No abstract

Many researchers have noted the similarities between causal judgment in humans and

Two experiments with rats as subjects investigated whether massive extinction can attenuate the renewal effect. Experiment 1 investigated whether moderate or massive extinction could prevent the return of conditioned responding following Pavlovian conditioning in Context A, extinction in Context B, and subsequent testing in Context C (i.e., ABC renewal). Experiment 2 examined whether massive extinction could prevent renewal following training in Context A, extinction in Context B, and testing in Context A (i.e., ABA renewal). Both experiments observed attenuated renewal following massive, but not moderate extinction. Results are discussed in terms of contemporary theories of extinction.

Three conditioned lick suppression experiments explored the effects on overshadowing of the temporal relationships of two conditioned stimuli (CSs) with an unconditioned stimulus (US). Assuming overshadowing is maximal when the potential information conveyed by two competing CSs is equivalent, the temporal coding hypothesis predicts that greater overshadowing will be observed when the CSs share the same temporal relationship with the US. Rats were exposed to an overshadowing CS that had either a forward, simultaneous, or backward relationship to the US. The relationship of the overshadowed CSs to the US was either forward (Experiment 1), simultaneous (Experiment 2), or backward (Experiment 3). The greatest amount of overshadowing was observed when both CSs had the same temporal relationship to the US. The data are discussed within the framework of the temporal coding hypothesis and of alternative models of Pavlovian conditioning based on the informational hypothesis.

Two experiments with rats investigated the temporal relationships under which conditioned inhibition will transfer to an independently conditioned excitor (CS) in a summation test. Experiment 1 trained 2 simultaneous inhibitors with either a trace or delay excitatory CS. Transfer of inhibitory behavioral control depended on the temporal relationship of the transfer CS to the unconditioned stimulus (US). Experiment 2 extended these findings by training 2 inhibitors (1 simultaneous and 1 serial) with a single delay excitatory CS. Again, testing with trace and delay transfer CSs found that transfer of inhibitor control depended on the temporal relationship of the transfer CS to the US. In both studies, maximal inhibition was observed when the inhibitor signaled US omission at the same time as the transfer excitor signaled US presentation. The results are discussed in terms of the temporal coding hypothesis.