Did you learn another language at school? Many of us started studying French, German or Spanish at age eleven and found it hard work getting our heads around complicated grammar and getting our mouths around unfamiliar sounds. But all of us, only a few years earlier, learnt our own mother tongue without any effort.

The amazing ability of very young children to pick up any language they are exposed to remains one of the great puzzles of psychology. Unravelling the mysterious process of learning to talk and to understand speech is so difficult because, as any parent knows, babies do not easily reveal what is going on in their minds.

One thing is clear – only humans are able to learn the complexities of human language. Even our closest living relatives, chimpanzees, cannot compete with the linguistic abilities of a three-year-old child. One problem is that chimpanzee mouth and lungs cannot generate the great variety of human speech sounds. However, they can use their hands effectively to make the shapes used in deaf sign languages. So, scientists in the 1960s and 1970s tried to teach chimpanzees to communicate using sign language. As seen in the 2011 film “Project Nim”, chimps can learn to recognise and even produce a vocabulary of a few hundred sign words, but never combine these words with the creativity and expressiveness of homo sapiens.

For thousands of years, people have been speculating why humans have this unique ability. A long-standing theory is that we are born with knowledge of how language works. In ancient times, some ethically-troubling experiments were carried out to test this theory. Pharaoh Psamtik I – hoping to discover what language children were born with – left two babies with a shepherd who was told never to speak to them. The pharaoh was disappointed when the first sounds uttered by the babies did not correspond to Egyptian, which he assumed was the authentic first language of all people.

In more recent times, various “feral” children have been discovered apparently raised by wild animals or otherwise deprived of human contact in infancy. These tragic cases demonstrate that children need to be exposed to a human language within the first seven to ten years of life, or they will never acquire full linguistic abilities. However, studies of deprivation cannot fully answer the burning questions. Are we born with knowledge of human language? What experience with speech do babies need to recognise and produce the sounds of their mother tongue? Can we help our children to use language more effectively?

Answers to these questions are closer than ever, because new child-friendly experimental techniques allow us to study young babies’ understanding of language, even before they produce their first words. “Babies are instinctively curious and often show a preference for new experiences, such as sounds they have not heard before,” says Dr Caroline Floccia, of Plymouth University’s Babylab. “We measure children’s reactions to familiar and unfamiliar sounds to discover whether they can perceive a difference between the two.”

These simple but invaluable experiments work with children as young as five-months-old. They sit on their carer’s lap while listening to speech sounds and looking at lights presented simultaneously. High-tech video equipment records the direction of the child’s gaze, and because lights and sounds are associated, the experimenter can tell when a child has a preference for a particular sound.

Armed with these experimental techniques, the Plymouth Babylab has recently been investigating how children recognise their first words. Early on, it seems that vowels are particularly important. Mispronounce a vowel in a babies’ name – “Imma” instead of “Emma” – and they will not recognise it, but they are happy to accept consonant swaps, such as “Taisy” for “Daisy”. This suggests that, as suspected, we may be born with mental biases influencing how we interpret the stream of sounds we are continually exposed to.

Another Babylab study highlights the importance of local environment on word learning. “We tested children living in Plymouth whose parents had accents from elsewhere in the country,” says Dr Floccia. “Against expectations, children prefer the pronunciation of words in the local accent, even though they only hear a different accent at home.” It seems that one of the most important factors influencing a baby’s language development is the need for them to interact socially with others. As humans, the best way we can socialise is through language, and so babies will learn to speak in the way that maximises their ability to interact with other people, not just their immediate family.

We have come a long way from the pharaoh’s dubious experiments on a child’s first words. It now seems that, although some of our power of language is passed on through our genes, the fundamental human need to socialise may be just as important.

If you are interested in contributing with this research and have a child aged 0 to 6 years, please contact us at the Plymouth Babylab on 01752 584865 or visit www.plymouthbabylab.org.

[This article first appeared in the Plymouth Magazine in April 2013.]