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Author |
Cameron, E.Z. |
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Title |
Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism |
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Journal Article |
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Year |
2004 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
271 |
Issue |
1549 |
Pages |
1723-1728 |
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Keywords |
Age Factors; Animals; Body Constitution; *Evolution; Female; Glucose/metabolism/physiology; Litter Size; Male; Mammals/*physiology; *Models, Biological; Reproduction/physiology; Seasons; Sex Factors; *Sex Ratio; Time Factors |
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Abstract |
Evolutionary theory predicts that mothers of different condition should adjust the birth sex ratio of their offspring in relation to future reproductive benefits. Published studies addressing variation in mammalian sex ratios have produced surprisingly contradictory results. Explaining the source of such variation has been a challenge for sex-ratio theory, not least because no mechanism for sex-ratio adjustment is known. I conducted a meta-analysis of previous mammalian sex-ratio studies to determine if there are any overall patterns in sex-ratio variation. The contradictory nature of previous results was confirmed. However, studies that investigated indices of condition around conception show almost unanimous support for the prediction that mothers in good condition bias their litters towards sons. Recent research on the role of glucose in reproductive functioning have shown that excess glucose favours the development of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition around conception. Furthermore, many of the conflicting results from studies on sex-ratio adjustment would be explained if glucose levels in utero during early cell division contributed to the determination of offspring sex ratios. |
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Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za |
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0962-8452 |
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PMID:15306293 |
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refbase @ user @ |
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413 |
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Author |
Zentall, T.R.; Weaver, J.E.; Clement, T.S. |
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Title |
Pigeons group time intervals according to their relative duration |
Type |
Journal Article |
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Year |
2004 |
Publication |
Psychonomic bulletin & review |
Abbreviated Journal |
Psychon Bull Rev |
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Volume |
11 |
Issue |
1 |
Pages |
113-117 |
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Keywords |
Animals; Columbidae; *Discrimination (Psychology); Reinforcement (Psychology); Time Factors; Time Perception |
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Abstract |
In the present research, we asked whether pigeons tended to judge time intervals not only in terms of their absolute value but also relative to a duration from which they must be discriminated (i.e., longer or shorter). Pigeons were trained on two independent temporal discriminations. In one discrimination, sample durations of 2 and 8 sec were associated with, for example, red and green hue comparisons, respectively, and in the other discrimination, sample durations of 4 and 16 sec were associated with vertical and horizontal line comparisons, respectively. If pigeons are trained on a temporal discrimination and tested with intermediate durations, the subjective midpoint typically occurs close to the geometric mean of the two trained values. The 4- and 8-sec values were selected to be the geometric mean of the two values in the other discrimination. When a 4-sec test sample was presented with the comparisons from the 2- and 8-sec discrimination, the pigeons preferred the comparison associated with the shorter sample. Similarly, when an 8-sec test sample was presented with the comparisons from the 4- and 16-sec discrimination, the pigeons preferred the comparison associated with the longer sample. Thus, a relative grouping effect was found. That is, durations that should have produced indifferent choice were influenced by their relative durations (shorter than or longer than the alternative) during training. |
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Department of Psychology, University of Kentucky, Lexington, Kentucky 40506-0044, USA. zentall@pop.uky.edu |
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1069-9384 |
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PMID:15116995 |
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Call Number |
refbase @ user @ |
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231 |
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Author |
Clement, T.S.; Zentall, T.R. |
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Title |
Choice based on exclusion in pigeons |
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Journal Article |
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Year |
2003 |
Publication |
Psychonomic bulletin & review |
Abbreviated Journal |
Psychon Bull Rev |
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Volume |
10 |
Issue |
4 |
Pages |
959-964 |
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Keywords |
Animals; Appetitive Behavior; *Association Learning; *Choice Behavior; *Color Perception; Columbidae; *Discrimination Learning; Memory, Short-Term; *Problem Solving; Psychomotor Performance; Reaction Time; Transfer (Psychology) |
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Abstract |
When humans acquire a conditional discrimination and are given a novel-sample-comparison choice, they often reject a comparison known to be associated with a different sample and choose the alternative comparison by default (or by exclusion). In Experiment 1, we found that if, following matching training, we replaced both of the samples, acquisition took five times longer than if we replaced only one of the samples. Apparently, the opportunity to reject one of the comparisons facilitated the association of the other sample with the remaining comparison. In Experiment 2, we first trained pigeons to treat two samples differently (to associate Sample A with Comparison 1 and Sample B with Comparison 2) and then trained them to associate one of those samples with a new comparison (e.g., Sample A with Comparison 3) and to associate a novel sample (Sample C) with a different, new comparison (Comparison 4). When Sample B then replaced Sample C, the pigeons showed a significant tendency to choose Comparison 4 over Comparison 3. Thus, when given the opportunity, pigeons will choose by exclusion. |
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University of Kentucky, Lexington, Kentucky, USA |
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1069-9384 |
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PMID:15000545 |
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no |
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Call Number |
refbase @ user @ |
Serial |
233 |
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Author |
Clement, T.S.; Feltus, J.R.; Kaiser, D.H.; Zentall, T.R. |
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Title |
“Work ethic” in pigeons: reward value is directly related to the effort or time required to obtain the reward |
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Journal Article |
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Year |
2000 |
Publication |
Psychonomic bulletin & review |
Abbreviated Journal |
Psychon Bull Rev |
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Volume |
7 |
Issue |
1 |
Pages |
100-106 |
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Keywords |
Animals; Behavior, Animal/*physiology; Cognition/physiology; Columbidae; Discrimination Learning/physiology; Female; Male; Reinforcement (Psychology); *Reward; Time Factors |
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Abstract |
Stimuli associated with less effort or with shorter delays to reinforcement are generally preferred over those associated with greater effort or longer delays to reinforcement. However, the opposite appears to be true of stimuli that follow greater effort or longer delays. In training, a simple simultaneous discrimination followed a single peck to an initial stimulus (S+FR1 S-FR1) and a different simple simultaneous discrimination followed 20 pecks to the initial stimulus (S+FR20 S-FR20). On test trials, pigeons preferred S+FR20 over S+FR1 and S-FR20 over S-FR1. These data support the view that the state of the animal immediately prior to presentation of the discrimination affects the value of the reinforcement that follows it. This contrast effect is analogous to effects that when they occur in humans have been attributed to more complex cognitive and social factors. |
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University of Kentucky, Lexington, USA |
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1069-9384 |
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Notes |
PMID:10780022 |
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no |
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Call Number |
refbase @ user @ |
Serial |
248 |
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Author |
Hodgson, D.; Howe, S.; Jeffcott, L.; Reid, S.; Mellor, D.; Higgins, A. |
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Title |
Effect of prolonged use of altrenogest on behaviour in mares |
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Year |
2005 |
Publication |
Veterinary journal (London, England : 1997) |
Abbreviated Journal |
Vet J |
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Volume |
169 |
Issue |
1 |
Pages |
113-115 |
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Keywords |
Administration, Oral; Anabolic Agents/adverse effects/*pharmacology; Animals; Behavior, Animal/*drug effects; Body Constitution/drug effects; Body Weight/drug effects; *Doping in Sports; Female; Horses/*physiology; Social Behavior; Social Dominance; Time Factors; Trenbolone/adverse effects/*analogs & derivatives/*pharmacology |
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Abstract |
Erratum in:
Vet J. 2005 May;169(3):321.
Corrected and republished in:
Vet J. 2005 May;169(3):322-5.
Oral administration of altrenogest for oestrus suppression in competition horses is believed to be widespread in some equestrian disciplines, and can be administered continuously for several months during a competition season. To examine whether altrenogest has any anabolic or other potential performance enhancing properties that may give a horse an unfair advantage, we examined the effect of oral altrenogest (0.044 mg/kg), given daily for a period of eight weeks, on social hierarchy, activity budget, body-mass and body condition score of 12 sedentary mares. We concluded that prolonged oral administration of altrenogest at recommended dose rates to sedentary mares resulted in no effect on dominance hierarchies, body mass or condition score. |
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Address |
Faculty of Veterinary Science, University of Sydney, Private Mailbag 4, Narellan Delivery Centre, Narellan, NSW 2567, Australia. davidh@camden.usyd.edu.au |
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ISSN |
1090-0233 |
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PMID:15683772 |
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no |
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Call Number |
refbase @ user @ |
Serial |
671 |
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Author |
Piccione, G.; Caola, G.; Refinetti, R. |
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Title |
Temporal relationships of 21 physiological variables in horse and sheep |
Type |
Journal Article |
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Year |
2005 |
Publication |
Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology |
Abbreviated Journal |
Comp Biochem Physiol A Mol Integr Physiol |
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Volume |
142 |
Issue |
4 |
Pages |
389-396 |
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Keywords |
Animals; Behavior, Animal/physiology; Blood Glucose/physiology; Body Temperature/*physiology; Circadian Rhythm/*physiology; Female; Horses/*physiology; Melatonin/blood/*physiology; Motor Activity/*physiology; Rectum/physiology; Sheep/*physiology; Time Factors |
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Abstract |
Daily or circadian oscillation has been documented in a variety of physiological and behavioral processes. Although individual variables have been studied in great detail, very few studies have been conducted on the temporal relationships between the rhythms of different variables. It is not known whether the circadian pacemaker generates each and every rhythm individually or whether most rhythms are simply derived from a few clock-controlled rhythms. As a first step in elucidating this issue, 21 physiological variables were recorded simultaneously in horse and sheep. The results indicated that, in both species, different variables exhibit different degrees of daily rhythmicity and reach their daily peaks at different times of the day. The variables exhibiting strongest rhythmicity were locomotor activity, rectal temperature, and plasma concentrations of melatonin and glucose. Comparison of rhythmicity and acrophase in the various rhythms allowed inferences to be made about mechanisms of causation. |
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Dipartimento di Morfologia, Biochimica, Fisiologia e Produzioni Animali, Facolta di Medicina Veterinaria, Universita degli Studi di Messina, 98168 Messina, Italy |
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ISSN |
1095-6433 |
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PMID:16290083 |
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no |
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Call Number |
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Serial |
1884 |
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Author |
Macfadden, B.J. |
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Title |
Evolution. Fossil horses--evidence for evolution |
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Journal Article |
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Year |
2005 |
Publication |
Science (New York, N.Y.) |
Abbreviated Journal |
Science |
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Volume |
307 |
Issue |
5716 |
Pages |
1728-1730 |
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Keywords |
Animals; Body Size; DNA, Mitochondrial; Diet; *Equidae/anatomy & histology/classification/genetics; *Evolution; Feeding Behavior; *Fossils; *Horses/anatomy & histology/classification/genetics; Paleodontology; Phylogeny; Time; Tooth/anatomy & histology |
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Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA. bmacfadd@flmnh.ufl.edu |
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1095-9203 |
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PMID:15774746 |
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no |
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Serial |
1892 |
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Author |
Petruso, E.J.; Fuchs, T.; Bingman, V.P. |
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Title |
Time-space learning in homing pigeons (Columba livia): orientation to an artificial light source |
Type |
Journal Article |
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Year |
2007 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Volume |
10 |
Issue |
2 |
Pages |
181-188 |
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Keywords |
Animals; Circadian Rhythm; Columbidae/*physiology; Homing Behavior/physiology; Learning/*physiology; *Light; Orientation/*physiology; Space Perception/*physiology; Time Perception/*physiology |
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Abstract |
Time-space learning reflects an ability to represent in memory event-stimulus properties together with the place and time of the event; a capacity well developed in birds. Homing pigeons were trained in an indoor octagonal arena to locate one food goal in the morning and a different food goal in the late afternoon. The goals differed with respect to their angular/directional relationship to an artificial light source located outside the arena. Further, the angular difference in reward position approximated the displacement of the sun's azimuth that would occur during the same time period. The experimental birds quickly learned the task, demonstrating the apparent ease with which birds can adopt an artificial light source to discriminate among alternative spatial responses at different times of the day. However, a novel midday probe session following successful learning revealed that the light source was interpreted as a stable landmark and not as a surrogate sun that would support compass orientation. Probe sessions following a phase shift of the light-dark cycle revealed that the mechanism employed to make the temporal discrimination was prevailingly based on an endogenous circadian rhythm and not an interval timing mechanism. |
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Department of Psychology and J.P. Scott Center for Neuroscience, Mind and Behavior Bowling Green State University, Bowling Green, OH 43403, USA |
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1435-9448 |
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PMID:17160343 |
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no |
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Equine Behaviour @ team @ |
Serial |
2432 |
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Author |
Lewis, K.P.; Jaffe, S.; Brannon, E.M. |
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Title |
Analog number representations in mongoose lemurs (Eulemur mongoz): evidence from a search task |
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Journal Article |
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Year |
2005 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Volume |
8 |
Issue |
4 |
Pages |
247-252 |
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Keywords |
Analysis of Variance; Animals; *Behavior, Animal; *Feeding Behavior; Female; Lemuridae/*psychology; Male; Mathematics; Odors; Smell/physiology; Time Factors |
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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. |
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Department of Anthropology, Washington University, St. Louis, MO 63130-4899, USA |
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1435-9448 |
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PMID:15660208 |
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no |
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Equine Behaviour @ team @ |
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2497 |
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Author |
Beran, M.J. |
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Title |
Long-term retention of the differential values of Arabic numerals by chimpanzees (Pan troglodytes) |
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Journal Article |
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Year |
2004 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Volume |
7 |
Issue |
2 |
Pages |
86-92 |
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Animals; Cognition; Female; Language; Longitudinal Studies; Male; *Mathematics; *Mental Recall; Pan troglodytes/*psychology; *Retention (Psychology); *Semantics; Time Factors |
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Abstract |
As previously reported (Beran and Rumbaugh, 2001), two chimpanzees used a joystick to collect dots, one-at-a-time, on a computer monitor, and then ended a trial when the number of dots collected was equal to the Arabic numeral presented for the trial. Here, the chimpanzees were presented with the task again after an interval of 6 months and then again after an additional interval of 3.25 years. During each interval, the chimpanzees were not presented with the task, and this allowed an assessment of the extent to which both animals retained the values of each Arabic numeral. Despite lower performance at each retention interval compared to the original study, both chimpanzees performed above chance levels in collecting a quantity of dots equal to the target numeral, one chimpanzee for the numerals 1-7, and the second chimpanzee for the numerals 1-6. For the 3.25-year retention, errors were more dispersed around each target numeral than in the original study, but the chimpanzees' performances again appeared to be based on a continuous representation of magnitude rather than a discrete representation of number. These data provide an experimental demonstration of long-term retention of the differential values of Arabic numerals by chimpanzees. |
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Language Research Center, Georgia State University, 3401 Panthersville Road, Decatur, GA 30034, USA. mjberan@yahoo.com |
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1435-9448 |
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PMID:15069607 |
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Call Number |
Equine Behaviour @ team @ |
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2533 |
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