BOTTLE-NOSED DOLPHINS CAN GENERALIZE RULES AND DEVELOP ABSTRACT CONCEPTS

Generalization of a rule is demonstrated if the rule govern a class of problem, and the subject, after successful experience with a limited number of problems, can apply the governing rule to new problems withi n that class. We show that the bottlenose dolphin (Tursiops truncatus) is capable of such generalization for classes of problems requiring t he matching of one of two alternative stimuli to a ''sample'' stimulus to which the animal had been previously exposed, regardless of the se nsory domain used: vision, passive listening, or active echolocation. We also show this generalization capability in a related class of prob lem requiring a judgment of whether a single ''probe'' stimulus is the same as, or different from, a stimulus or stimuli previously presente d. Further, one dolphin was shown capable of developing a true abstrac t concept of same/different through its ability to categorize pairs of simultaneously presented objects as identical or not. The suggestion that such generalization ability of dolphins may be in question becaus e of so-called exclusion effects is shown to be not tenable when the w hole body of available data is considered.