En réponse à Andy Canivet <[log in to unmask]>: > > However - the stereoscopic cells in the visual cortex are dependent on > eye > development - we detect distance / perspective using several visual > clues, > as well as special cells specifically adapted for the task. People > with > congenital myopia, astigmatism, etc., or whose eyes develop a little > more > slowly than normal, will have undeveloped stereoscopic cells. It isn't > much > of an impairment, except that without stereoscopic cells a person > probably > wouldn't be a very good fighter pilot or baseball player - and among > other > things, will never be able to see the secret picture in one of those > "Magic > Eye" illustrations, no matter how hard they try. > Well, I do have a sight good enough to become a fighter pilot (though I abandoned that path after 1 week in military school), but I do have difficulties seeing those "secret pictures". In fact, when I see them, they appear inversed to me (what should be in front appears back, and vice-versa). I don't know where it comes from... Christophe. http://rainbow.conlang.free.fr Take your life as a movie: do not let anybody else play the leading role.