Learning About Absent Outcome in the Presence of Conditioned Excitor and Inhibitor: A Study Using Conditioned Flavor Preference

We examined whether aversive conditioning of a previously established conditioned inhibitor (A) for sucrose solution (X) affects subsequent consumption and aversive conditioning of X. Experiment 1 established an appetitive conditioned inhibition procedure in which odor A became a conditioned inhibitor for X. In Phase 1 of Experiments 2 and 3, subjects received either inhibitory (Group INH: AB/BX/C) or excitatory conditioning of A (Group EXC: ABX/B/C), or a control treatment (Group CONT: AB/B/CX). In Phase 2, A was paired with an injection of lithium chloride (LiCl) and consumption of X was measured. X was paired with LiCl in Phase 3, and tested in extinction. After a moderate amount of Phase 1 treatment in Experiment 2, animals in Group EXC showed a reduction in consumption of X after A-LiCl pairings, while those in both Groups EXC and INH rapidly acquired an aversion to X during X-LiCl conditioning. However, when extended Phase 1 treatment was given in Experiment 3, animals in Group INH tended to acquire the aversion to X at a slower rate than those in Group CONT. Animals in Group EXC did not show any superiority in acquisition of the X aversion. The results are discussed in terms of mediation processes by event representations.