Do individuals with Down's syndrome possess right hemisphere language dominance?

Area of Science:

• Neuroscience
• Developmental Psychology
• Genetics

Background:

• Down's Syndrome is a genetic disorder associated with cognitive impairments.
• Previous research on hemispheric specialization in Down's Syndrome has yielded mixed results.
• Dichotic listening tasks are used to assess auditory processing and hemispheric asymmetry.

Purpose of the Study:

• To investigate auditory processing and hemispheric specialization in individuals with Down's Syndrome using a dichotic digits task.
• To examine the effects of selective listening and attention switching on performance.
• To test the hypothesis of reversed hemispheric specialization in this population.

Main Methods:

• A dichotic digits task was administered to 10 individuals with Down's Syndrome (ages 10-37).
• Participants were instructed to focus attention on one ear for 20 trials before switching to the other ear after a 5-minute interval.
• Data collected included correct response accuracy and intrusion errors from the unattended ear.

Main Results:

• A trend towards a right ear-left hemisphere advantage for correct responses was observed, but it was not statistically significant.
• Significantly more intrusion errors originated from the unattended right ear compared to the unattended left ear.
• No priming effects were detected during the task.

Conclusions:

• The findings do not support the hypothesis of reversed hemispheric specialization in Down's Syndrome.
• Results suggest a potential left hemisphere information processing disorder that may manifest as functional reversals in dichotic listening.
• Individuals with Down's Syndrome may possess an inherent left hemisphere advantage for language, but this can be affected by processing deficits.