This research compares the time required for perceptual discriminations among pairs of physically present objects (circles) with the time required to discriminate pairs of symbols (nonsense syllables) that subjects learned to associate uniquely with each of the circles. Four experiments show very large differences between symbolic and perceptual discriminations. Discrimination times for the perceptual stimuli declined systematically as their size ratio increased, but discriminations among the associated nonsense syllables showed only a strictly ordinal effect of position in the series. Discriminations among the symbolic stimuli showed a large semantic congruity effect, but the perceptual stimuli showed none. The research does not replicate previous results showing similarities between perceptual and symbolic processing suggestive of image processing. We conclude that in the symbolic task subjects use only ordinal information rather than images or analog representations of the associated circles. We propose that perceptual discriminations show a semantic congruity effect only when they are processed as if the perceptual stimuli were symbolic.The question of how we reason with serial orders is an important one in cognitive psychology, not only because we are frequently called upon to think in terms of serial orders, but also because an understanding of such reasoning will cast light on a broad set of cognitive activities, These cognitive activities include, for example, the process by which a child (or adult) infers a transitive linear ordering of objects on a dimension such as size from experience with a subset of the possible relations among the objects so ordered (cf. Potts, 1972;Trabasso & Riley, 1975), as well as the process by which reasoning with these orderings is accomplished once they are set up.A number of investigators have proposed that people answer questions about short serial orders by using mental imagery or by using "analog" processing that is similar in some respects to mental imagery (cf. Jamieson

The present experiment is similar to Bower's (1970) study on imagery as a relational organizer in paired-associate (PA) learning with normals. Three groups of 20 schizophrenic patients learned three different lists of 30 wordword prtired-associates, which used either interactive imagery, separation imagery, or rote repetition encoding. Ss were tested on stimulus iecognition and paired-associate recall, given recognition. Differences in stimulus recognition and paired-associate recall were not significant across the three encoding methods. Results suggest that schizophrenics are unable to benefit. from imaginal cues to facilitate learning in a manner similar to normals. These results are interpreted as providing additional support for the notion that the schizophrenics' cognitive deficit is associat,ed with the relational organizing process of learning.