Horse can tell a human’s emotions by our facial expressions, according to new research.

Researchers at the University of Sussex showed A3-sized photographs of male human faces looking angry and happy to 28 horses.

The horses were from five riding and livery stables in Sussex and Surrey, and were aged between four and 23 years old. There were 21 geldings and seven mares in the study, which took place between April 2014 and February 2015.

The results, which were published in the journal Biology Letters, showed that domestic horses “responded negatively” to angry expressions.

The horses looked at angry faces with their left eye, information from which is processed by the right side of the brain, which is specialised for processing negative stimuli.

The horses were also fitted with heart monitors, which showed that the angry faces caused their heart rates to increase.

The study presents “the first evidence” of horses’ ability to distinguish between happy and angry human expressions in photographs.

“The behavioural and physiological results reported here support the hypothesis that horses are able to recognise and respond in a functionally relevant way to human facial expressions of anger,” concluded the report.

“What stands out for me in these findings is that the heart rate of the horse went up when they saw an angry face,” said Andrew Bucher, chief veterinary officer of MedicAnimal.

“I’m sure a lot of owners will attest that the way they interact with their horse influences their behaviour — for instance, if they are feeling angry or annoyed, this will be reflected in tension and even misbehaviour in their animal. I’m pleased to see that this has been scientifically confirmed.”