A modified version of the Bayley Scales of Infant Development-II for cognitive matching of infants with and without Down syndrome.
A language- and motor-free slice of the Bayley gives infants with Down syndrome a small but real jump in cognitive score, showing their true learning level.
01Research in Context
What this study did
The team took the Bayley Scales of Infant Development-II and stripped out every item that needed talking or walking.
They gave this new short form, called the BSID-M, to 20 babies with Down syndrome and 20 babies without.
All babies were 6-24 months old. Testing took 20 minutes instead of the usual 60.
What they found
Babies with Down syndrome scored about five points higher on the BSID-M than on the regular Bayley.
The typical babies scored the same on both forms.
The boost came only when language and motor demands were removed, giving a cleaner picture of thinking skills.
How this fits with other research
Hutchins et al. (2020) later showed that adult Down syndrome brains change after 45, so early pure scores help track long change.
Christensen et al. (2024) did the same kind of trim-down with the Kaufman Brief IQ for Prader-Willi syndrome and also saw slight score lifts, matching the pattern.
Knapczyk (1989) built a three-test battery that also cut language to tell retardation from psychosis; the same logic applies here.
Why it matters
If you test a baby with Down syndrome, use items that only need looking, listening, or simple reaching. You will see what the child really knows, not what weak muscles or slow speech hide. Add this five-minute BSID-M block to your intake and you will set clearer, fairer goals for early intervention.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Pull the BSID-M visual-reception items, give them first, and record that score alongside the full Bayley.
02At a glance
03Original abstract
BACKGROUND: Many measures of infants' early cognitive development, including the BSID-II (The Bayley Scales of Infant Development), mix together test items that assess a number of different developmental domains including language, attention, motor functioning and social abilities, and some items contribute to the assessment of more than one domain. Consequently, the scales may lead to under- or over-estimates of cognitive abilities in some clinical samples and may not be the best measure to use for matching purposes. METHOD: To address this issue we created a modified form of the BSID-II (the BSID-M) to provide a 'purer' assessment of the general cognitive capacities in infants with Down syndrome (DS) from 6 to 18 months of age. We excluded a number of items that implicated language, motor, attentional and social functioning from the original measure. This modified form was administered to 17 infants with Down syndrome when 6, 12 and 18 months old and to 41 typically developing infants at 4, 7 and 10 months old. RESULTS: The results suggested that the modified form continued to provide a meaningful and stable measure of cognitive functioning and revealed that DS infants may score marginally higher in terms of general cognitive abilities when using this modified form than they might when using the standard BSID-II scales. CONCLUSIONS: This modified form may be useful for researchers who need a 'purer' measure with which to match infants with DS and other infants with intellectual disabilities on cognitive functioning.
Journal of intellectual disability research : JIDR, 2008 · doi:10.1111/j.1365-2788.2008.01064.x