including hand signs and signals.

Fast fact: Further work led me to believe that the most intelligent dogs might have mental abilities similar to a those of a 2½ to 3-year-old child. This meant they could learn at least 200 words.

At the time, I cautioned that we really didn’t know how far we could push a dog’s abilities until we specifically tried to train him for maximum comprehension of human language.

Building the canine vocabulary

If my estimates were correct, then it should be possible to train a bright dog to develop a vocabulary of several hundred words. A few years later, researchers confirmed that a Border Collie named Ricco had a language ability within that range. Ricco had been specially trained to enlarge his vocabulary.

Since that time, a number of other researchers, such as retired psychologist John Pilley and his dog Chaser have tried to see just how much language a dog can learn.

Fast fact: We should not judge the typical linguistic ability of our dogs by the achievements of a canine savant like Chaser. After all, we wouldn’t judge the average musical ability of a human child based on Mozart’s accomplishments.

Canine cognition that goes beyond language

Given the results suggesting our dogs’ linguistic ability is roughly equivalent to that of a human toddler, researchers began to wonder if other canine mental abilities were similar. After all, when we measure the intellects of children, we usually find synchronous development. For example, if a child’s vocabulary is at a 5-year-old level, then her mathematical ability will also be at a 5-year-old level, as will her ability to write, memorize, draw, and solve problems.

Researchers found this to be a good approach. For example, a human 2 to 3-year-old may be able to repeat the sequence of numbers from one to ten by rote. However, she typically only understands the concept of actually counting well enough to enumerate batches of three to five objects. Research has shown this is exactly the range of items dogs can count.

Fast fact: In formal retriever trials, the minimum number of items a dog must be able to count in order to do well is three. This is so he can remember how many ducks have fallen, in what order, and where they are.

Once we accept that we can compare a dog’s mind to that of a 2 to 3-year-old child, we can begin to explore other aspects of a dog’s mental life. In humans, for example, a systematic development of emotions and emotional expression takes place.

While a very young child can feel pleasure, pain, anger, disgust and love, complex social emotions such as guilt, shame or pride require a child to be nearly four years of age. So if you want to know whether your dog feels guilty after he has committed some transgression, your best estimate is that he does not. This is the way the most recent scientific data seems to be pointing.

So just how smart are our dogs?

First, we should limit our conclusions to mental and intellectual canine cognitive abilities. In terms of social consciousness, given their interest in sex, dominance, and social interactions, dogs are more like human teenagers when it comes to their mental functioning.

However, recent research suggests that dogs have cognitive abilities similar to those of humans aged 2 to 3 years, especially for language, problem-solving, and concept formation. This means if you’re posing a problem or teaching a task to your dog that would be too difficult for a human toddler to solve or learn, it’s likely to be beyond your dog’s capacity as well. Mentally challenging your dog is important to his happiness and well-being — just be sure the activity is within his intellectual reach!

Chaser – canine savant

Based on careful and controlled research, perhaps the most linguistically talented dog to date was Chaser, a Border Collie owned by a retired psychologist, John Pilley. Chaser had a vocabulary of around 1,000 words, which is the equivalent of what we might expect from a 3½-year-old human child.

Chaser not only understood single words, but also grasped concepts and categories such as “ball,” which may include various items of different sizes and textures.

Chaser’s skills did not come easily, however; they required a lot of training, with Dr. Pilley often spending four or more hours a day working with the dog. It therefore seems likely that his research pushed the upper limits of what a dog can be trained to understand.