Eyes are the window to the soul, which may explain why maintaining eye contact is such an important part of human interaction and language learning. However, there is a point in every person’s life when the lips and mouth is the most fascinating thing about the face

Read my lips

Recent scientific research has revealed that when babies reach about six months, they become intrigued by people’s lips. Before this stage, from the age of approximately six weeks, infants will look into the eyes of the people talking to and interacting with them. Yet a few short months later, a subtle shift takes place when the mouth becomes the focus of their attention. According to scientists at Florida Atlantic University, this change is an essential part of language learning.

Led by developmental psychologist David Lewkowicz, researchers tracked the eye gaze of infants aged between four and 12 months as they watched and listened to a woman reciting a monologue in English. According to the results, published in the Proceedings of the National Academy of Sciences of the United States of America, when the babies were between four and eight months old their gaze would move away from the eyes of the speaker and to their lips. At approximately 12 months old, the focus of their gaze would move back to the eyes.

The scientists posited that the shift in focus allowed the babies to learn how mouths formed the sounds they were hearing when people spoke. Mr Lewkowicz described it as an “incredibly complex process”, as although the stage only occurred for a few months, it enabled babies to learn how they should move their lips when imitating sounds.

Interestingly, the babies would shift their gaze back to the eyes of the speakers at around one year old when they were listening to their mother tongue language. However, when researchers played the babies from English-speaking homes film of a Spanish-language monologue, they would continue watching the mouth movements for longer. This suggests the infants understood they were listening to an unfamiliar language and had more to learn.

Professor Bob McMurray from the University of Iowa noted that the research indicates infants understand what they have to learn about and are able to deploy their attention to the relevant area at the correct point in their development. “It’s a pretty intriguing finding,” he added. It would also suggest that time spent talking face-to-face with a baby is integral to their development of language.

First words: a big achievement

The way children learn to talk is a complex process. Up until six months old, a baby’s babbling is gibberish, but as they connect the shapes people make with their mouths to the sounds they can hear, syllables enter their speech, which then become words. Syntax – the ability to arrange words into a sentence – appears later and is usually preceded by a period when the child will babble alone to themselves in their cot to practice making sentences.

However, language learning may start far earlier than this. Earlier this year, research led by Christine Moon, a professor of psychology at Pacific Lutheran University, revealed that babies appear to start learning their mother tongue while still in the womb. Published in Acta Paediatrica, the study revealed infants just a few hours old demonstrated greater interest in vowel sounds from a different language to their parents, than those of their mother tongue. This suggested it was because they were already familiar with their native language as they had begun to learn it while still in the womb.

A 2009 study conducted by Kathleen Wermke of the University of Würzburg in Germany and published in Current Biology, meanwhile, discovered that babies imitate their parents’ rhythm of speech when they cry. This means a baby born to French-speaking parents will have a different melody to their cry than one born to English speakers.

There is still so much left to discover about the process humans go through to learn to speak and these findings could be instrumental in understanding developmental disorders such as autism. One question science is no nearer to answering, however, is how humans acquired language in the first place. No other creature has ever evolved the ability to communicate with such complex speech. Indeed, no other creature uses syntax. Where humans’ ability to speak came from, and why it evolved in the first place, is a mystery likely to go unsolved.