ABSTRACT
This chapter discusses how search speeds reflect the pairwise similarities of forms, how these similarities may define significant aspects of form, and how these aspects may jointly contribute to the similarity and categorization of forms. Pigeons and humans seem to face many similar adaptive problems in the use of visual information. Pigeons learn search tasks easily and perform them with great accuracy, aided perhaps by their species-typical foraging predispositions. Instead of learning specific form discriminations one after the other, pigeons become equally familiar with all the forms. The method thus overcomes the effect of learning order, which may seriously confound the results of other procedures. Like humans, pigeons seem more easily to find objects marked by the presence of a feature than by the absence of a feature, and like humans, pigeons appear to bring memory more strongly to bear on a target than on a background.
