Ivan Pavlov experiment: Pavlov's dogs
Pavlov fed dogs and was looking at salivation in response to the food. At a certain point, whenever he entered the
room, the dog would start to salivate even when he was not bringing them food. This it is an unconditioned response to an unconditioned stimulus.
Mary Cover Jones experiment: "Little Peter" experiment
She tested a number of procedures to remove a irrational fear of a white rabbit in a boy named Peter. She treated him by "direct conditioning", in which a pleasant stimulus (food) was associated with the white rabbit.
John B. Watson experiment: "Little Albert" experiment
Watson exposed a child, named Albert to a series of stimuli like a rat, a
rabbit and more. At the begging the child showed no fear of any of the objects. Then Albert started to exposed those objects while making
loud noises. Naturally, the child
began to cry after hearing that and after repeatedly pairing the objects with the noise, Albert began to cry simply after seeing
the objects.