Executive functions in individuals with intellectual disability.
Adults with ID struggle with word fluency and dual-memory loads, yet inhibition can be intact—so test, don’t assume.
01Research in Context
What this study did
Danielsson et al. (2010) tested three parts of executive function in adults with intellectual disability.
They used simple paper tasks: name as many animals as you can, remember two things at once, and solve the Tower of Hanoi puzzle.
The same adults were tested again five years later to see if scores changed.
What they found
Adults with ID said fewer animals and made more memory mistakes than adults without ID.
Surprise: they solved the Tower puzzle just as well, meaning inhibition was spared.
Scores stayed flat five years later—no catch-up growth.
How this fits with other research
Danielsson et al. (2012) looked at kids with ID using the same tasks. Kids matched mental-age peers on fluency but fell behind on planning and inhibition.
The two studies seem to clash: kids show inhibition problems, adults do not. The gap is likely age—planning and inhibition may dip in childhood then level off.
Hong et al. (2021) meta-analysis of Down syndrome found huge verbal working-memory deficits across the life span. Henrik’s memory dual-task fits right inside that bigger picture.
Romanowich et al. (2010) showed many adults with ID fail delay-discounting tests until they get a short teaching loop. Together the papers say: expect slow word finding and fragile working memory, but don’t assume poor self-control—test it first.
Why it matters
When you write goals, separate fluency and memory from inhibition. Use extra wait time and visual cues for word-finding tasks. Keep working-memory loads light—one new step at a time. Don’t ban puzzles or self-control games; Tower data show these adults can succeed with clear rules.
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02At a glance
03Original abstract
The aim of the present study was to investigate executive functions in adults with intellectual disability, and compare them to a closely matched control group longitudinally for 5 years. In the Betula database, a group of adults with intellectual disability (ID, n=46) was defined from measures of verbal and non-verbal IQ. A control group, with two people for every person with intellectual disability (n=92), was chosen by matching on the following criterion in order of priority: IQ higher than 85, age, sex, sample, level of education, and years of education. Three types of tasks of executive functions were included on two occasions, with 5 years between testing sessions: The Tower of Hanoi, executively loaded dual task versions of word recall, and verbal fluency. Adults with ID showed significant impairments on verbal fluency and on the executively loaded dual task word recall task (at encoding but not at recall). There were no group differences on the Tower of Hanoi. No significant differences between the two test occasions were found. The results are interpreted in terms of individuals with ID having problems with speed of accessing lexical items and difficulties with working memory-related executive control at encoding, which includes shifting between tasks. There are, however, not necessarily problems with inhibition. The dual task results additionally imply that the adults with intellectual disability were more sensitive to strategy interruptions at encoding, but that dividing attention at recall did not have such detrimental effects.
Research in developmental disabilities, 2010 · doi:10.1016/j.ridd.2010.07.012