(no subject)

[anhinga_anhinga]

Reading "An Anthropologist on Mars" by Oliver Sacks.

It has 7 stories, I've just read the first one, about an artist who had a sudden onset of cerebral achromatopsia. It's a nice reading and a very interesting source of introspective information.

It is not clear, whether what Sacks writes about the role of V4 is entirely correct (or what is the status of his remark that Semir Zeki figured out how to induce this state temporarily in human using transcranial magnetic stumulation in light of uncertainties with V4). When one reads something which is so well written, one tends to forget that all this (and almost everything else in neuroscience) should be taken with a grain of salt.

Still, an entirely worthwhile reading...

I wonder whether I would risk to undertake such a trip if it were possible, just to see what this experience is like "with my own eyes" (temporary loss of colors in one's vision [or a half-field of vision] via transcranial magnetic stimulation)...


Русская версия другой его книжки: Человек, который принял жену за шляпу.

Comments

[spamsink]

Temporary loss of colors in one's vision happens naturally every night. Somewhat funny, but not ha-ha funny.

[anhinga-anhinga.livejournal.com]

No, this is a temporary complete loss (my night vision is actually full of colors), and it feels very different in full daylight, judging by the story. What's especially interesting, is an apprarently "funny shade of gray", they describe. It's sort of disgusting, people say, like these gray fruits on the front cover, but I am curious.

[spamsink]

I thought that I could be misunderstood but hoped you'd get it right. I was talking about dusk vision when there is not enough light for the cones.

[anhinga-anhinga.livejournal.com]

Frankly, I am not aware of any moment during the day when my color vision is lost.

I do experience certain visual impairment during onset of the evening twilight, because the visual adaptation to low brightness is not fast enough. However, the rods-based vision suffers even more in these conditions, I think, because the contrast is impaired, and, I think, motion detection (which is mostly rods-based) is impaired.

Of course, this is merely my introspection... But the bottom line is that I hate driving in the evening twilight, but I love walking during that time, because the colors are most beautiful then (for me).

In any case, I doubt that the effect is in receptors, I think the post-receptor contrast-correction mechanisms (both retinal and central) are too slow to adapt. I wonder, however, if there are published studies on this...

[spamsink]

Now I live in a more rustic setting (a detached house with a front lawn and a backyard) than I used to, and when I go out at night to turn on the watering system, I cannot tell the colors of the flowers, because I do not remeber which are which. When the cones are off and you have no way to correlate other visible traits with the expected colors, the perceived vision is truly monochromatic. It is eerie sometimes, no doubt.

[anhinga-anhinga.livejournal.com]

Also... The purpose would be to accumulate some first-hand instrospective material. Fun-wise this does not seem to be intesting enough to experience...

[spamsink]

Кстати о Саксе, в главе, где он описывает нарушение проприоцепции

У Кристины нет слов для описания этой утраты, этой сенсорной тьмы (или
тишины), сходной с переживанием слепоты и глухоты. Нет слов и у нас, у всех
окружающих, у общества -- и в результате нет ни сочувствия, ни сострадания.
Слепых мы, по крайней мере, жалеем: нам легко вообразить, каково им, и мы
относимся к ним соответственно. Но когда Кристина с мучительным трудом
забирается в автобус, ее встречают равнодушие или агрессия.
"Куда лезете, дама! -- кричат ей. -- Ослепли, что ли? Или спьяну?" Что
она может сказать в ответ -- что лишилась проприоцепции?..

он тривиально ошибается. У нас есть для этого бытовые слова, и большинство из нас наверняка испытывало минутную местную потерю проприоцепции, когда мы отлёживаем во сне руку или ногу и только что проснулись. Моторика на месте, тактильные ощущения - едва-едва, а ощущение конечности как своей - опаньки.
Несколько раз я ловил себя на том, что в таких случаях хочется взять "вещь" в руку и рассмотреть её.