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Author Jordan, K.E.; Brannon, E.M. doi  openurl
  Title Weber's Law influences numerical representations in rhesus macaques (Macaca mulatta) Type Journal Article
  Year 2006 Publication (up) Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 9 Issue 3 Pages 159-172  
  Keywords Animals; *Attention; *Discrimination (Psychology); Female; Macaca mulatta/*psychology; Mathematics; *Pattern Recognition, Visual; Perceptual Masking; *Problem Solving; Psychological Theory; Psychometrics  
  Abstract We present the results of two experiments that probe the ability of rhesus macaques to match visual arrays based on number. Three monkeys were first trained on a delayed match-to-sample paradigm (DMTS) to match stimuli on the basis of number and ignore continuous dimensions such as element size, cumulative surface area, and density. Monkeys were then tested in a numerical bisection experiment that required them to indicate whether a sample numerosity was closer to a small or large anchor value. Results indicated that, for two sets of anchor values with the same ratio, the probability of choosing the larger anchor value systematically increased with the sample number and the psychometric functions superimposed. A second experiment employed a numerical DMTS task in which the choice values contained an exact numerical match to the sample and a distracter that varied in number. Both accuracy and reaction time were modulated by the ratio between the correct numerical match and the distracter, as predicted by Weber's Law.  
  Address Department of Psychological & Brain Sciences, Center for Cognitive Neuroscience, Duke University, Box 90999, Durham, NC 27708, USA  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 1435-9448 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16575587 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2471  
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Author Lewis, K.P.; Jaffe, S.; Brannon, E.M. doi  openurl
  Title Analog number representations in mongoose lemurs (Eulemur mongoz): evidence from a search task Type Journal Article
  Year 2005 Publication (up) Animal Cognition Abbreviated Journal Anim. Cogn.  
  Volume 8 Issue 4 Pages 247-252  
  Keywords Analysis of Variance; Animals; *Behavior, Animal; *Feeding Behavior; Female; Lemuridae/*psychology; Male; Mathematics; Odors; Smell/physiology; Time Factors  
  Abstract 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.  
  Address Department of Anthropology, Washington University, St. Louis, MO 63130-4899, USA  
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  Series Volume Series Issue Edition  
  ISSN 1435-9448 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15660208 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2497  
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Author Brannon, E.M.; Cantlon, J.F.; Terrace, H.S. doi  openurl
  Title The role of reference points in ordinal numerical comparisons by rhesus macaques (Macaca mulatta) Type Journal Article
  Year 2006 Publication (up) Journal of Experimental Psychology. Animal Behavior Processes Abbreviated Journal J Exp Psychol Anim Behav Process  
  Volume 32 Issue 2 Pages 120-134  
  Keywords Animals; *Cognition; *Discrimination (Psychology); *Generalization (Psychology); Macaca mulatta/*psychology; Male; Mathematics; *Pattern Recognition, Visual  
  Abstract Two experiments examined ordinal numerical knowledge in rhesus macaques (Macaca mulatta). Experiment 1 replicated the finding (E. M. Brannon & H. S. Terrace, 2000) that monkeys trained to respond in descending numerical order (4-->3-->2-->1) did not generalize the descending rule to the novel values 5-9 in contrast to monkeys trained to respond in ascending order. Experiment 2 examined whether the failure to generalize a descending rule was due to the direction of the training sequence or to the specific values used in the training sequence. Results implicated 3 factors that characterize a monkey's numerical comparison process: Weber's law, knowledge of ordinal direction, and a comparison of each value in a test pair with the reference point established by the first value of the training sequence.  
  Address Center for Cognitive Neuroscience and Department of Psychological and Brain Sciences, Duke University, Durham, NC 27708, USA. brannon@duke.edu  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0097-7403 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16634655 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2761  
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Author Brannon, E.M.; Terrace, H.S. openurl 
  Title Representation of the numerosities 1-9 by rhesus macaques (Macaca mulatta) Type Journal Article
  Year 2000 Publication (up) Journal of Experimental Psychology. Animal Behavior Processes Abbreviated Journal J Exp Psychol Anim Behav Process  
  Volume 26 Issue 1 Pages 31-49  
  Keywords Animals; *Cognition; Macaca mulatta/*psychology; *Mathematics; Perception; Reaction Time  
  Abstract Three rhesus monkeys (Macaca mulatta) were trained to respond to exemplars of 1, 2, 3, and 4 in an ascending, descending, or a nonmonotonic numerical order (1-->2-->3-->4, 4-->3-->2--1, 3-->1-->4-->2). The monkeys were then tested on their ability to order pairs of the novel numerosities 5-9. In Experiment 1, all 3 monkeys ordered novel exemplars of the numerosities 1-4 in ascending or descending order. The attempt to train a nonmonotonic order (3-->1-->4-->2) failed. In Experiment 2A, the 2 monkeys who learned the ascending numerical rule ordered pairs of the novel numerosities 5-9 on unreinforced trials. The monkey who learned the descending numerical rule failed to extrapolate the descending rule to new numerosities. In Experiment 2B all 3 monkeys ordered novel exemplars of pairs of the numerosities 5-9. Accuracy and latency of responding revealed distance and magnitude effects analogous to previous findings with human participants (R. S. Moyer & T. K. Landaeur, 1967). Collectively these studies show that monkeys represent the numerosities 1-9 on at least an ordinal scale.  
  Address Department of Psychology, Columbia University, New York, New York 10027, USA. liz@psych.columbia.edu  
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  Language English Summary Language Original Title  
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  Series Volume Series Issue Edition  
  ISSN 0097-7403 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:10650542 Approved no  
  Call Number Equine Behaviour @ team @ Serial 2775  
Permanent link to this record
 

 
Author Cantlon, J.F.; Brannon, E.M. url  openurl
  Title How Much Does Number Matter to a Monkey (Macaca mulatta)? Type Journal Article
  Year 2007 Publication (up) Journal of Experimental Psychology: Animal Behavior Processes Abbreviated Journal  
  Volume 33 Issue 1 Pages 32-41  
  Keywords numerical cognition; Weber's law; nonhuman primates; numerosity  
  Abstract Although many animal species can represent numerical values, little is known about how salient number is relative to other object properties for nonhuman animals. In one hypothesis, researchers propose that animals represent number only as a last resort, when no other properties differentiate stimuli. An alternative hypothesis is that animals automatically, spontaneously, and routinely represent the numerical attributes of their environments. The authors compared the influence of number versus that of shape, color, and surface area on rhesus monkeys' (Macaca mulatta) decisions by testing them on a matching task with more than one correct answer: a numerical match and a nonnumerical (color, surface area, or shape) match. The authors also tested whether previous laboratory experience with numerical discrimination influenced a monkey's propensity to represent number. Contrary to the last-resort hypothesis, all monkeys based their decisions on numerical value when the numerical ratio was favorable.  
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  Notes Approved no  
  Call Number Equine Behaviour @ team @ Serial 2891  
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Author Brannon, E.M.; Terrace, H.S. openurl 
  Title Ordering of the numerosities 1 to 9 by monkeys Type Journal Article
  Year 1998 Publication (up) Science (New York, N.Y.) Abbreviated Journal Science  
  Volume 282 Issue 5389 Pages 746-749  
  Keywords Animals; *Discrimination (Psychology); Macaca mulatta/*psychology; *Mathematics; *Mental Processes  
  Abstract A fundamental question in cognitive science is whether animals can represent numerosity (a property of a stimulus that is defined by the number of discriminable elements it contains) and use numerical representations computationally. Here, it was shown that rhesus monkeys represent the numerosity of visual stimuli and detect their ordinal disparity. Two monkeys were first trained to respond to exemplars of the numerosities 1 to 4 in an ascending numerical order (1 --> 2 --> 3 --> 4). As a control for non-numerical cues, exemplars were varied with respect to size, shape, and color. The monkeys were later tested, without reward, on their ability to order stimulus pairs composed of the novel numerosities 5 to 9. Both monkeys responded in an ascending order to the novel numerosities. These results show that rhesus monkeys represent the numerosities 1 to 9 on an ordinal scale.  
  Address Department of Psychology, Columbia University, New York, NY 10027, USA. liz@psych.columbia.edu  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0036-8075 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:9784133 Approved no  
  Call Number refbase @ user @ Serial 606  
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