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Flavell JH. (1986). The development of children's knowledge about the appearance-reality distinction. Am. Psychol., 41, 418.
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Kortlandt A. (1986). The use of tools by wild-living chimpanzees and earliest hominids. J. Hum. Evol.,, 15, 77.
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Goodall, J. (1986). The Chimpanzees of Gombe.
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Berger, J. (1986). Wild horses of the Great Basin. Chicago: University of Chicago Press.
Abstract: Describes the behavior of wild horses living in the Great Basin Desert of Nevada and discusses the role of the horses in the area's ecology
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Keiper, R. R., & Sambraus, H. H. (1986). The stability of equine dominance hierarchies and the effects of kinship, proximity and foaling status on hierarchy rank. Appl. Anim. Behav. Sci., 16(2), 121–130.
Abstract: Dominance hierarchies were determined in four bands of feral horses living on Assateague Island. The bands varied in size from 10 to 16 horses, and consisted of one stallion, several mares and their offspring. The animals ranged in age from less than 1 to over 18 years. Field observation of all social interactions during the summer of 1981 was used to determine dominance. 1981 hierarchies for three of the bands were compared with hierarchies determined for the same bands in 1978, and showed that hierarchies change over time. Age was significantly correlated with rank. Mares with foals did not rank any higher in the hierarchies than mares without foals. Kinship did not appear to have an effect on dominance rank either, since neither juvenile nor adult offspring ranks correlated with the ranks of their mothers. The band stallion was not the highest-ranking animal of any band, but the location of the stallion peripheral to the main body of the band, the nature of his interactions with band members, and his length of residence in the band may have contributed to his low rank.
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Eccles, T. R., & Shackleton, D. M. (1986). Correlates and consequences of social status in female bighorn sheep. Anim. Behav., 34(5), 1392–1401.
Abstract: Dominance-subordinance relationships among a captive group of adule bighorn sheep (Ovis canadensis californiana) were studied from May 1977 to December 1978. Social interactions between females were brief in duration and infrequent. Although a dominance hierarchy was evident among the females, it was not linear. Horn length and body weight were not consistently correlated with social status. The highest ranking females were the most aggressive individuals, initiating more agonistic interactions than subordinates. Females with high social status did not have higher quality diets, lower activity costs, or higher productivity than low ranking females.
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Baker, A. E. M., & Crawford, B. H. (1986). Observational learning in horses. Appl. Anim. Behav. Sci., 15(1), 7–13.
Abstract: This experiment was designed to determine if a horse could learn the location of grain by watching another horse find grain in one of two feed buckets. Both experimental and control groups contained 9 quarter horses consisting of five 2-year-old mares, two 2-year-old geldings, and two 3-year-old geldings. Two mature geldings were used as “demonstrators”. An “experimental” was a horse that could watch three times daily another horse, the “demonstrator”, choose between and eat grain from a black or white bucket, only one of which contained grain. A “control” was a horse that could watch a demonstrator in the same arena for 3 min daily when both feed buckets were removed. When the demonstrator was removed on each of 15 successive days, the experimental or control horse was given five trials to determine if it could find the feed bucket with grain. No significant difference between experimentals and controls occurred for both first and total correct choices and for time to reach the feed bucket with grain. We conclude that no observational learning occurred. This experiment was also used to determine if the identity of horses that learned rapidly by trial and error could be predicted by the time it took to reach the feed bucket with grain. Data from the last three trials of experimentals and controls were combined. Significantly less time to find feed was needed by horses with more than the median number of correct choices. Both number of correct choices and time needed to contact a feed bucket summed over the first 5 days accurately predicted the same data summed over the last 10 days. We conclude that horses that learn rapidly by trial and error make correct choices rapidly, and that these horses can by identified after 5 days of testing.
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Heird, J. C., Lokey, C. E., & Cogan, D. C. (1986). Repeatability and comparison of two maze tests to measure learning ability in horses. Appl. Anim. Behav. Sci., 16(2), 103–119.
Abstract: Sixteen Quarter Horses were randomly divided into two groups after sorting by age and sex. After a 10-day preconditioning period, each animal was scored for emotionality and trainability. Each group then completed a series of learning tasks in a modified T-maze for 20 consecutive days. Group P/D was initially tested on a simple place-learning task, while Group D/P was trained in a visual discrimination task. The groups were tested alternately on the two tasks with 10-day extinction periods between each task. Upon reaching a criterion of 11 of 12 correct responses (the last 8 responses consecutive), a horse was retired for the day. If this criterion was not attained, the horse completed 20 trials. Learning occurred at a faster rate on the discrimination tasks compared to the gradual learning curves observed on place tasks. Animals learned more rapidly and reached higher levels of performance as the series of tasks progressed. Trainability and emotionality scores tended to predict the final level of learning achieved. Correlations of performance ranks within emotionality and training groups were higher between tasks of the same type than between the different tasks. Rank correlations between odd and even days on each task indicated that the within-group rankings were more consistent on the discrimination task than on the place task.
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Thouless, C. R., & Guinness, F. E. (1986). Conflict between red deer hinds: the winner always wins. Anim. Behav., 34(4), 1166–1171.
Abstract: Dominance relations between free-living, female red deer (hinds) (Cervus elaphus L.) on the Isle of Rhum, Scotland, were investigated. Most interactions were won by the older hind of the pair and this was the case even when both individuals had reached full body size. The younger hind was more likely to be the winner if the conflict was escalated or if the two hinds were strangers, in which case escalation was more frequent than usual. When outside their normal home range, older hinds were much more likely to lose, and younger ones more likely to win, than usual. These results can be best explained by the hinds using previous experience as a cue for conventional resolution of conflict, with the result that dominance relationships established early in life are perpetuated. No such cue is available if the hinds have not previously met.
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Zumpe, D., & Michael, R. P. (1986). Dominance index: A simple measure of relative dominance status in primates. Am. J. Primatol., 10(4), 291–300.
Abstract: A simple measure of relative dominance status (cardinal rank) is described which we have termed the dominance index. Like more familiar techniques for assessing rank order, it is based on the direction of aggressive and submissive behaviors between all possible paired combinations of animals in a social group. Using data from five groups of female rhesus monkeys, it reliably produced the same ordinal ranks as fight interaction matrices. There was also good agreement with the cardinal ranks produced by two additional measures of dominance and with those produced by observer ratings. The dominance index can be calculated when fights have not actually occurred and is largely independent of the frequency of agonistic interactions. It has, therefore, wide application and can estimate dominance during brief sampling periods (one hour) and also in stable groups when agonistic interactions are low. Its application is described in experiments in which the male in a group of females was changed and the hormonal status of the females was altered. Estrogen increased female dominance status relative to other females.
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