Functional deficits in phonological working memory in children with intellectual disabilities.
Kids with mild ID have smaller phonological storage, not slower rehearsal, and this bottleneck feeds later reading problems.
01Research in Context
What this study did
The team tested the kids with mild or borderline intellectual disability. They used simple memory games to see how many sounds the kids could hold in mind. Each child also took an IQ test so the scores could be fairly compared to younger kids of the same mental age.
The games got harder by adding more sounds. This let the researchers check if the problem was storage space or how fast the child could say the sounds back.
What they found
Kids with mild ID could hold fewer sounds than mental-age peers. Kids with borderline ID did just as well as their peers. The gap grew bigger when the sound lists got longer.
The trouble was not how fast they spoke or how well they repeated. It was simply less room in the phonological store.
How this fits with other research
McGonigle et al. (2014) extends these results. They tracked the same mild-borderline group over time and found verbal short-term memory stops growing around age 10. This lines up with O'Hearn et al. (2011) — once the store hits its small limit, it stays small.
van Wingerden et al. (2017) also extends the finding. They show that the same mild-ID kids with small phonological stores later struggle to sound out words and understand stories. The memory bottleneck ripples into reading.
Amore et al. (2011) used the the same’s quasi-experimental design but looked at social thinking instead of memory. Both papers prove you can isolate specific cognitive weak spots in mild-borderline ID, not just say "global delay."
Why it matters
When you assess a child with mild ID, check phonological storage with a quick digit-span task. If the score is low, plan shorter instructions, use visual supports, and pre-teach key sounds before reading tasks. This one tweak can ease both language and academic work.
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02At a glance
03Original abstract
Recent studies indicate that children with intellectual disabilities have functional limitations primarily in the phonological loop of working memory (Baddeley, 1986). These findings are indicative of a specific structural deficit. Building on this research, the present study examines whether it is possible to identify specific phonological subfunctions as causal factors in these qualitative deviations from typical development found in children with intellectual disabilities. In a three-group design, specific subfunctions of phonological working memory were examined in students of the same mental age (one group of 15-year-olds with mild intellectual disability [IQ 50-69], one group of 10-year-olds with borderline intellectual disability [IQ 70-84], and one group of 7-year-olds of average intelligence [IQ 85-115]). The automatic activation of the subvocal rehearsal process was operationalized by the word-length effect; the size of the phonological store, by a task involving repetition of nonwords of differing syllable length; and accuracy of processing, by both the phonological similarity effect and the quality of acoustic presentation of the nonword repetition task (distorted vs. undistorted item presentation). The results revealed impairment of the phonological store only in terms of reduced storage capacity, and showed that this deficit increased with length of the item sequences to be remembered. However, this deficit was observed only in children with mild intellectual disability; the performance of children with borderline intellectual disability corresponded with that of a control group of 7-year-olds matched for mental age. The findings are discussed in the context of the two-component model of the phonological loop. They indicate that deficits in storage capacity are associated with deficits in language development and thus seem to be one of the causes of cognitive impairment in individuals with mild intellectual disability.
Research in developmental disabilities, 2011 · doi:10.1016/j.ridd.2011.03.022