Animal Cognition

, Volume 8, Issue 4, pp 247–252 | Cite as

Analog number representations in mongoose lemurs (Eulemur mongoz): evidence from a search task

  • Kerrie P. Lewis
  • Sarah Jaffe
  • Elizabeth M. Brannon
Original Article


A wealth of data demonstrating that monkeys and apes represent number have been interpreted as suggesting that sensitivity to number emerged early in primate evolution, if not before. Here we examine the numerical capacities of the mongoose lemur (Eulemur mongoz), a member of the prosimian suborder of primates that split from the common ancestor of monkeys, apes and humans approximately 47–54 million years ago. Subjects observed as an experimenter sequentially placed grapes into an opaque bucket. On half of the trials the experimenter placed a subset of the grapes into a false bottom such that they were inaccessible to the lemur. The critical question was whether lemurs would spend more time searching the bucket when food should have remained in the bucket, compared to when they had retrieved all of the food. We found that the amount of time lemurs spent searching was indicative of whether grapes should have remained in the bucket, and furthermore that lemur search time reliably differentiated numerosities that differed by a 1:2 ratio, but not those that differed by a 2:3 or 3:4 ratio. Finally, two control conditions determined that lemurs represented the number of food items, and neither the odor of the grapes, nor the amount of grape (e.g., area) in the bucket. These results suggest that mongoose lemurs have numerical representations that are modulated by Weber’s Law.


Prosimians Lemurs Numerosity Analog magnitude Manual search 



We thank Sarah Cork and Sweta Saxena for assistance with experiment running, videotaping, and video coding; the Duke University Primate Center and its staff, especially Julie Ives and Bill Hess, for facilitating our research there, and in particular Bill Hylander for partial funding of this project. We also thank Jessica Cantlon and Kerry Jordan for helpful discussion, and Michael L. Platt for comments on the manuscript. This research was supported by the John Merck Fund to E.M.B. All procedures described comply with Federal Law concerning the use of animals in research


  1. Beran M (2001) Summation and numerousness judgments of sequentially presented sets of items by chimpanzees (Pan troglodytes). J Comp Psychol 115:181–191Google Scholar
  2. Beran MJ, Beran MM (2004) Chimpanzees remember the results of one-by-one addition of food items to sets over extended time periods. Psychol Sci 15:94–99CrossRefGoogle Scholar
  3. Brannon EM (2002) The development of ordinal numerical knowledge in infancy. Cognition 83:223–240CrossRefGoogle Scholar
  4. Brannon EM, Abbott S, Lutz D (2004) Number bias for the discrimination of large visual sets in infancy. Cognition 93:B59–B68CrossRefGoogle Scholar
  5. Brannon EM, Terrace HS (1998) Ordering of the numerosities 1–9 by monkeys. Science 282:746–749CrossRefGoogle Scholar
  6. Brannon EM, Terrace HS (2000) Representation of the numerosities 1–9 by rhesus monkeys (Macaca mulatta). J Exp Psychol Anim Behav Process 26:31–49CrossRefPubMedGoogle Scholar
  7. Feigenson L, Carey S (2003) Tracking individuals via object-files: evidence from infants’ manual search. Dev Sci 6:568–584CrossRefGoogle Scholar
  8. Feigenson L, Carey S (2005) On the limits of infants’ quantification of small object arrays. Cognition (in press)Google Scholar
  9. Feigenson L, Carey S, Hauser M (2002) The representations underlying infants’ choice of more: object files versus analog magnitudes. Psychol Sci 13:150–156CrossRefGoogle Scholar
  10. Hauser M, Carey S (1998) Building a cognitive creature from a set of primitives: evolutionary and developmental insights. In: Cummins D, Allen C (eds) The evolution of mind. Oxford University Press, New York, pp 51–106Google Scholar
  11. Hauser MD, Carey S, Hauser LB (2000) Spontaneous number representation in semi-free-ranging rhesus monkeys. Proc R Soc Lond 267:829–833CrossRefGoogle Scholar
  12. Hauser MD, Tsao F, Garcia P, Spelke ES (2003) Evolutionary foundations of number: spontaneous representations of numerical magnitudes by cotton-top tamarins. Proc R Soc Lond B 270:1441–1446PubMedGoogle Scholar
  13. Irwin MT, Samonds KE, Raharison JL, Wright PC (2004) Lemur latrines: observations of latrine behavior in wild primates and possible ecological significance. J Mammal 85:420–427Google Scholar
  14. Leslie A, Xu F, Tremoulet P, Scholl B (1998) Indexing and the object concept: developing ‘what’ and ‘where’ systems. Trends Cogn Sci 2:10–18CrossRefGoogle Scholar
  15. Lipton JS, Spelke ES (2003) Origins of number sense: large-number discrimination in human infants. Psychol Sci 14:396–401CrossRefPubMedGoogle Scholar
  16. Meck WH, Church RM (1983) A mode control model of counting and timing processes. J Exp Process Anim Behav Process 9:320–334Google Scholar
  17. Nieder A, Freedman DJ, Miller EK (2002) Representation of the quantity of visual items in the primate prefrontal cortex. Science 297:1708–1711CrossRefGoogle Scholar
  18. Nieder A, Miller EK (2003) Coding of cognitive magnitude: compressed scaling of numerical information in the primate prefrontal cortex. Neuron 37:149–157CrossRefGoogle Scholar
  19. Nieder A, Miller EK (2004a) Analog numerical representations in rhesus monkeys: evidence for parallel processing. J Cogn Neurosci 16:889–901CrossRefGoogle Scholar
  20. Nieder A, Miller EK (2004b) A parieto-frontal network for visual numerical information in the monkey. Proc Natl Acad Sci USA 101:7457–7462CrossRefGoogle Scholar
  21. Pylyshyn ZW, Storm RW (1988) Tracking multiple independent targets: evidence for a parallel tracking mechanism. Spatial Vision 3:179–197Google Scholar
  22. Santos LR, Barnes J, Mahajan N (2005) Expectations about numerical events in four lemur species (Eulemur fulvus, Eulemur mongoz, Lemur catta and Lemur variegatus ruber). Anim Cogn DOI 10.1007/s10071-005-0252-4Google Scholar
  23. Santos LR, Sulkowski GM, Spaepen GM, Hauser MD (2002) Object individuation using property/kind information in rhesus macaques (Macaca mulatta). Cognition 83:241–264CrossRefGoogle Scholar
  24. Simon TJ (1997) Reconceptualizing the origins of number knowledge: a “non-numerical account”. Cogn Dev 12:349–372CrossRefGoogle Scholar
  25. 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 117:217–225CrossRefGoogle Scholar
  26. Trick LM, Pylyshyn ZW (1993) What enumeration studies can show us about spatial attention: evidence for limited capacity preattentive processing. J Exp Psychol Hum Percept Perform 19:331–351CrossRefGoogle Scholar
  27. Trick LM, Pylyshyn ZW (1994) Why are small and large numbers enumerated differently? A limited capacity preattentive stage in vision. Psychol Rev 101:80–102CrossRefGoogle Scholar
  28. Uller C, Carey S, Huntley-Fenner G, Klatt L (1999) What representations might underlie infant numerical knowledge. Cogn Dev 14:1–36Google Scholar
  29. Wynn K (1992) Addition and subtraction by human infants. Nature 358:749–750CrossRefGoogle Scholar
  30. Xu F (2003) Numerosity discrimination in infants: evidence for two systems of representations. Cognition 89(1):B15–B25CrossRefGoogle Scholar
  31. Xu F, Spelke ES (2000) Large number discrimination in 6-month-old infants. Cognition 74:B1–B11CrossRefGoogle Scholar
  32. Yoder AD (2003) Phylogeny of the lemurs. In: Goodman M, Benstead J (eds) The natural history of Madagascar. University of Chicago Press, Chicago, pp 1242–1247Google Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Kerrie P. Lewis
    • 1
  • Sarah Jaffe
    • 2
  • Elizabeth M. Brannon
    • 2
  1. 1.Department of AnthropologyWashington UniversitySt. LouisUSA
  2. 2.Center for Cognitive NeuroscienceDuke UniversityUSA

Personalised recommendations