"Same, same but different": The optimal viewing position effect in developmental dyslexia, developmental coordination...

Area of Science:

• Cognitive psychology
• Developmental neuroscience
• Clinical ophthalmology

Background:

• The optimal viewing position (OVP) effect describes faster word identification when eye fixation is near the word's center.
• This effect is well-established in alphabetic languages for typical readers.

Purpose of the Study:

• To investigate the OVP effect in children with developmental dyslexia (DD), developmental coordination disorder (DCD), and comorbid DD+DCD.
• To determine if OVP anomalies are specific to DD and to assess the impact of comorbidity.

Main Methods:

• Utilized a variable-viewing-position technique to assess OVP in different child groups.
• Compared OVP curves and attentional scanning patterns across typically developing readers, DD, DCD, and DD+DCD groups.

Main Results:

• Typically developing readers exhibited automatized left-to-right scanning with an inverted J-shaped OVP curve.
• Children with DD showed non-prototypical OVP curves.
• Children with DCD (isolated or comorbid) displayed more typical scanning patterns compared to those with DD.
• No significant differences in OVP anomalies were found between comorbid and isolated DD or DCD groups.

Conclusions:

• Atypical OVP effects appear specific to children with developmental dyslexia.
• The OVP effect may serve as a clinical tool for identifying neurodevelopmental disorders like DD and DCD.