Authors
RIDDER, WILLIAM H. III,, OD, PhD, FAAO; BORSTING, ERIC, OD, MS, FAAO; BANTON, TOM, OD, PhD

All Developmental Dyslexic Subtypes Display an Elevated Motion Coherence Threshold

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Abstract/Introduction

Purpose

Psychophysical studies indicate that many dyslexics have a motion-processing deficit. The purpose of this study was to determine whether elevated motion coherence thresholds correlate with the specific dyslexic subtypes as defined by the Boder classification scheme.

 

Methods

Twenty-one dyslexics (seven dyseidetics, six dysphonetics, and eight dysphoneidetics) and 19 age- and gender-matched controls participated in the study. The dyslexics were identified by an exclusionary approach and then subtyped with the Adult Dyslexia Test or the Dyslexia Determination Test. Motion coherence thresholds were determined with random dot kinematograms composed of signal dots and noise dots. Signal dots moved either left or right on each trial, whereas noise dots moved in random directions. The percentage of dots that comprised the signal was varied randomly on each trial (0 to 21% in 3% increments). Subjects guessed the direction of signal dot motion on each trial (two-alternative forced-choice task). A 75% correct threshold was determined with a Weibull equation fit to the psychometric function.


Conclusion/Results

Results

All three dyslexic subtypes had elevated motion coherence thresholds (t-test; dyseidetics p = 0.01, dysphonetics p = 0.039, dysphoneidetics p = 0.048).

 

Conclusion

Motion-coherence deficits are not correlated with a specific dyslexic subtype, but, rather, are common to all subtypes. However, some individuals in each of the dyslexic subtypes were found to have normal motion coherence thresholds, suggesting that other factors must be considered to predict the motion sensitivity deficits found in dyslexia.


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Testimonials


My eight year old daughter was terrified to go to the eye doctor for fear of her eyes being dilated. The doctor was SO KID friendly! He immediately made her comfortable by engaging her in conversation. It was a geat experience.


Joya B.

Dr. Garbus spent an amazing amount of time to solve my very complicated visual problems. Over the years he has continually achieved results beyond what others felt possible. He is always up to date on the latest science. He is great!


Dolores K.

Family Vision Care Valencia makes it so easy. Staff is knows what they are doing and Dr. Garbus is thorough and kept me well informed during the exam.


Kristy B.

I have been coming to Family Vision Center for almost 20 years. Dr. Garbus has been able to help my vision when other doctors could not. Now my kids see him as well. I highly recommend this office!


Autumn C.

The Doctor is very good. I felt on this visit he seemed rushed. I had questions to ask him but he was already with another patient. I still do not know if my eyes are the same , worse, or better.


Howard B.

All the staff is friendly, helpful and knowledgeable, and has been for all the years I have been going there.


Mary Ann H.
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