p513fig13.42 A conditioned excitor extinguishes because the expectation that was learned of a shock during the learning phase is disconfirmed during the forgetting phase.<BR>||  Conditioned excitor extinguishes.  Learning phase: CS1 bell-> US; CS1-> Fear(-); CS1-> shock; CS1 is conditioned to an expectation of shock.  Forgetting phase:  CS2 bell-> forgetting;.  The expectation of shock is disconfirmed.