INTRODUCTION A horse`s performance relies, not only on its predisposition and genetics, but also on the trainers` and handlers` competence, and the horse`s health and environment. Worth may be determined by its aptitude for a specific type of work or its performance versatility. The ease in which a horse may be trained will add or detract from worth. A reliable method of assessing a horse`s ability to learn (its trainability), would be beneficial to most horsemen. Currently there is no efficient or accurate way to determine a horse`s trainability. Equine research has only begun to investigate learning ability, emotionality, physiology, genetics and how these things relate to performance and to each other (Wolff, Hausberger, and Le Scolan, 1997). If horses` intelligence can be correlated to trainability, then intelligence may be of predictive value. Assessing a horse`s intelligence poses difficulties. Perception, evolutionary function and communication differences in the horse, as with most research animals, constrain methodology and need to be identified. Research in equine perception has shown horses are able to perceive color. Results have been contradictory however, as to the exact colors they are able to see. Interpreting information from a study done in 1994, Budiansky (1997) suggests horses are capable of seeing only reds and blues, but not greens. The ability to perceive color was also investigated by Smith & Goldman (1999). Horses were able to correctly distinguish red, yellow, green and blue from a series of varying intensities of gray. Horses have been found to have at least dichromatic vision, seeing red and blue, although color-blindness may occur in some individuals. Evolution may play an active role in the types of information attended to and ability to learn certain concepts (Budiansky, 1997). Horses may also attend to differing cues than humans would normally attend. It has been suggested, artificially selected breed differences play a role in breed traits such as emotionality, behavior and learning ability (Mader & Price, 1980). Questions also remain concerning the ability of horses to learn through observation. Learning curves have been obtained, showing the observation group`s initial acquisition rate higher than the control group. Subsequent learning, however, suggested no statistically significant difference between the two groups (Baer, Potter, Friend, & Beaver, 1983). These results indicate observation of another horse performing the task has more of a priming effect than an overall increase in learning acquisition. Studies done in the past have measured the ability of a horse to observationally learn from another horse, rather than observation of a human performing a task (Linberg, Kelland, & Nicol, 1999; Clarke, Nicol, Jones, & McGreevy, 1996). Horses are capable of higher order learning. They are able to make at least 20 concurrent associations, compared to a mouse, which makes seven and a rat, which makes eight (Budiansky, 1997). Evelyn Hanggi, Ph.D. has done research illustrating the horses` capability in choosing one object over another, depending on the situation. This conditional concept is the seventh level of Roger Thomas` Hierarchy of Learning. Horses are also able to demonstrate ability in accomplishing the eighth, and last, level. This concept involves placing value on an object, where red is better than blue, but blue is better than green and so on. Contrary to popular belief, horses are capable of complex cognition (Pottenger, 1998). To some extent scientists have demonstrated horses` ability in memorization, spatial, and instrumental learning (Wolff & Hausberger, 1996). Recent studies have been done assessing instrumental learning and associative learning (Pottenger, 1998). In general horses are capable of learning many different tasks, but how this relates to performance and how performance on learning tasks relate to trainability, has yet to be ascertained. The concept of a relationship has been investigated, but no statistically significant differences were found between discrimination reversal learning and performance (Sappington, McCall, Coleman, Kuhlers, & Lishak, 1997). Further equine research, involving all types of learning needs to be done. Research into human cognition and intelligence indicators and predictors, is still being done and many questions remain. In the area of equine research, information about these concepts, are even further behind and moving at a slower rate. The purpose of this study was to provide further data, extending previous research in the area of equine learning and memory. A discrimination learning, observational learning and memory task was measured and compared in a single subject design using six horses.
METHODS PARTICIPANTS
Six horse subjects were drawn from and tested at, Rose Red Farm in Northeast Kansas. There were four mares at age five, consisting of three grade and one Thoroughbred. There was a two-year-old Quarter horse stallion, and a gelding Shetland pony over the age of 20. All horse subjects have differing backgrounds, breeding and training. All subjects are handled by and familiar with, the experimenter. Under non-experimental conditions, five of the horses are used for breeding purposes and the last of the six, as a companion for new horse arrivals. Subjects are pastured together and fed Brome hay during winter. All subjects, except the Shetland pony, receive a 12% protein sweet feed every day during fall and winter. Shelter and water are openly accessible at all times, to all subjects and each is familiar with the surroundings in which they have been tested. MATERIALS
Three testing procedures were done and measured. The first test was a discrimination learning task and the last a measurement of retention of the discrimination task. The equipment was a black and a white bucket identical, except in color, separated by a four by four feet wooden partition. Paper and pencil were used to record subject`s discrimination, and results for the memory task. The regular 12% protein feed was given as a positive reinforcer for all testing procedures. The second test was to assess the horse`s ability to learn through observation. Two purple buckets and a three feet high by five feet long wooden table for bucket placement were used. PROCEDURE
To insure sufficient motivation all subjects were given the morning feed at regular feeding time; testing for all tasks started no earlier than three hours after this and no later than one hour before the afternoon feeding. To minimize separation anxiety, all horses were separated, but within view of the test subject.Test 1. Each horse demonstrated discrimination learning ability. Testing was done in a small rectangular paddock. The positive reinforcer was always in the black bucket and the horse learned to choose this over the white bucket to the criteria of at least 80% of the time. The horses were given eight sessions composed of ten trials, to learn the discrimination. Two sessions were given on Saturday and Sunday, for two consecutive weekends. Patterns for the right and left placement of buckets were chosen prior to each session. No bucket was in the same position more than three consecutive trials. Each horse was held by the experimenter six feet away and centered on the wooden partition separating the black and white buckets. Once the assistant had prepared bucket placement for the trail, the horse was released and allowed to choose. A choice was made by selecting one side of the partition over another and so, one bucket color over another. Subject, session, trial, bucket placement, color and selection by the subject, were recorded on a pre-designed sheet. Test 2. This task involved observational learning assessment. Testing was done in one area of a round pen sixty-six feet in diameter. A purple bucket was placed at each end of the wooden table. Alternation of reinforcement placement was chosen prior to session start, as in the previous testing procedures. The subject, held by the experimenter four feet away from the buckets, was allowed to view the assistant placing the grain reinforcer in one of the buckets. The assistant faced away from the buckets, to minimize unconsciously given cues for correct bucket choice. The subject was then released to make a selection. The subject, trial, reinforcer placement and selection were recorded. The subject had successfully learned through observation when the correct bucket was selected 80% of the time during two consecutive sessions consisting of ten trials each. Test 3. Three weeks following initial discrimination learning, five subjects were tested for memory retention. The subject again discriminated between the black and white bucket, choosing the black bucket at least 80% of the time during a session of ten trials.
RESULTSA simple linear regression was calculated predicting subjects` discrimination learning based on session number. A significant regression equation was found (F (1, 46) = 52.181, p < .001), with an R2 of .531. Subjects` predicted discrimination is equal to 33.81 + 7.024 (session number). Subjects` average correct discrimination choice increased 7.024 for each session and is shown in comparison to mean results of all subjects in the observation task in Figure 1. A simple linear regression was also calculated predicting subjects` observation learning scores based on the session number. The regression equation was not significant (F (1, 46) = 1.269, p > .05) with an R2 of .027. The number of completed sessions could not be used to predict observational learning scores. Observation and discrimination percentages for each subject can be seen in Table 1. Mean correct response for five subjects on the discrimination learning memory task was calculated for each of the two sessions. The mean for the first session was eight correct with a Standard deviation of 1.225. The mean for the second session was 9.4 correct responses with a Standard deviation of .548. Subjects correctly responded about 80% of the time on the first session with a mean increase to 94 % correct on the second session (Table 2).
DISCUSSION The majority of horse training is done through negative reinforcement, while most laboratory experiments use positive reinforcement. Because of this, questions arise as to the validity in generalizing these experimental findings to a horse`s trainability. However, a study done in which horses were given tasks to learn with both positive and negative reinforcement, showed a high positive correlation between the two (Budiansky, 1997). This study assessed discrimination learning, observation learning and memory in six horses. All horses were able to learn the discrimination task and each session produced a predictable mean increase in learning. There were individual differences between each horse, with approximately 50% of the variance accounted for. From a subjective observation it was noted that the horses which learned quickest had also been the most difficult in training to ride. Observation learning and imitation is one theory explaining the horses` acquisition of stereotypic behavior, such as cribbing (Cooper, 1999; Siegal, 1996). Another theory is that horses stabled in the same environment tend to behaviorally react in the same manner. Experiments have failed to confirm an equine ability to learn from observing other horses or from humans (Budiansky, 1997; Baer, Potter, Friend, & Beaver, 1983). Results from the observational learning task lend further credence to the theory that horses may not necessarily acquire bad habits from other horses, but from conditions under which they are subjected. Not one horse from the six was able to demonstrate the ability to learn the appropriate bucket choice, even after just observing placement of the grain reinforcer. Horses have demonstrated, under experimental conditions, to have excellent memories. Mariner and Alexander (1994) demonstrated horses` ability to run errorless trials through a maze, two months after initial conditioning. From personal experience most owners and trainers know horses will remember associations once made, will be retained for extreme periods of time. It may also be difficult to reverse a behavior, once the horse has learned or made the association (Sappington, McCall, Coleman, Kuhlers, & Lishak, 1996). In this study subjects were assessed three weeks after initial acquisition of the discrimination task. In affirmation of memory ability, four horses achieved at least 85% accuracy by the second session. One horse obtained a score of 60% on the first session, but by the second session 90%. The below average performance for the one horse on the first session may have been due to nervousness or excitability. Generalization of these findings to the equine population can be made when viewed in conjunction with prior research. Although all subjects were representative of average horses at pasture, the sample size was small, selection biased. All subjects were selected for reproductive potential, not learning capability (trainability). Sample size, specific breed, emotionality and level of training should be taken into consideration when generalizing to the population. Results from further investigation, controlling these variables may be beneficial in providing accurate predictors of a horse`s performance potential. Operant conditioning tasks correlated with evaluations of a horse`s trainability or past successful performance may prove useful for assessing future equine purchases.
REFERENCES Baer, K. L., Potter, G. D., Friend, T. H., & Beaver, B. V. (1983). Observation effects on learning in horses. Applied Animal Ethology, 11, 123-129. Budiansky, S. (1997). The nature of horses: Exploring equine evolution, intelligence, and behavior. New York: The Free Press. Clark, J. V., Nicol, C. J., Jones, R., & McGreevy, P. D. (1996). Effects of observational learning on food selection in horses. Applied Animal Behavior Science, 50, 177-184. Cooper, J. (1999). Learning in horses. Available: http: equinevetnet.com/pages/ animalscience/behavior/papers/learning.html (1999, February 5). Lindberg, A. C., Kelland, A., & Nicol, C. J. (1999). Effects of observational learning on acquisition of an operant response in horses. Applied Animal Behavior Science, 61, 187-199. Mader, D. R., & Price, E. O. (1980). Discrimination learning in horses: Effects of breed, age and social dominance. Journal of Animal Science, 50, 962-965. Pottenger, D. (1998). Sense and sensibility. Horse Illustrated, November, 48-55. Sappington, B. F., McCall, C. A., Coleman, D. A., Kuhlers, D.L., & Lishak, R. S. (1997). A preliminary study of the relationship between discrimination reversal learning and performance tasks in yearling and 3-year-old horses. Applied Animal Behavior Science, 53, 157-166. Siegal, M. (1996). U. C. Davis book of horses: A complete medical reference guide for horses and foals. New York: Harper Collins. Smith, S., & Goldman, L. (1999). Color discrimination in horses. Applied Animal Behavior Science, 62, 13-25. Wolff, A., Hausberger, M., & Le Scolan, N. (1997). Experimental tests to assess emotionality in horses. Behavioral Processes, 40, 209-221. Wolff, A., & Hausberger, M. (1996). Learning and memorization of two different tasks in horses: The effects of age, sex and sire. Applied Animal Behavior Science, 46, 137-143.
TABLE 1 Table 1 Discrimination and Observation Percentage Scores Over Eight Sessions for All Subjects Subject | Test | Session 1 | Session 2 | Session 3 | Session 4 | Session 5 | Session 6 | Session 7 | Session 8 | | | | | | | | | | | Cricket | Discrim. % | 30 | 80 | 50 | 100 | 60 | 80 | 80 | 90 | | Observ. % | 60 | 70 | 40 | 50 | 40 | 40 | 70 | 70 | | | | | | | | | | | Sweety | Discrim. % | 30 | 60 | 60 | 40 | 60 | 30 | 90 | 90 | | Observ. % | 50 | 40 | 30 | 50 | 40 | 30 | 60 | 50 | | | | | | | | | | | Mokey | Discrim. % | 60 | 50 | 50 | 60 | 90 | 80 | 90 | 100 | | Observ. % | 70 | 60 | 40 | 50 | 80 | 30 | 40 | 60 | | | | | | | | | | | Mouse | Discrim.% | 20 | 50 | 50 | 50 | 60 | 60 | 90 | 90 | | Observ. % | 40 | 20 | 40 | 30 | 50 | 60 | 60 | 40 | | | | | | | | | | | Al | Discrim, % | 40 | 70 | 40 | 50 | 40 | 80 | 100 | 90 | | Observ. % | 30 | 50 | 60 | 50 | 30 | 70 | 40 | 70 | | | | | | | | | | | Red | Discrim. % | 60 | 40 | 50 | 70 | 50 | 90 | 90 | 100 | | Observ. % | 60 | 40 | 60 | 70 | 30 | 40 | 50 | 70 |
TABLE 2 Table 2 Means and Standard Deviations of Correct Discrimination Choice for Memory Test _____________________________________________ Subject | | Session 1 | Session 2 | | | | | Mokey | | 9 | 10 | | | | | Mouse | | 6 | 9 | | | | | Cricket | | 8 | 10 | | | | | Sweety | | 8 | 9 | | | | | Al | | 9 | 9 | | | | | Mean | | 8 | 9.4 | | | | | SD | | 1.225 | 0.548 |
Figure 1 |
