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Monard, A.-M.; Duncan, P.; Fritz, H.; Feh, C. |
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Title |
Variations in the birth sex ratio and neonatal mortality in a natural herd of horses |
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1997 |
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Behavioral Ecology and Sociobiology |
Abbreviated Journal |
Behav. Ecol. Sociobiol. |
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41 |
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4 |
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243-249 |
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Variations in birth sex ratios and sex differences in juvenile mortality occur in a number of mammalian species, and in many cases have been linked to resource availability. Most of these biases in offspring sex ratios concern polygynous species with pronounced sexual dimorphism, and where females only are philopatric. Data on species with unusual life-history strategies, such as slight sexual dimorphism or dispersal by both sexes, are of particular interest. In this study of a natural herd of horses (Equus caballus) which experienced an eruptive cycle, and therefore a period of nutritional stress, male offspring had higher neonatal mortality rates in nutritionally poor years than in good ones, whereas “year quality” had no effect on the mortality of female offspring; year quality could therefore be used by mares as predictor of sex-specific offspring survival. We show that the environmental conditions that predicted lower survival of males were negatively related to their production: the birth sex ratio the following year was female-biased; and mares were less likely to produce a son when they had produced a son the preceding year. There was no significant effect of mother's parity, age or rank, or the timing of conception or birth on offspring sex ratios. The mechanism leading to biases in the birth sex ratio could have been the loss of male embryos by mares that did not foal. As there was no evidence for selective abortion of male foetuses in females that did foal the next year, it is not necessary to invoke maternal adjustment, though this remains a possibility. Finally, there was a suggestion that male offspring were more costly to raise than females, since mothers that reared a son in poor years tended to experience an increase in the interbirth interval between their two subsequent offspring. |
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Equine Behaviour @ team @ |
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2388 |
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Munthali, S.M.; Banda, H.M. |
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Distribution and abundance of the common ungulates of Nyika National Park |
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1992 |
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Afr. J. Ecol |
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Afr. J. Ecol |
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30 |
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203-212 |
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Equine Behaviour @ team @ |
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2390 |
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Hvorecny, L.M.; Grudowski, J.L.; Blakeslee, C.J.; Simmons, T.L.; Roy, P.R.; Brooks, J.A.; Hanner, R.M.; Beigel, M.E.; Karson, M.A.; Nichols, R.H.; Holm, J.B.; Boal, J.G. |
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Title |
Octopuses (Octopus bimaculoides) and cuttlefishes (Sepia pharaonis, S. officinalis) can conditionally discriminate |
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2007 |
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Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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In complex navigation using landmarks, an animal must discriminate between potential cues and show context (condition) sensitivity. Such conditional discrimination is considered a form of complex learning and has been associated primarily with vertebrates. We tested the hypothesis that octopuses and cuttlefish are capable of conditional discrimination. Subjects were trained in two maze configurations (the conditions) in which they were required to select one of two particular escape routes within each maze (the discrimination). Conditional discrimination could be demonstrated by selecting the correct escape route in each maze. Six of ten mud-flat octopuses (Octopus bimaculoides), 6 of 13 pharaoh cuttlefish (Sepia pharaonis), and one of four common cuttlefish (S. officinalis) demonstrated conditional discrimination by successfully solving both mazes. These experiments demonstrate that cephalopods are capable of conditional discrimination and extend the limits of invertebrate complex learning. |
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Department of Biology, Millersville University, 50 East Frederick Street, Millersville, PA, 17551-0302, USA, jean.boal@millersville.edu |
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1435-9448 |
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PMID:17437139 |
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Equine Behaviour @ team @ |
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2405 |
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Lyn, H. |
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Mental representation of symbols as revealed by vocabulary errors in two bonobos (Pan paniscus) |
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2007 |
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Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Error analysis has been used in humans to detect implicit representations and categories in language use. The present study utilizes the same technique to report on mental representations and categories in symbol use from two bonobos (Pan paniscus). These bonobos have been shown in published reports to comprehend English at the level of a two-and-a-half year old child and to use a keyboard with over 200 visuographic symbols (lexigrams). In this study, vocabulary test errors from over 10 years of data revealed auditory, visual, and spatio-temporal generalizations (errors were more likely items that looked like sounded like, or were frequently associated with the sample item in space or in time), as well as hierarchical and conceptual categorizations. These error data, like those of humans, are a result of spontaneous responding rather than specific training and do not solely depend upon the sample mode (e.g. auditory similarity errors are not universally more frequent with an English sample, nor were visual similarity errors universally more frequent with a photograph sample). However, unlike humans, these bonobos do not make errors based on syntactical confusions (e.g. confusing semantically unrelated nouns), suggesting that they may not separate syntactical and semantic information. These data suggest that apes spontaneously create a complex, hierarchical, web of representations when exposed to a symbol system. |
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Language Research Center, Georgia State University, 3401 Panthersville Rd, Atlanta, GA, 30034, USA |
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1435-9448 |
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PMID:17436026 |
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Equine Behaviour @ team @ |
Serial |
2406 |
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Subiaul, F.; Romansky, K.; Cantlon, J.F.; Klein, T.; Terrace, H. |
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Cognitive imitation in 2-year-old children (Homo sapiens): a comparison with rhesus monkeys (Macaca mulatta) |
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Journal Article |
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2007 |
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Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Here we compare the performance of 2-year-old human children with that of adult rhesus macaques on a cognitive imitation task. The task was to respond, in a particular order, to arbitrary sets of photographs that were presented simultaneously on a touch sensitive video monitor. Because the spatial position of list items was varied from trial to trial, subjects could not learn this task as a series of specific motor responses. On some lists, subjects with no knowledge of the ordinal position of the items were given the opportunity to learn the order of those items by observing an expert model. Children, like monkeys, learned new lists more rapidly in a social condition where they had the opportunity to observe an experienced model perform the list in question, than under a baseline condition in which they had to learn new lists entirely by trial and error. No differences were observed between the accuracy of each species' responses to individual items or in the frequencies with which they made different types of errors. These results provide clear evidence that monkeys and humans share the ability to imitate novel cognitive rules (cognitive imitation). |
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Department of Speech and Hearing Science, The George Washington University, 1922 F Street, NW # 406E, Washington, DC, 20001, USA, subiaul@aol.com |
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1435-9448 |
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PMID:17287996 |
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Equine Behaviour @ team @ |
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2420 |
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Anderson, J.R.; Kuwahata, H.; Fujita, K. |
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Gaze alternation during “pointing” by squirrel monkeys (Saimiri sciureus)? |
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Journal Article |
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Year |
2007 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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10 |
Issue |
2 |
Pages |
267-271 |
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*Animal Communication; Animals; *Attention; Behavior, Animal/*physiology; *Cues; Female; Humans; *Learning; Male; Saimiri/*physiology |
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Gaze alternation (GA) is considered a hallmark of pointing in human infants, a sign of intentionality underlying the gesture. GA has occasionally been observed in great apes, and reported only anecdotally in a few monkeys. Three squirrel monkeys that had previously learned to reach toward out-of-reach food in the presence of a human partner were videotaped while the latter visually attended to the food, a distractor object, or the ceiling. Frame-by-frame video analysis revealed that, especially when reaching toward the food, the monkeys rapidly and repeatedly switched between looking at the partner's face and the food. This type of GA suggests that the monkeys were communicating with the partner. However, the monkeys' behavior was not influenced by changes in the partner's focus of attention. |
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Department of Psychology, University of Stirling, Stirling, FK9 4LA, Scotland, UK. jra1@stir.ac.uk |
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1435-9448 |
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PMID:17242934 |
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no |
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Equine Behaviour @ team @ |
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2424 |
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Author |
Naug, D.; Arathi, H.S. |
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Sampling and decision rules used by honey bees in a foraging arena |
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Journal Article |
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Year |
2007 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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10 |
Issue |
2 |
Pages |
117-124 |
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Animals; Bees/*physiology; *Choice Behavior; Cooperative Behavior; *Feeding Behavior; Flight, Animal |
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Animals must continuously choose among various available options to exploit the most profitable resource. They also need to keep themselves updated about the values of all available options, since their relative values can change quickly due to depletion or exploitation by competitors. While the sampling and decision rules by which foragers profitably exploit a flower patch have attracted a great deal of attention in theory and experiments with bumble bees, similar rules for honey bee foragers, which face similar foraging challenges, are not as well studied. By presenting foragers of the honey bee Apis cerana with choice tests in a foraging arena and recording their behavior, we investigate possible sampling and decision rules that the foragers use to choose one option over another and to track other options. We show that a large part of the sampling and decision-making process of a foraging honey bee can be explained by decomposing the choice behavior into dichotomous decision points and incorporating the cost of sampling. The results suggest that a honey bee forager, by using a few simple rules as part of a Bayesian inference process, is able to effectively deal with the complex task of successfully exploiting foraging patches that consist of dynamic and multiple options. |
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Department of Biology, Colorado State University, Fort Collins, CO 80523, USA. dhruba@lamar.colostate.edu |
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1435-9448 |
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PMID:16941157 |
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Equine Behaviour @ team @ |
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2441 |
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Lacreuse, A.; Martin-Malivel, J.; Lange, H.S.; Herndon, J.G. |
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Title |
Effects of the menstrual cycle on looking preferences for faces in female rhesus monkeys |
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Journal Article |
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Year |
2007 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Volume |
10 |
Issue |
2 |
Pages |
105-115 |
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Animals; *Behavior, Animal; Discrimination Learning; Estradiol/blood; *Face; Female; Humans; Macaca mulatta/*physiology; Male; Menstrual Cycle/blood/*physiology; *Pattern Recognition, Visual |
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Fluctuations of ovarian hormones across the menstrual cycle influence a variety of social and cognitive behaviors in primates. For example, female rhesus monkeys exhibit heightened interest for males and increased agonistic interactions with other females during periods of high estrogen levels. In the present study, we hypothesized that females' preference for males during periods of high estrogen levels is also expressed at the level of face perception. We tested four intact females on two face-tasks involving neutral portraits of male and female rhesus monkeys, chimpanzees and humans. In the visual preference task (VP), monkeys had to touch a button to view a face image. The image remained on the screen as long as the button was touched, and the duration of pressing was taken as an index of the monkey's looking time for the face stimulus. In the Face-Delayed Recognition Span Test (Face-DRST), monkeys were rewarded for touching the new face in an increasing number of serially presented faces. Monkeys were tested 5 days a week across one menstrual cycle. Blood was collected every other day for analysis of estradiol and progesterone. Two of the four females were cycling at the time of testing. We did not find an influence of the cycle on Face-DRST, likely due to a floor effect. In the VP however, the two cycling individuals looked longer at conspecific male faces than female faces during the peri-ovulatory period of the cycle. Such effects were absent for human and chimpanzee faces and for the two noncycling subjects. These data suggest that ovarian hormones may influence females' preferences for specific faces, with heightened preference for male faces during the peri-ovulatory period of the cycle. Heightened interest for stimuli of significant reproductive relevance during periods of high conception risk may help guide social and sexual behavior in the rhesus monkey. |
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Department of Psychology, University of Massachusetts-Amherst, Tobin Hall, 135 Hicks Way, Amherst, MA 01003, USA. alacreuse@psych.umass.edu |
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1435-9448 |
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PMID:16909232 |
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Equine Behaviour @ team @ |
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2452 |
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Shoshani, J.; Kupsky, W.J.; Marchant, G.H. |
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Elephant brain. Part I: gross morphology, functions, comparative anatomy, and evolution |
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Journal Article |
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Year |
2006 |
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Brain Research Bulletin |
Abbreviated Journal |
Brain Res Bull |
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70 |
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2 |
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124-157 |
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Animals; Brain/*anatomy & histology/blood supply/*physiology; Cats; Chinchilla; Elephants/*anatomy & histology/*physiology; Equidae; *Evolution; Female; Guinea Pigs; Haplorhini; Humans; Hyraxes; Male; Pan troglodytes; Sheep; Wolves |
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We report morphological data on brains of four African, Loxodonta africana, and three Asian elephants, Elephas maximus, and compare findings to literature. Brains exhibit a gyral pattern more complex and with more numerous gyri than in primates, humans included, and in carnivores, but less complex than in cetaceans. Cerebral frontal, parietal, temporal, limbic, and insular lobes are well developed, whereas the occipital lobe is relatively small. The insula is not as opercularized as in man. The temporal lobe is disproportionately large and expands laterally. Humans and elephants have three parallel temporal gyri: superior, middle, and inferior. Hippocampal sizes in elephants and humans are comparable, but proportionally smaller in elephant. A possible carotid rete was observed at the base of the brain. Brain size appears to be related to body size, ecology, sociality, and longevity. Elephant adult brain averages 4783 g, the largest among living and extinct terrestrial mammals; elephant neonate brain averages 50% of its adult brain weight (25% in humans). Cerebellar weight averages 18.6% of brain (1.8 times larger than in humans). During evolution, encephalization quotient has increased by 10-fold (0.2 for extinct Moeritherium, approximately 2.0 for extant elephants). We present 20 figures of the elephant brain, 16 of which contain new material. Similarities between human and elephant brains could be due to convergent evolution; both display mosaic characters and are highly derived mammals. Humans and elephants use and make tools and show a range of complex learning skills and behaviors. In elephants, the large amount of cerebral cortex, especially in the temporal lobe, and the well-developed olfactory system, structures associated with complex learning and behavioral functions in humans, may provide the substrate for such complex skills and behavior. |
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Department of Biology, University of Asmara, P.O. Box 1220, Asmara, Eritrea (Horn of Africa). hezy@bio.uoa.edu.er |
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0361-9230 |
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PMID:16782503 |
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Equine Behaviour @ team @ |
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2623 |
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Hostetter, A.B.; Russell, J.L.; Freeman, H.; Hopkins, W.D. |
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Now you see me, now you don't: evidence that chimpanzees understand the role of the eyes in attention |
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Journal Article |
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2007 |
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Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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10 |
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1 |
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55-62 |
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Animal Husbandry/methods; Animals; *Attention; Awareness; Female; Fixation, Ocular/*physiology; Humans; Male; Pan troglodytes/*psychology; *Social Behavior; *Social Perception |
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Chimpanzees appear to understand something about the attentional states of others; in the present experiment, we investigated whether they understand that the attentional state of a human is based on eye gaze. In all, 116 adult chimpanzees were offered food by an experimenter who engaged in one of the four experimental manipulations: eyes closed, eyes open, hand over eyes, and hand over mouth. The communicative behavior of the chimpanzees was observed. More visible behaviors were produced when the experimenter's eyes were visible than when the experimenter's eyes were not visible. More vocalizations were produced when the experimenter's eyes were closed than when they were open, but there were no differences in other attention getting behaviors. There was no effect of age or rearing history. The results suggest that chimpanzees use the presence of the eyes as a cue that their visual gestures will be effective. |
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Department of Psychology, University of Wisconsin-Madison, 1202 W. Johnson Street, Madison, WI 53706, USA. abhostetter@wisc.edu |
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1435-9448 |
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PMID:16847659 |
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Equine Behaviour @ team @ |
Serial |
2457 |
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