September 2005
Volume 5, Issue 8
Free
Vision Sciences Society Annual Meeting Abstract  |   September 2005
Use of spatial frequencies information in normal readers and a letter-by-letter dyslexic patient
Author Affiliations
  • Fiset Daniel
    Centre de Recherche en Neuropsychologie et Cognition, Departement de psychologie, Universite de Montreal, and Centre de recherche, Institut Universitaire de Geriatrie de Montreal.
  • Chauvin Alan
    Centre de Recherche en Neuropsychologie et Cognition, Departement de psychologie, Universite de Montreal, and Centre de recherche, Institut Universitaire de Geriatrie de Montreal.
  • Dupuis-Roy Nicolas
    Centre de Recherche en Neuropsychologie et Cognition, Departement de psychologie, Universite de Montreal
  • Blais Caroline
    Centre de Recherche en Neuropsychologie et Cognition, Departement de psychologie, Universite de Montreal, and Centre de recherche, Institut Universitaire de Geriatrie de Montreal.
  • Arguin Martin
    Centre de Recherche en Neuropsychologie et Cognition, Departement de psychologie, Universite de Montreal, and Centre de recherche, Institut Universitaire de Geriatrie de Montreal.
  • Gosselin Frederic
    Centre de Recherche en Neuropsychologie et Cognition, Departement de psychologie, Universite de Montreal
Journal of Vision September 2005, Vol.5, 811. doi:10.1167/5.8.811
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      Fiset Daniel, Chauvin Alan, Dupuis-Roy Nicolas, Blais Caroline, Arguin Martin, Gosselin Frederic; Use of spatial frequencies information in normal readers and a letter-by-letter dyslexic patient. Journal of Vision 2005;5(8):811. doi: 10.1167/5.8.811.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

We employed the Bubbles technique (Gosselin & Schyns, 2001) to examine the use of spatial frequencies in normal (N = 10) and letter-by-letter (N = 1) reading. Each stimulus sampled either an individual letter, or one of 2,000 four-to-seven-letter words (one letter spanned 0.38 deg of visual angle × 0.6 deg of visual angle) by dot multiplying their Fourier spectrum with white Gaussian noise convolved with a Gaussian function (Std = 0.156 of the Nyquist frequency). Accuracy was 97% on average for normal readers and of 71 % for LH, a so-called letter-by-letter dyslexic. Multiple linear regression was performed on reading latency and sampling noise. We found that normal letter identification is mediated by a single frequency band centered at 3 cycles per letter (see also Solomon & Pelli, 1994), and normal word reading, by another, partly overlapping, frequency band peaking at 1.6 cycles per letter. We found a different pattern of results for LH: in letter recognition, he uses a frequency band centered at 1.9 cycles per letter and, in word recognition, a somewhat narrower frequency band centered at 1.6 cycles per letter. Our results suggest that letter-by-letter reading is caused by a deficit in using the spatial frequencies normally associated with letter recognition and that this deficit is exacerbated in word recognition. We will argue that spatial frequencies around 3 cycles per letter are necessary for the explicit word identification, and that lower spatial frequencies are responsible for the implicit effects found in normal and pathological reading.

Daniel, F. Alan, C. Nicolas, D.-R. Caroline, B. Martin, A. Frederic, G. (2005). Use of spatial frequencies information in normal readers and a letter-by-letter dyslexic patient [Abstract]. Journal of Vision, 5(8):811, 811a, http://journalofvision.org/5/8/811/, doi:10.1167/5.8.811. [CrossRef]
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