Visual crowding in normal and dyslexicchildren: Who benefits from extra letter spacingand why?Jurgen Tijms, Britt Hakvoort, Madelon van denBoer, Tineke Leenaars, & Petra BosRudolf Berlin Center, University of Amsterdamj.tijms@uva.nlReading is inherently a cross-modal process inwhich visual information on letter-strings needsto be integrated with the corresponding auditoryspeech-sound information. The role of visualprocesses in reading has received surprisinglylittle attention, compared to the role of auditoryphonologicalprocesses. Visual crowding is aphenomenon by which the recognition of anobject can be hindered by flankering objects. Interms of reading, the recognition of letters canbe hindered by surrounding letters, dependingon the interletter spacing.In this study we aimed to provide a windowon the impact of visual crowding on reading indyslexic and typical readers. We presented textsin normal letter spacing and extra-large interletterspacing in several conditions to dyslexicand non-dyslexic children. Our results revealedthat for all children extra letter-spacing hadno effect on reading speed, while it did have apositive effect on text reading accuracy whensentences were presented fully at once, but not when sentences were presented word by word.Dyslexic and normal readers benefitted equallyfrom extra-large letter spacing.The results suggest that visual crowding impactsreading accuracy on the inter-word level, andnot so much at an inter-letter level, and thatsensitivity to visual crowding is not a typicalaetiological factor in dyslexia.
