Laterality of horses associated with emotionality in novel situations

Abstract

We have established that lateral biases are characteristic of visual behaviour in 65 horses. Two breeds, Trotters and French Saddlebreds aged 2 to 3, were tested on a novel object test. The main finding was a significant correlation between emotionality index and the eye preferred to view the novel stimulus: the higher the emotionality, the more likely that the horse looked with its left eye. The less emotive French Saddlebreds, however, tended to glance at the object using the right eye, a tendency that was not found in the Trotters, although the emotive index was the same for both breeds. The youngest French Saddlebreds did not show this trend. These results are discussed in relation to the different training practices for the breeds and broader findings on lateralisation in different species.

We are grateful to the different horse breeders for allowing us to test their horses, and to Séverine Marcq for her help in the experimental tests. This study was supported by a grant from COST “Haras Nationaux” and an invited professorship for LJR from the University of Rennes 1. We are most grateful to Dr Peters who provided very helpful comments, as did the anonymous reviewers.