There are various published theories regarding the stages of language development in children that discuss everything from early facial expressions and cooing sounds through to complex speech used as an adult.
Probably the most comprehensive study was by Sir Lee Vygotsky, a psychologist who earned recognition for his unfinished work about the impact of the community and social interaction in the cognitive and language development of a child. The theory was never completed but it did earn him acknowledgement as one of the most influential psychologist of his time.
According to Vygotsky, language development in children comes in stages. These stages are so pronounced an observant parent could probably pinpoint where their child is even if they’ve never heard of Vygotsky and don’t know his theoretical name for the stage - which is pretty much most of us!
The first phase comes with a baby’s first sounds. Although the coos and gurgles are important for speech, they aren’t initially meant for communicating. These sounds are simply the baby’s way of exploring and exercising the mechanisms for speech and hearing it was born with. According to Vygotsky, babies have thoughts at this stage but make no connection between the sounds they make and they ability to use these sounds to communicate.
Babies then begin honing in on single sounds or words. Most parents have heard there child’s first “Ma” or “Ma-ma” or “Da” or “Da-da” with pride but at first, there is little meaning in these words for the child, it’s only as we parents respond with delight or confusion that the child begins to grasp the meaning of these “sounds” and connections begin to take place. It is this social reaction to early communication attempts that Vygotsky maintained is so important.
From this point on, young children begin solidifying the sounds and primitively connecting words, i.e., “Mum go” and begin to understand how connecting different words/sounds creates different reactions from those around them. The child "assumes" the "meaning" of these connected words by the reactions they elicit from those around him/her.
As language ability develops, children start to externalize and give meaning through association to objects. An example of this would be when a child picks up a book and shows it to a parent at bedtime. In this scenario, the child is using an external object (the book) to express that he or she wants a bedtime story before sleeping.
Rhyming and song are excellent during this stage to develop word recognition through repetition, as well as dual language books for bilingual children to solidify both primary and secondary languages. Children will also often talk aloud almost as though they are trying to explain things to themselves. This helps them to “organise” things in their minds.
This externalization of thought lessens as the child develops until they eventually begin to draw everything back in, and start to keep thoughts in the head to undertake tasks involving logic internally as opposed to talking out loud (i.e., counting or reading in their heads and not aloud). Just as practice helped the speech to develop in the initial phases, this stage helps the child to further develop internal, logical thought.
Certainly, as a parent, being conscious of the phases and roughly what is going on inside our children’s heads can help us to choose better ways to communicate with them. It also provides clues on how we can help their development further. But remember, no matter how they grasp and begin to use language, it is our reaction to the words that gives them true meaning.