15th International Congress of Phonetic Sciences (ICPhS-15)

Barcelona, Spain
August 3-9, 2003

Factors Affecting Frequency Discrimination by Poor Readers

Peter Bailey (1), Yvonne Griffiths (2), Nick Hill (2), Maggie Snowling (1)

(1) University of York, UK
(2) University of Essex, UK

Experiments on frequency discrimination by groups of poor readers have produced mixed results: some show impairments relative to normal-reading control groups, whilst others show no reliable group differences. It remains unclear to what extent these differences in outcome are attributable to individual differences in the severity of a sensory processing deficit associated with dyslexia, or to use of different psychophysical procedures that make different demands of higher-level cognitive processes such as memory and attention, which may be compromised in dyslexia. To explore these issues, pure-tone frequency difference limens (DLFs) were measured for groups of dyslexic adults and normal-reading controls in conditions incorporating a range of procedural manipulations. Dyslexic and control participants' DLFs did not differ reliably when the procedure involved 4-interval trials, but dyslexics' DLFs were larger than controls using 2-interval trials. The relative difference between dyslexic and control participants' DLFs found using 2-interval trials did not differ systematically across conditions involving a fixed or roving standard frequency, long or short duration stimuli, long or short interstimulus intervals, or interstimulus intervals that were either silent or included interpolated tones. The results suggest no obvious link between elevated DLFs and impaired short-term pitch memory in these dyslexic participants.

Full Paper

Bibliographic reference.  Bailey, Peter / Griffiths, Yvonne / Hill, Nick / Snowling, Maggie (2003): "Factors affecting frequency discrimination by poor readers", In ICPhS-15, 1449-1452.