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Guo, K., Meints, K., Hall, C., Hall, S., & Mills, D. (2009). Left gaze bias in humans, rhesus monkeys and domestic dogs. Anim. Cogn., 12(3), 409–418.
Abstract: While viewing faces, human adults often demonstrate a natural gaze bias towards the left visual field, that is, the right side of the viewee’s face is often inspected first and for longer periods. Using a preferential looking paradigm, we demonstrate that this bias is neither uniquely human nor limited to primates, and provide evidence to help elucidate its biological function within a broader social cognitive framework. We observed that 6-month-old infants showed a wider tendency for left gaze preference towards objects and faces of different species and orientation, while in adults the bias appears only towards upright human faces. Rhesus monkeys showed a left gaze bias towards upright human and monkey faces, but not towards inverted faces. Domestic dogs, however, only demonstrated a left gaze bias towards human faces, but not towards monkey or dog faces, nor to inanimate object images. Our findings suggest that face- and species-sensitive gaze asymmetry is more widespread in the animal kingdom than previously recognised, is not constrained by attentional or scanning bias, and could be shaped by experience to develop adaptive behavioural significance.
Keywords: Biomedical and Life Sciences
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Hall, C. (2007). The impact of visual perception on equine learning. Behav. Process., 76, 29–33.
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Hall, C., Crowell-Davis, S. L., & Warren, R. J. (1993). Maternal and developmental behavior of the feral horses of Cumberland Island, Georgia. Appl. Anim. Behav. Sci., 37(1), 85.
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Hall, C., Rigg, V., Truswell, M., & Owen, H. (2012). Picture recognition of con-specifics and facial expression in the horse (Equus caballus). In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: The management of the domestic horse often requires them to be kept in isolation from con-specifics. Installing a picture of a horse (generally head and neck view) with a view to providing surrogate companionship has been shown to reduce the negative impact of this isolation. This study aimed firstly to compare the spontaneous response of horses (N=10) to a 2-D image of a horse’s face (FP) with their response to a comparable abstract 2-D image (AP). Secondly, the spontaneous response of horses (N=20) to a 2-D image of a horse’s face with the ears forward (PFP positive) was compared with the response to a 2-D image of a horse’s face with the ears back (NFP negative). The posters were A1 sized and displayed in the horse’s own stable. In study 1, one poster was displayed for 5 minutes and the horse’s behaviour video-recorded. This was removed and the second poster was displayed for 5 minutes and the behaviour video-recorded. FP was displayed first for 5 of the horses and AP displayed first for the other 5. The video footage was observed and the behaviour of the horses and number of times they touched the poster recorded. For the purpose of identifying the area of the poster that was touched by the horse it was divided into 4 equal quarters (TL, TR, BL, BR). In FP the nose of the horse in the 2-D image was located in BL, eyes and ears in TL, chest and lower neck in BR and upper neck in TR. In AP each area contained similar but unique abstract patterns of comparable colour to FP. Differences in behaviour were found according to which poster was displayed. FP was touched significantly more than AP (p=0.001) and was looked at more often (p=0.008). With FP the horses spent significantly longer with their ears forward (p=0.008) and licking and chewing (p=0.016). When the number of touches per poster area was compared (FP and AP) a significant difference was found in the number of times that BL (nose) and BR (chest/lower neck) were touched (p=0.011). Both areas were touched more frequently on FP, with BL being touched the most. In study 2 the same experimental protocol was used to compare responses to positive (PFP) or negative (NFP) 2-D images of a horse’s face (same horse in both PFP and NFP). Again, differences in behaviour were found in response to the two posters. PFP was touched significantly more than NFP (p=0.002) and on both posters the area BL (nose) was touched more frequently than the other areas (PFP: p=0.02, NFP: p=0.01). More ears back behaviour (p<0.001) and more ear locked on behaviour (p=0.008) was shown with NFP. The results of these studies indicate that horses can recognize 2-D images as con-specifics as well as responding to differences in facial expression. There is now the potential for further investigation into the importance of other visual cues in recognition and social interaction as well as the application of findings to enhance equine welfare.
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Hall, C. A., & Cassaday, H. J. (2006). An investigation into the effect of floor colour on the behaviour of the horse. Appl. Anim. Behav. Sci., 99(3-4), 301–314.
Abstract: Adverse reactions of the domestic horse to environmental stimuli can be problematic in training and management. Hesitation and alarm reactions to visual features of the ground can occur in both ridden work and when handling horses. To assess the effect of one visual feature (colour) on the behaviour of the domestic horse, the reactions of 16 riding horses to 8 different coloured mats were recorded. The effect of stimulus position on these reactions was assessed by presenting them in two different positions, either on the ground (where the horses had to walk over them) or against a wall (where the horses walked past them). Each colour/position combination was presented twice in order to assess the effect of previous experience. An alleyway was constructed to allow the horses to be tested unconstrained and freely walking throughout. The time taken to traverse the alleyway and the observed reaction to the colour was recorded. Significant differences in both measures were found in relation to the position of the colour and whether the subject had previous experience of that colour/position combination. The initial presentation of the colours on the ground produced the highest percentage of adverse reactions. Certain colours encountered for the first time on the ground (yellow, white, black and blue) were found to cause a greater number of adverse reactions than others (green, red, brown and grey) and an increase in time taken to traverse the alleyway. Although a significant difference in relation to colour was found in the behaviour observed during the second presentation on the ground, no difference was found in relation to the time taken to traverse the alleyway. No significant effect of colour was found when the coloured stimuli were presented against the wall. These findings have important implications for situations where the colour of flooring could be controlled in order to minimise adverse behavioural reactions, in particular during initial training.
Keywords: Horse; Colour aversion; Flooring; Vision
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Hall, C. A., Cassaday, H. J., & Derrington, A. M. (2003). The effect of stimulus height on visual discrimination in horses. J. Anim Sci., 81(7), 1715–1720.
Abstract: This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice, black/white discrimination with stimuli presented at one of two heights: ground level or at a height of 70 cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was four consecutive sessions of 70% correct responses. Performance was found to be better when stimuli were presented at ground level with respect to the number of trials taken to reach the criterion (P < 0.05), percentage of correct first choices (P < 0.01), and repeated errors made (P < 0.01). Thus, training horses to carry out tasks of visual discrimination could be enhanced by placing the stimuli on the ground. In addition, the results of the present study suggest that the visual appearance of ground surfaces is an important factor in both horse management and training.
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Hall, C. A., Cassaday, H. J., Vincent, C. J., & Derrington, A. M. (2006). Cone excitation ratios correlate with color discrimination performance in the horse (Equus caballus). J Comp Psychol, 120(4), 438–448.
Abstract: Six horses (Equus caballus) were trained to discriminate color from grays in a counterbalanced sequence in which lightness cues were irrelevant. Subsequently, the pretrained colors were presented in a different sequence. Two sets of novel colors paired with novel grays were also tested. Performance was just as good in these transfer tests. Once the horse had learned to select the chromatic from the achromatic stimulus, regardless of the specific color, they were immediately able to apply this rule to novel stimuli. In terms of the underlying visual mechanisms, the present study showed for the first time that the spectral sensitivity of horse cone photopigments, measured as cone excitation ratios, was correlated with color discrimination performance, measured as accuracy, repeated errors, and latency of approach.
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Kay, R., & Hall, C. (2009). The use of a mirror reduces isolation stress in horses being transported by trailer. Appl. Anim. Behav. Sci., 116(2-4), 237–243.
Abstract: Horse trailers are a common form of transportation for horses and ponies and often require the animal to travel alone or with a single companion. The current study investigated the effect of transporting horses alone, in company or with an acrylic safety mirror (measuring 81cm61.5cm) that provided surrogate companionship. The behavioural and physiological responses of 12 mature horses during a 30-min journey by trailer under the three treatments were compared. Behaviours (vocalisation, eating, head-tossing, pawing, and head-turning) were recorded. In order to assess circulatory changes that occur as part of the response to transport, heart rate (HR), rectal (Tr) and ear-pinna (Tp) temperatures were recorded. When travelling with a live companion significantly less time was spent vocalising (p<0.001), head-turning (p<0.001), head-tossing (p<0.01) and pawing (p<0.01); eating behaviour increased (p<0.05). Physiological responses (increases in HR and Tr and decreases in Tp) were also significantly reduced when travelling with a live companion (p<0.01). Travelling with the mirror did not significantly affect physiological responses compared with travelling alone, but the rise in Tr and fall in Tp was reduced (p=0.052 and p=0.051, respectively) and can be considered a trend. When travelling with a mirror significantly less time was spent turning the head (p<0.01), vocalising (p<0.05) and head-tossing (p<0.05); eating behaviour increased (p<0.05). The only significant difference between travelling with a live companion and a mirror was that the time spent turning the head round was less with a live companion (p<0.05). The provision of surrogate companionship in the form of a mirror was found to be preferable to travel alone, but where possible a live companion is recommended. Isolation during transportation was found to suppress feeding behaviour. Although peripheral blood flow (Tp) has been used to assess transport stress in other species it has not previously been used in the horse. Further evaluation of this non-invasive measure is now required.
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König v. Borstel, U., Visser, E. K., & Hall, C. (2017). Indicators of stress in equitation. Appl. Anim. Behav. Sci., 190, 43–56.
Abstract: Abstract Stress is a generic concept describing the body's reaction to external stimuli, including both physiological and psychological factors. Therefore, by definition, the assessment of psychological stress in the exercising horse encompasses the problem of teasing apart the psychological and physiological factors both of which result in stress responses. The present study reviews the existing literature on various measures of stress taken specifically in the context of equitation science. Particular attention has been paid to short-term effects, and commonly used measurements of short-term stress include heart rate, a number of heart rate variability parameters, blood or saliva cortisol levels, eye temperature, and various behaviour parameters including in particular behaviour patterns presumably indicative of conflict with the rider's/trainer's aids. Inspection of the individual studies' results revealed that disagreement between these different measures of stress is commonplace. For physiological parameters, the largest proportion of agreement (i.e. both parameters simultaneously indicated either higher, insignificant or lower stress compared to a control treatment) was found for heart rate and heart rate variability parameters, while generally limited agreement was found for cortisol. It appears that cortisol levels may not be particularly useful for assessing/assessment of the valence of a situation in the exercising horse as cortisol levels are predominantly linked to activation and exercise levels. Although heart rate variability parameters reflect in theory more closely sympathovagal balance compared to cortisol levels, great care has to be taken regarding the use of appropriate time-frames, appropriate raw data correction methods as well as the use of appropriate equipment. In spite of its wide-spread and apparently successful use, popular equipment may in fact not be accurate enough under field conditions. Eye temperature is another promising parameter for assessment of psychological stress, but the technique is likewise susceptible to application errors. Given the high susceptibility of physiological parameters to errors at various experimental stages, behavioural rather than physiological parameters may in fact provide more accurate measures of valence when conducting experiments in the exercising horse. Behavioural parameters that appear to be particularly practical in assessing stress in ridden horses' behaviour are associated with frequencies of behaviour indicative of conflict. However, while increased frequencies of are a good indicator of stress, the absence of conflict behaviour does not provide proof of the absence of stress due to the possible occurrence of conditions such as Learned Helplessness. In future studies, the above issues should be taken into consideration when designing experiments to assess psychological stress in ridden horses.
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Owen, H., Hall, C., Hallam, S., & Smith, E. (2012). The use of GPS to measure feeding behaviour and activity patterns in the horse (Equus caballus). In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: The global positioning system (GPS) has been used to record activity and monitor habitat use in many animal species. In the horse (Equus caballus) the monitoring of activity and feeding patterns has been used to assess the impact of environmental factors on behaviour and welfare. In free-ranging animals GPS can provide such information but the accuracy and reliability of these devices has yet to be confirmed. The aim of this study was: 1) to compare the results of visual observation with GPS recordings of the horse’s head and neck position (head up (HU) and down (HD)) used to quantify time spent grazing; 2) to test the use of GPS collars to monitor activity patterns where distance, speed and location paths were recorded. In both studies two animals were fitted with Lotek GPS 3300S collars (with integrated GPS data logger and removable battery pack) round the top of the neck. In study 1 two horses were fitted with collars and turned loose into a 20x40m sand arena for 45 minutes. Feed balls and hay were provided (in nets and on the ground) to encourage movement and feeding behaviour for comparison using the two methods (observation from digital video recordings and GPS). HD was recorded by the GPS collars for a significantly longer time (interpreted as feeding/grazing time) than that recorded by observation (p=0.004). However when the visual observation was split into HU, HD and also head in mid-way position (HMW), where the nose of the horse was level or just above the chest, then no difference between the collar (HU and HD) and visual observation for (HU and HD+HMW) was found. It is likely that when in HMW the GPS collar may not be sufficiently angled to trigger the sensor to record HU or the collar may move on the neck. Conclusions relating to time spent feeding should be treated with caution. In study 2, the collars were fitted to two ponies with access to 2.02 hectares of lowland grazing. Activity (distance travelled and speed) and location was recorded for 2 days. The total distance travelled by the ponies in 24 hours (2.84km) and their average speed (4.04m/minute) was calculated and showed no significant difference between day and night. The total area was split into four equal segments and there was no significant difference in the time the ponies spent in each area although they were found to move at slower speeds and stand for longer in some areas. Movement paths could be identified by inputting the GPS collar data into ArcGIS and viewed on Google Maps. There was a high level of comparability observed between the two ponies confirming behavioural synchronicity. As in other species, the use of GPS collars to monitor the movement and location of horses/ponies was found to be effective, but data relating to head position did not provide a reliable means of recording the time spent feeding.
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