Horses are sensitive to baby talk: pet-directed speech facilitates communication with humans in a pointing task and during grooming.

Pet-directed speech (PDS) is a type of speech humans spontaneously use with their companion animals. It is very similar to speech commonly used when talking to babies. A survey on social media showed that 92.7% of the respondents used PDS with their horse, but only 44.4% thought that their horse was sensitive to it, and the others did not know or doubted its efficacy. We, therefore, decided to test the impact of PDS on two tasks. During a grooming task that consisted of the experimenter scratching the horse with their hand, the horses (n = 20) carried out significantly more mutual grooming gestures toward the experimenter, looked at the person more, and moved less when spoken to with PDS than with Adult-directed speech (ADS). During a pointing task in which the experimenter pointed at the location of a reward with their finger, horses who had been spoken to with PDS (n = 10) found the food significantly more often than chance, which was not the case when horses were spoken to with ADS (n = 10). These results thus indicate that horses, like certain non-human primates and dogs are sensitive to PDS. PDS could thus foster communication between people and horses during everyday interactions.