Perception of Linguistic and Non-Linguistic Visual Stimuli among Dyslexic and Non-Dyslexic Readers

Research on language perception involves a study of the visual attributes that distinguish written language from other types of visual input. Such studies further our understanding of the mechanisms responsible for language perception, and how these mechanisms differ from those used in other visual domains. Here, we re-examined the hypothesis that difficulties experienced by dyslexic readers are linked to a deficit in processing visual patterns. We compared the performance of dyslexic versus skilled readers on a pattern-completion task consisting of both linguistic and non-linguistic visual inputs. Our results show that while dyslexic subjects need more visual information than skilled readers to successfully recognize patterns of letters and words (linguistic input), the two groups perform equally well on patterns depicting familiar objects (non-linguistic input). Our findings support the idea that dyslexia involves a visual pattern-processing deficit, and suggest that this deficit is not domain-general, but rather targets visual language-processing exclusively.