Second Order Conditioning
Second Order Conditioning (also known as Higher Order Conditioning) is a classical conditioning term that refers to a situation in which a stimulus that was previously neutral (e.g., a light) is paired with a conditioned stimulus (e.g., a tone that has been conditioning with food to produce salivating - this is the "first" order) to produce the same conditioned response as the conditioned stimulus. Wow...if you understand how a neutral stimulus becomes a conditioned stimulus (conditioning), you understand second order conditioning because this is really just extending the conditioning one more level - to the Second Order...the conditioning is happening not by pairing the stimulus with something that naturally produces a response, but with something that has been conditioned to produce a response.