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Murray, J. K., Singer, E. R., Morgan, K. L., Proudman, C. J., & French, N. P. (2004). Memory decay and performance-related information bias in the reporting of scores by event riders. Preventive Veterinary Medicine, 63(3-4), 173–182.
Abstract: We used data from a case-control study investigating risk factors for horse falls in the cross-country phase of eventing in Great Britain (GB) to examine evidence for memory decay and information bias. Responses to two questions obtained by telephone for 173 cases and 521 controls were examined for evidence of differential reporting according to the respondent's case-control status and performance in the dressage and cross-country phases of competitions. Information bias was found in the accuracy of reporting dressage penalty scores when analysed as a function of performance level (good/poor). Poor dressage performers were less likely to report accurate dressage scores than good performers. The accuracy of reporting dressage scores decreased as the time between the event and questionnaire completion increased, with no case-control interaction. Competitors who incurred cross-country jumping penalties at the event preceding the selected event reported their cross-country scores with less accuracy when compared with competitors who incurred no penalties. No information bias was found when the reporting of dressage and cross-country scores were analysed as a function of respondent category (case/control).
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Mendl, M. (1999). Performing under pressure: stress and cognitive function. Appl. Anim. Behav. Sci., 65(3), 221–244.
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.
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Griffiths, D. P., & Clayton, N. S. (2001). Testing episodic memory in animals: A new approach. Physiol. Behav., 73(5), 755–762.
Abstract: Episodic memory involves the encoding and storage of memories concerned with unique personal experiences and their subsequent recall, and it has long been the subject of intensive investigation in humans. According to Tulving's classical definition, episodic memory “receives and stores information about temporally dated episodes or events and temporal-spatial relations among these events.” Thus, episodic memory provides information about the `what' and `when' of events (`temporally dated experiences') and about `where' they happened (`temporal-spatial relations'). The storage and subsequent recall of this episodic information was thought to be beyond the memory capabilities of nonhuman animals. Although there are many laboratory procedures for investigating memory for discrete past episodes, until recently there were no previous studies that fully satisfied the criteria of Tulving's definition: they can all be explained in much simpler terms than episodic memory. However, current studies of memory for cache sites in food-storing jays provide an ethologically valid model for testing episodic-like memory in animals, thereby bridging the gap between human and animal studies memory. There is now a pressing need to adapt these experimental tests of episodic memory for other animals. Given the potential power of transgenic and knock-out procedures for investigating the genetic and molecular bases of learning and memory in laboratory rodents, not to mention the wealth of knowledge about the neuroanatomy and neurophysiology of the rodent hippocampus (a brain area heavily implicated in episodic memory), an obvious next step is to develop a rodent model of episodic-like memory based on the food-storing bird paradigm. The development of a rodent model system could make an important contribution to our understanding of the neural, molecular, and behavioral mechanisms of mammalian episodic memory.
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McLean, A. N. (2004). Short-term spatial memory in the domestic horse. Appl. Anim. Behav. Sci., 85(1-2), 93–105.
Abstract: This study investigates the ability of horses to recall a feeding event in a two-point choice apparatus. Twelve horses were individually tested whereby they were maintained immobile in a test arena and visually and aurally experienced the delivery of food into one of two feed goals. The horses were then released to make their choice in two experimental contexts: immediate release after experiencing the delivery of food, and release 10 s after food delivery. Each horse performed 40 immediate-release (IR) trials, followed by forty 10-s release trials over a 3-day period. In addition, the same horses were tested 3 months later in the spring with the same number and sequence of trials. Results were analysed by log-linear analysis of frequencies. Results showed that while horses were able to achieve the correct feed goal choice in the immediate-release trials, they were unsuccessful with the 10-s release trials. This suggests that there are limitations in recall abilities in horses, in that they may not possess a prospective type of memory. There are welfare and training implications in these findings concerning the effects of overestimating the mental abilities of horses during training and the effects of delays in reinforcements.
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Murphy, J., & Arkins, S. (2007). Equine learning behaviour. Behav. Process., 76(1), 1–13.
Abstract: Scientists and equestrians continually seek to achieve a clearer understanding of equine learning behaviour and its implications for training. Behavioural and learning processes in the horse are likely to influence not only equine athletic success but also the usefulness of the horse as a domesticated species. However given the status and commercial importance of the animal, equine learning behaviour has received only limited investigation. Indeed most experimental studies on equine cognitive function to date have addressed behaviour, learning and conceptualisation processes at a moderately basic cognitive level compared to studies in other species. It is however, likely that the horses with the greatest ability to learn and form/understand concepts are those, which are better equipped to succeed in terms of the human-horse relationship and the contemporary training environment. Within equitation generally, interpretation of the behavioural processes and training of the desired responses in the horse are normally attempted using negative reinforcement strategies. On the other hand, experimental designs to actually induce and/or measure equine learning rely almost exclusively on primary positive reinforcement regimes. Employing two such different approaches may complicate interpretation and lead to difficulties in identifying problematic or undesirable behaviours in the horse. The visual system provides the horse with direct access to immediate environmental stimuli that affect behaviour but vision in the horse is of yet not fully investigated or understood. Further investigations of the equine visual system will benefit our understanding of equine perception, cognitive function and the subsequent link with learning and training. More detailed comparative investigations of feral or free-ranging and domestic horses may provide useful evidence of attention, stress and motivational issues affecting behavioural and learning processes in the horse. The challenge for scientists is, as always, to design and commission experiments that will investigate and provide insight into these processes in a manner that withstands scientific scrutiny.
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Levy, F., Keller, M., & Poindron, P. (2004). Olfactory regulation of maternal behavior in mammals. Horm Behav, 46(3), 284–302.
Abstract: In mammals, olfactory cues are extensively used in many aspects of maternal care to ensure the coordination of mother-infant interactions and consequently the normal development of the offspring. Outside the period of parturition and lactation, when the young are not a behavioral priority, olfactory cues play an inhibitory role on maternal responsiveness since in most mammalian species studied so far, nonpregnant females find the odor of young aversive. On the contrary at the time of parturition, a shift in the hedonic value of infantile odors occurs so that the young now become a very potent stimulus and this sensorial processing constitutes an important part of the maternal motivational system. Moreover, infants' odors provide a basis for individual recognition by their mothers and some species (ungulates) have developed highly specialized mechanisms for processing of the infant signals. Perception of the smell of the young also regulates various aspects of maternal behavior. Dodecyl propionate, a compound released by of pup's preputial glands, has been shown to influence anogenital licking behavior, a fundamental pattern of maternal behavior in rodents. While there is no functional specificity of either the main or the accessory olfactory systems in the development of maternal behavior amongst species, it appears that only the main olfactory system is implicated when individual odor discrimination of the young is required. Neural structures, such as the main olfactory bulb, undergo profound changes when exposed to offspring odors at parturition. These changes in synaptic circuitry contribute both to maternal responsiveness to these odors, to their memorization, and to effects of long-term maternal experience.
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Wolff, A., & Hausberger, M. (1996). Learning and memorisation of two different tasks in horses: the effects of age, sex and sire. Appl. Anim. Behav. Sci., 46(3-4), 137–143.
Abstract: Learning and memory abilities of 1-3 year old horses were assessed using instrumental and spatial tasks. No important differences were observed in the success of learning of the instrumental task (chest opening) according to sex or age. Younger females, however, seemed to learn more quickly. The offspring of a particular stallion were slower to learn than other horses. All horses memorised this task and opened the chest in a very short time in the second session. The animals that learned the task easily were not necessarily faster in the memorisation test. In the spatial task, learning ability did not seem to be related to age but more females than males were successful. The offspring of one stallion were more successful than other horses. Only 76% of the horses succeeded in the memorisation test, independently of age or sex. No correlation was found between the tasks in the latencies of either the learning or the memorisation tests for the same horses. The instrumental and spatial tasks may involve different processes.
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Allcroft, D. J., Tolkamp, B. J., Glasbey, C. A., & Kyriazakis, I. (2004). The importance of `memory' in statistical models for animal feeding behaviour. Behav. Process., 67(1), 99–109.
Abstract: We investigate models for animal feeding behaviour, with the aim of improving understanding of how animals organise their behaviour in the short term. We consider three classes of model: hidden Markov, latent Gaussian and semi-Markov. Each can predict the typical `clustered' feeding behaviour that is generally observed, however they differ in the extent to which `memory' of previous behaviour is allowed to affect future behaviour. The hidden Markov model has `lack of memory', the current behavioural state being dependent on the previous state only. The latent Gaussian model assumes feeding/non-feeding periods to occur by the thresholding of an underlying continuous variable, thereby incorporating some `short-term memory'. The semi-Markov model, by taking into account the duration of time spent in the previous state, can be said to incorporate `longer-term memory'. We fit each of these models to a dataset of cow feeding behaviour. We find the semi-Markov model (longer-term memory) to have the best fit to the data and the hidden Markov model (lack of memory) the worst. We argue that in view of effects of satiety on short-term feeding behaviour of animal species in general, biologically suitable models should allow `memory' to play a role. We conclude that our findings are equally relevant for the analysis of other types of short-term behaviour that are governed by satiety-like principles.
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Marinier, S. L., & Alexander, A. J. (1994). The use of a maze in testing learning and memory in horses. Appl. Anim. Behav. Sci., 39(2), 177–182.
Abstract: Two mazes were used to test the learning ability and memory of horses, and changes in these abilities. Testing was done on four occasions. On Occasion 1, the horses were run through Maze A until they had reached the criterion of three consecutive correct runs. A week later (Occasion 2), they were retested in Maze A to the same criterion as a measure of memory. On Occasion 3,2 months later, the horses were run through Mazes A and B until they reached the criterion. Occasion 4 took place 1 week later when they were run through Mazes A and B. An estimation of changes in ability to learn came from a comparison of results from Occasions 1 and 3. Similarly, changes in ability to remember came from a comparison of results from Occasions 2 and 4. Nine horses with a variable amount of riding training were the subjects. All horses were able to learn the maze, but the ability varied among horses. There was no obvious correlation between quality of handling of the horses and learning ability. Once the horses had learned the maze, they remembered it perfectly on subsequent occasions. There were changes in the memory and learning ability of the horses, but no clear explanation for this could be found.
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Baragli, P., Cozzi, A., Rugani, R., Sighieria, C., & Regolin, L. (2008). Delayed search for non-social goals by Equids (Equus caballus and Equus asinus). In IESM 2008.
Abstract: Delayed-responses have been traditionally employed to investigate the temporal characteristics of animals“ ability to represent and recall objects that have disappeared. In the typical condition, the animal, usually a mammal, observes the experimenter hiding an interesting goal (e.g. some food) in a certain location. A delayed-response task (DRT) was administered to 4 female Esperia pony (2 years old) coming from a free-range breed (Frosinone, Italy) and to 7 female Amiata donkeys (4.2±2 years old) coming from a conservation stock (University of Pisa, Italy). The DRT's apparatus was located in a square fence. A single ”U-shaped“ screen (330x160x140 cm) made by wood shavings blocks was positioned in the centre of the fence. A gap (40x50 cm) on the ground was in the middle of the central side of the U-shaped-screen and served to make the food-attractor disappear. The food-attractor consisted in cereal flakes and fresh grass for ponies and cereal flakes for donkeys. A bucket full of food was placed on a dolly tied on a rope which could be pulled by an experimenter. In a preliminary training each animal was allowed to eat food from the bucket and, while the animal was eating, the dolly was gently pulled away from the animal, and beyond the screen through the gap. The subjects needed to move around of the screen in order to retrieve the food. As a reinforcement, they were allowed to eat some food from the bucket once behind the screen. From trial to trial, the bucket was presented farther and farther (starting with a distance of 1 m in front of the screen to reach 7 m). Therefore subjects were tested in the DRT requiring them to rejoin the bucket with the goal-food disappearing behind the screen as in the preliminary training but following a 10 s delay. For the DRT, the bucket was placed 7 m in front of the screen, 3 m away from the animal's starting area. Then the dolly was pulled away from the animal. Ten seconds after the disappearance of the dolly behind the screen the animal was released from the starting area. The DRT ended when the subject had reached the attractor behind the screen on 3 consecutive trials. Results showed that all animals were able to rejoin the food behind the screen after 10 s delay. The mean time of the delayed-response (mean±sd, in s) in the ponies (1st: 19.8±8; 2nd: 10.8±2.2; 3rd: 12.8±2.8) and in the donkeys (1st: 28.4±10; 2nd: 26.9±13; 3rd: 24.3±16.6) showed a trend to decrease from first trial to third. These preliminary results suggest that like other mammals our ponies and donkeys can maintain a working memory trace of the location where biologically attractive objects have been seen to disappear. In conclusion, this study paves the way to set up a viable model system for the investigation of the more sophisticated aspects of Equids” cognitive abilities such as working memory.
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