higher order conditioning
A form of classical conditioning in which a conditioned stimulus CS1 is first paired with an unconditioned stimulus, in the usual way, until CS1 elicits a conditioned response, then a new conditioned stimulus CS2 is paired with CS1, without the unconditioned stimulus, until CS2 elicits the original conditioned response. For example, the ticking of a metronome may be paired with food powder until it elicits salivation, then a bell may be paired with the metronome until the bell elicits salivation, and so on. This process can be extended further back. The corresponding phenomenon in operant conditioning is secondary reinforcement.