Animal Cognition

, Volume 15, Issue 4, pp 711–717

Further evidence for addition and numerical competence by a Grey parrot (Psittacus erithacus)

Short Communication


A Grey parrot (Psittacus erithacus), able to quantify sets of eight or fewer items (including heterogeneous subsets), to sum two sequentially presented sets of 0–6 items (up to 6), and to identify and serially order Arabic numerals (1–8), all by using English labels (Pepperberg in J Comp Psychol 108:36–44, 1994; J Comp Psychol 120:1–11, 2006a; J Comp Psychol 120:205–216, 2006b; Pepperberg and Carey submitted), was tested on addition of two Arabic numerals or three sequentially presented collections (e.g., of variously sized jelly beans or nuts). He was, without explicit training and in the absence of the previously viewed addends, asked, “How many total?” and required to answer with a vocal English number label. In a few trials on the Arabic numeral addition, he was also shown variously colored Arabic numerals while the addends were hidden and asked “What color number (is the) total?” Although his death precluded testing on all possible arrays, his accuracy was statistically significant and suggested addition abilities comparable with those of nonhuman primates.


Parrot cognition Parrot numerical competence Nonhuman addition Avian cognition 

Supplementary material

10071_2012_470_MOESM1_ESM.doc (30 kb)
Supplementary material 1 (DOC 28 kb)
10071_2012_470_MOESM2_ESM.doc (26 kb)
Supplementary material 2 (DOC 27 kb)

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Department of PsychologyHarvard UniversityCambridgeUSA

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