It’s tough to see things in their right perspective.

New Yorker (June 19, 2006) にOliver Sacksが書いていたある女性の立体視に関わるエピソード, “Stereo Sue: Why two eyes are better than one.” を読んでいる。約9ページ。もともとは、2学期の高3ライティングに用いるdescriptive passageのモデルを探していて、monocular visionとbinocular visionではどのように世界が見えているかという記述が使えるのではないか、とあたりをつけて買ったのだが、そんなことは脇に置いておいて読んでいて面白かった。
If there are even small islands of function in the visual cortex, there may be a fair chance of reactivating and expanding them in later life, even after a lapse of decades, if vision can be made optically possible.ということでCross-eye(斜視)の矯正のため手術を受けた人が立体視を失い、その後vision therapyにより立体視を獲得していく、というプロセスも興味深いが、Sueの見る世界の描写記述がとてもlyrical。ちょっと紹介。

  • When I was eating lunch, I looked down at my fork over the bowl of rice and the fork was poised in the air in front of the bowl. There was space between the fork and the bowl. I had never seen that before.... I kept looking at a grape poised at the edge of my fork. I could see it in depth. (p.70)
  • The snow was falling lazily around me in large, wet flakes. I could see the space between each flake, and all the flakes together produced a beautiful three-dimensional dance. In the past, the snow would have appeared to fall in a flat sheet in one plane slightly in front of me. I would have felt like I was looking in on the snowfall. But now, I felt myself within the snowfall, among the snowflakes. Lunch forgotten, I watched the snow fall for several minutes, and, as I watched, I was overcome with a deep sense of joy. A snowfall can be quite beautiful --- especially when you see it for the first time.” (p.73)