Читать книгу Animal Behavior for Shelter Veterinarians and Staff - Группа авторов - Страница 85

One way that associative learning takes place is when a stimulus gets paired with another stimulus, a process called classical or respondent conditioning. Pavlov famously demonstrated this process in the early 1900s. While researching the physiology of digestion in dogs, Pavlov observed that dogs salivated in the presence of food. This was no surprise because Pavlov knew that salivation was a reflex elicited by the presence of food. However, Pavlov was puzzled when he noticed that the dogs began to salivate in the presence of the technician who normally fed the dogs. Pavlov began an experiment based on his serendipitous findings to uncover the process that he informally observed. In his experiment, he presented the sound of a metronome (commonly misreported as having been a “bell”) right before giving the dogs food. By itself, the metronome did not elicit salivation. However, after several pairings of the metronome followed by food, the metronome became associated with food and elicited salivation by itself!

The process of classical conditioning can be easily understood if we divide it into three phases: before conditioning, during conditioning, and after conditioning. Before conditioning, a stimulus automatically elicits an unlearned behavior (i.e., produces an involuntary response). This is the unconditioned stimulus because it automatically triggers a response. For similar reasons, the response that is naturally triggered by the stimulus is the unconditioned response. The food in Pavlov’s experiment served as the unconditioned stimulus and the salivation as the unconditioned response. Initially, the metronome was a neutral stimulus because it did not produce a response (yet!).

During conditioning, the neutral stimulus and the unconditioned stimulus are repeatedly presented together. The most effective method by which classical conditioning takes place is when the neutral stimulus precedes the unconditioned stimulus. The association occurs less effectively if the neutral stimulus occurs after or during the unconditioned stimulus, or if there is a long period of time between their presentations. During this phase, the metronome and food were repeatedly paired. This is the phase in which associative learning takes place; the metronome and food become related and the animal learns to salivate in the presence of the metronome.

After conditioning, the neutral stimulus becomes a conditioned stimulus and can reliably elicit the response by itself. When a conditioned stimulus elicits the response, the response is called a conditioned response. The conditioned response and unconditioned response are the same response; the difference is in what stimulus caused the response to happen. The associative learning is demonstrated in this phase when the metronome can produce salivation by itself. The metronome is now a conditioned stimulus and salivation produced by the metronome is the conditioned response. This example is a common one, but it can be hard to translate processes discovered in a laboratory to the real world. Instead, let’s look at an example you may have witnessed yourself.

When a caregiver enters the kennel area to feed, from a dog’s perspective the person makes a lot of noise, and these sounds are distinct. An animal that is naive to the shelter environment might not notice these sounds. Thus, the sound of the first run door opening is a neutral stimulus: one that elicits no response and thus has no meaning. Food is the unconditioned stimulus. It requires no conditioning to elicit a response (in this case, salivation). The animal’s salivation is the unconditioned response, because if caregivers present the animal with food, it will salivate automatically (without training). After multiple pairings of the first door opening with the daily feeding, the once‐neutral stimulus (the sound of the door opening) is now the conditioned stimulus and causes a conditioned response (salivating at the sound of the run door opening). See another example in Box 3.1 and try to label the neutral stimulus, unconditioned stimulus, unconditioned response, conditioned response, and the conditioned stimulus yourself.