Transfer between tasks involving frustrative nonreward in rats: From consummatory to instrumental successive negative contrast

In tasks involving frustrative nonreward, animals learn to expect a large reward and eventually the reward is unexpectedly (i.e., without signals) downshifted to a small reward. Rats exposed to such tasks exhibit a transient rejection of the reward (in consummatory successive negative contrast, cSNC), or a transient deterioration of anticipatory behavior (in instrumental successive negative contrast, iSNC). When these tasks are administered in series, animals trained first in the cSNC task exhibit a reduced iSNC effect. This cSNC-to-iSNC transfer effect has been attributed to counterconditioning learning during cSNC postshift sessions, that is, to pairings of anticipatory frustration (a negative emotional response) with a reward. This hypothesis was tested in two experiments that manipulated the number of postshift trials in a cSNC task (Phase 1) before switching animals to the iSNC task (Phase 2). In these experiments, animals that received a single downshift session in the cSNC task (Phase 1) exhibited a stronger iSNC effect (Phase 2) than animals that had received either five (Experiment 1) or eight (Experiment 2) downshift sessions. More extensive downshift experience created more opportunities to develop counterconditioning. These results lend support to a role of counterconditioning in the recovery from reward downshift and in the development of transfer effects across reward downshift tasks that differ in terms of response requirements, reward type, and contextual cues.