title: A few remarks on relating reaction time to magnocellular activity.
abstract: Studies have found dyslexic readers to have longer reaction times than nondyslexic readers. These results have been discussed relative to the hypothesis that dyslexia is caused by a magnocellular deficit. We here point out that attempts to link reaction times in dyslexic readers to magnocellular sensitivity face at least two serious problems: (a) The reaction time differences between dyslexics and controls appear too large to be attributable to deficits in the magnocellular system; (b) there is evidence to suggest that in the case of stimuli with contrast above about 10% behavioral reaction times may reflect parvocellular rather than magnocellular activity.
authors.affiliation: Skottun Research, Ramah, NM, USA.
authors.forename: Bernt C
authors.initials: BC
authors.lastname: Skottun
authors.forename: John R
authors.initials: JR
authors.lastname: Skoyles
mesh_terms: D015350:Contrast Sensitivity / Q000502:physiology; D004410:Dyslexia / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D005074:Evoked Potentials, Visual / Q000502:physiology; D005829:Geniculate Bodies / Q000166:cytology / Q000502:physiology / Q000503:physiopathology; D006801:Humans; D009474:Neurons / Q000502:physiology; D010468:Perceptual Disorders / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology*; D011932:Reading; D012160:Retina / Q000166:cytology / Q000502:physiology / Q000503:physiopathology; D014795:Visual Pathways / Q000166:cytology / Q000502:physiology* / Q000503:physiopathology; D014796:Visual Perception / Q000502:physiology*