This is all very interesting (and not so crazy a question). Incautiously (i.e. off the top of my head), wouldn't a visual field loss with macular sparing fit into this? Such a perimetry chart would show intact foveal representation despite a complete hemifield loss. The rationale has always been that the fovea is represented multiple times cortically, and so cortical damage to V1 wouldn't necessarily result in a loss of foveal representation. I'm not sure how this fits into the question, but it's my 2 cents (and if you want change back let me know).
Carol (I just realized how frequently I use parentheses.) On Thu, Apr 14, 2011 at 9:26 PM, <[email protected]> wrote: > Just a little while ago, I posted this to TIPS: > > > The fovea has special representation with both > > hemispheres, so as soon as she focused directly on a target, both > > hemispheres would be informed. She'd have to somehow suppress the urge > > to look directly at something and view the world only with peripheral > > vision, which doesn't seem likely. > > This was all incautiously off the top of my head. I haven't had to > think about the visual system for quite some time now. So note the > absence of references. > > So I started thinking about it, which meant a google search. I may > be now out of date, because there appears to be something called a > "split fovea theory" which claims the fovea is split into halves, > each of which projects to the opposite hemisphere. It seems what I > said in my quoted paragraph was the "traditional account" of > "bilateral projection theory". The new theory appears to have at > least some support, but I have no idea whether it has yet made it > into textbooks. > > Here's a recent study which lays out the basics: > > Ellis, A., and Brysbaert, M. (2010). Split fovea theory and the role > of the two cerebral hemispheres in reading: A review of the evidence. > Neuropsychologia, 48, 353-365. > > The abstract (all I've seen) says: > > Split fovea theory proposes that when the eyes are fixated within a > written word, visual information about the letters falling to the > left of fixation is projected initially to the right cerebral > hemisphere while visual information about the letters falling to the > right of fixation is projected to the left cerebral hemisphere. The > two parts of the word must be re-united before the word can be > recognised. Bilateral projection theory proposes instead that visual > information is projected simultaneously to both hemispheres provided > that it falls within the fovea (defined as the central 2-3°). On this > more traditional account, no interhemispheric transfer would be > required in order to read a word presented within the fovea. We > review the evidence in support of split fovea theory and consider > some of the objections that have been raised. We argue that a split > fovea affects the reading of words at fixation, something that must > be recognised and accounted for by cognitive, computational and > neural models of reading. > > > Stephen > -------------------------------------------- > Stephen L. Black, Ph.D. > Professor of Psychology, Emeritus > Bishop's University > Sherbrooke, Quebec, Canada > e-mail: sblack at ubishops.ca > --------------------------------------------- > > --- > You are currently subscribed to tips as: [email protected]. > To unsubscribe click here: > http://fsulist.frostburg.edu/u?id=177920.a45340211ac7929163a0216244443341&n=T&l=tips&o=10027 > or send a blank email to > leave-10027-177920.a45340211ac7929163a0216244443...@fsulist.frostburg.edu > -- Carol DeVolder, Ph.D. Professor and Chair, Department of Psychology St. Ambrose University 518 West Locust Street Davenport, Iowa 52803 563-333-6482 This e-mail might be confidential, so please don't share it. --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=10028 or send a blank email to leave-10028-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
