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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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Kratzer, D. D., Netherland, W. M., Pulse, R. E., & Baker, J. P. (1977). Maze Learning in Quarter Horses. J. Anim Sci., 45(4), 896–902.
Abstract: A two-compartment maze providing a single left- or right-side choice was used to test maze-learning ability in 37 quarter horses. Preference for left- or right-side choices varied among the horses. The taller and thinner horses tended to go left. The horses showed learning ability based on decreases in latency and decreases in errors as trials progressed in a right-side escape pattern. The rate of learning an opposite escape pattern, left-side escape, was faster but owing to the large number of errors occurring when the pattern was reversed, the level of errors did not reduce to a level comparable to that achieved in the right-side escape pattern until adverse stimuli were presented in the blind compartment. Heavier horses took longer to escape from the maze when adverse stimuli were presented. Differences in learning ability for horses fed various levels of dietary protein were not consistent. N1 -
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Heird, J. C., Lennon, A. M., & Bell, R. W. (1981). Effects of early experience on the learning ability of yearling horses. J. Anim Sci., 53(5), 1204–1209.
Abstract: Twenty-four yearling Quarter Horse fillies were divided into three groups (I) very limited handling, (II) intermediate handling and (III) extensive handling. At about 14 months of age, each horse was preconditioned for 2 weeks and then run in a simple place-learning T-maze test in which it had to locate its feed. Thirty trials were run daily for 20 days, with the location of the feed changed each day. To retire from the maze, a horse had to meet the criterion: 11 correct responses in 12 tries, with the last eight being consecutive. Horses in Group II required the fewest trials to reach criterion. These horses also learned more and had the highest percentage of correct responses (P less than .05). Mean trainability tended to predict learning ability; however, trainability and trials to criterion were not significantly correlated. Mean emotionality scores indicated a tendency for horses in the intermediately handled group to be less emotional than those in Group I or III. Results indicated that horses with an intermediate amount of handling scored higher on an intermediate test of learning. All handled horses scored higher on learning tests than those not handled.
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McCall, C. A., Hall, S., McElhenney, W. H., & Cummins, K. A. (2006). Evaluation and comparison of four methods of ranking horses based on reactivity. Appl. Anim. Behav. Sci., 96(1-2), 115–127.
Abstract: Four methods of ranking horses on reactivity were evaluated and compared: isolation from conspecifics, presentation of a static novel stimulus, traversing a novel stimulus in a runway (isolation, novel stimulus and runway tests, respectively) and assigning subjective emotionality scores. In all tests, horses' heart rates were recorded and behaviour was videotaped. To be considered a valid test of reactivity, at least one heart rate and one behavioural measurement in the test had to change significantly between treatments (tranquilizer administation versus sham tranquilizer administration), and behavioural measures had to be displayed in at least 75% of the trials. Forty horses performed each of the three tests daily on three different days in a switchback design. Horses were assigned randomly to a daily test sequence, which was maintained throughout the study. In the runway test, no significant difference in heart rate values in tranquilized and non-tranquilized horses was found, and no behavioural attribute was displayed in more than 52% of the trials; therefore it was rejected as a valid test of reactivity. Both isolation and novel stimulus tests produced valid measurements. Mean heart rate was the most precise physiological measure for these tests, and walking and defecation frequency were the most precise behavioural measures for novel stimulus and isolation tests, respectively. Mean heart rates on the novel stimulus and isolation tests were correlated (rs = 0.79, P < 0.01) indicating that these tests produced similar rankings based on physiological responses. However, behavioural measures ranked horses differently (rs = 0.27, P < 0.10) on the tests. Rank correlations between mean heart rates and behavioural measures were higher in the novel stimulus (rs = 0.66, P < 0.01) than the isolation test (rs = 0.55, P < 0.01), indicating that the novel stimulus test ranked horses based on either physiological or behavioural responses more similarly than did the isolation test. Therefore, the novel stimulus test was considered the more accurate evaluation of reactivity. Subjective emotionality scores were correlated moderately with mean heart rates (rs > 0.33, P < 0.01) from the novel stimulus and isolation tests and with walking scores (rs = 0.47, P < 0.01) from the novel stimulus test. Assignment of subjective emotionality scores was not as accurate as the novel stimulus or isolation tests in ranking horses for reactivity. Using physiological data alone, combining physiological and behavioural measurements or using more than one behavioural measurement in reactivity tests may reflect the reactivity of the horse better than a single behavioural measurement.
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Williams, J. L., Friend, T. H., Nevill, C. H., & Archer, G. (2004). The efficacy of a secondary reinforcer (clicker) during acquisition and extinction of an operant task in horses. Appl. Anim. Behav. Sci., 88(3-4), 331–341.
Abstract: “Clicker training” is a popularly promoted training method based on operant conditioning with the use of a secondary reinforcer (the clicker). While this method draws from theories of learning and is used widely, there has been little scientific investigation of its efficacy. We used 60 horses, Equus callabus, and assigned each horse to one of six reinforcement protocols. The reinforcement protocols involved combinations of reinforcers administered (primary versus secondary plus primary), schedule of reinforcement (continuous versus variable ratio), and reinforcers applied during extinction (none or secondary). There were no differences (P>=0.11) between horses which received a secondary reinforcer (click) followed by the primary reinforcer (food) and those which received only the primary reinforcer (food) in the number of trials required to train the horses to touch their noses to a plastic cone (operant response). There also were no differences (P>=0.12) between horses which received the secondary reinforcer plus primary reinforcer and those which received only the primary reinforcer in regards to the number of trials to extinction. We conclude that there is no difference in the amount of training required to learn the operant task or in the task's resistance to extinction between horses that received a secondary reinforcer followed by a primary reinforcer versus horses which received only a primary reinforcer.
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Langbein, J., Siebert, K., Nuernberg, G., & Manteuffel, G. (2007). The impact of acoustical secondary reinforcement during shape discrimination learning of dwarf goats (Capra hircus). Appl. Anim. Behav. Sci., 103(1-2), 35–44.
Abstract: The use of secondary reinforcement is widely accepted to support operant learning in animals. In farm animals, however, the efficacy of secondary reinforcement has up to now been studied systematically only in horses (“clicker training”), and the results are controversial. We investigated the impact of acoustical secondary reinforcement on voluntary, self-controlled visual discrimination learning of two-dimensional shapes in group-housed dwarf goats (Capra hircus). Learning tests were conducted applying a computer-controlled learning device that was integrated in the animals' home pen. Shapes were presented on a TFT-screen using a four-choice design. Drinking water was used as primary reinforcement. In the control group (Gcontrol, n = 5) animals received only primary reinforcement, whereas in the sound group (Gsound, n = 6) animals got additional acoustical secondary reinforcement. Testing recall of shapes which had been successfully learned by the goats 6 weeks earlier (T1), we found a weak impact of secondary reinforcement on daily learning success (P = 0.07), but not on the number of trials the animals needed to reach the learning criterion (trials to criterion, n.s.). Results in T1 indicated that dwarf goats did not instantly recall previously learned shapes, but, re-learned within 250-450 trials. When learning a set of new shapes (T2), there was a strong influence of secondary reinforcement on daily learning success and on trials to criterion. Animals in Gsound reached the learning criterion earlier (P < 0.05) and needed fewer trials (1320 versus 3700; P < 0.01), compared to animals in Gcontrol. Results suggest that acoustical secondary reinforcement supports visual discrimination learning of dwarf goats, especially when the task is new and the salience of S+ is low.
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McCall, C. A., Salters, M. A., Johnson, K. B., Silverman, S. J., McElhenney, W. H., & Lishak, R. S. (2003). Equine utilization of a previously learned visual stimulus to solve a novel task. Appl. Anim. Behav. Sci., 82(3), 163–172.
Abstract: Forty-four horses were used to determine if a learned stimulus could be used to increase acquisition of a response unrelated to the original learned task. Horses were paired by age, breed and sex. One randomly chosen horse from each pair served as the control while the remaining horse was trained to respond to a visual stimulus by pushing a lever to obtain a food reward. In Experiment I (n=28), the food reward was delivered in a feed box located equidistant between two levers located 2.7 m apart on one wall of the test stall. Trained horses were given 30 training trials daily until they achieved at least 85% correct responses in three nonconsecutive days. After each trained horse reached criterion, both horses in the pair were tested in 30 trials daily for five consecutive days in a modified Y maze. The stimulus that indicated the correct lever in the initial training task was used to signify the correct arm of the maze for both the control and trained horses. The correct arm of the maze was changed randomly during each daily session, and correct choices resulted in a food reward. In Experiment II (n=16), levers were located on opposite walls (11 m apart) of the test stall, and the stimulus and modified Y maze were simplified. Trained horses received 15 training trials daily until they reached at least 85% correct responses on three consecutive days. As each trained horse achieved this criterion, both horses in the pair were tested in a maze for 15 trials daily for 7 days. Again, the stimulus from initial lever-pressing task was used to signify the rewarded arm of the maze. Correct choices of trained and control horses in both experiments were compared using a paired t-test. In Experiment I, no differences (P>0.34) in mean correct responses were detected between trained and control horses on the first day in the maze (15.3 and 16.8, respectively) or after 5 days in the maze (84.0 and 82.1, respectively). Similarly, in Experiment II, trained and control horses did not differ (P>0.50) in mean correct responses on the first day (6.9 and 7.4, respectively) or after 7 days in the maze (63.6 and 61.6, respectively). These results indicate that the stimuli used to solve the lever-pressing task were not utilized by horses in the maze task, and that horses may have difficulty transferring learned visual stimuli to new tasks.
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Heird, J. C., Whitaker, D. D., Bell, R. W., Ramsey, C. B., & Lokey, C. E. (1986). The effects of handling at different ages on the subsequent learning ability of 2-year-old horses. Appl. Anim. Behav. Sci., 15(1), 15–25.
Abstract: Forty weanling Quarter Horses, from the Pitchfork Ranch, Dickens, Texas, were randomly assigned to one of five groups based on the amount of handling they would receive. The five groups were: (1) limited handling; (2) 1 week of handling; (3) 2 weeks of handling; (4) 3 weeks of handling; (5) continuous handling for 18 months. As 2-year-olds, the horses were tested in a simple place-learning T-maze after being preconditioned. A maximum of 30 daily trials were conducted for 20 consecutive days, with feed location alternating between sides on successive days. If a horse met the criterion of 11 out of 12 correct responses with 8 correct responses being consecutive, it was retired without completing the 30 trials. Group 1 made fewer correct responses during the 20 days than any other group except Group 3. All groups achieved learning by Day 10, but the most-handled group reached a consistently higher percentage of correct responses earlier than the less-handled groups. Group 5, the group receiving the most handling, was the least emotional, as determined by the animals' reactivity to a novel stimulus, and received the highest scores for trainability after being ridden. Preconditioning trainability scores, or estimates of the horses' ability to learn prior to conditioning and testing, tended to predict maze-learning ability. These scores were also significantly correlated with post-maze training scores.
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Bachmann, I., Bernasconi, P., Herrmann, R., Weishaupt, M. A., & Stauffacher, M. (2003). Behavioural and physiological responses to an acute stressor in crib-biting and control horses. Appl. Anim. Behav. Sci., 82(4), 297–311.
Abstract: The responses of eleven pairs of crib-biting and non-crib-biting horses (controls) to an arousal-inducing stimulus were studied. Video-observation of the horses revealed that crib-biting horses spent between 10.4 and 64.7% of their stabling time performing the stereotypy. During the first 2 days of an experimental period, the horses were conditioned to receive food from a special bucket. On the third day the food bucket was presented, but the horses were not allowed to feed. Arousal behaviour and crib-biting intensity as well as plasma cortisol concentration, heart rate (HR) and heart rate variability (HRV) were recorded at rest, and during and after presentation of the food stimulus. The stimulus induced a significant increase of HR and arousal behaviour in crib-biters and in controls, whereas the crib-biting frequency decreased. Power spectral analysis of the HRV revealed significant differences between crib-biters and controls at rest: crib-biters had a lower vagal tone (high frequency component, HF) and a higher sympathetic tone (low frequency component, LF) than controls. The lower basal parasympathetic activity might be an indication why crib-biting horses, in contrast to the controls, showed neither a significant decrease of the HF component during presentation of the food stimulus nor an increase of the HF component after presentation. Thus, there might be differences in the tuning of the autonomous nervous system and of the stress reactivity in crib-biting and in control horses. The results suggest that the crib-biting horses are more stress sensitive and physiologically and psychologically less flexible than the control horses.
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McBride, S. D., Hemmings, A., & Robinson, K. (2004). A preliminary study on the effect of massage to reduce stress in the horse. Journal of Equine Veterinary Science, 24(2), 76–81.
Abstract: The use of massage (as a potential form of acupressure) has long been documented as a human relaxation aid. However, little scientific research has been carried out into its potential use as a form of stress reduction in the horse. This preliminary study investigated the effect of massage at six different sites (thoracic trapezius [withers], mid-brachiocephalicus, cervical ventral serrate and cervical trapezius [mid-neck], proximal gluteal fascia and proximal superficial gluteal [croup], proximal and mid-semitendinosus [second thigh], lateral triceps, proximal extensor carpi radialis and proximal common digital extensor [forearm], proximal brachiocephalicus, proximal splenius and ear [poll and ears) on stress-related behavioral and physiological (heart rate [HR]) measures in the horse. Ten riding school ponies/horses were massaged at each of the six sites (three preferred and three nonpreferred sites of allogrooming (mutual grooming between conspecifics) and changes in HR and behavior were recorded. The results indicated that during massage, all sites except the forearm resulted in a significant reduction in HR (P < .05) with massage at the withers, mid-neck, and croup having the greatest effect (preferred sites of allogrooming). Massage at preferred sites of allogrooming also elicited significantly more (P < .05) positive behavioral responses compared with the three nonpreferred sites. The practical implications of this study are discussed.
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