Biomedical subjects

Steven Stout

Publications and source records attributed to Steven Stout.

3 recordsLinked to original sources

PubMed2006

When more is less: extending training of the blocking association following compound training attenuates the blocking effect.

Three conditioned lick suppression experiments with rats were performed to assess the influence, following compound training of two stimuli (A and X) with the same outcome (AX-O trials), of extending training of the blocking association (i.e., A-O) on responding to the target stimulus (X) at test. In Experiment 1, backward blocking was attenuated when the blocking association was extensively trained. Experiment 2 showed that forward blocking was also attenuated by extensive further training of the blocking association following the AX-O trials. Experiment 3 contrasted candidate explanations of the results of Experiments 1 and 2 and demonstrated that these results are consistent with the framework of the extended comparator hypothesis (Denniston, Savastano, & Miller, 2001).

Animals↗

PubMed2004

Comparing excitatory backward and forward conditioning.

Three Pavlovian lick suppression studies with rats were conducted to compare the role of the conditioning context in excitatory backward and forward conditioning. The experiments explored the possibility that excitatory backward conditioning, but not forward conditioning, is mediated by the context. That is, in excitatory backward conditioning, the conditioning context may function as an excitatory mediator, which supports second-order conditioning of the target cue. This possibility contrasts with traditional accounts, which suggests that common processes underlie excitatory backward and forward conditioning. Experiment 1 found that conditioned responding following backward conditioning was attenuated as a result of posttraining extinction of the training context, but the same manipulation elevated responding after forward conditioning. Experiments 2 and 3 found that posttraining and pretraining associative inflation of the context (presenting unsignalled USs) increased conditioned responding to the target of a backward conditioning procedure but either had no effect or reduced responding to the target of a forward conditioning procedure. Thus, excitatory backward and forward conditioning appear to differ in their dependence on the status of the conditioning context.

Analysis of Variance↗

PubMed2004

Trial number and compound stimuli temporal relationship as joint determinants of second-order conditioning and conditioned inhibition.

Two conditioned lick suppression experiments with rats used feature-negative training (A-footshock trials intermixed with nonreinforced XA presentations) to analyze the role of the number of XA compound presentations and the temporal relationship of the elements within the compound (simultaneous or serial) as determinants of the resulting behavioral control. Second-order conditioning (i.e., excitatory behavioral control by X) was observed to decline as the number of XA compound trials was increased. This decline was more rapid if X and A were presented simultaneously, as opposed to serially (i.e., X before A; Experiment 1). Conditioned inhibition to X, as assessed by a summation test (Experiment 1) and a retardation test (Experiment 2), increased with the number of XA trials and did so more quickly for simultaneous than for serial pairings of X and A. The results help to clarify previously discrepant findings regarding factors that promote excitation versus inhibition with this protocol.

Animals↗