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Beckers, T., Miller, R. R., De Houwer, J., & Urushihara, K. (2006). Reasoning rats: forward blocking in Pavlovian animal conditioning is sensitive to constraints of causal inference. J Exp Psychol Gen, 135(1), 92–102.
Abstract: Forward blocking is one of the best-documented phenomena in Pavlovian animal conditioning. According to contemporary associative learning theories, forward blocking arises directly from the hardwired basic learning rules that govern the acquisition or expression of associations. Contrary to this view, here the authors demonstrate that blocking in rats is flexible and sensitive to constraints of causal inference, such as violation of additivity and ceiling considerations. This suggests that complex cognitive processes akin to causal inferential reasoning are involved in a well-established Pavlovian animal conditioning phenomenon commonly attributed to the operation of basic associative processes.
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McCall, C. A., Hall, S., McElhenney, W. H., & Cummins, K. A. (2006). Evaluation and comparison of four methods of ranking horses based on reactivity. Appl. Anim. Behav. Sci., 96(1-2), 115–127.
Abstract: Four methods of ranking horses on reactivity were evaluated and compared: isolation from conspecifics, presentation of a static novel stimulus, traversing a novel stimulus in a runway (isolation, novel stimulus and runway tests, respectively) and assigning subjective emotionality scores. In all tests, horses' heart rates were recorded and behaviour was videotaped. To be considered a valid test of reactivity, at least one heart rate and one behavioural measurement in the test had to change significantly between treatments (tranquilizer administation versus sham tranquilizer administration), and behavioural measures had to be displayed in at least 75% of the trials. Forty horses performed each of the three tests daily on three different days in a switchback design. Horses were assigned randomly to a daily test sequence, which was maintained throughout the study. In the runway test, no significant difference in heart rate values in tranquilized and non-tranquilized horses was found, and no behavioural attribute was displayed in more than 52% of the trials; therefore it was rejected as a valid test of reactivity. Both isolation and novel stimulus tests produced valid measurements. Mean heart rate was the most precise physiological measure for these tests, and walking and defecation frequency were the most precise behavioural measures for novel stimulus and isolation tests, respectively. Mean heart rates on the novel stimulus and isolation tests were correlated (rs = 0.79, P < 0.01) indicating that these tests produced similar rankings based on physiological responses. However, behavioural measures ranked horses differently (rs = 0.27, P < 0.10) on the tests. Rank correlations between mean heart rates and behavioural measures were higher in the novel stimulus (rs = 0.66, P < 0.01) than the isolation test (rs = 0.55, P < 0.01), indicating that the novel stimulus test ranked horses based on either physiological or behavioural responses more similarly than did the isolation test. Therefore, the novel stimulus test was considered the more accurate evaluation of reactivity. Subjective emotionality scores were correlated moderately with mean heart rates (rs > 0.33, P < 0.01) from the novel stimulus and isolation tests and with walking scores (rs = 0.47, P < 0.01) from the novel stimulus test. Assignment of subjective emotionality scores was not as accurate as the novel stimulus or isolation tests in ranking horses for reactivity. Using physiological data alone, combining physiological and behavioural measurements or using more than one behavioural measurement in reactivity tests may reflect the reactivity of the horse better than a single behavioural measurement.
Keywords: Horse; Reactivity tests; Heart rate; Emotionality; Temperament
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Huebener, E. (2006). How the Horse-Appropriate “Self-Acting” Leg Aid Could Be Better Communicated. Tierärztl. Umschau, 8, 403.
Abstract: From the base to the top of the sport horses are being coerced into “obedience” or the performance of exercises by force. Campaigns against the “Rollkur” or “Hyperflexion” fill the media. However the root of evil lies a lot deeper. The base of cultured riding in high harmony between horse and rider are sensitive, almost invisible aids which are being timed by the movements of the horse's back and trunk. Anchoring the knowledge of this interrelation in rider's minds has to this day been unsuccessful.
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Daniel J. Povinelli, & Timothy J. Eddy. (2006). Chimpanzees: Joint Visual Attention. Psychol Sci, 7(3), 129–135.
Abstract: Gaze following is a behavior that draws the human infant into perceptual contact with objects or events in the world to which others are attending One interpretation of the development of this phenomenon is that it signals the emergence of joint or shared attention, which may be critical to the development of theory of mind An alternative interpretation is that gaze following is a noncognitive mechanism that exploits social stimuli in order to orient the infant (or adult) to important events in the world We report experimental results that chimpanzees display the effect in response to both movement of the head and eyes in concert and eve movement alone Additional tests indicate that chimpanzees appear able to (a) project an imaginary line of sight through invisible space and (b) understand How that line of sight can be impeded by solid, opaque objects This capacity may have arisen because of its reproductive payoffs in the context of social competition with conspecifics, predation avoidance, or both.
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Edwards, D. H., & Spitzer, N. (2006). 6. Social dominance and serotonin receptor genes in crayfish. Curr Top Dev Biol, 74, 177–199.
Abstract: Gene expression affects social behavior only through changes in the excitabilities of neural circuits that govern the release of the relevant motor programs. In turn, social behavior affects gene expression only through patterns of sensory stimulation that produce significant activation of relevant portions of the nervous system. In crayfish, social interactions between pairs of animals lead to changes in behavior that mark the formation of a dominance hierarchy. Those changes in behavior result from changes in the excitability of specific neural circuits. In the new subordinate, circuits for offensive behavior become less excitable and those for defensive behavior become more excitable. Serotonin, which is implicated in mechanisms for social dominance in many animals, modulates circuits for escape and avoidance responses in crayfish. The modulatory effects of serotonin on the escape circuits have been found to change with social dominance, becoming excitatory in dominant crayfish and inhibitory in subordinates. These changes in serotonin's effects on escape affect the synaptic response to sensory input of a single cell, the lateral giant (LG) command neuron for escape. Moreover, these changes occur over a 2-week period and for the subordinate are reversible at any time following a reversal of the animal's status. The results have suggested that a persistent change in social status leads to a gradual change in the expression of serotonin receptors to a pattern that is more appropriate for the new status. To test that hypothesis, the expression patterns of crayfish serotonin receptors must be compared in dominant and subordinate animals. Two of potentially five serotonin receptors in crayfish have been cloned, sequenced, and pharmacologically characterized. Measurements of receptor expression in the whole CNS of dominant and subordinate crayfish have produced inconclusive results, probably because each receptor is widespread in the nervous system and is likely to experience opposite expression changes in different areas of the CNS. Both receptors have recently been found in identified neurons that mediate escape responses, and so the next step will be to measure their expression in these identified cells in dominant and subordinate animals.
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Moses, S. N., Villate, C., & Ryan, J. D. (2006). An investigation of learning strategy supporting transitive inference performance in humans compared to other species. Neuropsychologia, 44(8), 1370–1387.
Abstract: Generalizations about neural function are often drawn from non-human animal models to human cognition, however, the assumption of cross-species conservation may sometimes be invalid. Humans may use different strategies mediated by alternative structures, or similar structures may operate differently within the context of the human brain. The transitive inference problem, considered a hallmark of logical reasoning, can be solved by non-human species via associative learning rather than logic. We tested whether humans use similar strategies to other species for transitive inference. Results are crucial for evaluating the validity of widely accepted assumptions of similar neural substrates underlying performance in humans and other animals. Here we show that successful transitive inference in humans is unrelated to use of associative learning strategies and is associated with ability to report the hierarchical relationship among stimuli. Our work stipulates that cross-species generalizations must be interpreted cautiously, since performance on the same task may be mediated by different strategies and/or neural systems.
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Musterle, B., Furst, A., Geyer, H., Raber, M., & Weishaupt, M. A. (2006). [Interactive educational DVD on hoof protection, horseshoeing and diseases of the hoof]. Schweiz Arch Tierheilkd, 148(2), 81–85.
Abstract: Good cooperation between farrier, veterinarian and horse owner is an important prerequisite for optimal support of the horse with regards to shoeing and hoof health. The introduction of a joint educational aid aims to improve the level of education of both veterinarians and farriers. The interactive, multimedia approach represents an innovative new dimension in instruction techniques, predominantly provided through images and videos. The contents of the new teaching aid will focus on detailed anatomy of the foot and distal limb, as well as currently accepted shoeing practices and techniques and pathologic conditions of the hoof and foot.
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Amé, J. - M., Halloy, J., Rivault, C., Detrain, C., & Deneubourg, J. L. (2006). Collegial decision making based on social amplification leads to optimal group formation. Proc. Natl. Acad. Sci. U.S.A., 103(15), 5835–5840.
Abstract: Group-living animals are often faced with choosing between one or more alternative resource sites. A central question in such collective decision making includes determining which individuals induce the decision and when. This experimental and theoretical study of shelter selection by cockroach groups demonstrates that choices can emerge through nonlinear interaction dynamics between equal individuals without perfect knowledge or leadership. We identify a simple mechanism whereby a decision is taken on the move with limited information and signaling and without comparison of available opportunities. This mechanism leads to optimal mean benefit for group individuals. Our model points to a generic self-organized collective decision-making process independent of animal species.
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Bonnie, K. E., & de Waal, F. B. M. (2006). Affiliation promotes the transmission of a social custom: handclasp grooming among captive chimpanzees. Primates, 47(1), 27–34.
Abstract: Handclasp grooming is a unique social custom, known to occur regularly among some, but not all populations of chimpanzees (Pan troglodytes). As with other cultural behaviors, it is assumed that this distinctive grooming posture is learned socially by one individual from another. However, statistical comparisons among factors thought to influence how a behavior spreads within a group have never, to our knowledge, been conducted. In the present study, the origination and spread of handclasp grooming in a group of captive chimpanzees was followed throughout more than 1,500 h of observation over a period of 12 years. We report on the frequency, bout duration, and number and demography of performers throughout the study period, and compare these findings to those reported for wild populations. We predicted that dyads with strong affiliative ties, measured by time spent in proximity to and grooming one another, were likely to develop a handclasp grooming partnership during the study period. A quadratic assignment procedure was used to compare correlations among observed frequencies of grooming and proximity with handclasp grooming in all possible dyads within the group. As predicted, the formation of new handclasp grooming dyads was positively correlated with the rate of overall grooming and proximity within a dyad. In addition, in nearly all dyads formed, at least one individual had been previously observed to handclasp groom. We concluded that affiliation and individual experience determines the transmission of handclasp grooming among captive chimpanzees.
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Pell, M. D. (2006). Cerebral mechanisms for understanding emotional prosody in speech. Brain and Language, 96(2), 221–234.
Abstract: Hemispheric contributions to the processing of emotional speech prosody were investigated by comparing adults with a focal lesion involving the right (n = 9) or left (n = 11) hemisphere and adults without brain damage (n = 12). Participants listened to semantically anomalous utterances in three conditions (discrimination, identification, and rating) which assessed their recognition of five prosodic emotions under the influence of different task- and response-selection demands. Findings revealed that right- and left-hemispheric lesions were associated with impaired comprehension of prosody, although possibly for distinct reasons: right-hemisphere compromise produced a more pervasive insensitivity to emotive features of prosodic stimuli, whereas left-hemisphere damage yielded greater difficulties interpreting prosodic representations as a code embedded with language content.
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