In classical conditioning, what becomes a conditioned stimulus?

A neutral stimulus that has been paired with an unconditioned stimulus becomes a conditioned stimulus in classical conditioning. This is the fundamental principle of classical conditioning, where a previously neutral stimulus (which does not elicit a particular response initially) is associated with an unconditioned stimulus (which naturally and automatically triggers an unconditioned response).

Through repeated pairings, the neutral stimulus becomes conditioned, meaning it can now evoke a response on its own. This transformation illustrates how learning occurs through association, as the organism begins to respond not just to the unconditioned stimulus but also to the newly conditioned stimulus.

In this context, understanding the relationship between the neutral stimulus and the unconditioned stimulus is crucial. The other options do not accurately describe how a conditioned stimulus arises. Exploring those misconceptions further clarifies why choice A is the correct answer. An unconditioned stimulus that is no longer effective would not have the capacity to condition a response; a stimulus that elicits a response initially but is neither neutral nor conditioned cannot become a conditioned stimulus; and a previously conditioned response does not reflect the process of conditioning a stimulus. Therefore, the path from neutral to conditioned through pairing is what solidifies the definition of a conditioned stimulus.