Journal of Comparative Psychology 117 (3), 2003 Bloomfield, Laurie L., Christopher B. Sturdy, Leslie S. Phillmore, and Ronald G. Weisman. 2003. Open-ended categorization of chick-a- dee calls by Black-Capped Chickadees (Poecile atricapilla). pp. 290�301.
Abstract: The authors trained black-capped chickadees (Poecile atricapilla) in an operant discrimination with exemplars of black-capped and Carolina chick-a-dee calls, with the goal of determining whether the birds memorized the calls of conspecifics and heterospecifics or classified the calls by species. Black-capped calls served as both rewarded (S+) and unrewarded (S-) stimuli (the within-category discrimination), whereas Carolina chick-a-dee calls served as S-s (the between-category discrimination) in the black-capped chick-a- dee call S+ group. The Carolina call S+ group had Carolina calls as S+s and S-s (within-category) and black-capped calls as S-s (between-category). Both groups discriminated between call categories faster than within a call category. In 2 subsequent experiments, both S+ groups showed transfer to novel calls and propagation back to between-category calls. The results favor the hypothesis that the acoustically similar social calls of the 2 species constitute separate open-ended categories. ----------------------------------------------------------- Mag. Lidia Eva Wysocki Institute of Zoology, University of Vienna Althanstrasse 14 A-1090 Vienna, Austria Phone: ++43-1-4277/54515 Fax: ++43-1-4277-9544 E-mail: [EMAIL PROTECTED]
