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Macquarie Centre for Cognitive Science

Does rapid auditory perception underlie the phonological awareness difficulties found in children with dyslexia?

Katrina Sheraton

Katrina SheratonPrevious research has found that groups of individuals with dyslexia (impaired reading) perform worse than controls on tasks requiring rapid visual and auditory perception. The magnocellular deficit is one theory that has been proposed to explain such findings in the auditory and visual domain. This suggests that people with dyslexia may have a general deficit in "magnocellular" cells that are responsible for perception of transient and rapid stimuli in a variety of senses. However, there have been inconsistent results and large variations in scores found within groups with dyslexia on similar tasks. Children's wavering and inconsistent attention has been one variable found to confound previous studies in perception. In particular, it has been proposed that students that have difficulty with sustained and/or shifting attention have shown inferior performance on tasks of auditory perception and in reading.
To explore whether a "magnocellular deficit" may underlie poor phonemic awareness and word reading, I tested a group of 43 Grade 3 children for their rapid auditory perception as well as their frequency discrimination, reading, phonemic awareness, attention, memory and non-verbal IQ. After controlling for attention, memory and non-verbal IQ, phonemic awareness and reading were not related to rapid auditory perception but were related to frequency discrimination. Interesting, phonemic awareness was not associated with reading.

Overall, these findings suggest reading ability is related to frequency discrimination rather than rapid auditory perception. This fails to support the theory that a magnocellular deficit is a causal risk factor for dyslexia.

See Dr. Genevieve McArthur for further information