Human perception of vocalizations of domestic piglets and modulation by experience with domestic pigs (Sus scrofa).

Interspecific communication between humans and pets is possible through vocal cues. We studied how humans with differing experience with domestic pigs (Sus scrofa) interpret pig vocalizations. Forty-eight ethologists studying pigs, 31 pig-caretakers and 54 naive students evaluated the emotional intensity and valence (negative/positive) of recordings from two negative (castration, isolation) and two positive (reunion with the sow, postsuckling) contexts. They also identified the context in which the recordings were made. Castration vocalizations were evaluated as highly intense and unpleasant. The positive contexts were evaluated as low in intensity and positive in valence, and isolation fell in the middle for both intensity and valence. Compared with the other two groups, pig-caretakers evaluated the intensity of vocalizations as lower, and ethologists evaluated the valence as more negative. The level of successful classification exceeded that expected by chance for all four contexts but was especially accurate for castration. Ethologists achieved better recognition than students. Classifying (right context) and understanding the emotional content (valence, intensity) of pig vocalizations is thus a general ability of humans, although it varies according to an individual's experience with pigs.