Are rods and cones of dyslexics anomalous?
Grosser and Spafford (in this journal, 1989) have advanced an hypothesis and presented measurements which they believe support the idea of an excess of cones in the peripheral retinae of dyslexics. This note points out that their hypothesis is based on the erroneous assumption that normals have no peripheral cones. Further, their data can be explained by at least two alternative, though uninteresting, methodological hypotheses, that uncontrolled eye movements or experimenter suggestion (or both) could have produced their results. Finally, the requisite methods for assessing color vision, and the cones, were not met in the study.
Cohn
T E
TE
School of Optometry, University of California-Berkeley 94720.
D002648:Child; D003118:Color Perception / Q000502:physiology; D004410:Dyslexia / Q000503:physiopathology*; D006801:Humans; D010786:Photoreceptor Cells / Q000002:abnormalities* / Q000503:physiopathology; D011601:Psychophysics; D014794:Visual Fields