Linguistic lateralization in adolescents with Down syndrome revealed by a dichotic monitoring test.
Down syndrome teens show a left-ear edge on dichotic listening, hinting at reversed language lateralization.
01Research in Context
What this study did
The team gave teens with Down syndrome a simple headphone test. Two different words played at the same time, one in each ear. Kids pressed a button when they heard a target word.
The study also tested typically developing teens and teens with other intellectual disabilities. All groups were the same age range.
What they found
Most people pick out words faster in the right ear because the left brain handles language. These Down syndrome teens did the opposite. They responded faster to words in the left ear.
The other disability group and the typical teens showed the usual right-ear edge. This flip suggests the language wires are organized differently in Down syndrome.
How this fits with other research
Losin et al. (2009) scanned adults with Down syndrome while they listened to stories. The MRI showed weak left-side language sparks and scattered parietal lights. Both studies, same year, point to reduced left-brain dominance.
Amore et al. (2011) ran a semantic task inside an MRI and found the same group recruits frontal areas for visual-spatial work. Together the three papers build one picture: Down syndrome brains share language work across both sides.
Amore et al. (2011) also watched adults build puzzles with both hands. Right-handed Down syndrome adults led with the left hand, another reversed-laterality marker. Language, motor, and sensory findings all line up.
Why it matters
If you test receptive language, do not assume left-brain strategies will work best. Try presenting targets to both ears or both visual fields. When teaching verbal skills, pair them with visual or motor cues that tap the right side. Check handedness before you set up fine-motor tasks. These small shifts honor the brain wiring your kids actually have.
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02At a glance
03Original abstract
Linguistic lateralization in 10 adolescents with Down syndrome (average age: 15.7 years), 15 adolescents with intellectual disabilities of unknown etiology (average age: 17.8 years), 2 groups of children without disabilities (11 children, average age: 4.7 years; 10 children, average age: 8.5 years), and 14 adolescents without disabilities (average age: 18.7 years) was examined, using a dichotic monitoring test (DMT). Different Japanese words with 2 consonant-vowel syllables were presented to each ear simultaneously. Participants pressed a button when they heard the target word. The younger children without disabilities and the adolescents with intellectual disabilities exhibited a right-ear advantage, whereas the adolescents with Down syndrome showed the reverse pattern, i.e., a left-ear advantage. These results suggest that there is atypical linguistic lateralization in adolescents with Down syndrome.
Research in developmental disabilities, 2009 · doi:10.1016/j.ridd.2008.03.004