Stimulus salience and negative patterning.

Rats in Experiment 1 received a negative patterning discrimination in which food was delivered after either of two auditory stimuli when they were presented individually, but not when they were presented in compound. The stimuli were of different intensity. The discrimination between the compound and the stimulus of lower intensity was acquired more readily than was the discrimination between the compound and the more intense stimulus. A similar pattern of results was found in the remaining two experiments, which also employed a negative patterning discrimination, but either with stimuli from different modalities (Experiment 2) or with pigeons rather than rats (Experiment 3). The results were predicted more readily by a configural than by an elemental theory of conditioning.