Specific language impairment and developmental dyslexia: What are the boundaries? Data from Greek children.
SLI shows wide language-memory gaps; DD shows tight decoding gaps—test both to tell them apart.
01Research in Context
What this study did
The team tested 47 Greek-speaking children. 24 had Specific Language Impairment (SLI). 23 had Developmental Dyslexia (DD).
Each child took tests for reading, listening, and remembering sounds. The goal was to see where SLI ends and DD begins.
What they found
SLI kids scored low on almost every task. They struggled to understand stories and to repeat nonsense words.
DD kids had a sharper problem. They could understand stories but stumbled when asked to read or sound out new words.
The line between the two labels is real, but you must test both areas to see it.
How this fits with other research
Vugs et al. (2014) adds weight. They found preschoolers with SLI also have weak working memory and poor self-control. This shows SLI deficits start early and spread wide.
Kalliontzi et al. (2022) tells the same story in Greek 4- to young learners. Kids with Developmental Language Disorder (the new name for SLI) had both language and executive-function gaps. The pattern matches the current study, giving a cross-age Greek picture.
Broc et al. (2013) flips the lens to spelling. They showed SLI kids spell better when writing stories than when taking dictation. This adds task detail to the broad SLI profile seen here.
Choi et al. (2012) looks forward. They found that letter knowledge in kindergarten predicts later spelling failure in SLI. Together, these papers form a timeline: early risk markers, broad language-memory gaps, and context-sensitive spelling problems.
Why it matters
Before you write SLI or DD on a report, run both comprehension and decoding probes. If the child fails both, lean toward SLI. If only decoding breaks, lean toward DD. This simple two-test rule keeps your labels clean and your treatment plans sharp.
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02At a glance
03Original abstract
This study examines the significance (between-groups comparisons) and frequency (within-group analyses) of deficits in developmental dyslexia (DD, mainly deficits in decoding and phonemic awareness), specific language impairment (SLI, mainly deficits in listening comprehension), or both (mainly deficits in phonological short-term memory [STM]). Participants included two groups of children who had received a diagnosis of either SLI (N=15) or DD (N=15). For the between-groups comparison, the groups were matched pairwise on nonverbal IQ to 30 chronological age controls (CAC) and 30 reading level controls (RLC). For the within-group analyses, the participants were compared to 91 CACs and 63 RLCs. We developed tasks not used for the diagnoses to assess phonological skills (decoding, phonemic awareness, phonological STM) and non-phonological skills (listening and reading comprehension). SLI children scored lower than both DD children and RLCs on tasks assessing listening and reading comprehension, and lower than RLCs on phonological STM and phonemic awareness. Within-group comparisons showed that a higher proportion of SLI than DD children presented severe deficits in the same four domains. The opposite pattern was found for decoding skills (7 SLI children with a severe deficit, versus 13 in the DD group). These findings are discussed in the light of models explaining the overlap between SLI and DD. They highlight the need to assess both phonological and non-phonological skills in SLI and DD children, using both between- and within-groups designs.
Research in developmental disabilities, 2016 · doi:10.1016/j.ridd.2015.12.014