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Symposium; vision

Thursday stream 1 Session 14.00 - 15.40 Length 25 minutes

Natural variation in both position coding and visual attention affect visual word recognition

Piers Cornelissen, Ruth Lavis, Charity Cooper and Kristen Pammer

University of Newcastle, Newcastle upon Tyne, UK p.l.cornelissen@ncl.ac.uk

Abstract

Letter position coding is known to be important in text processing, and may be impaired in those with reading difficulty. We have studied the natural variability in, and possible relation between, relative position coding (for non-word stimuli) and visual word recognition. An unselected sample of 50 adults performed a series of tasks including measurement of attentional dwell time, visual word recognition (assessed using a lexical decision task), coherent motion detection, colour detection and relative position coding. We measured the latter with a paradigm based on the lexical decision task but which required the subject to process the relative order of a string of novel symbols. Results: Controlling for age, IQ and reading ability, accurate visual word recognition was best predicted by independent contributions from both the attentional dwell time and position coding tasks. Previous findings were also replicated with regard to coherent motion detection and lexical decision (Cornelissen et al. 1998, Vision Research, 38, 2181-2191). Subjects' performance in colour detection was uncorrelated with their performance in the attention, motion and position tasks. Conclusion: Since many developmental dyslexics exhibit poor performance on dynamic visual tasks, these findings may have implications for whether reading difficulties can be caused by visual system impairment.