Final answer:
Robert Rescorla proposed the contingency theory of classical conditioning, which is an important advancement that indicates the necessity of predictive information in the classical conditioning process.
Step-by-step explanation:
The psychologist who proposed the contingency theory of classical conditioning is Robert Rescorla. Rescorla's work emphasized the need for the conditioned stimulus to provide predictive information about the unconditioned stimulus, altering the understanding that just pairing two stimuli could lead to conditioning. This idea is known as the Rescorla-Wagner model, which was a significant development in the study of conditioning and learning.
While Ivan Pavlov is famous for discovering classical conditioning, and B.F. Skinner is known for his research on operant conditioning, it was neither of these researchers who developed the contingency theory of classical conditioning. Instead, it was Robert Rescorla who advanced our understanding of classical conditioning by demonstrating that the temporal contingency between paired stimuli is critical to the learning process.