Mirror invariance dies hard during letter processing by dyslexic college students

Area of Science:

• Cognitive Psychology
• Neuroscience
• Developmental Psychology

Background:

• Reversal errors (e.g., b/d) are common in early reading and persist in developmental dyslexia.
• This difficulty is linked to mirror invariance, a tendency to perceive mirror images as equivalent.
• Dyslexia impacts orthographic processing, affecting how individuals process visual word forms.

Purpose of the Study:

• To investigate if dyslexic adults exhibit persistent difficulties with mirror-image discrimination.
• To examine differences in processing reversible versus nonreversible letters in dyslexic readers.
• To determine if mirror invariance affects orthographic processing in adults with dyslexia.

Main Methods:

• A masked priming lexical decision task was employed.
• Participants included dyslexic and neurotypical adults.
• Primes varied by letter-type (reversible/nonreversible) and condition (identity, control, mirrored, rotated).

Main Results:

• Both groups showed identity priming effects.
• Neurotypical readers exhibited mirror and rotation costs for all letter types.
• Dyslexic adults showed no mirror cost for nonreversible letters, indicating residual mirror invariance sensitivity.

Conclusions:

• Adults with dyslexia demonstrate persistent difficulties with mirror-image discrimination, particularly for nonreversible letters.
• Findings suggest that orthographic processing in dyslexic college students remains sensitive to mirror invariance.
• This residual sensitivity may contribute to reading difficulties in individuals with developmental dyslexia.