West, G., Melby-Lervåg, M., & Hulme, C. (2021). Is a procedural learning deficit a causal risk factor for developmental language disorder or dyslexia? A meta-analytic review. Developmental Psychology, 57(5), 749.
Aim of the paper:
Difficulty in procedural learning has been widely discussed as a possible cause for language learning disorders, such as developmental language disorder (DLD) and developmental dyslexia (DD). However, studies examining this theory have been inconsistent in their findings, making it difficult to judge whether the theory is scientifically accurate. This study ran meta-analyses of many studies that investigated the theory to explore whether individuals with DLD or DD show impairments in procedural learning across different studies. The effects of the severity of language disorder and the type of task used for procedural learning were also examined.
Procedural learning: unconscious or incidental learning that is critical for abstracting the rule-based structures of language. For example, learning how to say phrases automatically instead of thinking of each individual words.
What was found:
· Participants with a language disorder (DLD or DD) performed poorer on all four procedural learning tasks compared to those without a language disorder.
· However, there was no significant correlation between procedural learning performance and language skills.
· The severity of the language learning disorder did not have a significant effect on procedural learning performance.
· The group difference in procedural learning performance varied based on the task used to measure procedural learning.
What does this mean?
Reviewing the current data, a clear conclusion cannot be made about whether difficulties in procedural learning cause language learning disorders such as DLD or DD. As finding a cause for language disorders is important for developing effective assessments and treatments, reliable and accurate measures of procedural learning need to be developed to further examine the theory. The authors suggested that future research should measure several different types of learning alongside procedural learning to determine whether a specific type of learning is impaired while other types of learning are not impaired. This paper is also limited by combining both DLD and DD together. While there are similarities and co-morbidities between the conditions, there may be different causal factors dependent on whether they are co-morbid or not.
Where can I read this paper?
This paper is not open access. If you wish to read the full paper, please email E-DLD@bath.ac.uk and request a copy of the paper.