In a set of studies, Ivan Pavlov first touched a dog lightly on the side of its body and a few seconds later placed vinegar on the dog’s tongue. The vinegar made the dog salivate. After several pairings of touch and vinegar, the dog began to salivate as soon as it was touched and before it was given the vinegar. In these studies which of the following was the conditioned stimulus?
a) touch to the body
b) vinegar to the tongue
c) salivation to the vinegar
d) salivation to the touch
e) time interval between touch and vinegar