Categorical perception and conceptual judgments by nonhuman primates: The paleological monkey and the analogical ape

Studies of the conceptual abilities of nonhuman primates demonstrate the su bstantial range of these abilities as well as their limitations. Such abili ties range from categorization on the basis of shared physical attributes, associative relations and functions to abstract concepts as reflected in an alogical reasoning about relations between relations. The pattern of result s from these studies point to a fundamental distinction between monkeys and apes in both their implicit and explicit conceptual capacities. Monkeys, b ut not apes, might be best regarded as "paleo-logicans" in the sense that t hey form common class concepts of identity on the basis of identical predic ates (i.e., shared features). The discrimination of presumably more abstrac t relations commonly involves relatively simple procedural strategies media ted by associative processes likely shared by all mammals. There is no evid ence that monkeys con perceive, let alone judge, relations-between-relation s. This analogical conceptual capacity is found only in chimpanzees and hum ans. Interestingly, the "analogical ope," like the child, can make its anal ogical knowledge explicit only if it is first provided with a symbol system by which propositional representations con be encoded and manipulated.