title: The role of reference points in ordinal numerical comparisons by rhesus macaques (Macaca mulatta).
abstract: Two experiments examined ordinal numerical knowledge in rhesus macaques (Macaca mulatta). Experiment 1 replicated the finding (E. M. Brannon & H. S. Terrace, 2000) that monkeys trained to respond in descending numerical order (4-->3-->2-->1) did not generalize the descending rule to the novel values 5-9 in contrast to monkeys trained to respond in ascending order. Experiment 2 examined whether the failure to generalize a descending rule was due to the direction of the training sequence or to the specific values used in the training sequence. Results implicated 3 factors that characterize a monkey's numerical comparison process: Weber's law, knowledge of ordinal direction, and a comparison of each value in a test pair with the reference point established by the first value of the training sequence.
authors.affiliation: Center for Cognitive Neuroscience and Department of Psychological and Brain Sciences, Duke University, Durham, NC 27708, USA. brannon@duke.edu
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Brannon
authors.forename: Jessica F
authors.initials: JF
authors.lastname: Cantlon
authors.forename: Herbert S
authors.initials: HS
authors.lastname: Terrace
mesh_terms: D000818:Animals; D003071:Cognition; D004192:Discrimination, Psychological; D005793:Generalization, Psychological; D008253:Macaca mulatta / Q000523:psychology*; D008297:Male; D008433:Mathematics; D010364:Pattern Recognition, Visual