Final Answer:
One key experiment designed to differentiate between S-S and S-R theories of classical conditioning involved blocking. It showed that when a new neutral stimulus (CS2) is presented after an already established CS (CS1) and the unconditioned stimulus (US), it acquires less conditioned response (CR) compared to when presented alone. This finding supports the S-S theory, suggesting that the CS directly activates the US representation in the brain, not just elicits a response.
Step-by-step explanation:
S-S (Stimulus-Stimulus) Theory: This theory proposes that during conditioning, an association forms directly between the CS and the internal representation of the US in the brain. When the CS is presented, it activates this representation, leading to the CR without requiring any additional response or processing.
S-R (Stimulus-Response) Theory: This theory suggests that conditioning involves forming an association between the CS and the CR itself. The CS triggers the CR directly, without involving any internal representation of the US.
Blocking Experiment:
Two groups of animals were conditioned:
Group 1: CS1 (light) paired with US (food) repeatedly.
Group 2: CS1 (light) paired with US, then CS2 (tone) presented before CS1-US pairing.
Both groups were tested with CS2 alone.
Results:
Group 1: CS2 elicited a strong CR (light-food association established).
Group 2: CS2 elicited a weaker CR or none at all (light-tone association overshadowed the light-food association).
Interpretation:
Blocking suggests that CS2 could not form a strong association with the US because the existing CS1-US association was already established. This supports the S-S theory, where the CS directly activates the US representation, making additional CS-US pairings less effective.
Additional Notes:
Blocking is not absolute and can be influenced by various factors like stimulus intensity and timing.
Other experiments have also provided evidence for both S-S and S-R theories, suggesting that both processes may contribute to classical conditioning depending on the specific situation.
This experiment, along with others, has helped shed light on the complex mechanisms of classical conditioning and the ongoing debate between S-S and S-R theories.