RESUMO
Three experiments were conducted to examine the role of novel contextual stimuli in producing the unconditioned stimulus (US) preexposure effect. Experiment 1 demonstrated that novel contextual stimuli produce a significantly stronger US preexposure effect than familiar or "latently inhibited" contextual stimuli. Moreover, subjects preexposed in the presence of latently inhibited contextual cues failed to show a significant US preexposure effect. Experiments 2 and 3 attempted to provide evidence that the addition of a single novel stimulus to the latently inhibited context would result in a significantly stronger US preexposure effect than when no such novel cue was present. Experiment 3 was able to demonstrate this effect. Results are consistent with the Rescorla-Wagner (1972) model of conditioning.
RESUMO
Differential responding to changes in the stimulus situation, long central to the concept of stimulus control, also provides the implicit conceptual basis for assessing the nature of a variety of associative relationships. However, there is substantial evidence that the perception of stimulus similarity is not a static property. Generalization gradients to contextual as well as discriminative stimuli flatten over time, and this increase in perceived similarity presumably reflects forgetting of the detailed characteristics or attributes of stimuli. Methodologically, the flattening of the gradient imposes an important constraint: The effect of a stimulus shift will be highly sensitive to the length of the delay interval between training and testing. Conceptually, the loss of memory for stimulus attributes also implies that the sources of interference in retention can increase over time.
