Morton, D. B. (2000). Self-consciousness and animal suffering. Biologist (London), 47(2), 77–80.
Abstract: Animals with relatively highly developed brains are likely to experience some degree of self-awareness and the ability to think. As well as being interesting in its own right, self-consciousness matters from an ethical point of view, since it can give rise to forms of suffering above and beyond the immediate physical sensations of pain or distress. This article surveys the evidence for animal self-consciousness and its implications for animal welfare.
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Cloutier, S., Newberry, R. C., & Honda, K. (2004). Comparison of social ranks based on worm-running and aggressive behaviour in young domestic fowl. Behav. Process., 65(1), 79–86.
Abstract: Worm-running is behaviour in which a chick runs carrying a worm-like object while flock mates follow and attempt to grab the object from its beak. We hypothesised that social ranks based on worm-running frequency are stable over time and are positively correlated with social ranks based on success in aggressive interactions when older. At 8-12 days of age, we scored worm-running in 17 groups of 12 female White Leghorn chicks during three 10-min tests. Based on instantaneous scans at 5-s intervals, the bird carrying the `worm' most often was placed in rank one and so on down the rank order. These tests were repeated at 68-70 days of age. An aggression index for each bird was calculated as the number of aggressive acts given, divided by the number given and received, during three 1-h observation periods when the birds were 68-70 days. Ranks obtained in worm-running tests were positively correlated over the two age periods (P<0.05) but were not correlated with ranks based on the aggression index (P>0.05). Our results indicate that worm-running ranks are not predictive of success in aggressive interactions. Instead, worm-running fits some criteria for play.
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Foster, T. M., Temple, W., Cameron, B., & Poling, A. (1997). Demand curves for food in hens: Similarity under fixed-ratio and progressive-ratio schedules. Behav. Process., 39(2), 177–185.
Abstract: Demand curves were generated for five domestic hens under progressive-ratio 5 schedules of food delivery and under fixed-ratio schedules of food delivery that began at fixed-ratio 5 and were incremented by 5 each session. All sessions ended after 10 consecutive minutes without a response. Although response rates at a given ratio were higher under the progressive-ratio schedule, all hens completed higher ratios under the fixed-ratio schedule. Similar, but not identical, demand curves were generated under progressive-ratio and fixed-ratio schedules. Under both schedules, consumption (reinforcers earned) decreased as cost (ratio size) increased. Data generally were well described by an equation in which elasticity of demand is constant, although an equation in which elasticity could vary accounted for slightly more of the variance.
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Poling, A., Temple, W., & Foster, T. M. (1996). The differential outcomes effect: A demonstration in domestic chickens responding under a titrating-delayed-matching-to-sample procedure. Behav. Process., 36(2), 109–115.
Abstract: The differential outcomes effect refers to the increase in speed of acquisition or terminal accuracy that occurs in discrimination training when each of two or more discriminative stimuli is correlated with a different outcome (e.g. type of reinforcer). The present study demonstrated this effect in domestic hens exposed to a titrating-delayed-matching-to-sample procedure, under which correct responses increased (and incorrect responses decreased) the delay between the offset of a sample stimulus and the onset of two comparison stimuli. Colors of key illumination (red, green) were used as sample and comparison stimuli and correct responses resulted in 1- or 4-s food deliveries. When 1-s food deliveries consistently followed correct responses to one key color and 4-s food deliveries followed correct responses to the other key color, the maximum delay reached by the hens and their overall accuracy was significantly higher than when 1- and 4-s food deliveries were randomly arranged following correct responses to both key colors. These data constitute the first demonstration of the differential outcomes effect in chickens, and in any species evaluated under a titrating-delayed-matching-to-sample procedure.
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Petherick, J. C., Waddington, D., & Duncan, I. J. H. (1991). Learning to gain access to a foraging and dustbathing substrate by domestic fowl: is `out of sight out of mind'? Behav. Process., 22(3), 213–226.
Abstract: Domestic fowl were deprived of the opportunity to perform litter-related behaviour for three or four days and were tested in a Y-maze (which they had previously been trained to run) for their ability to associate a coloured cue with gaining access to peat. When the goal boxes were within sight of the choice point, most birds chose peat. However, when the birds had to rely solely on the coloured cue only one bird from 12 showed learning. However, the birds seemed to have some expectation of a reward, as they ran faster if, on the previous trial, they had chosen peat. The inability of the birds to learn the association may have been an artefact of the schedule of deprivation and testing, for when they were hungry and tested in the same way they were again unable to learn an association between the same coloured cue and food reward. The experiment with peat was repeated using “massed” trials (several trials in immediate succession) during training and testing and six from 15 birds showed learning. These results suggest that the initial failure to learn was probably due to the training and testing schedule, that access to peat appears to be rewarding and that hens can learn an association between an abstract cue and a rewarding consequence. This is consistent with the possibility that domestic fowls may have some cognitive representation of peat when it is out of sight.
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Zucca, P., Cerri, F., Carluccio, A., & Baciadonna, L. (). Space availability influence laterality in donkeys (Equus asinus). Behav. Process., In Press, Uncorrected Proof.
Abstract: Cerebral lateralization is the portioning of the cognitive functions between the two cerebral hemispheres. Several factors, like embryological manipulations, light exposure, health conditions, sex and age can influence the left-right brain asymmetries and contribute to increasing the variability in the strength and direction of laterality within most species. We investigated the influence of an environmental constraint, namely space availability, as a new source of variation on laterality in an adult vertebrate model, the donkey. In a baseline condition we tested whether donkeys show a motor lateralization bias at population level, while in an experimental condition we manipulated space availability to verify if a reduction in this parameter could represent a new source of variation in laterality. Results show that donkeys are lateralized at population level with a strong bias to standing with the right forelimb advanced over the left and that a reduction of space availability is an important source of variation in the laterality strength and direction within this species. The comparative analysis of the environmental and developmental factors that give origin to neural and behavioural laterality in animal models will be very important for a better understanding of the evolutionary origin of such multifaceted phenomenon.
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Brubaker, L., & Udell, M. A. R. (2016). Cognition and learning in horses (Equus caballus): What we know and why we should ask more. Behavioural Processes, 126, 121–131.
Abstract: Abstract Horses (Equus caballus) have a rich history in their relationship with humans. Across different cultures and eras they have been utilized for work, show, cultural rituals, consumption, therapy, and companionship and continue to serve in many of these roles today. As one of the most commonly trained domestic animals, understanding how horses learn and how their relationship with humans and other horses impacts their ability to learn has implications for horse welfare, training, husbandry and management. Given that unlike dogs and cats, domesticated horses have evolved from prey animals, the horse-human relationship poses interesting and unique scientific questions of theoretical value. There is still much to be learned about the cognition and behaviour of horses from a scientific perspective. This review explores current research within three related areas of horse cognition: human-horse interactions, social learning and independent learning in horses. Research on these topics is summarized and suggestions for future research are provided.
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Rochais, C., Henry, S., Fureix, C., & Hausberger, M. (2016). Investigating attentional processes in depressive-like domestic horses (Equus caballus). Behavioural Processes, 124, 93–96.
Abstract: Abstract Some captive/domestic animals respond to confinement by becoming inactive and unresponsive to external stimuli. Human inactivity is one of the behavioural markers of clinical depression, a mental disorder diagnosed by the co-occurrence of symptoms including deficit in selective attention. Some riding horses display ‘withdrawn’ states of inactivity and low responsiveness to stimuli that resemble the reduced engagement with their environment of some depressed patients. We hypothesized that ‘withdrawn’ horses experience a depressive-like state and evaluated their level of attention by confronting them with auditory stimuli. Five novel auditory stimuli were broadcasted to 27 horses, including 12 ‘withdrawn’ horses, for 5 days. The horses’ reactions and durations of attention were recorded. Non-withdrawn horses reacted more and their attention lasted longer than that of withdrawn horses on the first day, but their durations of attention decreased over days, but those of withdrawn horses remained stable. These results suggest that the withdrawn horses’ selective attention is altered, adding to already evidenced common features between this horses’ state and human depression.
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Siniscalchi, M., Padalino, B., Lusito, R., & Quaranta, A. (2014). Is the left forelimb preference indicative of a stressful situation in horses? Behav. Process., 107, 61–67.
Abstract: Abstract Evidence for behavioural and brain lateralisation is now widespread among the animal kingdom; lateralisation of limb use (pawedness) occurs in several mammals including both feral and domestic horses. We investigated limb preferences in 14 Quarter Horse during different motor tasks (walking, stepping on and off a step, truck loading and unloading). Population lateralisation was observed in two tasks: horses preferentially used their left forelimb during truck loading and stepping off a step. The results also revealed that horses showed higher scores for anxious behaviours during truck loading suggesting that the use of the left forelimb in this task may reflect the main role of the right hemisphere in control of behaviour during stressful situation.
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Siniscalchi, M., Sasso, R., Pepe, A. M., Vallortigara, G., & Quaranta, A. (2010). Dogs turn left to emotional stimuli. Behav. Brain. Res., 208(2), 516–521.
Abstract: During feeding behaviour, dogs were suddenly presented with 2D stimuli depicting the silhouette of a dog, a cat or a snake simultaneously into the left and right visual hemifields. A bias to turn the head towards the left rather than the right side was observed with the cat and snake stimulus but not with the dog stimulus. Latencies to react following stimulus presentation were lower for left than for right head turning, whereas times needed to resume feeding behaviour were higher after left rather than after right head turning. When stimuli were presented only to the left or right visual hemifields, dogs proved to be more responsive to left side presentation, irrespective of the type of stimulus. However, cat and snake stimuli produced shorter latencies to react and longer times to resume feeding following left rather than right monocular visual hemifield presentation. Results demonstrate striking lateralization in dogs, with the right side of the brain more responsive to threatening and alarming stimuli. Possible implications for animal welfare are discussed.
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