Effects of Stimulus Discriminability on the Acquisition of Conditional Discriminations in Adult Humans

The current study investigated the effects of the discriminability of sample and comparison stimuli on the acquisition of conditional discriminations in adult humans. In an arbitrary matching-to-sample procedure, five university students were trained on four types of conditional discriminations between simple (one-element) and complex (two-element) stimuli. The matching-to-sample task involved simple-simple, simple-complex, complex-simple, and complex-complex conditional discriminations, where the first term designates the type of sample and the second term designates the type of comparison stimuli. The effects of the discriminability of sample stimuli on the acquisition of conditional discriminations did not differ greatly from those of the comparison stimuli. Nevertheless, the results are in general agreement with prior findings showing that, in a matching-to-sample procedure, the rate of acquisition of conditional discriminations is a function of the discriminability of the sample and comparison stimuli and that the former is a more important variable with respect to the rate of acquisition than the latter.