Sensory laterality in affiliative interactions in domestic horses and ponies (Equus caballus)

Abstract

Many studies have been carried out into both motor and sensory laterality of horses in agonistic and stressful situations. Here we examine sensory laterality in affiliative interactions within four groups of domestic horses and ponies (N = 31), living in stable social groups, housed at a single complex close to Vienna, Austria, and demonstrate for the first time a significant population preference for the left side in affiliative approaches and interactions. No effects were observed for gender, rank, sociability, phenotype, group, or age. Our results suggest that right hemisphere specialization in horses is not limited to the processing of stressful or agonistic situations, but rather appears to be the norm for processing in all social interactions, as has been demonstrated in other species including chicks and a range of vertebrates. In domestic horses, hemispheric specialization for sensory input appears not to be based on a designation of positive versus negative, but more on the perceived need to respond quickly and appropriately in any given situation.Electronic supplementary materialThe online version of this article (10.1007/s10071-018-1196-9) contains supplementary material, which is available to authorized users.

Female horses spontaneously identify a photograph of their keeper, last seen six months previously

“…For example, goats showed a right-hemisphere bias of processing of visuospatial cues in a maze before they had understood the rule 33 . Horses also show right hemisphere preference for social processing 34,35 . That could have explained why in our study, they could have chosen the right side of the screen to observe the faces with their left eye when they were unsure and trying to decide.…”

Lateral position preference in grazing feral horses

“…In sum, we found that spatial positioning of nearest neighbours is lateralised among adult feral horses during foraging. Previous studies reported that the left eye and right hemisphere are frequently used during agonistic and affiliative behaviours in horses and other species (Austin & Rogers, , ; Deckel, ; Farmer et al, ; Garbanati et al, ). In addition, offspring of various mammal species tend to monitor their mother using their left eye (Karenina et al, ).…”

“…Several studies have reported laterality in behaviours including agonistic and affiliative behaviours in counter‐directed positions, vigilance to auditory stimuli and relative spatial positioning in mother–infant relationships in horses in co‐directed positions (i.e. two individuals facing the same direction) (Austin & Rogers, , ; Farmer, Krueger, & Byrne, ; Farmer, Krüger, Byrne, & Marr, ; Karenina et al, ; Karenina, Giljov, & Malashichev, ). According to previous studies, horses frequently use their left eyes during these behaviours, similar to other species.…”

From Science to Practice: A Review of Laterality Research on Ungulate Livestock

“…In the last review [44], there was insufficient evidence on sex and positive social contexts to draw any clear conclusions. Fortunately, more evidence has been gathered for these contexts since then, most of which seem to point to right hemispheric dominance [84,85,114,121,122,155]. For instance, a significant majority of horses showed a left eye bias during grooming and other mutual affiliative behaviors [121].…”

“…Fortunately, more evidence has been gathered for these contexts since then, most of which seem to point to right hemispheric dominance [84,85,114,121,122,155]. For instance, a significant majority of horses showed a left eye bias during grooming and other mutual affiliative behaviors [121]. In contrast, horses have been found to show a preference to hold their right ear forward/ left ear backward when attending to human laughter [125].…”