Revisiting Strephosymbolie: The Connection between Interhemispheric Transfer and Developmental Dyslexia

Area of Science:

• Neuroscience
• Developmental Psychology
• Cognitive Science

Background:

• Atypical hemispheric specialization is increasingly linked to developmental dyslexia (DD).
• Orton's theory suggests underlying neurological differences in dyslexia.
• Interhemispheric transfer (IHT) processes are a potential area of investigation in DD.

Purpose of the Study:

• To investigate the role of interhemispheric transfer (IHT) processes in developmental dyslexia (DD).
• To examine differences in IHT between children with DD and typically developing controls.

Main Methods:

• Tested 13 children with DD and 13 controls (ages 8-13) on four tasks.
• Included tactile transfer, Poffenberger paradigm, and visual object discrimination tasks.
• Assessed performance accuracy, response times, and mirror-drawing/writing behaviors.

Main Results:

• Dyslexic children exhibited less accurate tactile transfer and slower response times.
• Controls showed distinct crossed vs. uncrossed condition differences, unlike dyslexic children.
• Dyslexic children displayed increased response asymmetry and higher rates of mirror-writing.

Conclusions:

• Children with DD demonstrate impairments in interhemispheric transfer.
• Performance variations suggest diverse underlying psychophysiological mechanisms in DD.
• Connectivity problems are proposed as a common origin for these IHT impairments.