Abstract

Tests were carried out on 18 primates, using the direct method involved in the authors’ previous studies. The results showed “increased capacity in order from the lemur, platyrrhine monkeys, catarrhine monkeys to the baboons. Attention is especially called to the clear superiority of the latter, since they have often been thought inferior. There was found in these tests a consistent performance characteristic of the groups. Some indications of age differences in primate capacity for delay are cited.”