Working Memory and Developmental Language Disorder
Working memory is the ability to hold and manipulate information in mind. Here are a few tasks that require working memory:
Remembering the cost of items while trying to sum them in your head.
Recalling a new name you heard so you can Google it.
Repeating a string of numbers while someone is talking to you about something else.
Working memory has a limited capacity
We can’t remember everything we want to remember. If you want to remember something for longer than a moment, you must focus attention on it. Have you ever thought all morning about something you need to take with you, but then forget it when you put on your coat and find your keys? When you shift your attention to getting ready to go, you stop focusing on the thing you wanted to remember. That thing fades from your working memory and is forgotten.
Working memory load varies with different tasks
Some things are harder to hold in mind than others. It is easier to remember familiar information than new information. For example, it will be easier for you to recall these letters: ‘tdyaserey,’ if they are arranged this way: ‘yesterday.’ That’s because ‘yesterday’ is a word you know as one chunk, so the working memory load is low. A strange sequence of letters, on the other hand, has to be remembered as a string of separate items because the sequence isn’t familiar as a single chunk to you.
Working memory load depends on the complexity of the information you’re holding in mind too. If you ask for directions and hear ‘turn right at the next stop sign,’ the demands on your working memory are low. If instead you hear ‘turn right at the next stop sign, go three miles and turn left, then stop at the third building on the right,’ the demands on your working memory are high.
Working memory load also depends on how much you are juggling in the moment, too
For example, it might be harder for you to remember things if you are upset. The capacity for remembering other things is reduced when your emotions occupy your working memory.
Working memory also varies with your knowledge of the thing to be remembered
Imagine hearing a talk about astronomy. If you’re an expert in astronomy, it will be easy for you to hold the ideas in mind and follow the lecture. If you don’t know much about astronomy, though, you might find your working memory overloaded after the first few mentions of unfamiliar constellations!
Working memory holds different kinds of information. Sometimes we hold and manipulate nonverbal information in our working memory. For example, if you were trying to fix a child’s broken toy, you would hold visuospatial information about how one part fits together with another. At other times, we hold and manipulate verbal information in our working memory. We might be trying to recall sentences people have said or information we have read. Someone with a particular difficulty holding verbal information in mind might do poorly on working memory tasks involving verbal information, but well on working memory tasks focused on visuospatial information.
What does working memory have to do with Developmental Language Disorder (DLD)?
Children with developmental language disorder (DLD) often have difficulty with verbal working memory. For example, children with DLD can recall fewer numbers in a list than their peers. Sometimes children with DLD also have a bit of difficulty with visuospatial working memory tasks.
It’s hard to know exactly why children with DLD have poor verbal working memory. It might be low working memory capacity. If so, the child will have trouble with both verbal and nonverbal information. It might be difficulty processing phonological (speech sound) information. In this case, the child will have more difficulty recalling verbal than nonverbal information. It might be that language difficulties interfere with working memory functioning. A child with DLD may know fewer words or have more trouble understanding sentences than other children. Because it is harder to remember things that are unknown or poorly understood, this child will not do as well on memory tasks as children who have stronger language skills.
References:Archibald, L. (2018). The reciprocal influences of working memory and linguistic knowledge on language performance: Considerations for the assessment of children with developmental language disorder. Language, Speech, and Hearing Services in Schools, 29, 424-433.
Archibald, L. (2017). Working memory and language learning: A review. Child Language Teaching and Therapy, 33(1), 5-17.