Sequential spatial frequency discrimination is consistently impaired among adult dyslexics

Gal Ben-Yehudah, Merav Ahissar*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

The degree and nature of dyslexics' difficulties in performing basic visual tasks have been debated for more than thirty years. We recently found that dyslexics' difficulties in detecting temporally modulated gratings are specific to conditions that require accurate comparisons between sequentially presented stimuli [Brain 124 (2001) 1381]. We now examine dyslexics' spatial frequency discrimination (rather than detection), under simultaneous (spatial forced choice) and sequential (temporal forced choice) presentations. Sequential presentation (at SOAs of 0.5, 0.75 and 2.25 s) yielded better discrimination thresholds among the majority of controls (around 0.5 c/° reference), but not among dyslexics. Consequently, there was a (large and significant) group effect only for the sequential conditions. Within the same dyslexic group, performance on a sequential auditory task, two-tone frequency discrimination, was impaired in a smaller proportion of the participants. Taken together, our findings indicate that visual paradigms requiring sequential comparisons are difficult for the majority of dyslexic individuals, perhaps because deficits either in visual perception or in visual memory could both lead to difficulties on these paradigms.

Original languageAmerican English
Pages (from-to)1047-1063
Number of pages17
JournalVision Research
Volume44
Issue number10
DOIs
StatePublished - May 2004

Bibliographical note

Funding Information:
We wish to thank the following researchers for permission to use the tests they designed in the current study: Drs. Deutsch and Bentin for the single non-words, Dr. Ben-Dror and Peleg for the Spoonerism test, Shalem and Lachman for the spelling test. This study was supported by a “Center of Excellence” grant from the Israeli Science Foundation and by the United States–Israel Bi-National Science Foundation (BSF).

Keywords

  • Attention
  • Auditory frequency
  • Dyslexia
  • Memory
  • Spatial frequency discrimination

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