Research suggests infants may be able to perceive that speech can communicate unobservable objects that are essential for social interactions.

In a study conducted by scholars from New York University and McGill University, one-year old infants were monitored to determine whether or not they would be able to identify that speech can communicate both congruent (observable) and incongruent (unobservable) items. Observable items include objects and people, whereas unobservable items relate to social interactions and/or one's intentions.

Study author Athena Vouloumanos, assistant professor at NYU, and co-authors Kristine Onishi, an associate professor in the Department of Psychology at Canada's McGill University, and Amanda Pogue, a graduate student at the University of Waterloo, observed infants as they had other adults acted out short scenes. The method utilized to measure the infants' detection of unobservable scenes was observing how long the infants stared at an incongruent scene.

The scenes included an adult who was the communicator that failed in their attempt to stack a ring on a funnel because the funnel was out of reach. Prior studies demonstrated that infants would interpret the actor's failed behavior as signaling the actor's intention to stack the ring. Following actor one's failed attempts, researchers presented a second actor as the recipient, who was able to reach all objects. During an important scene, actor one (the communicator) coughed or uttered a unique word "koba," which was unfamiliar to infants, to the recipient.

While infants always knew the communicator's intention from observing her prior failed stacking attempts, the recipient only sometimes had the required information to accomplish the communicator's intended action–specifically, when the communicator expressed appropriately using speech, but not when she coughed.

Results revealed infants looked longer when the recipient performed a different action such as imitating the communicator's prior failed attempts or stacking the ring elsewhere other than stacking the ring on the funnel, suggesting these are surprising outcomes—incongruent.

"As adults, when we hear people speaking, we have the intuition that they're providing information to one another, even when we don't understand the language being spoken. And it's the same for infants," Onishi said. "Even when they don't understand the meaning of the specific words they hear, they realize that words—like our nonsense word 'koba'—can provide information in a way that coughing cannot."

According to Vouloumanos, the results suggest infants have ways of communicating that was not previously known. She also suggested if infants can understand that speech can convey information about incongruent things, then they [infants] can use this tool to obtain insight into other people helping them develop into competent adults.

The study was published in the Proceedings of the National Academy of Science.