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König von Borstel, U., Pasing, S., & Gauly, M. (2011). Towards a more objective assessment of equine personality using behavioural and physiological observations from performance test training. Appl. Anim. Behav. Sci., 135(4), 277–285.
Abstract: Current definitions of horse personality traits are rather vague, lacking clear, universally accepted guidelines for evaluation in performance tests. Therefore, the aim of the present study was to screen behavioural and physiological measurements taken during riding for potential links with scores the same horses received in the official stallion performance test for rideability and personality traits. Behaviour, heart rate (HR) and HR variability from thirty-six stallions participating in a performance test were recorded repeatedly during their performance test training. Using the coefficient of determination, regression analysis revealed that about 1/3 of variation (ranging between r = 0.26 (“constitution” (i.e. fitness, health)) and r = 0.46 (rideability)) in the personality trait scores could be explained by selecting the three most influential behaviour patterns per trait. These behaviour patterns included stumbling (with all traits except character), head-tossing (temperament, rideability), tail-swishing (willingness to work), involuntary change in gait (character) and the rider's use of her/his hands (constitution, rideability), voice (temperament) or whip (constitution). Subsequent mixed model analysis revealed a significant (P < 0.05) influence of the behaviour pattern “horse-induced change in gait” on character (-0.98 ± 0.31 scores per additional occurrence of change in gaits), of head-tossing (-0.25 ± 0.08 scores) and rider's use of voice (-0.51 ± 0.25; P = 0.0594) on temperament, and of stumbling on each of the following: willingness to work (-2.5 ± 1.2), constitution (-2.5 ± 1.2 scores; P = 0.0516) and rideability scores (-3.3 ± 1.4). In addition, constitution scores tended (P = 0.0889) to increase with higher low frequency/high frequency heart rate variation ratios (LF/HF), indicating a shift towards sympathetic dominance and thus a higher stress load in horses with higher scores for constitution. Rideability scores from the training phase were also significantly influenced by head-tossing (-0.5 ± 0.1), and in addition rideability scores from the final test were influenced by the training rider, ranging between average estimated rideability scores of 6.8 ± 0.4 for one training rider and 8.36 ± 0.3 scores for another training rider. Horses ridden with their nose-line predominantly behind the vertical received higher scores for rideability (8.3 ± 0.3) than horses ridden with their nose-line at the vertical (7.7 ± 0.2). These findings indicate that either judges perceive horses to have a better rideability when they readily offer a more extreme poll flexion, or that riders make use of horses’ better rideability by imposing a more extreme poll flexion. Several of the above described associations, but also of the non-existing links (e.g. no association between shying or heart rate and temperament) between behaviour patterns and scores for personality traits are rather surprising, warranting further investigation regarding the underlying causes of these relationships. Some of these behaviour patterns should be considered when redesigning the current guidelines for evaluation of personality traits during breeding horse performance tests, ultimately leading to improved genetic selection for equine personality traits. However, ethical implication of defining aversive behaviour such as head-tossing as an indicator of, for example, poor temperament, should not be neglected when devising new guidelines: such aversive behaviour may in fact be an indication of inadequate training techniques rather than poor horse personality.
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König v. Borstel, U., Pirsich, W., Gauly, M., & Bruns, E. (2012). Repeatability and reliability of scores from ridden temperament tests conducted during performance tests. Appl. Anim. Behav. Sci., 139(3–4), 251–263.
Abstract: Current scores for equine personality traits assessed during performance tests are characterised by high means and inadequate variation, hampering genetic selection for these traits. A number of temperament and related behaviour tests have been developed in order to make assessment of equine personality more objective. However, rarely these tests have been validated for their use as a selection tool. Thus, as a first step the aim of the present study was to integrate a temperament tests into horse performance tests, in order to assess variability and repeatability of horses’ reactivity under the rider and the reliability of the judges’ assessment thereof. The temperament test was comprised of three novel stimuli, including a visual stimulus (BALL), a visual and tactile stimulus (GATE), and a visual and auditory stimulus (CANS). A total of 224 mares and stallions were subjected to the test during their participation in station performance tests for riding horses, and 133 of these horses were subjected to the test a second time either 2–3 weeks or 18 weeks after the first test. Horses were ridden in the test by professional riders, and their reactions to the stimuli were evaluated each by two judges and the rider using scores on a scale from 1 (task not concluded) to 10 (completely calm but attentive horse). Mean scores (±SD) ranged between 6.6 ± 2.4 (GATE) and 7.8 ± 2.1 (BALL), demonstrating lower means and considerably higher standard deviations than the same horses’ scores from present evaluation of the trait labelled temperament (8.1 ± 0.9) or related personality traits (e.g. character: 8.3 ± 0.8). Using variance components from mixed model analysis, inter-observer agreement between the two judges was for the individual stimuli very high (0.95 (BALL), 0.96 (GATE), 0.89 (CANS)), and there was likewise high agreement between the judges’ and the riders’ combined scores (0.93). Repeatabilities of horses’ scores were 0.72 (BALL), 0.75 (GATE), and 0.69 (CANS). Correlations to traits from the present evaluation of personality were low or non-existent, indicating that these traits are not a reflection of anxiety or fear reactivity as assessed by novel object tests. Horses’ improvement in judges’ combined scores from first to second test was not (P > 0.1) influenced by differences in time between tests, but differed between breed-types and individual riders. Also, not surprisingly, the higher horses’ scores in the first test were, the lower their improvement in the second test was (-0.45 ± 0.06 per additional score in the first test). Temperament tests using novel stimuli presented to horses under a rider may be a practical and valid tool for improving the current assessment of equine personality traits during performance tests. Considering a combination of absolute scores and horses’ improvement in scores of repeated tests, rather than measuring only absolute scores yields relevant information about horses’ personality, and at the same time it may prevent owners from deliberately training their horses for low reactions to the test-stimuli.
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Bouchard, T. J. J., & Loehlin, J. C. (2001). Genes, evolution, and personality. Behav Genet, 31(3), 243–273.
Abstract: There is abundant evidence, some of it reviewed in this paper, that personality traits are substantially influenced by the genes. Much remains to be understood about how and why this is the case. We argue that placing the behavior genetics of personality in the context of epidemiology, evolutionary psychology, and neighboring psychological domains such as interests and attitudes should help lead to new insights. We suggest that important methodological advances, such as measuring traits from multiple viewpoints, using large samples, and analyzing data by modern multivariate techniques, have already led to major changes in our view of such perennial puzzles as the role of “unshared environment” in personality. In the long run, but not yet, approaches via molecular genetics and brain physiology may also make decisive contributions to understanding the heritability of personality traits. We conclude that the behavior genetics of personality is alive and flourishing but that there remains ample scope for new growth and that much social science research is seriously compromised if it does not incorporate genetic variation in its explanatory models.
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Weiss, A., King, J. E., & Figueredo, A. J. (2000). The heritability of personality factors in chimpanzees (Pan troglodytes). Behav Genet, 30(3), 213–221.
Abstract: Human personality and behavior genetic studies have resulted in a growing consensus that five heritable factors account for most variance in human personality. Prior research showed that chimpanzee personality is composed of a dominance-related factor and five human-like factors--Surgency, Dependability, Emotional Stability, Agreeableness, and Openness. Genetic, shared zoo, and nonshared environmental variance components of the six factors were estimated by regressing squared phenotypic differences of all possible pairs of chimpanzees onto 1 – Rij, where Rij equals the degree of relationship and a variable indicating whether the pair was housed in the same zoo. Dominance showed significant narrow-sense heritability. Shared zoo effects accounted for only a negligible proportion of the variance for all factors.
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Preston, S. D., & de Waal, F. B. M. (2002). Empathy: Its ultimate and proximate bases. Behav Brain Sci, 25(1), 1–20; discussion 20–71.
Abstract: There is disagreement in the literature about the exact nature of the phenomenon of empathy. There are emotional, cognitive, and conditioning views, applying in varying degrees across species. An adequate description of the ultimate and proximate mechanism can integrate these views. Proximately, the perception of an object's state activates the subject's corresponding representations, which in turn activate somatic and autonomic responses. This mechanism supports basic behaviors (e.g., alarm, social facilitation, vicariousness of emotions, mother-infant responsiveness, and the modeling of competitors and predators) that are crucial for the reproductive success of animals living in groups. The Perception-Action Model (PAM), together with an understanding of how representations change with experience, can explain the major empirical effects in the literature (similarity, familiarity, past experience, explicit teaching, and salience). It can also predict a variety of empathy disorders. The interaction between the PAM and prefrontal functioning can also explain different levels of empathy across species and age groups. This view can advance our evolutionary understanding of empathy beyond inclusive fitness and reciprocal altruism and can explain different levels of empathy across individuals, species, stages of development, and situations.
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Cattell, R. B., & Korth, B. (1973). The isolation of temperament dimensions in dogs. Behav Biol, 9(1), 15–30.
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McClearn, G. E. (1971). Behavioral genetics. Behav Sci, 16(1), 64–81.
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Lafferty, K. D. (2005). Look what the cat dragged in: do parasites contribute to human cultural diversity? Behav. Process., 68(3), 279–282.
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Kotrschal, K., Schöberl, I., Bauer, B., Thibeaut, A. - M., & Wedl, M. (2009). Dyadic relationships and operational performance of male and female owners and their male dogs. Behav. Process., 81(3), 383–391.
Abstract: In the paper we investigate how owner personality, attitude and gender influence dog behavior, dyadic practical functionality and the level of dog salivary cortisol. In three meetings, 12 female and 10 male owners of male dogs answered questionnaires including the Neo-FFI human personality inventory. Their dyadic behavior was video-taped in a number of test situations, and saliva samples were collected. Owners who scored highly in neuroticism (Neo-FFI dimension one) viewed their dogs as social supporters and spent much time with them. Their dogs had low baseline cortisol levels, but such dyads were less successful in the operational task. Owners who scored highly in extroversion (Neo-FFI dimension two) appreciated shared activities with their dogs which had relatively high baseline cortisol values. Dogs that had female owners were less sociable-active (dog personality axis 1) than dogs that had male owners. Therefore, it appears that owner gender and personality influences dyadic interaction style, dog behavior and dyadic practical functionality.
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Watanabe, N. M., Stahlman, W. D., Blaisdell, A. P., Garlick, D., Fast, C. D., & Blumstein, D. T. (2012). Quantifying personality in the terrestrial hermit crab: Different measures, different inferences. Behav. Process., 91(2), 133–140.
Abstract: There is much interest in studying animal personalities but considerable debate as to how to define and evaluate them. We assessed the utility of one proposed framework while studying personality in terrestrial hermit crabs (Coenobita clypeatus). We recorded the latency of individuals to emerge from their shells over multiple trials in four unique manipulations. We used the specific testing situations within these manipulations to define two temperament categories (shyness-boldness and exploration-avoidance). Our results identified individual behavioral consistency (i.e., personality) across repeated trials of the same situations, within both categories. Additionally, we found correlations between behaviors across contexts (traits) that suggested that the crabs had behavioral syndromes. While we found some correlations between behaviors that are supposed to measure the same temperament trait, these correlations were not inevitable. Furthermore, a principal component analysis (PCA) of our data revealed new relationships between behaviors and provided the foundation for an alternate interpretation: measured behaviors may be situation-specific, and may not reflect general personality traits at all. These results suggest that more attention must be placed on how we infer personalities from standardized methods, and that we must be careful to not force our data to fit our frameworks.
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