Lexical factors in the word-superiority effect

Area of Science:

• Cognitive Psychology
• Neuroscience
• Linguistics

Background:

• Fluent readers identify letters better in words than in non-words or single letters (lexicality and word-letter effects).
• These effects are thought to involve lexical processing, relying on access to visual word form.
• Adult acquired dyslexia impairs visual word form access, potentially disrupting these recognition effects.

Purpose of the Study:

• To investigate whether lexicality and word-letter effects in the Reicher-Wheeler task are disrupted in adult acquired dyslexic subjects.
• To determine if these effects are influenced by a lexical factor and visual word form access.

Main Methods:

• Adult acquired dyslexic subjects and matched controls performed the Reicher-Wheeler task.
• Lexical decision tasks were used to assess word recognition and access to visual word form.
• Correlational analyses examined the relationship between lexical decision performance and Reicher-Wheeler task effects.

Main Results:

• Both dyslexic and control groups exhibited a lexicality effect.
• Control subjects showed a normal word-letter effect, while dyslexic subjects displayed a reversed letter-superiority effect.
• Improved lexical decision performance correlated with better word identification in the Reicher-Wheeler task for all subjects.

Conclusions:

• A lexical factor underlies both the lexicality and word-letter effects.
• The abnormal letter-superiority effect in dyslexia may result from competing cognitive factors.
• Findings suggest visual word form access is crucial for normal letter processing within words.