Second-order conditioning

Second-order conditioning (SOC) occurs in three phases. In the first training phase, a conditioned stimulus, (CS1) is followed by an unconditioned stimulus (US). In the second phase, a second-order conditioned stimulus (CS2) is presented along with CS1. Finally, in the test phase, CS2 is presented alone to the subjects while their responses are recorded.

Evidence suggests that a second-order conditioned stimulus is able to persist for weeks, and that a third or higher order may be possible. The first-order conditioned stimulus can stabilize and serve as the foundation for multiple conditioned stimuli "superimposed upon it" as opposed to just one.

Models of second-order conditioning

Theoretical models for how second-order conditioning (SOC) works have a basis in associative learning theories. There are four broad models based on the associations formed during SOC. The first model suggests that the second-order stimulus (CS2) and the conditioned response (CR) form a direct link which is strengthened by the presence of the first-order stimulus (CS1). The second model suggests that in successful SOC an associative representation of each stimulus is created. The presentation of the CS2 would evoke a representation of the CS1, which would evoke a representation of the unconditioned stimulus (US), thus leading to the CR. The third model suggests a direct link between the CS2 and a representation of the US which leads to the CR. The fourth model suggests that the CS2 elicits a CR through a CS1 representation because a connection exists between the CS2 and the CS1 representation. Second-order conditioning helps explain why some people desire money to the point that they hoard it and value it even more than the objects it purchases. Money is initially used to purchase objects that produce gratifying outcomes, such as an expensive car. Although money is not directly associated with the thrill of a drive in a new sports car, through second-order conditioning, money can become linked with this type of desirable quality. Money (CS2) becomes directly associated with a conditioned response because of its link to physical assets (CS1) that lead to a satisfying unconditioned stimulus.