Abstract: The effect of short periods of strenuous exertion, in this case treadmill exercise, on the subsequent behavior of Standardbred horses was examined. Six horses were exercised on a high-speed treadmill 4 or 5 days per week, for 3-4 miles (approximately 1.8 m s-1 for 3 min, 5 m s-1 for 12 min, 9 m s-1 for 3 min, 3 m s-1 for 3 min, 1.8 m s-1 for 3 min). The behavior of the horses was observed in the horse's home stall immediately after exercise and 2-7 h after exercise. Focal animal sampling for a total of 150 h revealed that the horses spent significantly more time drinking and less time resting after exercise than they did on control (non-exercise or rest days). The greatest influence on behavior was seen immediately after exercise. The horses spent 13.2+/-2.7 s per 15 min drinking after exercise and 7.2+/-2.3 s per 15 min drinking on non-exercise days. They spent 7.3+/-1.5 min h-1 stand resting after exercise and 9.7+/-2.1 min h-1 on non-exercise days. These changes in behavior may be related to the physiological changes that accompany exercise. Eating, walking, elimination and self-grooming were not significantly influenced by exercise. In a second experiment the activities of two groups of six Standardbred mares were compared. One group was exercised on the treadmill and the other was not. The exercised horses spent more time drinking and lying, but urinated less than the non-exercised group.

Abstract: An attempt to replicate Grzimek (1952; Z. Tierpsychol., 27: 330-338) is reported where a Quarter-Horse mare chose between colored and gray stimuli for food reinforcement. Stimuli varied across a broad range of reflectance values. A double-blind procedure with additional controls for auditory, olfactory, tactile, and position cues was used. The subject could reliably discriminate blue (462 nm) vs. gray, and red (700 nm) vs. gray without regard to reflectance (P<0.001), but could not discriminate green (496 nm) vs. gray. It is suggested that horses are dichromats in a manner similar to swine and cattle.

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.

Abstract: Horses are well able to form classical and instrumental associations and so the focus of much recent research has been on the stimulus control of instrumental learning. Horses appear to discriminate using spatial cues more easily than other stimulus features, as indicated both by the speed of initial task acquisition and by the extent to which acquired discriminations can be reversed. Phenomena associated with discrimination learning in laboratory animals, including generalisation and peak shift, have been demonstrated in horses. However, the ability of horses to classify stimuli into categories is more controversial. Although there is some evidence that horses may be able to form categories based on similarities in the physical appearance of different stimuli, there is currently no evidence that they are able to develop abstract concepts. Their performance on social learning tasks has also been poor. Few correlations are observed between the learning ability of individual horses on different tasks, suggesting that it may not be possible to classify individual horses as `good' or `poor' learners. Better learning performance by horses that are naturally calm is probably due to reduced interference in the learning process. Correct handling procedures can lower reactivity levels in horses, and may facilitate learning in some circumstances. Future research on equine learning needs to take into account the complex nature of equine social interaction. Studies on the effects of stress on learning, and on social and spatial cognition, are also particularly needed.