title: Number-related discrimination and summation by squirrel monkeys (Saimiri sciureus sciureus and S. boliviensus boliviensus) on the basis of the number of sides of polygons.
abstract: In Experiment 1, with the number of sides or angles of irregular polygons as cues, programmed training, and a 90% correct criterion (36 of 40), 2 squirrel monkeys' (Saimiri sciureus sciureus and S. boliviensus boliviensus) best performances were to discriminate heptagons from octagons, a 3rd's best was hexagons from heptagons, and a 4th's best was pentagons from heptagons. In Experiment 2, on most trials 2 polygons on one or both discriminanda had to be summed to determine which discrimination had the total fewer sides. Only 1 monkey met criterion (27 of 30) on the 2 tasks, 6 vs. 8 and 7 vs. 8 sides, but the other 3 performed better than chance on the 6 vs. 8 task. We conclude that previous studies of animals' discrimination of polygons in terms of complexity were minimally relevant to this work, and counting and subitizing were rejected in favor of a prototype-matching process to explain our monkeys' performances.
authors.affiliation: Department of Psychology, University of Georgia, Athens 30602.
authors.forename: D F
authors.initials: DF
authors.lastname: Terrell
authors.forename: R K
authors.initials: RK
authors.lastname: Thomas
mesh_terms: D000818:Animals; D001288:Attention; D003463:Cues; D004193:Discrimination Learning; D008297:Male; D008433:Mathematics; D009949:Orientation; D010364:Pattern Recognition, Visual; D011340:Problem Solving; D012453:Saimiri / Q000523:psychology*; D012858:Size Perception; D013045:Species Specificity