The Matthew effect is an important phenomenon for speech-language pathologists to be aware of
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A few years ago, I was very intrigued when I first read about The Matthew effect, as it relates to vocabulary growth in kids with dyslexia and other language-based reading difficulties. Here's a brief description:
In 1986, a psychologist named Keith Stanovich (reference below) posited the idea that kids with a strong foundation in reading accumulate all reading-related skills faster, while kids who don't have a strong foundation in reading do not grow as quickly in their reading-related skills. Stanovich called this the Matthew effect.
The term "Matthew effect" is analogous to the aphorism that "the rich get richer and the poor get poorer." Its name and the phenomenon it describes are related to a Christian bible verse in the book of Matthew.
In 2015, Duff, Tomblin & Catts published a study that narrowed the focus of this potential effect on broader reading skills; they hypothesized that "reading skill in general, and word reading skill in particular, could be related to the rate of vocabulary growth."
The study concluded that "there is strong support for the existence of a Matthew effect between word-reading skill and vocabulary."
If you think about this for even a few seconds, it makes good sense. Consider these facts outlined in the study:
a great deal of the word learning kids do occurs through exposure to written text
print material contains many more low-frequency (tier 2 and tier 3) words than oral language does
around 3rd or 4th grade, children start to encounter words they have not yet heard in oral language through the texts they read (after they make the transition many educators refer to as going from "learning to read to reading to learn")
average strong readers in the 3rd and 4th grades read at home more times per week than weaker readers
Given all this, it seems logical that the vocabulary growth of weaker readers will occur at a slower rate, resulting in a reduced vocabulary overall.
The Matthew effect in reading: it goes both ways
I want to take a moment here to highlight that many kids on our speech-language therapy caseloads struggle with reading and reading comprehension. If you recall the Simple View of Reading, introduced by Gough and Tunmer in 1986 (busy year!), you'll know it goes like this:
Decoding x Language Comprehension = Reading Comprehension
Our students often have weak reading comprehension skills, due to difficulties with decoding, difficulties with language comprehension, or both. (51% of kids with developmental language disorder (DLD) also have dyslexia! For 6 things every SLP should know about DLD, see this blog post.)
So, given the Matthew effect, it would make sense that our students with DLD and dyslexia have vocabularies that are reduced, given their lower volume of effective reading comprehension.
It's important to remember that we also know the converse is true: A limited vocabulary can lead to decoding difficulties. In another article by Duff, published in 2023, she described how "a strong vocabulary knowledge is one of a number of factors that impact a child’s skill in 'set for variability.'" She explained that this is the skill of generating phonologically similar words and recognizing real words, a critical step in the “self-teaching” process for words with irregular spellings. In other words, if, while reading, a child encounters a word they can't automatically decode/recognize, they'll have a better chance of decoding it successfully if they're already familiar with that word in their oral language.
In addition, it's hard to comprehend a text that contains a lot of unfamiliar vocabulary. Kids with DLD need an average of 36 exposures to a new word before learning it. (https://doi.org/10.1044/lle22.4.131). Kids with typically developing language need 12 or less. Given this need for many more exposures to new words, word learning happens much more slowly for kids with DLD. This leads to lower vocabulary skills overall.
So here's a diagram that shows how the components here are all interrelated. (For a more comprehensive picture of all the skills that underlie skilled reading, check out Scarborough's Reading Rope.):
What do I do about the Matthew effect in reading as an SLP?
For my students who have weak decoding skills, weak comprehension skills, or both, I now take into account the Matthew effect on their vocabulary, especially if they are in the third grade or higher. While I have encountered some dyslexic students with reasonably strong vocabularies, I am now fairly certain that their vocabularies would be even broader if their reading volume had been greater.
When I'm assessing students and looking at their vocabularies, I now take the Matthew effect into account.
And what do I do in therapy now that I know that reading impacts vocabulary and vocabulary impacts reading? I do my best to accelerate and support each language-based component of the simple view of reading, along with my students' vocabularies. I know that it's all interdependent, and as you support each component, the whole system strengthens. In turn, each component develops more. It's the opposite of a vicious cycle - a virtuous circle!
Here are specific materials and strategies I use to develop my students' skills in these areas:
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References:
Stanovich, K. E. (1986). Matthew effects in reading: Some consequences of individual differences in the acquisition of literacy. Reading Res Q 21 (4): 360–407.