Horses can distinguish between dominant and submissive body postures in humans, even if they don't know the person in question, according to a new study from the University of Sussex.

The new findings, published in the journal Animal Cognition, broaden our understanding of how animals communicate with other species using body postures.

For the study, researchers set up experiments using 30 domesticated horses to see whether they were more likely to approach a person displaying a dominant body posture – in which the person was standing straight, with arms and legs apart and their chest expanded – or a submissive posture – slouching, keeping arms and legs close to the body, relaxed knees.

Previously, the horses had been given food rewards by each person when they were standing with a neutral body posture. However, the researchers found that the horses were far more likely to approach the people displaying a submissive posture.

"Horses are often thought to be good at reading human body language based on anecdotal evidence such as the 'Clever Hans effect'," said Amy Smith, co-lead author of the study from Sussex. "However, little research has tested this empirically. These results raise interesting questions about the flexibility of cross-species communication."

Leanne Proops, co-author from the University of Portsmouth, added: "Evolutionarily speaking, animals - including humans - tend to use larger postures to indicate dominance, or threat, and smaller postures to indicate submissiveness. Horses may therefore have an instinctual understanding of larger vs. smaller postures."

Smith demonstrated in a previous study, published last year, that horses were able to distinguish between happy and angry human facial expressions.

The latest findings could be especially beneficial for horse trainers.

"We were interested in dominant and submissive postures with horses specifically because, although many trainers use posture as a training cue, little research has investigated whether horses would be sensitive to these cues without any specific training," said Clara Wilson, another co-author from Sussex.

"Results like these encourage us to be more conscious of the signals we exhibit when interacting with horses and other animals to facilitate a smooth animal-human relationship."