Inference based on transitive relation in tree shrews (Tupaia belangeri) and rats (Rattus norvegicus) on a spatial discrimination task

Six tree shrews and 8 rats were tested for their ability to infer transitively in a spatial discrimination task. The apparatus was a semicircular radial-arm maze with 8 arms labeled A through H. In Experiment 1, the animals were first trained in sequence on 4 discriminations to enter 1 of the paired adjacent arms, AB, BC, CD, and DE, with right (or left, for half the animals) symbols signifying positive options, then they were tested with the previously unused pair of arms, FH. All tree shrews and 4 rats transitively chose H (or F for half the animals). In Experiment 2, all tree shrews and 5 rats transitively chose H (or F) on 3-option tests of FGH. The results suggest that these animals used transitive relation in solving novel problems.