Researchers have discovered that part of what babies are doing when they are learning to how to talk involves lip reading. There is potential that this finding could one day lead to an earlier way to detect autism in infants.
How do babies learn how to talk? In the past, people presumed that babies learned to talk by listening to their parents when the parents were speaking. I think that the general belief was that infants gained the ability to babble, and then to talk, after hearing certain words repeated enough of times.
A new study, done by researchers from Florida Atlantic University set out to discover what infants were actually doing when adults were speaking to them. They tested a group of infants who ranged in age from four months old to twelve months of age. They compared what they learned from the babies with a group of adults, who went through the same testing.
The babies, (and then later, the “control group” of adults) watched videos. There were two different types of videos that were shown. One had a woman who was speaking English. All of the babies in the study had English as their “native language”. In other words, English was the language that they heard adults speaking at home.
The other video had a woman who was speaking Spanish. This language was selected because it was unfamiliar to the babies. The researchers needed a comparison between what the babies did when they heard language that they might understand, to what they did when they heard language that was entirely new to them.
An eye tracker device was used so the researchers could study the babies eye movements when they were shown the videos. The researchers also looked at the babies’ developmental changes in the attention they paid to the eyes, and mouth, of the woman in the video.
They discovered that the babies that were four months old were focusing almost entirely on the woman’s eyes. When they got older, (somewhere between six to eight months), the babies entered the “babbling stage”. Now, they were focusing on the lips of the woman who was speaking, instead of the eyes. They were lip reading. This behavior continued until they became about ten months old, when the babies got better at some of the basics of language. That was when the babies shifted their focus back to the eyes.
Things worked differently when the babies were shown the video of the woman who was speaking Spanish. The babies were between four and twelve months of age. The babies continued to lip read as late as twelve months of age, because they had not yet grasped the basics of the Spanish language.
There is the potential that these results can be used as a clue that could indicate which babies might have an autism spectrum disorder. For example, a baby who is twelve months old, (or older), who continues to focus primarily on the mouth’s of speakers may not be developing age-appropriate perceptual and cognitive skills.
Image by Keith McDuffee on Flickr