How did Pavlovian conditioning differ from Thorndike’s instrumental conditioning?

Pavlovian conditioning (or classical conditioning) and instrumental conditioning differ primarily in the contingency of the reinforcement.1

• Pavlovian Conditioning: This process involves the association of two stimuli. A neutral stimulus (the conditional stimulus) is paired with a biologically significant one (the unconditional stimulus, such as food). The subject’s response, such as salivation, is reflexively elicited by the stimulus and is not contingent upon the subject's actions; the dog receives food regardless of whether it salivates.21
• Instrumental Conditioning: In this model, reinforcement is contingent upon the learner’s response. The subject must perform a specific action—such as pressing a lever or opening a latch—to obtain a reward or escape an aversive situation.21

While Pavlovian conditioning is often associated with involuntary, autonomic responses, and instrumental conditioning with voluntary skeletal movements, research has shown that both forms of learning are fundamental to how animals adapt their behavior based on their environment and the consequences of their actions.13