Habituation

The gradual decrease in an animal’s response to repeated exposure to a stimulus is known as habituation (Mazur 2016; McGreevy and Boakes 2011). It is important to note that habituation occurs “naturally”; that is, this change in behavior occurs regardless of whether you want it to or not. For instance, a dog might initially startle at a loud noise. Over time, if the noise has no significant consequences (neither positive nor negative), the dog may learn to ignore the noise and stop reacting.

Sensitization

In contrast, sensitization involves an increase in an animal’s response following repeated exposure to a stimulus (Mazur 2016; McGreevy and Boakes 2011). Unlike habituation, the stimulus in sensitization is often (but not necessarily) aversive. Sensitization can develop more quickly than habituation. It is imperative to understand that sensitization can lead to an increase in reactivity and serious behavior problems in the future.

Classical Conditioning

Classical conditioning is a type of associative learning that relies on reflexes rather than conscious effort. This learning process occurs when an unconditioned stimulus, which naturally elicits an unconditioned response, is paired with a neutral stimulus. Over time, the neutral stimulus alone begins to trigger the response, even in the absence of the unconditioned stimulus. The precise order and timing of the presentation of these stimuli are critical for classical conditioning to take place (Mazur 2016; McGreevy and Boakes 2011).

Classical conditioning can also be undone through a process called extinction. Extinction happens when the conditioned stimulus is no longer followed by the unconditioned stimulus. After enough instances where the conditioned stimulus is not reinforced, the learned behavior diminishes, and the conditioned stimulus loses its ability to predict the unconditioned response. This process should not be confused with habituation, as the mechanisms and outcomes are distinct.

A well‐known example of classical conditioning is Pavlov’s experiments with dogs. In these experiments, Pavlov paired the sound of a bell (neutral stimulus) with the presentation of food (unconditioned stimulus). Initially the bell had no effect on the dogs, but the food naturally caused them to salivate (unconditioned response). As Pavlov repeatedly presented the food alongside the ringing bell, the dogs began to associate the two. Eventually, the sound of the bell alone was enough to make the dogs salivate, demonstrating that the bell had become a conditioned stimulus eliciting a conditioned response.

Example of Classical Conditioning with a Puppy, a Clicker, and Food 

Consider a young puppy starting their training sessions. In these sessions the trainer uses a clicker, a small device that makes a clicking sound, followed by giving the puppy a treat. At first, the clicker’s sound is a neutral stimulus to the puppy, meaning it does not naturally elicit any specific response, as the puppy has no prior association with this sound.

As the training continues a pattern emerges: each time the trainer clicks the clicker, a treat is promptly given to the puppy. The treat acts as an unconditioned stimulus since it naturally brings about engaging emotions from the puppy, such as expectation of food or salivation (the unconditioned response).

After repeated pairings of the clicker’s sound with the treat, the puppy begins to expect the treat as soon as they hear the click. The clicker’s sound has now transformed into a conditioned stimulus (Figure 3.1). It elicits a conditioned response in the puppy, which is now used to mark new and desirable behaviors.

Counterconditioning

Counterconditioning involves modifying an animal’s emotional reaction to a stimulus, particularly transforming a negative emotion into a positive one (Mazur 2016; McGreevy and Boakes 2011). In other words, the goal of counterconditioning is to change an established conditioned emotional response (CER) to an alternative one. The process requires the pairing of the original conditioned stimulus, which initially elicits a negative emotional response (CER–), with a new unconditioned stimulus that triggers a strong, positive emotional response (CER+). This positive response should be incompatible with the original negative one. Over time, the association that forms between the original conditioned stimulus and the unconditioned stimulus will decrease the magnitude of the original conditioned response, and it may eventually eliminate the conditioned response entirely.

Fear Conditioning

Fear conditioning is a particular type of classical conditioning where an individual learns to associate a neutral stimulus with a fear‐inducing stimulus, resulting in a fear response to the previously neutral stimulus. During this learning process, a neutral stimulus (e.g., a sound or visual cue) is paired with an aversive or fear‐inducing stimulus (e.g., a loud noise or an electric shock). Over time, the neutral stimulus becomes a conditioned stimulus that triggers the fear response without the need for the aversive stimulus.

One example of fear conditioning involves using a shock collar to stop barking. The shock collar itself serves as the neutral stimulus. When the dog barks excessively (the undesired behavior), the caregiver activates the shock collar, delivering an electric shock to the dog as the aversive stimulus. This action is intended to deter the dog from barking.

Through repeated experiences, the dog learns to associate the presence of the shock collar with the painful electric shocks they receive when they bark excessively. Over time, the shock collar becomes a conditioned stimulus that predicts the aversive stimulus, even when it is not actively delivering a shock.

As a result of this fear conditioning, the dog may display signs of fear and anxiety when the caregiver is attempting to put the shock collar on the dog or in a particular location where the shock had previously occurred (e.g., in the yard, in the front hall, on the deck). The dog might even show signs of fear while wearing the shock collar, even when not actively in use. This fear response reflects a learned association between the presence of the collar and the aversive experiences they have endured. This is why shock collars are considered inhumane and are never recommended for training or behavior modification (Blackwell and Casey 2006; China et al. 2020; Cooper et al. 2014; Fernandes et al. 2017; Masson et al. 2018; Overall 2007; Ziv 2017).

Operant Conditioning

Operant conditioning involves a process where an animal’s voluntary actions control their learning experience. This type of conditioning is centered around the concept that the consequences of an animal’s behavior determine how frequently that behavior is performed in the future. In other words, the behavior itself triggers a response, which then influences the probability of the behavior’s recurrence (Mazur 2016; McGreevy and Boakes 2011).

This form of conditioning can involve both positive and negative forms of punishment and reinforcement, which play a role in either increasing or decreasing the likelihood of a behavior. B.F. Skinner’s experiments with mice in a box are classic examples of operant conditioning. In his experiments, a mouse placed in a box with a lever learned that pressing the lever resulted in receiving food. This positive reinforcement (receiving food) increased the likelihood of the lever‐pressing behavior. Conversely, when the mice scratched the walls of the box, they were subjected to a loud noise. This positive punishment (introduction of an unpleasant stimulus) decreased the frequency of the wall‐scratching behavior.

Through these experiments, Skinner demonstrated the fundamental principles of operant conditioning: behaviors that are rewarded (reinforced) are more likely to be repeated, and behaviors that result in an unpleasant outcome (punished) are less likely to occur again. This principle is a cornerstone of learning and is widely applied in various settings, including animal training. Operant conditioning is based on four contingencies, and in this context “negative” refers to the removal of a stimulus, while “positive” indicates the addition of a stimulus and not necessarily “good” or “bad.”

Positive Punishment (P+)

This occurs when an additional element is introduced to decrease the frequency of a behavior. For instance, spraying a cat with water to prevent them from jumping on the counter is an example of positive punishment. Here, the water spray (an added factor) is meant to decrease the cat’s counter‐jumping behavior. (See “Effective Punishment.”)

Negative Punishment (P−)

Negative punishment happens when something is taken away to decrease a behavior’s frequency. For example, withdrawing attention from a dog that jumps on someone entering the home. In this case, the removal of attention (the subtracted factor) is meant to reduce the jumping behavior.

Positive Reinforcement (R+)

This involves adding something to increase the frequency of a behavior. For example, giving a dog a treat after they sit is positive reinforcement.

Negative Reinforcement (R−)

Negative reinforcement occurs when removing a factor increases the frequency of a behavior. For example, easing leash pressure when a dog stops pulling on the leash is negative reinforcement. The reduction of leash tension (the removed element) encourages the dog to walk without pulling.

Escape Conditioning

Escape conditioning is a specific form of operant conditioning in which an animal learns to engage in particular behaviors to remove themselves or escape from an unpleasant situation. This type of conditioning can progress into avoidance conditioning, where the animal anticipates the unpleasant situation and proactively displays behaviors to avoid it entirely. Distinct from fear conditioning, negative reinforcement rather than positive punishment often leads to this type of behavior.

In avoidance conditioning, the animal recognizes a specific stimulus as a predictor of an unpleasant experience and alters their behavior to prevent encountering that situation. For example, as noted by Mills (1997), a dog that has a strong dislike of car rides might initially resist or struggle when being put into a car. Over time, this dog may learn to associate certain cues, such as the caregiver picking up car keys or putting on shoes, with the unpleasant experience of car rides. As a result, the dog might start to hide whenever these cues appear in an attempt to avoid the car‐ride experience altogether.