The Clock Counts - Length Effects in English Dyslexic Readers

Area of Science:

• Cognitive Psychology
• Neuroscience
• Developmental Psychology

Background:

• Length effects (LEs) in reading, an increase in reading time with word length, can differentiate whole-word from serial letter processing.
• LEs are often considered a hallmark of developmental dyslexia (DD), primarily studied in transparent orthographies.
• Research is needed to understand LEs in opaque orthographies like English.

Purpose of the Study:

• To investigate the presence and significance of length effects (LEs) in adults with developmental dyslexia (DD) reading English, an opaque orthography.
• To compare LEs in individuals with DD to those in typical readers.
• To determine if LEs are a critical characteristic of DD in the context of English reading.

Main Methods:

• A sample of 18 adults with developmental dyslexia (DD) participated.
• A matched sample of typical readers served as the control group.
• Participants' reading speed was measured for words and non-words to assess length effects.

Main Results:

• Adults with developmental dyslexia (DD) exhibited significant length effects (LEs) in reading.
• These LEs were particularly pronounced in low-frequency words and non-words.
• The findings confirmed the prediction of marked LEs in the DD group compared to typical readers.

Conclusions:

• Length effects (LEs) are a relevant characteristic of developmental dyslexia (DD) even in an opaque orthography like English.
• The pronounced LEs in low-frequency words and non-words suggest difficulties in whole-word recognition and reliance on serial processing in DD.
• These findings have significant theoretical implications for understanding the nature of developmental dyslexia.