title: Tests for control by exclusion and negative stimulus relations of arbitrary matching to sample in a "symmetry-emergent" chimpanzee.
abstract: In the present experiments, controlling relations in arbitrary matching-to-sample performance were tested in a 9-year-old female chimpanzee who showed statistically significant emergence of symmetry in previous two-choice conditional discrimination experiments. In Experiment 1, a novel (undefined) sample stimulus was followed by a pair of trained (defined) and undefined comparison stimuli to assess the control by exclusion in arbitrary matching. The chimpanzee selected the undefined shape comparison, excluding the defined one, in color-sample-to-shape-comparison probe trials, although stimulus preferences were relatively stronger than control by exclusion in shape-sample trials. An additional test for control by relations of the sample to the positive comparison (S+ control) showed that her behavior was also under the control of relations of the sample to the positive comparison. In Experiment 2, a defined sample was followed by a pair of negatively defined and undefined comparisons to test control by the relations of the sample to the negative comparison. (S- control). The subject selected undefined comparisons in both color-shape and shape-color test trials. These results clearly indicate that the conditional discrimination behavior of this "symmetry-emergent" chimpanzee was under both S+ and S- control. Furthermore, her performance was also under control by exclusion in color-shape arbitrary matching, unlike other chimpanzees who showed no evidence of symmetry but only S+ control of arbitrary matching.
authors.affiliation: Department of Psychology, Kyoto University, Aichi, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Tomonaga
mesh_terms: D000818:Animals; D001288:Attention; D003118:Color Perception; D003210:Concept Formation; D004193:Discrimination Learning; D005260:Female; D011939:Mental Recall; D002679:Pan troglodytes / Q000523:psychology*; D010364:Pattern Recognition, Visual