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Biederman, G. B., Robertson, H. A., & Vanayan, M. (1986). Observational learning of two visual discriminations by pigeons: a within-subjects design. J Exp Anal Behav, 46(1), 45–49.
Abstract: Pigeon's observational learning of successive visual discrimination was studied using within-subject comparisons of data from three experimental conditions. Two pairs of discriminative stimuli were used; each bird was exposed to two of the three experimental conditions, with different pairs of stimuli used in a given bird's two conditions. In one condition, observers were exposed to visual discriminative stimuli only. In a second condition, subjects were exposed to a randomly alternating sequence of two stimuli where the one that would subsequently be used as S+ was paired with the operation of the grain magazine. In a third experimental condition, subjects were exposed to the performance of a conspecific in the operant discrimination procedure. After exposures to conspecific performances, there was facilitation of discriminative learning, relative to that which followed exposures to stimulus and reinforcement sequences or exposures to stimulus sequences alone. Exposure to stimulus and food-delivery sequences enhanced performance relative to exposure to stimulus sequences alone. The differential effects of these three types of exposure were not attributable to order effects or to task difficulty; rather, they clearly were due to the type of exposure.
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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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Miller J,. (1986). National forest management of wild horses and burros: Current position and policy. J Equine Vet Sc, 6, 259–260.
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Crowell-Davis, S. L., Houpt, K. A., & Carini, C. M. (1986). Mutual grooming and nearest-neighbor relationships among foals of Equus caballus. Appl. Anim. Behav. Sci., 15(2), 113–123.
Abstract: A 3-year study was carried out on the developmental behavior of foals from birth to 24 weeks of age and the behavior of mares living with foals. Mutual-grooming partners of foals were primarily other foals. The peak frequency of mutual grooming occurred during Weeks 9-12, when fillies mutual-groomed 1.6 times h-1 and colts mutual-groomed 0.9 times h-1. Fillies mutual-groomed more frequently than colts (P < 0.025). Fillies mutual-groomed randomly with colts and other fillies (P < 0.05), whereas colts mutual-groomed almost exclusively with fillies (P = 0.03). At all ages studied, if a foal's nearest neighbor was not its mother, it was more likely to be another foal than would be expected if the foal was associating randomly with non-mother ponies. Fillies were more likely than expected to have a filly rather than a colt as their nearest neighbor (P = 0.01). Thus, during their first few months of life, the foals studied exhibited patterns of behavior which were consistent with the development of the usual social milieu of unmanaged adults, in which several mares form a cohesive herd with one or more stallions associating with them.
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George Jr M, R. O. (1986). Mitochondrial DNA evolution in the genus Equus. Molecular Biol Evol, 3, 535–546.
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Craig, J. V. (1986). Measuring social behavior: social dominance. J. Anim Sci., 62(4), 1120–1129.
Abstract: Social dominance develops more slowly when young animals are kept in intact peer groups where they need not compete for resources. Learned generalizations may cause smaller and weaker animals to accept subordinate status readily when confronted with strangers that would be formidable opponents. Sexual hormones and sensitivity to them can influence the onset of aggression and status attained. After dominance orders are established, they tend to be stable in female groups but are less so in male groups. Psychological influences can affect dominance relationships when strangers meet and social alliances within groups may affect relative status of individuals. Whether status associated with agonistic behavior is correlated with control of space and scarce resources needs to be determined for each species and each kind of resource. When such correlations exists, competitive tests and agonistic behavior associated with gaining access to scarce resources can be useful to the observer in learning about dominance relationships rapidly. Examples are given to illustrate how estimates of social dominance can be readily attained and some strengths and weaknesses of the various methods.
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Crowell-Davis, S. L., & Houpt, K. A. (1986). Maternal behavior. Vet Clin North Am Equine Pract, 2(3), 557–571.
Abstract: Parturition in mares is rapid and is followed by a brief period of sensitivity to imprinting on a foal. There is large individual variation in normal maternal style, but normal mothers actively defend their foal, remain near the foal when it is sleeping, tolerate or assist nursing, and do not injure their own foal. Disturbance of a mare and foal during the early imprinting period can predispose a mare to rejection of her foal; therefore, it should be avoided. There are a variety of forms of foal rejection and numerous etiologies. Therefore, each case should be evaluated individually.
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Boyles Js,. (1986). Managing America's wild horses and burros. J Equine Vet. Sc., 6, 261.
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Liang, K. - Y., & Zeger, S. L. (1986). Longitudinal data analysis using generalized linear models. Biometrika, 73(1), 13–22.
Abstract: This paper proposes an extension of generalized linear models to the analysis of longitudinal data. We introduce a class of estimating equations that give consistent estimates of the regression parameters and of their variance under mild assumptions about the time dependence. The estimating equations are derived without specifying the joint distribution of a subject's observations yet they reduce to the score equations for niultivariate Gaussian outcomes. Asymptotic theory is presented for the general class of estimators. Specific cases in which we assume independence, m-dependence and exchangeable correlation structures from each subject are discussed. Efficiency of the pioposecl estimators in two simple situations is considered. The approach is closely related to quasi-likelihood.
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Heffner, R. S., & Heffner, H. E. (1986). Localization of tones by horses: use of binaural cues and the role of the superior olivary complex. Behav Neurosci, 100(1), 93–103.
Abstract: The ability of horses to use binaural time and intensity difference cues to localize sound was assessed in free-field localization tests by using pure tones. The animals were required to discriminate the locus of a single tone pip ranging in frequency from 250 Hz to 25 kHz emitted by loudspeakers located 30 degrees to the left and right of the animals' midline (60 degrees total separation). Three animals were tested with a two-choice procedure; 2 additional animals were tested with a conditioned avoidance procedure. All 5 animals were able to localize 250 Hz, 500 Hz, and 1 kHz but were completely unable to localize 2 kHz and above. Because the frequency of ambiguity for the binaural phase cue delta phi for horses in this test was calculated to be 1.5 kHz, these results indicate that horses can use binaural time differences in the form of delta phi but are unable to use binaural intensity differences. This finding was supported by an unconditioned orientation test involving 4 additional horses, which showed that horses correctly orient to a 500-Hz tone pip but not to an 8-kHz tone pip. Analysis of the superior olivary complex, the brain stem nucleus at which binaural interactions first take place, reveals that the lateral superior olive (LSO) is relatively small in the horse and lacks the laminar arrangement of bipolar cells characteristic of the LSO of most mammals that can use binaural delta I.
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