Horses prefer their rider: A strange situation test adaptation shows behavioural evidence for partner-specific...

The relationship between horses and humans is often described as cooperative and affective, yet empirical studies on horse-rider bond remain scarce. Previous findings on horse-human relationships yielded conflicting results on whether and how horses show bonding like behaviour toward their owners.

We tested whether horses show partner-specific approach and proximity toward their primary rider compared with an unfamiliar experimenter in an adapted Strange Situation Test, and whether the rider's presence was associated with behavioural patterns indicative of safe haven and secure base effects.

Thirty horse-rider pairs participated in a behavioural test conducted in an indoor riding arena, which included several episodes: recall by owner/experimenter, separation both from rider and experimenter, reunion with rider/experimenter, and exposure to a potentially frightening object in order to examine secure base effect. We compared horses' social behaviours (i.e. proximity, approach, gazing behaviour, etc.) toward their riders versus the unfamiliar experimenter, as well as their stress-related signals (i.e. manure, vocalization) across these episodes.

We found that horses approached their rider significantly faster than the experimenter during recall and reunion episodes and spent significantly more time in close proximity to the rider across multiple contexts. Our findings indicate that horses' gazing behaviour is influenced more by the human's level of interactiveness than by familiarity. However, no conclusive evidence emerged for a "safe haven" effect during exposure to the frightening stimulus. Rider sex had no effect on the horses' social or stress related behaviours.

These findings suggest that horses may form specific bonds with their riders, characterized by different social behaviours consistent with certain criteria of attachment theory. The study highlights the importance of incorporating socio-emotional components into analyses of human-horse relationships and underscores the relevance of comparative attachment frameworks in equine behaviour research.