Explaining Dyslexia using the WMM

spelling;

impaired working memory;

reading;

phonology;

comprehension;

sounds

As you know, Miller (1956) suggests that we can hold on average seven bits of information in working memory. The duration of working memory is usually limited up to 30 seconds. Once information is lost from working memory, it cannot be retrieved.

The student who “loses” some of the steps for directions delivered orally will not be able to retrieve the steps without repetition or some other form of assistance.

The working memory system includes verbal and visual-spatial short-term memory stores. Verbal short-term memory holds information that can be expressed in numbers, words, and sentences. Visual-spatial short-term memory holds images, pictures, and information about location in space. Working memory also has the CE that helps us resist distractions and remain focused when engaged in a task that requires working memory.

Working memory is the “go-between” for short and long-term memory. For example, solving a maths word problem involves holding on to the details of the word problem in verbal short-term memory while retrieving from long-term memory the basic maths facts needed to carry out the calculations involved in solving the problem.

Individuals with an impaired working memory tend to have trouble planning, organizing, and carrying out daily chores such as running errands, because it requires mentally formulating a “to do” list organized by time and location. Study skills may also suffer. Working memory allows us to keep track of priorities and helps us block the external or internal distractors that can derail us from the task at hand. Working memory helps us persist with tasks that require focused attention over time. Any of us, even those with strong working memories, can experience working memory problems when overly tired, anxious, or stressed.

An impaired working memory can impede phonological learning and production at all levels. Consider a frequent rhyming exercise for young children. “Tell me which word rhymes with fox: truck, dog, box.”

To identify the two rhyming words, the child must hold and then compare all of the words in working memory (fox/truck, fox/dog, fox/box). When older children attempt to sound out new words, they must use their working memory to hold the entire sequence of sounds long enough to blend those sounds together.