1. Aydin A, Pearce JM (1994) Prototype effects in categorization by pigeons. J Exp Psychol ABP 20:264–277
2. Cerella J (1979) Visual classes and natural categories in the pigeon. J Exp Psychol HPP 5:68–77
3. Cook RG, Wright AA, Kendrick DF (1990) Visual categorization by pigeons. In: Commons ML, Herrnstein RJ, Kosslyn SM, Munford DB (eds) Quantitative analysis of behavior, vol 8. Hillsdale, NJ: Erlbaum, pp 187–214
4. Evans TA, Howell S, Westergaard GC (2005) Auditory-visual cross-modal preception of communicative stimuli in tufted capuchin monkeys (Cebus apella). J Exp Psychol ABP 31:399–406
5. Fischer J, Call J, Kaminski J (2004) A pluralistic account of word learning. Trends Cogn Sci 8:481