A. Pavlov's Model

Russian scientist who was interested in digestion and discovered classic conditioning

Pavlov was using dogs to study digestion. He began noticing that when the dogs saw him carrying the bowl of food, the dogs began salivating. He recognized that salivation to the sight of the experimenter/bowl had to be a learned response rather than a reflexive response.

Any response that is conditioned/learned. Pavlov discovered that it could not have been a reflexive response, since the stimuli had become associated with something that triggered the response.

The question is how animals can come to have learned responses if animals mainly have just reflexes and instincts. The answer is that the ability of the organism to form associations AND the possession of reflexes could allow the organism to learn.

The two discoveries were experimental excitation and experimental extinction. Experimental excitation refers to the ability of a new stimulus to elicit a response. After Pavlov paired the sound of a bell with the sight of food enough times, just the sound of a bell was enough for the dogs to begin drooling. In experimental extinction, the new stimulus, now called the conditioned stimulus, no longer comes to elicit the response. This was discovered when Pavlov no longer brought out the food. The dog eventually stopped salivating to the sound of the bell without the food.

An unconditional stimulus (UCS) will elicit an unconditional response (UCR). The UCR is a reflexive response to the UCS, with the UCS being the trigger. When a novel stimulus, or the conditioned stimulus (CS) is paired enough times with the unconditional stimulus, the CS alone will come to elicit the conditioned response (CR). UCS-------->UCR ( +) CS -------->CR The plus sign is not always there, and should be assumed.

The CS is a neutral stimulus because it does not cause the response on its own. The CS isn't a neutral stimulus because it causes an orienting reflex in the animal, since it is a novel stimulus.

After you have a CR from continuously presenting the CS with the UCS, present the CS alone, and the CR will get weaker, until there is no more CR. There is NO needed diagram. Once the dog is salivating to both the food and the bell, the bell is presented by itself, leading to a decrease of salivation, until there is no more salivating.

The learned reflex results from the CS eliciting the CR. The unlearned reflex results from the UCS eliciting the UCR.

Watson believed that behavior was learned on the periphery, along the sensory organs, taking on the view known as peripheralism. Pavlov believed that behavior was learned in the brain, becoming a centralist. Pavlov believed that the CS center was activated/excited in the brain, spreading to the UCS center, and activating the response.

1. The CR and UCR should be the same type of response. 2. CR should normally be weaker than the UCR. 3. The strength of the response will depend on the strength of the stimulus (for both conditional and unconditional). 4. Prediction of directionality, in that an excitatory CR should occur only if the CS is presented before the UCS during training; activation flows between centers. 5. Prediction of temporal contiguity in that the time intervals between the CS and the UCS should be short in order for learning to occur. The predictions tend to be very accurate.