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Arni Kristjonsson, Hilda Danielsdottir, Margret Gudmundsdottir, Kristjan Hjartarson, Elin Thorarinsdottir, Heida Sigurdardottir; Dyslexics show deficiencies in visual statistical learning: Evidence for a high-level visual processing deficit in dyslexia. Journal of Vision 2016;16(12):540. doi: https://doi.org/10.1167/16.12.540.
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© ARVO (1962-2015); The Authors (2016-present)
Dyslexia is generally considered to have linguistic roots and to involve impairments in phonological processing. But recent evidence from our laboratory indicates that people with dyslexia are impaired in their recognition of faces and other visually complex objects. This raises the question of whether the difficulty that people with dyslexia experience with reading might be the most salient manifestation of a more general high-level visual deficit. The visual word-form area (VWFA) in the left fusiform gyrus – which is involved in the processing of words but also faces and other objects – has consistently been shown to be hypoactive in dyslexics. Most importantly for the current goals, its responses appear to be shaped by visual statistical learning (VSL). If such learning is compromised, people should be less sensitive to statistically likely visual fragments – including word fragments – and impaired visual word and object recognition should be expected. No direct tests of whether dyslexia involves impairments in VSL have been performed, however. Forty diagnosed dyslexics and 40 matched typical readers participated in tests of temporal visual statistical learning of base pairs of novel shapes that frequently appeared together. Recognition of both individual shapes and base pairs (a measure of VSL) was tested. Dyslexics were impaired in VSL in comparison to typical readers, suggesting that VSL deficits contribute to dyslexia. Deficiencies in VSL may prevent experience-driven shaping of neuronal tuning in the VWFA, that otherwise occurs automatically. The VSL deficit was neither accounted for by differences in spatial attention paid to the stimuli nor by the ability to remember individual shapes.
Meeting abstract presented at VSS 2016
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