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Encoding of rapid time-varying information is impaired in poor readers

Johnston, Richard; Pitchford, Nicola J.; Roach, Neil W.; Ledgeway, Timothy

Authors

Richard Johnston

Nicola J. Pitchford

Neil W. Roach

Timothy Ledgeway



Abstract

A characteristic set of eye movements and fixations are made during reading, so the position of words on the retinae is constantly being updated. Effective decoding of print requires this temporal stream of visual information to be segmented or parsed into its constituent units (e.g., letters or words). Poor readers' difficulties with word recognition could arise at the point of segmenting time-varying visual information, but the mechanisms underlying this process are little understood. Here, we used random-dot displays to explore the effects of reading ability on temporal segmentation. Thirty-eight adult readers viewed test stimuli that were temporally segmented by constraining either local motions or analogous form cues to oscillate back and fourth at each of a range of rates. Participants had to discriminate these segmented patterns from comparison stimuli containing the same motion and form cues but these were temporally intermingled. Results showed that the motion and form tasks could not be performed reliably when segment duration was shorter than a temporal resolution (acuity) limit. The acuity limits for both tasks were significantly and negatively correlated with reading scores. Importantly, the minimum segment duration needed to detect the temporally segmented stimuli was longer in relatively poor readers than relatively good readers. This demonstrates that adult poor readers have difficulty segmenting temporally changing visual input particularly at short segment durations. These results are consistent with evidence suggesting that precise encoding of rapid time-varying information is impaired in developmental dyslexia.

Journal Article Type Article
Publication Date May 1, 2017
Journal Journal of Vision
Electronic ISSN 1534-7362
Publisher Association for Research in Vision and Ophthalmology
Peer Reviewed Peer Reviewed
Volume 17
Issue 5
Article Number 1
APA6 Citation Johnston, R., Pitchford, N. J., Roach, N. W., & Ledgeway, T. (2017). Encoding of rapid time-varying information is impaired in poor readers. Journal of Vision, 17(5), https://doi.org/10.1167/17.5.1
DOI https://doi.org/10.1167/17.5.1
Keywords Poor readers, Segmentation, Motion perception, Form perception, Temporal vision
Publisher URL https://doi.org/10.1167/17.5.1
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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