Research and Links

Dr. Irene Pepperberg has been studying the intelligence and reasoning abilities of the African Grey parrot for almost 40 years. She has published consistently and extensively in some of the most highly respected scientific journals in her field.

Below is a partial list of her papers with links to download in PDF format. If you don’t have Adobe Acrobat Reader, which is necessary to view PDF files, you can download it free by clicking here.

These papers are being provided for private use only, and cannot be published or reprinted without the express permission of the publisher. Quotes from these articles can be used only within the specifications of each publisher. Please consult the individual publishers about their particular guidelines.

We hope you’ll enjoy reading some of Dr. Pepperberg’s research, which has demonstrated the amazing intelligence of African Grey parrots to the scientific world. The list of papers available for download will be expanded as time permits.




Pepperberg, I. M. (2016). Animal language studies: What happened? Psychonomic Bulletin & Review Psychon Bull Rev. doi:10.3758/s13423-016-1101-y

Pepperberg, I. M., & Nakayama, K. (2016). Robust representation of shape in a Grey parrot (Psittacus erithacus). Cognition, 153, 146-160. doi:10.1016/j.cognition.2016.04.014

Koepke, A. E., Gray, S. L., & Pepperberg, I. M. (2015). Delayed gratification: A grey parrot (Psittacus erithacus) will wait for a better reward. Journal of Comparative Psychology, 129(4), 339-346. doi:10.1037/a0039553

Pepperberg, I. M. (2015). Reply to Jaakkola (2014): “Do animals understand invisible displacement? A critical review”. Journal of Comparative Psychology, 129(2), 198-201. doi:10.1037/a0038319

Pepperberg, I. M., & Hartsfield, L. A. (2014). Can Grey parrots (Psittacus erithacus) succeed on a “complex” foraging task failed by nonhuman primates (Pan troglodytes, Pongo abelii, Sapajus apella) but solved by wrasse fish (Labroides dimidiatus)? Journal of Comparative Psychology, 128(3), 298-306. doi:10.1037/a0036205

Péron, F., Thornberg, L., Gross, B., Gray, S., & Pepperberg, I. M. (2014). Human–Grey parrot (Psittacus erithacus) reciprocity: A follow-up study. Animal Cognition Anim Cogn, 17(4), 937-944. doi:10.1007/s10071-014-0726-3

Pepperberg, I. M., Koepke, A., Livingston, P., & Hartsfield, L. A. (2013). Reasoning by inference: Further studies on exclusion in grey parrots (Psittacus erithacus). PsycEXTRA Dataset. doi:10.1037/e598032013-086

Pepperberg, I. M. (2012). Further evidence for addition and numerical competence by a Grey parrot (Psittacus erithacus). Animal Cognition Anim Cogn, 15(4), 711-717. doi:10.1007/s10071-012-0470-5

Pepperberg, I.M., Carey, S. (2012). Grey Parrot Number Acquisition: The Inference of Cardinal Value from Ordinal Position on the Numeral List COGNIT2474

Péron, F., John, M., Sapowicz, S., Bovet, D., & Pepperberg, I. M. (2012). A study of sharing and reciprocity in grey parrots (Psittacus erithacus). Animal Cognition Anim Cogn, 16(2), 197-210. doi:10.1007/s10071-012-0564-0

Schachner, A., Brady, T. F., Pepperberg, I. M., & Hauser, M. D. (2009). Spontaneous Motor Entrainment to Music in Multiple Vocal Mimicking Species. Current Biology, 19(10), 831-836. doi:10.1016/j.cub.2009.03.061

Pepperberg, I.M., Vicinay, J., Cavanagh, P. (2008) The Muller-Lyer illusion is processed by a Grey Parrot (Psittacus erithacus). Perception 37:765-781.

Pepperberg, I.M. (2007a). Grey parrots do not always “parrot”: Phonological awareness and the creation of new labels from existing vocalizations. Language Sciences 29: 1-13.

Pepperberg, I.M. (2006a). Ordinality and inferential abilities of a Grey Parrot (Psittacus erithacus)Journal of Comparative Psychology, 120: 205-216.

Pepperberg, I.M. (2006b). Grey Parrot (Psittacus erithacus) numerical abilities: addition and further experiments on a  zero-like concept. Journal of Comparative Psychology, 120: 1-11.

Pepperberg, I.M., and Gordon, J.D. (2005). Number Comprehension by a Grey Parrot (Psittacus erithacus), Including a Zero-Like ConceptJournal of Comparative. Psychology, 2005, Vol. 119, No. 2, 197-209

Pepperberg, I.M. (2001). Lessons from cognitive ethology: Animal models for ethological computing. Proceedings of the First Conference on Epigenetic Robotics, C. Balkenius, J. Zlatev, H. Kozima, K. Dautenhahn, & C. Breazeal, Eds., Lund University Cognitive Science Series No. 85, Lund, Sweden (online only)

Pepperberg, I.M., Willner, M.R., and Gravitz, L.B. (1997). Development of Piagetian object permanence in a Grey parrot (Psittacus erithacus). J. Comp. Psych. 111:63-75.


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