A comparative evaluation of the cognitive skills of the chimpanzee and the monkey.

A review of selected aspects of cognitive performance in apes and in monkeys suggests that only rarely can we at this time demonstrate greater cognitive competence in the ape than in the monkey. Instead it seems that the ape's cognitive style differs qualitatively from that of the monkey: not in the direction of greater capacity (using this term as a measure of continuously increasing ability), but in the way that the ape applies itself to a novel situation. From this it would follow that the greater discontinuity lies between man and apes, not between apes and monkeys.