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Lejeune, H., Macar, F., & Zakay, D. (1999). Attention and timing: dual-task performance in pigeons. Behav. Process., 45(1-3), 141–157.
Abstract: Pigeons were exposed to an analog of a `dual-task' procedure used to test attentional models of timing in humans. After separate training on an auditory duration discrimination and on a variable ratio (VR) schedule, VR episodes lasting for 5 s were superimposed on the stimuli to be timed, either early (E) or late (L) during the trial. Trials with VR yielded underestimation of the target durations (increased % of `short' choices), relative to trials without VR, and this effect was stronger under the L than under the E condition. Data were similar to those collected with humans and support attentional models of timing according to which the simultaneous non-timing task uses processing resources which are diverted from the timing mechanisms.
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DUNN, L. J. (1999). PRELIMINARY INVESTIGATION OF EQUINE LEARNING AND MEMORY.
Abstract: ABSTRACT
Six horses demonstrated observation and discrimination learning and memory ability. The purpose of this study was to gain further knowledge in the area of equine learning. Performance on each task was compared in a single subject design. Subjects learned to discriminate between a black and a white bucket. The criterion for learning was set at 80% correct black bucket choice. All subjects successfully performed the discrimination task by the eighth session. Observation learning was unsuccessful; no subject reached the 80% correct criterion. Five horses were tested for memory retention of the discrimination task three weeks after the initial learning. All subjects performed the discrimination by the second session of two. These data support existing results from similar learning and memory tasks. |
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Hanggi, E. B. (1999). Categorization Learning in Horses (Equus caballus). J. Comp. Psychol., 113(3), 243–252.
Abstract: Categorization learning was investigated in 2 horses (Equus caballus). Both horses learned to select a 2-dimensional black stimulus with an open center instead of a filled stimulus in a 2-choice discrimination task. After a criterion of 10 out of 10 correct responses in a random series for 2 consecutive sessions was reached, 15 additional pairs of open-center versus filled stimuli were tested. Each was run to criterion and then incorporated into sessions of randomly mixed problems. Both horses solved the 1st problem by simple pattern discrimination and showed evidence of categorical processing for subsequent problems. New pairs were learned with few or no errors, and correct responses on novel trials were significantly above chance. These results suggest that the horses were making their selections on the basis of shared characteristics with the training stimuli and were using categorization skills in problem solving.
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Rogers, C. W., Davies, A. S., Pfeiffer, D. U., & Davie, P. S. (1999). Linear and temporal stride characteristics of 3-day event horses at a CCI*** 3-day event horse inspection. N Z Vet J, 47(6), 193–197.
Abstract: AIMS: To quantify the linear and temporal characteristics of the trot of 3-day event horses during the preliminary horse inspection of an advanced grade CCI* 3-day event. METHODS: A cross sectional study was made of the kinematics of 24 3-day-event horses during the first horse inspection at a CCI* level S-day event. Video footage was digitised and linear and temporal measurements were made. RESULTS: The horses trotted for an average of 10.44+/-1.55 strides. Spatial measurements were made on an average of 5.66+/-0.92 consecutive strides when the horses were within the calibration zone. The horses increased and then obtained a constant velocity within the calibration zone. Trotting on the asphalt track did not alter the relationships between stride length, stride duration and velocity when compared with previously published values. Horse-specific differences in stance and retraction percentages were identified. CONCLUSION: Horse specific differences were identified that may contribute to each horse's unique gait or kinematic fingerprint. It is proposed that the initiation of, and completion of, stance by the hind limb first may represent engagement of the hind quarters and be a response to dressage training.
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Odberg, F. O., & Bouissou, M. F. (1999). The development of equestrianism from the baroque period to the present day and its consequences for the welfare of horses. Equine Vet J Suppl, (28), 26–30.
Abstract: Many saddle horses are slaughtered at a young age which could be indicative of a welfare problem. Bad riding is probably an underestimated source of poor welfare. Widespread knowledge of 'academic' riding should be encouraged and should be beneficial to all horses, at all schooling levels, for all purposes. In particular, 18th century principles tend to be forgotten and in this article the authors illustrate some differences to modern dressage. Various suggestions are made in order to improve welfare.
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Clayton, H. M., Lanovaz, J. L., Schamhardt, H. C., & van Wessum, R. (1999). The effects of a rider's mass on ground reaction forces and fetlock kinematics at the trot. Equine Vet J Suppl, 30, 218–221.
Abstract: Ground reaction force (GRF) measurements are often normalised to body mass to facilitate inter-individual comparisons. The objective of this study was to explore the effect of a rider on the GRFs and fetlock joint kinematics of trotting horses. The subjects were 5 dressage-trained horses and 3 experienced dressage riders. Ground reaction force measurements and sagittal view videotapes were recorded as the horses trotted at the same velocity in hand (3.49 +/- 0.52 m/s) and with a rider (3.49 +/- 0.46 m/s). Data were time-normalised to stance duration. Ground reaction force measurements were expressed in absolute terms and normalised to the system mass (horse or horse plus rider). All the horses showed changes in the same direction when comparing the ridden condition with the in-hand condition. There was an increase in the absolute peak vertical GRFs of the fore- and hindlimbs with a rider. However, the mass-normalised peak vertical GRFs were lower for the ridden condition, with the peak occurring later in the forelimbs and earlier in the hindlimbs compared with the inhand condition. Maximal fetlock angle and its time of occurrence were similar for the 2 conditions, but the fore fetlock joint was more extended during the later part of the stance phase in ridden horses. The presence of a rider appeared to affect the GRFs and fetlock joint kinematics differently in the fore- and hindlimbs, and the ridden horse did not seem to be equivalent to a proportionately larger horse. This should be considered when normalising for body mass in studies comparing horses in hand and ridden horses.
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Grandin, T. (1999). Safe handling of large animals. Occup Med, 14(2), 195–212.
Abstract: The major causes of accidents with cattle, horses, and other grazing animals are: panic due to fear, male dominance aggression, or the maternal aggression of a mother protecting her newborn. Danger is inherent when handling large animals. Understanding their behavior patterns improves safety, but working with animals will never be completely safe. Calm, quiet handling and non-slip flooring are beneficial. Rough handling and excessive use of electric prods increase chances of injury to both people and animals, because fearful animals may jump, kick, or rear. Training animals to voluntarily cooperate with veterinary procedures reduces stress and improves safety. Grazing animals have a herd instinct, and a lone, isolated animal can become agitated. Providing a companion animal helps keep an animal calm.
Keywords: Accidents, Occupational/*prevention & control/statistics & numerical data; Aggression/physiology/psychology; Animal Husbandry/*methods; Animals; *Behavior, Animal/physiology; Cattle; Conditioning, Operant/physiology; Crowding/psychology; Fear/physiology/psychology; Female; *Horses/physiology/psychology; Humans; Male; Movement/physiology; *Occupational Health; Risk Factors; *Ruminants/physiology/psychology
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Hodson, E. F., Clayton, H. M., & Lanovaz, J. L. (1999). Temporal analysis of walk movements in the Grand Prix dressage test at the 1996 Olympic Games. Appl. Anim. Behav. Sci., 62(2-3), 89–97.
Abstract: Video analysis was used to measure temporal characteristics of the collected walk, extended walk and half pirouette at walk of eleven competitors during the team dressage competition at the 1996 Summer Olympic Games in Atlanta, GA. Forelimb stance durations, hind limb stance durations, lateral step intervals and diagonal step intervals were symmetrical for the right and left sides in the collected and extended walk strides, but there were left-right asymmetries in the forelimb stance duration and in the lateral step interval in the half pirouette strides. For both collected and extended walk strides, hind limb stance duration was significantly longer than forelimb stance duration. The mean values for the group of eleven horses showed that the collected and extended walks had a regular rhythm. The half pirouette strides showed an irregularity in which there was a short interval between footfalls of the outside forelimb and inside hind limb, and along interval between footfalls of the inside hind limb and inside forelimb. This irregularity reflected an early placement of the inside hind limb. The stance times of both hind limbs were prolonged and this finding, in combination with the early placement of the inside hind limb, led to an increase in the period of tripedal support in each stride of the half pirouette. This was interpreted as a means of maintaining the horses' balance in the absence of forward movement.
Keywords: Dressage; Horse; Kinematics; Locomotion; Gait
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Cioni, P., & Strambini, G. B. (1999). Pressure/temperature effects on protein flexibilty from acrylamide quenching of protein phosphorescence. Journal of Molecular Biology, 291(4), 955–964.
Abstract: Pressure is an effective modulator of protein structure and biological function. The influence of hydrostatic pressure ([less-than-or-equals, slant]3 kbar, 10-50[degree sign]C) on conformational dynamics was assessed from the rate of migration of acrylamide through the protein interior. Migration rates in apoazurin, alcohol dehydrogenase and alkaline phosphatase were obtained from the phosphorescence quenching rate constant (kq) of the deeply buried Trp residues. The dominant effect of applied pressure is to slow the diffusion process, although at low temperature, high pressure may also accelerate it. For apoazurin, alcohol dehydrogenase and alkaline phosphatase the activation free volumes, ΔVobs++, derived from the pressure-dependence of kq, ranges from +10, +16 and +20 ml mol-1 at 50[degree sign]C to -20, +5 and 0 ml mol-1 at 10[degree sign]C, respectively. Analysing ΔVobs++ in terms of a positive contribution from cavity expansion and a negative one from peptide hydration, the results emphasise that whereas at warm temperature the formation of cavities plays a dominant role in the migration process, at low temperature the required flexibility may be conferred by internal protein hydration. The relatively small magnitude of both ΔVobs++ and the activation enthalpy (ΔH++=10-20 kcal mol-1) indicates that acrylamide diffusion jumps inside these proteins appear to involve relatively small amplitude structural fluctuations not requiring major unfolding-like transitions. The implication of these findings for the thermodynamic stability of proteins under pressure is discussed.
Keywords: phosphorescence; tryptophan; acrylamide; quenching; protein dynamics
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Rendall, D. (1999). Review of Machiavellian Intelligence II: Extensions and Evaluations. Ethology, 105(2), 178–182.
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