Classical conditioning: Pavlov’s research

• Classical conditioning (later developed by Watson, in 1913) involves learning to associate an unconditioned stimulus that already brings about a particular response (i.e., a reflex) with a new (conditioned) stimulus, so that the new stimulus brings about the same response
• Neutral Stimulus (NS): A stimulus that initially does not elicit a particular response or reflex action. In other words, before any conditioning takes place, the neutral stimulus has no effect on the behavior or physiological response of interest.
• Unconditioned Stimulus (UCS): This is a stimulus that naturally and automatically triggers a response without any learning needed.
• Conditioned Stimulus (CS): This is a previously neutral stimulus that, after being repeatedly associated with an unconditioned stimulus, comes to trigger a conditioned response
• Conditioned Response (CR): This is a learned response to the conditioned stimulus. It typically resembles the unconditioned response but is triggered by the conditioned stimulus instead of the unconditioned stimulus
• Unconditioned Response (UR): This is an automatic, innate reaction to an unconditioned stimulus. It does not require any learning.
• Pavlov (1902) started from the idea that there are some things that a dog does not need to learn. For example, dogs don’t learn to salivate whenever they see food. This reflex is ‘hard-wired’ into the dog
• Pavlov showed that dogs could be conditioned to salivate at the sound of a bell if that sound was repeatedly presented at the same time that they were given food.
• Pavlov’s dogs were individually situated in secluded environments, secured within harnesses. 
• A food bowl was positioned before them, and a device was employed to gauge the frequency of their salivary gland secretions.
• The data from these measurements were systematically recorded onto a rotating drum, allowing Pavlov to meticulously monitor the rates of salivation throughout the course of the experiments.
• First, the dogs were presented with the food, and they salivated. The food was the unconditioned stimulus and salivation was an unconditioned (innate) response. (i.e., a stimulus-response connection that required no learning).
• In his experiment, Pavlov used a metronome as his neutral stimulus. By itself, the metronome did not elicit a response from the dogs
• Next, Pavlov began the conditioning procedure, whereby the clicking metronome was introduced just before he gave food to his dogs.
• After a number of repeats (trials) of this procedure, he presented the metronome on its own And the sound of the metronome by itself now caused an increase salivation
• the dog had learned an association between the metronome and the food, and a new behavior had been learned.
• Because this response was learned (or conditioned), it is called a conditioned response (and also known as a Pavlovian response). The neutral stimulus has become a conditioned stimulus.
• Pavlov found that for associations to be made, the two stimuli had to be presented close together in time. this is known as the law of temporal contiguity