Abstract: The way in which cognitive functioning is affected by stressors is an important area of research for applied ethologists because stress caused by captive conditions may disrupt cognitive processes and lead to welfare and husbandry problems. Such problems may be minimised through an understanding of the links between stress and cognition. The effects of stress on cognitive function have been studied in disciplines ranging from human perceptual psychology to animal neuroscience. The aim of this paper is to provide an introduction to this research, focusing on the effects of stressors on attention, memory formation and memory recall. Findings from such a diverse literature with little apparent inter-disciplinary communication are inevitably complex and often contradictory. Nevertheless, some generalities do emerge. The idea that an inverted U-shaped relationship exists between an individual's state of stress or arousal and its ability to perform a cognitive task effectively, the so-called Yerkes-Dodson law, is commonly encountered. The law has limited explanatory value because it is unlikely that different stressors act on cognitive function via the same intervening, non-specific state. Furthermore, the law only provides a very general description of the relationship between stress and cognitive function. Empirical research on attention and memory processes reveals more specific findings. Stressors appear to cause shifts, lapses and narrowing of attention, and can also influence decision speed. These processes may be viewed as serving an adaptive role helping the animal to search for and scrutinise a source of danger. There is conflicting evidence as to whether hormones involved in the hypothalamic-pituitary-adrenal stress response play a part in these processes. These hormones and those involved in the sympathetic-adrenomedullary stress response do appear to play an important role in memory formation. Low or moderate concentrations of circulating glucocorticoids and catecholamines can enhance memory formation, while excessively high or prolonged elevations of these hormones can lead to memory disruption. The effects of stressors on memory recall are less clear. There is evidence for disruptive effects, and for facilitatory effects indicating state-dependent memory recall; events experienced under conditions of high arousal may be best recalled under similar conditions. Applied ethologists have the opportunity to extend work in this area, which often involves studies of single stressors/stress hormones acting in isolation and limited measures of cognitive function, by focusing on real-life husbandry stressors encountered by captive animals. This will yield fundamental information which also has direct relevance to animal welfare and management issues.

Abstract: Behavioural tests using operant conditioning were conducted to examine how miniature pigs discriminate between people. During a 3-week handling period, six 8-week-old pigs were touched and fed raisins as a reward whenever they approached their handler. In subsequent training, the handler and a non-handler wearing dark blue and white coveralls, respectively, and wearing different eau de toilette fragrances sat at each end of a Y-maze. Pigs were rewarded with raisins when they chose the handler. Successful discrimination occurred when the pig chose the handler at least 15 times in 20 trials (P<0.05: by χ2 test). When all pigs exhibited successful discrimination under these standard conditions, they were exposed to Experiments 1 through 4. In Experiment 1, (1) handler and non-handler exchanged colours of coveralls; (2) handler and non-handler exchanged eau de toilette; (3) handler and non-handler exchanged both cues. The non-handler was chosen significantly more often following the exchange of coverall colours and the exchange of both coverall colours and eau de toilette. However, the handler was chosen significantly more frequently following exchange of eau de toilette only. In Experiment 2, when both handler and non-handler wore coveralls of the handler's original colour, the pigs had difficulty discriminating between them. In Experiment 3, both handler and non-handler wore coveralls of new colours. The pigs easily chose the handler wearing red or blue vs. white coveralls. In Experiment 4, (1) two novel people wore coveralls of the original colours of handler and non-handler; (2) the test with the original experimenters was conducted under the original conditions but in a novel place. Between novel people, the one wearing the handler's original colour of coveralls was preferentially chosen by the pigs. The pigs had difficulty discriminating the handler from the non-handler in a novel place. Pigs appear to discriminate between a familiar handler and a non-familiar person based primarily on visual cues, prominent of which is colour of clothing.

Abstract: The domestic cat exhibits a wide variety of social behavior. The aim of this experiment was to investigate factors which influence the affiliative and aggressive behavior of the indoor-only neutered domestic cat. Some 60 households comprised of either two males, two females or a male and female cat were observed. The cats were between 6 months and 8 years old, and were always restricted to the indoors. Each pair of housemates was observed for 10 h. There were no significant differences in affiliative or aggressive behavior based on cat gender. However, females were never observed to allorub other females. The male/male households did spend more time in close proximity. The amount of time the cats had lived together was negatively correlated with the amount of aggression observed during the study. Factors such as size of the house and weight difference between the cats did not correlate with the aggression rate. Large standard deviations and the correlations of social behavior between housemates indicated the importance of individual differences in behavior.

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.

Abstract: A behavioral assessment of horses who were being used and not used in therapeutic riding programs was conducted to help determine useful methods of selecting horses for use in therapeutic riding programs. A total of 103 horses (76 horses from five therapeutic riding centers and 27 non-therapeutic riding horses from four sites) were used. Temperament survey for each horse were completed by three riding instructors at each therapeutic riding center or by the individual most knowledgeable about the horse at the other sites. Twenty personality traits from the survey were used to quantify temperament. Concentrations of plasma cortisol, norepinephrine and epinephrine were also measured in each horse. A reactivity test was then conducted which involved introducing three novel stimuli: a walking and vocalizing toy pig placed on a cardboard surface in front of the horse for 20 s; popping a balloon near the horse's flank area; and suddenly opening an umbrella and holding it open in front of the horse for 20 s. Reactions (expressions, vocalizations and movement) to each of the stimuli were scored and used to calculate an average reactivity score for each horse. The therapeutic riding instructors did not often agree on the temperament of their center's horses. The personality trait ratings made by the therapeutic riding instructors at each center were on average significantly correlated (P<0.01, r>0.52) for only 37.8% of the horses for any two instructors and 7.8% for three instructors. No significant correlations were found between temperament, reactivity, and the hormone concentrations (r<0.19), but regression analysis indicated a possibility of predicting temperament from the reactivity score and hormone concentrations (P<0.08). There was also a tendency for relationships between extremes in temperament (desirable vs. undesirable) and the hormone concentrations (P<0.09), and between extremes in reactivity (low vs. high) and the hormone concentrations (P=0.08). The difference in ratings among riding instructors indicates a need for more collaboration between instructors when evaluating horse temperament. This study also indicates that it was very difficult to objectively determine the suitability of horses for therapeutic riding programs regarding their temperament and reactivity, probably because other traits (e.g., smoothness of gait) are also considered very important.