Conditions favoring superconditioning of irrelevant conditioned stimuli.

Three appetitive conditioning experiments with rats found partial learning of complex XA+, XB+, XAB- (+ stands for reinforced; - stands for unreinforced) negative patterning discriminations with intermixed A+ and B+ trials (Experiment 1). AB+ trials (Experiment 2), and A+, B+, and AB+ trials (Experiment 3). In all experiments, differential responding emerged more slowly during the learning of the negative patterning discriminations than during learning of the XA+, XB+, XC- control discriminations. Additionally, the negative patterning groups responded more to X than to a separately reinforced Y on unreinforced test trials: thus, X derived superexcitatory properties. This pattern was reversed in the control groups. Results are consistent with theories that allow for different activation patterns when elements are combined. (c) 2004 APA, all rights reserved