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Author Pepperberg, I.M.; Brezinsky, M.V. doi  openurl
  Title Acquisition of a relative class concept by an African gray parrot (Psittacus erithacus): discriminations based on relative size Type Journal Article
  Year 1991 Publication Journal of Comparative Psychology Abbreviated Journal J Comp Psychol  
  Volume 105 Issue 3 Pages 286-294  
  Keywords Animals; Aptitude; *Concept Formation; *Discrimination Learning; Form Perception; Male; Mental Recall; *Parrots; *Size Perception; Vocalization, Animal  
  Abstract (up) We report that an African gray parrot (Psittacus erithacus), Alex, responds to stimuli on a relative basis. Previous laboratory studies with artificial stimuli (such as pure tones) suggest that birds make relational responses as a secondary strategy, only after they have acquired information about the absolute values of the stimuli. Alex, however, after learning to respond to a small set of exemplars on the basis of relative size, transferred this behavior to novel situations that did not provide specific information about the absolute values of the stimuli. He responded to vocal questions about which was the larger or smaller exemplar by vocally labeling its color or material, and he responded “none” if the exemplars did not differ in size. His overall accuracy was 78.7%.  
  Address Northwestern University  
  Corporate Author Thesis  
  Publisher Place of Publication Washington, D.C. : 1983 Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0735-7036 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:1935007 Approved yes  
  Call Number Equine Behaviour @ team @ Serial 3610  
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Author Fischer, J.; Cheney, D.L.; Seyfarth, R.M. doi  openurl
  Title Development of infant baboons' responses to graded bark variants Type Journal Article
  Year 2000 Publication Proceedings. Biological sciences / The Royal Society Abbreviated Journal Proc Biol Sci  
  Volume 267 Issue 1459 Pages 2317-2321  
  Keywords *Animal Communication; Animals; Behavior, Animal; Female; Male; Models, Psychological; Papio/growth & development/*physiology; *Vocalization, Animal  
  Abstract (up) We studied the development of infant baboons' (Papio cynocephalus ursinus) responses to conspecific 'barks' in a free-ranging population in the Okavango Delta, Botswana. These barks grade from tonal, harmonically rich calls into calls with a more noisy, harsh structure. Typically, tonal variants are given when the signaller is at risk of losing contact with the group or a particular individual ('contact barks'), whereas harsh variants are given in response to predators ('alarm barks'). We conducted focal observations and playback experiments in which we presented variants of barks recorded from resident adult females. By six months of age, infants reliably discriminated between typical alarm and contact barks and they responded more strongly to intermediate alarm calls than to typical contact barks. Infants of six months and older also recognized their mothers by voice. The ability to discriminate between different call variants developed with increasing age. At two and a half months of age, infants failed to respond at all, whereas at four months they responded irrespective of the call type that was presented. At six months, infants showed adult-like responses by responding strongly to alarm barks but ignoring contact barks. We concluded that infants gradually learn to attach the appropriate meaning to alarm and contact barks.  
  Address Department of Psychology, University of Pennsylvania, 3815 Walnut Street, Philadelphia, PA 19104, USA. fischerj@eva.mpg.de  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0962-8452 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:11413649 Approved no  
  Call Number refbase @ user @ Serial 694  
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