Infants match humans’ faces with speech, monkeys with monkey calls

WASHINGTON - A new study has revealed that the infants as young as five months are able to correctly identify humans as the source of speech and monkey as the source of monkey calls.

The study has shown that human infants are able to correctly match different kinds of vocalizations to different species.

Although young children know that humans speak, monkeys grunt, and ducks quack, it’s not clear when they come to know which vocalizations each of these animals produce.

Much is known about infants’ abilities to match properties of human voices to faces, such as emotion, it is unknown whether infants are able to match vocalizations to the specific species that produces them.

In the new study, the researchers sought to determine whether infants can identify the sources of vocalizations produced by other species.

During the study, the researchers showed five-month-old infants from English- and French-speaking homes a sequence of individually presented pictures of human faces and rhesus monkey faces paired either with human speech or with rhesus vocalizations.

They then examined whether infants preferentially attended to the human faces when human vocalizations were presented (two Japanese single words “nasu” and “haiiro”), and whether infants preferentially attended to the rhesus faces when rhesus vocalizations (a coo and a gekker call) were presented.

It has already been shown that infants tend to look longer at sounds and images that correctly match, so the researchers predicted that if infants identified the sources of vocalizations, they would look longer when the vocalizations and faces matched.

The study showed that the infants looked longer at the pictures of human faces when human speech was presented and looked longer at pictures of rhesus monkey faces when rhesus vocalizations were presented.

The study appears in Proceedings of the National Academy of Sciences (PNAS). (ANI)