- Horses distinguish between happy and angry human emotions, study says
- Heart rate increases when looking at negative facial expressions
(CNN)A smile can get you a long way with people -- and animals, it turns out.
Horses can distinguish between happy and angry facial expressions on humans, a new study has shown for the first time.
The 28 horses were shown large color photographs of different facial expressions for 30 seconds, and their reactions monitored as part of the research by psychologists at the UK's University of Sussex.
When presented with photographs of angry male faces -- frowning with bared teeth -- the horses' heart rate significantly increased.
Importantly, the equines also moved their heads to look at the aggressive photos through their left eye -- a mannerism associated with negative stimuli.
Information from the horses' left eye is processed in the brain's right hemisphere -- an area specializing in threatening environments, said researchers.