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 I may be now out of date, because there appears to be something called a "split fovea theory" which claims the fovea is split into halves, each of which projects to the opposite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=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=10027 or send a blank email to leave-10027-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
