Learning and transfer of relational matching-to-sample by pigeons

We trained pigeons on a relational matching-to-sample task to see whether a nonprimate species can discriminate higher-order “relations between relations.” We required the birds to relationally match arrays of 16 items that were chosen from five nonoverlapping sets of 20 colored computer icons. On each trial, randomly selected icons from one set were placed into a 4×4 grid to form a sample; onsame trials, all 16 icons were identical to each other, whereas ondifferent trials, all 16 icons were different from each other. After 10-20 pecks, 16-itemsame anddifferent testing arrays were presented that were created from an entirely different icon set. Because no icons were common to the sample and testing arrays, discriminating higher-order relations was required for success on the tests. As have primates in similar tasks, pigeons successfully learned and transferred this relational discrimination, suggesting that both birds and mammals possess the cognitive antecedents of analogical reasoning.