conditioned emotional response (CER)
A procedure used to determine the strength of a relationship between a CS and a US that combines operant or instrumental conditioning and classical conditioning. In phase 1, animals learn an instrumental or operant response to the point that it is emitted at a steady rate. In phase 2, the classical conditioning phase, a CS is paired with a US a number of times. In phase 3, as animals are again performing the instrumental or operant response, the CS from phase 2 is presented, and its effect on the rate of responding is noted. Depending on how the CS and US were paired in phase 2, it is found that presenting the CS in phase 3 facilitates, inhibits, or has no effect on the rate with which the instrumental or operant behavior is emitted.