Mark was a no-nonsense kind of guy. He employed several schools of thought about dog training, choosing the methods most appropriate for each dog and owner. And while he favored positive training methods, he acknowledged that punishment was also necessary from time to time.

Even though I hadn’t yet bonded emotionally with Callie, I did enjoy working with her in Mark’s obedience class. Lyra had taken this class too, but she had never had the level of intensity that Callie brought to the table. Callie wasn’t warm and cuddly, but I had to respect her work ethic. She couldn’t get enough training. She would do anything for a bit of hot dog. I was amazed that she learned basic commands like “sit,” “stay,” and “come” in just a few tries. The CPT teachers loved to use Callie as an example, because she watched them intently and worked tirelessly for a treat.

As Mark was the only dog trainer I knew, it made sense to approach him about the idea of training dogs to go into an MRI. He took an almost academic approach to dog training, so I hoped he would find the idea of scanning dogs’ brains interesting enough to do for fun.

Much to my delight, Mark agreed to meet.

The modern study of dog behavior began with every biologist’s hero, Charles Darwin. In The Expression of the Emotions in Man and Animal, Darwin devoted a great deal of attention to the dog—as an owner himself, his study of dog behavior didn’t require a trip to the Galapagos Islands. What Darwin understood, and what every dog owner knows—but many research scientists seem to have forgotten—is that dogs have a rich set of expressions and body language. Darwin had no problem discerning joy, fear, and rage in dogs. He was primarily concerned with observing the expression of these emotions, not with the intent of training these intelligent animals, but rather to understand how human emotions evolved.

It was the famous Russian physiologist Ivan Pavlov who launched the modern era of dog training. Unlike Darwin, Pavlov had no love for dogs himself. He was just using them to study the digestive system. The problem was that his dogs started salivating before he fed them, and this messed up his data. Regardless of what you think about Pavlov, his “failed” experiment led to the most important discovery in psychology of the twentieth century, for which he was awarded the Nobel Prize in 1904. His discovery has completely dominated theories of dog training ever since.

Pavlov’s discovery is called classical conditioning (although some people honor him by calling it Pavlovian conditioning). During the period in which Pavlov was doing his experiments, physiologists thought of the entire nervous system as a collection of reflexes, like the involuntary leg jerk when a doctor raps on your knee. They believed that all behaviors, even complex ones, were basically a series of reflexive actions. A reflex could be broken down into two parts: the unconditioned stimulus (US) and the unconditioned response (UR). For the knee reflex, the US is the hammer hitting the patellar tendon and the UR is the quadriceps contraction that results in the leg jerking upward. Pretty simple.

Pavlov realized that his dogs were having reflexive responses, but they weren’t natural. Hungry dogs will always salivate when presented with food. This is a natural, and thus unconditioned, response. But, as Pavlov discovered, if something neutral, like the ringing of a bell, regularly precedes the presentation of the food, the dog will start salivating at the sound of the bell. The bell, a neutral stimulus, becomes a conditioned stimulus (CS), and the salivation it evokes is now a conditioned response (CR). The terminology of unconditioned and conditioned refers to stimuli and responses that are either natural or created by the experimenter.

By itself, classical conditioning doesn’t say much about dog training. The responses are so simple that they don’t constitute anything remotely resembling a behavior, and it is hard to imagine cobbling together a string of these conditioned responses into something as simple as “sit.” This is where instrumental learning comes in.

In instrumental learning the animal must do a purposeful behavior. While classical conditioning trains an involuntary response like salivation, instrumental learning aims to train a voluntary action. Instrumental learning forms the basis of every dog-training method ever published. Teaching the “sit” command is based on instrumental learning. Here, the stimulus is either a hand signal or a spoken word, and the desired behavior is the act of sitting. When the dog sits and he is immediately rewarded, he makes an association between the act and the reward. In instrumental learning, the link between stimulus (“sit”) and act (sitting) is called the stimulus-response (S-R) relationship. Instrumental learning is also called operant conditioning because the animal learns to operate on, or affect, the environment.

Psychologists have classified four different types of instrumental learning based on whether a behavior is rewarded or punished. A reward is something that the animal likes, such as food or praise. Punishment is something he doesn’t like, such as a loud noise. Rewards and punishments can be either given or withheld, which leads to the four types of learning. For example, the removal of something unpleasant reinforces behavior, so we call it negative reinforcement, negative meaning “removal.” Positive reinforcement comes from the delivery of a reward, while positive punishment comes from the delivery of something unpleasant. The final combination, negative punishment, occurs when you take something desirable away from the animal. Negative punishment is a popular tactic among parents trying to curb undesirable behavior in their children. The suspension of computer privileges is a classic negative punishment and should, according to theory, decrease the frequency of the offending behavior.

The use of instrumental learning to change behavior is broadly referred to as behaviorism. Psychologist Edward Thorndike described many of its basic laws. The law of effect states that S-R relationships are determined by how much the animal likes the reward. The more he likes it, the stronger the S-R link. Thorndike’s law of exercise states that an S-R relationship is strengthened through use and weakened through disuse. Thorndike’s laws were further elaborated by the legendary psychologist B. F. Skinner, who thought that all behavior could be reduced to a set of S-R relationships. He is most famously associated with the Skinner box, a device that automatically trains rats or pigeons to learn behaviors.

After Pavlov’s basic discovery and Thorndike’s and Skinner’s elaborations on it, behaviorism flourished. It reached its peak in popularity in the 1960s, when psychologists and psychiatrists began applying these theories of animal learning to human behavior. Techniques that targeted everything from smoking cessation to learning to make friends were all rooted in the behaviorist tradition. While some of its prominence has waned in recent years, behaviorist techniques remain the most commonly used “talk therapies” for depression and anxiety in humans, which is called cognitive-behavioral therapy (CBT).

When it comes to dogs, much has been said and written about positive and negative training methods. While they are all based in the behaviorist tradition, different schools of thought place different emphases on rewards like food and praise and punishments like noises, scolding, or pain. There is no doubt that the administration of a punishment can cause an immediate effect on a dog’s behavior. What is unclear is whether the dog actually learns anything from it. The child who has lost her TV privileges may have learned not to repeat her offense, or she may simply have learned not to get caught.