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Author (up) 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 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 (up) Ward, C.; Smuts, B.B. doi  openurl
  Title Quantity-based judgments in the domestic dog (Canis lupus familiaris) Type Journal Article
  Year 2007 Publication Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 10 Issue 1 Pages 71-80  
  Keywords Animals; *Choice Behavior; Dogs; Female; Food; Male; *Size Perception  
  Abstract We examined the ability of domestic dogs to choose the larger versus smaller quantity of food in two experiments. In experiment 1, we investigated the ability of 29 dogs (results from 18 dogs were used in the data analysis) to discriminate between two quantities of food presented in eight different combinations. Choices were simultaneously presented and visually available at the time of choice. Overall, subjects chose the larger quantity more often than the smaller quantity, but they found numerically close comparisons more difficult. In experiment 2, we tested two dogs from experiment 1 under three conditions. In condition 1, we used similar methods from experiment 1 and tested the dogs multiple times on the eight combinations from experiment 1 plus one additional combination. In conditions 2 and 3, the food was visually unavailable to the subjects at the time of choice, but in condition 2, food choices were viewed simultaneously before being made visually unavailable, and in condition 3, they were viewed successively. In these last two conditions, and especially in condition 3, the dogs had to keep track of quantities mentally in order to choose optimally. Subjects still chose the larger quantity more often than the smaller quantity when the food was not simultaneously visible at the time of choice. Olfactory cues and inadvertent cuing by the experimenter were excluded as mechanisms for choosing larger quantities. The results suggest that, like apes tested on similar tasks, some dogs can form internal representations and make mental comparisons of quantity.  
  Address Department of Psychology, University of Michigan, 1012 East Hall, 530 Church Street, Ann Arbor, MI 48109-1043, USA. rameses@unich.edu  
  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 1435-9448 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16941158 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2440  
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