Distinguishing where one word ends and the next begins is a skill essential to understanding language, and new research suggests that it is one that we pick up long before we can speak. According to findings presented in the June issue of the Journal of Experimental Psychology: Human Perception and Performance, babies as young as eight and a half months can sense word boundaries.

Researchers from Johns Hopkins University looked into the matter using the so-called head turn preference procedure. The child sits on a caretaker's lap inside a booth, which features a green light in front of the infant and red lights to each side. Initially, the green light is lit. Then, when the experiment begins, one of the red lights is turned on to attract the child's attention. Next, a loudspeaker behind the red light plays words or text passages. An observer notes how long the infant pays attention to the recording, using the baby's gaze in the direction of the red light as an indicator.

For this study, the researchers first "taught" the infant a word by having a singsong female voice repeat the word over and over again. They then played text passages that contained the word, didn't contain the word or anything resembling the word, or contained a "misparsed" passage in which the sound sequences making up the target word occur between two successive words. After familiarizing an infant with the word "dice," for example, the researchers then played a "target present" passage containing the phrase "two dice" and a misparsed passage containing "weird ice." Control group passages featured totally unrelated sounds.

Intriguingly, the children exhibited a listening preference for the target-present passages. "Infants seem to be more interested when they can pick up something they recognize as familiar amidst the new words of the passages," team member Sven Mattys remarks. "It's as if you heard your name in a conversation at a table next to yours."