Animal Cognition

, Volume 9, Issue 4, pp 377–391 | Cite as

Grey parrot numerical competence: a review

  • Irene M. PepperbergEmail author


The extent to which humans and nonhumans share numerical competency is a matter of debate. Some researchers argue that nonhumans, lacking human language, possess only a simple understanding of small quantities, generally less than four. Animals that have, however, received some training in human communication systems might demonstrate abilities intermediate between those of untrained nonhumans and humans. Here I review data for a Grey parrot (Psittacus erithacus) that has been shown to quantify sets of up to and including six items (including heterogeneous subsets) using vocal English labels, to comprehend these labels fully, and to have a zero-like concept. Recent research demonstrates that he can also sum small quantities. His success shows that he understands number symbols as abstract representations of real-world collections, and that his sense of number compares favorably to that of chimpanzees and young human children.


Parrot Numerical ability Cognition 


  1. Benoit L, Lehalle H, Jouen F (2004) Do young children acquire number words through subitizing or counting? Cogn Dev 19:291–307CrossRefGoogle Scholar
  2. Beran MJ (2001) Summation and numerousness judgements of sequentially presented sets of items by chimpanzees (Pan troglodytes). J Comp Psychol 115:181–191PubMedCrossRefGoogle Scholar
  3. Beran MJ (2004) Chimpanzees (Pan troglodytes) respond to nonvisible sets after one-by-one addition and removal of items. J Comp Psychol 118:25–36PubMedCrossRefGoogle Scholar
  4. Beran MJ, Rumbaugh DM (2001) “Constructive” enumeration by chimpanzees (Pan troglodytes) on a computerized task. Anim Cogn 4:81–89CrossRefGoogle Scholar
  5. Bialystok E, Codd J (2000) Representing quantity beyond whole numbers: some, none and part. Can J Exp Psychol 54:117–128PubMedGoogle Scholar
  6. Biro D, Matsuzawa T (2001) Use of numerical symbols by the chimpanzee (Pan troglodytes): cardinals, ordinals, and the introduction of zero. Anim Cogn 4:193–199CrossRefGoogle Scholar
  7. Bowmaker JK, Heath LA, Das D, Hunt DM (1994) Spectral sensitivity and opsin structure of avian rod and cone visual pigments. Invest Ophthalmol Vis Sci 35:1708Google Scholar
  8. Bowmaker JK, Heath LA, Wilkie SE, Das D, Hunt DM (1996) Middle-wave cone and rod visual pigments in birds: spectral sensitivity and opsin structure. Invest Ophthalmol Vis Sci 37:S804Google Scholar
  9. Boysen ST (1993) Counting in chimpanzees: nonhuman principles and emergent properties of number. In: Boysen ST, Capaldi EJ (eds) The development of numerical competence: animal and human models. Erlbaum, Hillsdale, NJ, pp 39–59Google Scholar
  10. Boysen ST, Berntson GG (1989) Numerical competence in a chimpanzee. J Comp Psychol 103:23–31PubMedCrossRefGoogle Scholar
  11. Boysen ST, Berntson GG (1990) The development of numerical skills in the chimpanzee. In: Parker ST, Gibson KR (eds) ‘Language’ and intelligence in monkeys and apes: comparative developmental perspectives. Cambridge University Press, Cambridge, UK, pp 435–450Google Scholar
  12. Boysen ST, Hallberg KI (2000) Primate numerical competence: contributions toward understanding nonhuman cognition. Cogn Sci 24:423–443CrossRefGoogle Scholar
  13. Brannon EM, Terrace HS (1998) Ordering of the numerosities 1–9 by monkeys. Science 282:746–749PubMedCrossRefGoogle Scholar
  14. Brannon EM, Terrace HS (2000) Representation of the numerosities 1–9 by rhesus macaques. J Exp Psychol: Anim Behav Proc 26:31–49CrossRefGoogle Scholar
  15. Brannon EM, Wusthoff CJ, Gallistel CR, Gibbon J (2001) Numerical subtraction in the pigeon: evidence for a linear subjective number scale. Psychol Sci 12:238–243PubMedCrossRefGoogle Scholar
  16. Braun H (1952) Uber das Unterscheidungsvermögen unbenannter Anzahlen bei Papageien [Concerning the ability of parrots to distinguish unnamed numbers.] Z Tierpsychol 9:40–91Google Scholar
  17. Brysbaert M (1995) Arabic number reading: on the nature of the numerical scale and the origin of phonological recoding. J Exp Psychol: Gen 125:435–452Google Scholar
  18. Butterworth B (1995) Editorial. Math Cogn 1:1–2Google Scholar
  19. Butterworth B, Zorzi M, Girelli L, Jonckheere AR (2001) Storage and retrieval of addition facts: the role of number comparison. Q J Exp Psychol 54A:1005–1029CrossRefGoogle Scholar
  20. Call J (2000) Estimating and operating on discrete quantities in orangutans (Pongo pygmaeus). J Comp Psychol 114:136–147PubMedCrossRefGoogle Scholar
  21. Carey S (2004) Bootstrapping & the origin of concepts. Dædalus Winter:1–10Google Scholar
  22. Clearfield M (2004) Infants' enumeration of dynamic displays. Cogn Dev 19:309–324CrossRefGoogle Scholar
  23. Colvin MK, Funnell MG, Gazzaniga MS (2005) Numerical processing in the two hemispheres: studies of a split-brain patient. Brain Cogn 57:43–52PubMedCrossRefGoogle Scholar
  24. Coull JT, Nobre A (1998) Where and when to pay attention: the neural systems for directing attention to spatial locations and to time intervals as revealed by both PET and fMRI. J Neurosci 18:7426–7435PubMedGoogle Scholar
  25. Davis H, Pérusse R (1988) Numerical competence in animals: definitional issues, current evidence, and a new research agenda. Behav Brain Sci 11:561–615Google Scholar
  26. Dehaene S (1997) The number sense. Oxford University Press, OxfordGoogle Scholar
  27. Dehaene S (2001) Subtracting pigeons: logarithmic or linear? Psychol Sci 12:244–246PubMedCrossRefGoogle Scholar
  28. Dehaene S, Changeux J (1993) Development of elementary numerical abilities: a neuronal model. J Cogn Neurosci 5:390–407CrossRefGoogle Scholar
  29. Dehaene S, Cohen L (1994) Dissociable mechanisms of subitizing and counting: neuropsychological evidence from simultanoagnosis patients. J Exp Psychol: Hum Percept Perform 20:958–975CrossRefGoogle Scholar
  30. Dehaene S, Spelke E, Pinel P, Stanescu R, Tsivkin S (1999) Sources of mathematical thinking: behavioral and brain imaging evidence. Science 284:970–974PubMedCrossRefGoogle Scholar
  31. Dehaene S, Piazza M, Pinel P, Cohen L (2003) Three parietal circuits for number processing. Cogn Neuropsychol 20:487–506CrossRefGoogle Scholar
  32. Dehaene S, Molko N, Cohen L, Wilson A (2004) Arithmetic and the brain. Cur Opin Neurobiol 14:218–224CrossRefGoogle Scholar
  33. Emmerton J, Lohmann A, Niemann J (1997) Pigeons’ serial ordering of numerosity with visual arrays. Anim Learn Behav 25:234–244Google Scholar
  34. Feigenson L (2005) A double-dissociation in infants' representations of object arrays. Cognition 95:B37–B48PubMedCrossRefGoogle Scholar
  35. Feigenson L, Dehaene S, Spelke E (2004) Core systems of number. Trends Cogn Sci 8:307–314PubMedCrossRefGoogle Scholar
  36. Fias W, Lammertyn J, Reynvoet B, Dupont P, Orban GA (2003) Parietal representation of symbolic and nonsymbolic magnitude. J Cogn Neurosci 15:47–57PubMedCrossRefGoogle Scholar
  37. Fuson KC (1988) Children's counting and concepts of number. Springer-Verlag, Berlin Heidelberg New YorkGoogle Scholar
  38. Gallistel CR (1988) Counting versus subitizing versus the sense of number. Behav Brain Sci 11:585–586Google Scholar
  39. Gallistel CR, Gelman R (1992) Preverbal and verbal counting and computation. Cognition 44:43–74PubMedCrossRefGoogle Scholar
  40. Gelman R, Gallistel CR (1986) The child's understanding of number, 2nd edn. Harvard University Press, Cambridge, MAGoogle Scholar
  41. Glanville AD, Dallenbach KM (1929) The range of attention. Am J Psychol 41:207–236CrossRefGoogle Scholar
  42. Göbel SM, Rushworth MFS (2004) Cognitive neuroscience: acting on numbers. Curr Biol 14:R517–R519PubMedCrossRefGoogle Scholar
  43. Göbel SM, Rushworth MFS, Walsh V (2001a) rTMS disrupts the representation of small numbers in supramarginal gyrus. NeuroImage 13(Suppl 1):40Google Scholar
  44. Göbel SM, Walsh V, Rushworth MFS (2001b) The mental number line and the human angular gyrus. NeuroImage 14:1278–1289PubMedCrossRefGoogle Scholar
  45. Göbel SM, Johansen-Berg H, Behrens T, Rushworth MFS (2004) Response-selection-related parietal activation during number comparison. J Cogn Neurosci 16:1536–1551PubMedCrossRefGoogle Scholar
  46. Golinkoff RM, Hirsh-Pasek K, Cauley KM, Gordon L (1987) The eyes have it: lexical and syntactic comprehension in a new paradigm. J Child Lang 14:23–45PubMedGoogle Scholar
  47. Gordon P (2004) Numerical cognition without words: evidence from Amazonia. Science 306:496–499PubMedCrossRefGoogle Scholar
  48. Gorsuch RL, Figueredo AJ (1991) Sequential canonical analysis as an exploratory form of path analysis. Paper presented at the American Evaluation Association Conference, October, Chicago, ILGoogle Scholar
  49. Greeno JG, Riley MS, Gelman R (1984) Conceptual competence and children's counting. Cogn Psychol 16:94–143CrossRefGoogle Scholar
  50. Jarvis ED, Güntürkün O, Bruce L, Csillag A, Karten H, Kuenzel W, Medina L, Paxinos G, Perkel DJ, Shimizu T, Striedter G, Wild JM, Ball GF, Dugas-Ford J, Durand SE, Hough GE, Husband S, Kubikova L, Lee DW, Mello CV, Powers A, Siang C, Smulders TV, Wada K, White SA, Yamamoto K, Yu J, Reiner A, Butler AB (2005) Avian brains and a new understanding of vertebrate evolution. Nat Rev Neurosci 6:151–159PubMedCrossRefGoogle Scholar
  51. Jevons WS (1871) The power of numerical discrimination. Nature 3:281–282Google Scholar
  52. Jordan KE, Brannon EM (2006) Weber's Law influences numerical representations in rhesus macaques (Macaca mulatta). Anim Cogn 9:159–172PubMedCrossRefGoogle Scholar
  53. Jordan K, Schadow J, Wuestenberg T, Heinze H-J, Jäncke L (2004) Different cortical activations for subjects using allocentric or egocentric strategies in a virtual navigation task. Brain Imaging 15:135–140Google Scholar
  54. Kaufman EL, Lord MW, Reese TW, Volkmann J (1949) The discrimination of visual number. Am J Psychol 62:498–525PubMedCrossRefGoogle Scholar
  55. Kawai N, Matsuzawa T (2000) Numerical memory span in a chimpanzee. Nature 403:39–40PubMedCrossRefGoogle Scholar
  56. Kilian A, Yaman S, von Fersen L, Güntürkün O (2003) A bottlenosed dolphin discriminates visual stimuli differing in numerosity. Learn Behav 31:133–142PubMedGoogle Scholar
  57. Kline M (1972) Mathematical thought from ancient to modern times - Oxford University Press, New YorkGoogle Scholar
  58. Koehler O (1943) ‘Zähl’-Versuche an einem Kolkraben und Vergleichsversuche an Menschen [Number assessment by a raven and comparative assessments by humans]. Z Tierpsychol 5:575–712Google Scholar
  59. Koehler O (1950) The ability of birds to ‘count’. Bull Anim Behav Soc 9:41–45Google Scholar
  60. Lemer C, Dehaene S, Spelke E, Cohen L (2003) Approximate quantities and exact number words: dissociable systems. Neuropsychologia 41:1942–1958PubMedCrossRefGoogle Scholar
  61. Lenneberg EH (1971) Of language, knowledge, apes, and brains. J Psychol Res 1:1–29CrossRefGoogle Scholar
  62. Lewis KP, Jaffe S, Brannon EM (2005) Analog number representations in mongoose lemurs (Eulemur mongoz): evidence from a search task. Anim Cogn 8:247–252PubMedCrossRefGoogle Scholar
  63. Lögler P (1959) Versuche zur Frage des “Zahl” Vermögens an einem Graupapagei und Vergleichsversuche an Menschen [Experiments regarding the counting ability of a gray parrot and comparative experiments with humans]. Z Tierpsychol 16:179–217Google Scholar
  64. Lyon BE (2003) Egg recognition and counting reduce costs of avian conspecific brood parasitism. Nature 422:495–499PubMedCrossRefGoogle Scholar
  65. Mandler G, Shebo BJ (1982) Subitizing: an analysis of its component processes. J Exp Psychol: Gen 111:1–22CrossRefGoogle Scholar
  66. Matsuzawa T (1985) Use of numbers by a chimpanzee. Nature 315:57–59PubMedCrossRefGoogle Scholar
  67. McComb K, Packer C, Pusey A (1994) Roaring and numerical assessment in contests between groups of female lions, Pantera leo. Anim Behav 47:379–387CrossRefGoogle Scholar
  68. Meck W, Church R (1983) A mode control model of counting and timing processes. J Exp Psychol: Anim Behav Proc 9:320–334CrossRefGoogle Scholar
  69. Mitchell RW, Yao P, Sherman PT, O’Regan M (1985) Discriminative responding of a dolphin (Tursiops truncatus) to differentially rewarded stimuli. J Comp Psychol 99:218–225CrossRefGoogle Scholar
  70. Mix K, Huttenlocher J, Levine SC (2002) Quantitative development in infancy and early childhood. Oxford University Press, New YorkGoogle Scholar
  71. Murofushi K (1997) Numerical matching behavior by a chimpanzee (Pan troglodytes): subitizing and analogue magnitude estimation. Jpn Psychol Res 39:140–153CrossRefGoogle Scholar
  72. Nieder A, Miller EK (2003) Coding of cognitive magnitude: compressed scaling of numerical information in the primate prefrontal cortex. Neuron 37:149–157PubMedCrossRefGoogle Scholar
  73. Nieder A, Freedman DJ, Miller EK (2002) Representation of the quantity of visual items in the primate prefrontal cortex. Science 297:1708–1711PubMedCrossRefGoogle Scholar
  74. Olthof A, Roberts WA (2000) Summation of symbols by pigeons (Columba livia): the importance of number and mass of reward items. J Comp Psychol 114:158–166PubMedCrossRefGoogle Scholar
  75. Olthof A, Iden CM, Roberts WA (1997) Judgments of ordinality and summation of number symbols by squirrel monkeys (Saimiri sciureus). J Exp Psychol: Anim Behav Proc 23:325–333CrossRefGoogle Scholar
  76. Orlov T, Yakovlev V, Amit D, Hochstein S, Zohary E (2002) Serial memory strategies in macaque monkeys: behavioral and theoretical aspects. Cerebral Cortex 12:306–317PubMedCrossRefGoogle Scholar
  77. Patterson DK, Pepperberg IM (1994) A comparative study of human and parrot phonation: I. Acoustic and articulatory correlates of vowels. JASA 96:634–648Google Scholar
  78. Patterson DK, Pepperberg IM (1998) A comparative study of human and Grey parrot phonation: acoustic and articulatory correlates of stop consonants. JASA 103:2197–2213Google Scholar
  79. Peignot P, Anderson JR (1999) Use of experimenter-given manual and facial cues by gorillas (Gorilla gorilla) in an object-choice task. J Comp Psychol 113:253–260CrossRefGoogle Scholar
  80. Pepperberg IM (1981) Functional vocalizations by an African Grey parrot. Z Tierpsychol 55:139–160Google Scholar
  81. Pepperberg IM (1987) Evidence for conceptual quantitative abilities in the African Grey parrot: labeling of cardinal sets. Ethology 75:37–61CrossRefGoogle Scholar
  82. Pepperberg IM (1988) Comprehension of ‘absence’ by an African Grey parrot: learning with respect to questions of same/different. JEAB 50:553–564CrossRefGoogle Scholar
  83. Pepperberg IM (1990) Cognition in an African Grey parrot (Psittacus erithacus): further evidence for comprehension of categories and labels. J Comp Psychol 104:41–52CrossRefGoogle Scholar
  84. Pepperberg IM (1992) Proficient performance of a conjunctive, recursive task by an African Grey parrot (Psittacus erithacus). J Comp Psychol 106:295–305PubMedCrossRefGoogle Scholar
  85. Pepperberg IM (1994) Evidence for numerical competence in an African Grey parrot (Psittacus erithacus). J Comp Psychol 108:36–44CrossRefGoogle Scholar
  86. Pepperberg IM (1999) The Alex studies: cognitive and communicative abilities of Grey parrots. Harvard University Press, Cambridge, MAGoogle Scholar
  87. Pepperberg IM (2006a) Grey Parrot numerical abilities: addition and further experiments on a zero-like concept. J Comp Psychol 120:1–11PubMedCrossRefGoogle Scholar
  88. Pepperberg IM (2006b) Ordinality and transitive inference abilities of a Grey parrot. J Comp Psychol 120Google Scholar
  89. Pepperberg IM, Brezinsky MV (1991) Acquisition of a relative class concept by an African Grey Parrot (Psittacus erithacus): discriminations based on relative size. J Comp Psychol 105:286–294PubMedCrossRefGoogle Scholar
  90. Pepperberg IM, Gordon JD (2005) Number comprehension by a Grey parrot (Psittacus erithacus), including a zero-like concept. J Comp Psychol 119:197–209PubMedCrossRefGoogle Scholar
  91. Premack D (1976) Intelligence in ape and man. Erlbaum, Hillsdale, NJGoogle Scholar
  92. Premack D (1983) The codes of man and beast. Behav Brain Sci 6:125–176CrossRefGoogle Scholar
  93. Rousselle L, Palmer E, Noël M-P (2004) Magnitude comparison in preschoolers: what counts? Influence of perceptual variables. J Exp Child Psychol 87:57–84PubMedCrossRefGoogle Scholar
  94. Rumbaugh DM, Savage-Rumbaugh ES, Hegel M (1987) Summation in a chimpanzee (Pan troglodytes). J Exp Psychol: Anim Behav Proc 13:107–115CrossRefGoogle Scholar
  95. Rumbaugh DM, Savage-Rumbaugh ES, Pate JL (1988) Addendum to “Summation in a chimpanzee (Pan troglodytes).” J Exp Psychol: Anim Behav Proc 14:118–120CrossRefGoogle Scholar
  96. Santos LR, Barnes JL, Mahajan N (2005) Expectations about numerical events in four lemur species (Eulemur fulvus, Eulemur mongoz, Lemur catta and Varecia rubra). Anim Cogn 8:253–262PubMedCrossRefGoogle Scholar
  97. Savage-Rumbaugh ES, Rumbaugh DM, Boysen S (1980) Do apes use language? Am Sci 68:49–61Google Scholar
  98. Savage-Rumbaugh S, Murphy J, Sevcik RA, Brakke KE, Williams SL, Rumbaugh DM (1993) Language comprehension in ape and child. Mono Soc Res Child Dev 233:1–258Google Scholar
  99. Seibt U (1982) Zahlbegriff und Zählverhalten bei Tieren: (Neue Versuche und Deutungen). Z Tierpsych 60:325–341Google Scholar
  100. Shumaker RW, Palkovich AM, Beck BB, Guagnano GA, Morowitz H (2001) Spontaneous use of magnitude discrimination and ordination by the orangutan (Pongo pygmaeus). J Comp Psychol 115:385–391PubMedCrossRefGoogle Scholar
  101. Siegel LS (1982) The development of quantity concepts: perceptual and linguistic factors. In: Brainerd CJ (ed) Children's logical and mathematical cognition. Springer-Verlag, Berlin Heidelberg New York, pp 123–155Google Scholar
  102. Siegler RS (1987) The perils of averaging data over strategies: an example from children's addition. J Exp Psychol: Gen 12:349–372Google Scholar
  103. Simon TJ (1999) The foundations of numerical thinking in a brain without numbers. TINS 3:363–365Google Scholar
  104. Smirnova AA, Lazareva OF, Zorina ZA (2000) Use of number by crows: investigation by matching and oddity learning. JEAB 73:163–176CrossRefGoogle Scholar
  105. Smith BR, Piel AK, Candland DK (2003) Numerity of a socially housed hamadryas baboon (Papio hamadryas) and a socially housed squirrel monkey (Saimiri sciureus). J Comp Psychol 117:217–225PubMedCrossRefGoogle Scholar
  106. Sophian C (1995) Children's numbers. Brown and Benchmark, Madison, WIGoogle Scholar
  107. Spelke ES, Tsivkin S (2001) Language and number: a bilingual training study. Cognition 78:45–88PubMedCrossRefGoogle Scholar
  108. Starkey P, Cooper RG (1995) The development of subitizing in young children. Br J Dev Psychol 13:399–420Google Scholar
  109. Sulkowski GM, Hauser MD (2001) Can rhesus monkeys spontaneously subtract? Cognition 79:239–262PubMedCrossRefGoogle Scholar
  110. Templeton CN, Greene E, Davis K (2005) Allometry of alarm calls: black-capped chickadees encode information about predator size. Science 5730:1934–1937CrossRefGoogle Scholar
  111. Thompson NS (1968) Counting and communication in crows. Commun Behav Biol 2:223–225Google Scholar
  112. Trick L, Pylyshyn Z (1989) Subitizing and the FNST spatial index model. University of Ontario, Ontario, Canada, COGMEM #44Google Scholar
  113. Trick L, Pylyshyn Z (1994) Why are small and large numbers enumerated differently? A limited-capacity preattentive stage in vision. Psychol Rev 101:80–102PubMedCrossRefGoogle Scholar
  114. Uller C, Carey S, Huntley-Fenner G, Klatt L (1999) What representations might underlie infant numerical knowledge? Cogn Dev 14:1–36CrossRefGoogle Scholar
  115. Vick S-J, Anderson JR (2003) Use of human visual attention cues by olive baboons (Papio anubis) in a competitive task. J Comp Psychol 117:209–216PubMedCrossRefGoogle Scholar
  116. von Glasersfeld E (1982) Subitizing: the role of figural patterns in the development of numerical concepts. Arch Psychol 50:191–218Google Scholar
  117. Walsh V (2003) Cognitive neuroscience: numerate neurons. Curr Biol 13:R447–R448PubMedCrossRefGoogle Scholar
  118. Watanabe S, Huber L (2006) Animal logics: decision in the absence of human language. Anim Cogn 9 DOI 10.1007/s10071-006-0043-6Google Scholar
  119. Waxman SR, Markow DB (1995) Words as invitations to form categories: evidence from 12- to 13-month-old infants. Cogn Psychol 29:257–302CrossRefPubMedGoogle Scholar
  120. Wellman HM, Miller KF (1986) Thinking about nothing: development of concepts of zero. Br J Dev Psychol 4:31–42Google Scholar
  121. West RE, Young RJ (2002) Do domestic dogs show any evidence of being able to count? Anim Cogn 5:183–186PubMedGoogle Scholar
  122. Wolfgramm J, Todt D (1982) Pattern and time specificity in vocal responses of blackbirds Turdus merula L. Behaviour 81:264–286Google Scholar
  123. Wynn K (1990) Children's understanding of counting. Cognition 36:155–193PubMedCrossRefGoogle Scholar
  124. Xia L, Siemann M, Delius JD (2000) Matching of numerical symbols with number of responses by pigeons. Anim Cogn 3:35–43CrossRefGoogle Scholar
  125. Xia L, Emmerton J, Siemann M, Delius JD (2001) Pigeons (Columba livia) learn to link numerosities with symbols. J Comp Psychol 115:83–91PubMedCrossRefGoogle Scholar
  126. Xu F (2003) Numerosity discrimination in infants: evidence for two systems of representations. Cognition 89:B15–B25PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Department of PsychologyBrandeis UniversityWalthamUSA
  2. 2.Department of PsychologyHarvard University, William James Hall, Vision Science CenterCambridgeUSA

Personalised recommendations