How are Language Development and Motor Development Linked?
People have been asking for a long time whether children who are good, or poor, at motor (movement) skills are likely to be good, or poor, at language skills. Here’s what we know so far. When you look at walking, running, jumping and other gross motor skills you don’t find any link between these and language – children who are slow or fast to walk are not necessarily slow or fast to talk. However there is a lot of evidence that hand gestures (including things like waving bye-bye and pointing – communicative gestures – and things like showing what you do with scissors or a comb, without having them in your hand – symbolic gestures) are linked to language abilities. Children who use hand gestures early are likely to be early talkers. Children who are late to use gestures are likely to be late talkers, and are more likely than children whose gestures are on schedule to remain delayed in their language use. There is also an association in older children between having disordered or delayed language development and having difficulties with control of limb movements – it is not just a link in early life.
So, we know a lot about how arm and hand movements are related to language development and language disorders. But most people speak with their mouths. What do we know about oral (mouth) movements – such as sticking out the tongue, licking the lips, and kissing in a grown-up way – and language development? In fact, very little. Here’s a short summary of what we do know:
Typical Oral Motor Development
We actually know very little about how typically developing children develop mouth movements. Most research so far has been on feeding in young infants, without relating this to language development or looking at how mouth movements develop in older children. What we do know is also a little contradictory: some research suggests that children do not learn how to control their mouth movements at an adult level until after they are about 14 years old, while other researchers suggest that there is no real change in children’s skills from a much younger age – maybe 5 years, maybe 8. This is something that my research group is looking into at the moment. We are testing children’s mouth movement skills from the age of 1 year to the age of 8 years to see how they develop.
Oral Motor Development in Children with Language Difficulties
Likewise, until recently we have known only a little about how mouth movements develop in children who have language problems for whatever reason. There are a wide variety of reasons for children to have language development difficulties but in many different syndromes we do see some oral motor difficulties. For example, nonfluent developmental dysphasia (a speech output difficulty without any associated learning disabilities or hearing/social difficulties) tends to be associated with oral dyspraxia (a diagnosed difficulty in coordinating oral movements). In children with specific language impairment (or SLI, a very similar problem where children have delayed or disordered language, without any difficulty in hearing, a general learning disability, or any social difficulties such as autism) the children who find the most difficulty with oral movements are the same children who find most difficulty with pronouncing new words.
Oral movements also tend to be difficult for children with other types of language difficulties – those due to autism and Down Syndrome, for example. Most of these studies tend to look at whether or not a child has a diagnosis of oral dyspraxia, however, and then see whether this diagnosis tends to coincide with a diagnosis of a language difficulty. Two studies that I have been involved in have taken a different approach: we wanted to see if language development could be associated with more subtle variation in oral motor skill, where the mouth movement abilities were not poor enough to be diagnosed as oral dyspraxia. In the first study we looked at a group of individuals who have a developmental language impairment and in the second we looked at a large group of children whose language was – as far as we know – developing in a typical fashion.
Oral Motor Abilities and Developmental Language Impairment
About 5% of children have a specific language impairment (SLI). Children with this disorder have difficulty in constructing sentences, learning new words, and/or speaking. This often runs in families and we studied a large family – which we’ll call the KE family – who had such a disorder. Half of the family members had the disorder and just as many boys as girls developed the disorder. When the family first agreed to take part in research, a paper was published by another research group which said that the family members had difficulties with forming sentences – in particular with regular grammatical endings such as “-ed” on “walked” – but not with any other speech and language skills, and also not with other, non-language skills.
When my research group first got to know members of the family we thought that something couldn’t be quite right about this, as many of the children and even the adults in the family struggle with their speech and are occasionally very hard to understand. I decided to see if, as I suspected, they also had difficulty with non-language skills such as mouth movements. Other people in the group also went on to look at a wide variety of language skills, too, and not just regular grammatical endings – affected family members turned out to have a problem with a wide range of language skills.
We tested family members’ mouth movement skills by looking at:
- Simple mouth movements – such as opening the mouth
- Complex mouth movements – such as whistling
- Combinations of mouth movements – such as three in a sequence (first open your mouth, then put your lips tightly together, then stick out your tongue) or three at the same time (open your mouth, stick out your tongue and make a “h” sound in your throat)
- Repeated movements – such as opening and closing the mouth again and again, as fast as possible.
We compared the abilities of family members who have the speech and language problem, with those who do not and some additional volunteers who were the same age as the family members with the speech and language problems. The mouth movements we asked them to do were first of all described to them, as above, and then shown to them to copy. We found that affected family members were poorer at performing most of the kinds of movements we gave them – but not all of them. They found the combinations of movements more difficult, but the simple movements on their own were not more difficult, and nor was performing repeated single movements quickly. So, it seems that these individuals have problems with coordinating several muscles in one movement, or coordinating several movements at the same time – which is exactly what you need to do when you are speaking. The other thing we found was that these types of movements were hard whether we showed the family members what to do, or described the movements. From this we could conclude that any difficulty with the movements was not due to a difficulty in understanding the instructions, which could easily hinder performance if someone has a language problem.
This finding was very interesting and it led us to ask what relationship there might be between mouth movement abilities and language abilities in children who are typically developing – who do not have any language difficulties.
Oral Motor Development in Children with Typically Developing Language
Most children develop language without any problems, but the rate at which children develop varies widely. Typically developing children mostly seem to start their language development slowly and then, at an average age of about 21 months, suddenly pick up speed and start to learn words much faster and also to combine words into baby sentences such as “doggie bark” or “more juice”. Because development is so fast at this stage, children can be very different from each other – so if we want to find out what it is that makes children different from each other, this is an ideal age to look at.
What Do We Already Know About Mouth Movements and Typically Developing Language?
Again, very little! There is a little bit of research with children who are just starting to speak to suggest that children who are good at coordinating simple feeding movements are not necessarily good at coordinating speech movements but then, we already know that very simple movements are not so closely related to speech movements. However, there is also some research suggesting that older children who have poorer mouth movements also have poorer speech abilities – even up to 10 years of age.
We decided to investigate this further. We looked at 60 children aged 21 months who we recruited through our local hospital when the children were born. As with the older children and adults we tested simple movements (opening the mouth), complex movements (licking the lips) and repeated movements. We also looked at children’s language abilities (by giving the parents a questionnaire to fill in with a list of words children might know at this age, as well as ways in which children can use words and put them together), and children’s cognitive or problem-solving abilities (again using a questionnaire that asks about children’s play skills).
What We Found
The main finding was that the higher a child’s vocabulary was (the more words they knew), the better their mouth movement skills were. We also found that both mouth movements and cognitive abilities were related to each other and to language – but after we removed the variability associated with the cognitive abilities, we still found that mouth movement ability was related to vocabulary. So children who are better at mouth movements are better at language – and it’s not just because they are the cleverer or more able children overall.
One particularly interesting finding was that children who were poor at mouth movements were almost invariably poor at language. Children who were good at mouth movements could however be either good or poor at language. What this suggests is that children need good oral motor skill to be good at language – but they need a lot of other skills too.
What We Concluded
Although the initial reports of the difficulties experienced by the KE family, and a lot of theories of language development, suggest that language is a separate skill that does not depend on other skills such as motor or cognitive skills, our research suggests that this is not true – language and oral movements are linked in both typical and atypical development, and this link is not due to some children being more advanced in all abilities.
There are a number of reasons this might be the case: children who are good at imitating one thing may simply be good at imitating, and therefore learning, new words. However when we looked at older children we found that those with language difficulties also had problems when the movements were explained to them. So this cannot be the only reason for the link we found.
Alternatively, children who are poorer at coordinating any movements of their mouths might, as a result of this, have problems both with carrying out the kinds of movements we gave them to do, and with carrying out speech movements. This would mean they had a hard time pronouncing words and therefore demonstrating what they knew in the way of vocabulary to parents and others. We didn’t find as strong a link between children’s comprehension of words and their mouth movements, which suggests this might be the reason.
However, it is true that children who talk more practice using their mouth more – since that’s how they talk! So we can’t rule out that the link might be the other way round – children who have had more practice in talking have, on the whole, had more of a chance to exercise their mouths, so they would be better at the non-speech mouth movements we gave them.
So, where do we go from here? Well, one thing people ask is whether practicing mouth movements can help children who have speech and language problems. It is fair to say we don’t have enough evidence to conclude that – if children have a basic problem with mouth movement control that applies both to speech and non-speech movements, then helping them with their non-speech movements may or may not help them with their speech movements. If however they lack practice with speech movements and this means they then find non-speech movements difficult, then practicing the non-speech movements is probably not going to help.
About the author: Dr. Katie Alcock combined her early interests in languages and in how the brain works by doing a Ph.D. at Oxford University looking at developmental language disorders and comparing them to those that follow a stroke. Since then she has carried out research in Tanzania (investigating the impact of ill health on cognitive development) and La Jolla (researching the cognitive psychology of language) and is currently a Lecturer at Lancaster University, where she continues research on language development, developmental language disorders, and the impact of health and poverty on language and cognitive development, with current projects in Kenya and Indonesia. To read more about Dr. Alcock’s research go to http://www.psych.lancs.ac.uk/people/KatieAlcock.html.