A CALIFORNIA SEA LION (ZALOPHUS-CALIFORNIANUS) IS CAPABLE OF FORMING EQUIVALENCE-RELATIONS

If a nonhuman animal matches the silhouette ''crab'' (A) to that of a ''tulip'' (B) and is further taught to match ''tulip'' (B) to the silhouette ''radio'' (C), will it immediately match ''radio'' (C) to ''crab'' (A)? To date formation of an equivalence relation of this type has not been demonstrated in animals. In our study, designed to give a sea lion match-to-sample experience with examples of sample and comparison stimuli switching roles, a 7-year-old female (Rio) was trained and tested with 30 potential classes, each consisting of 3 different shapes. Twelve of the 30 classes were used for training relational properties of symmetry and transitivity, and 18 classes were reserved for a final equivalence test. Following an initial failure to do symmetry on the first trial of novel relations (B-->A: 8/12), Rio did symmetry (C-->B: 11/12) and transitivity. (A-->C: 11/12) before mastering equivalence on the first trial of 18 novel relations (C-->A: 16/18). Results suggest that equivalence concepts are not mediated by language, but may be a prerequisite for linguistic competence.