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双眼视觉

维基百科，自由的百科全书

这是本页的一个历史版本，由Jiapeng（留言 | 贡献）在2012年4月17日 (二) 04:46 （→优势眼：​ 段落翻译）编辑。这可能和当前版本存在着巨大的差异。

人的两只眼睛。
鹰的眼睛。

双眼视觉，英文Binocular vision，是指生物在双眼视野范围互相重叠下，所产生的视觉。英文binocular的两个词根均来自于拉丁文，bini的意思是双，colulous的意思是眼睛[1]。 其成因为双眼因具有瞳距，而在视网膜产生有差别但又基本相似的图像，这种视觉信号传送至大脑之后，大脑将两幅图像之间的差异进行整合，即可判断出眼睛到物体之间的精准距离关系[2]。 与单眼视觉相比，双眼视觉有四个明显的好处：

  1. 比一只眼睛多一个备份，减少因损坏影响生存的几率。
  2. 视场范围更大。比如说，人们两只眼睛的总视场有近 200 度，中间部分大概有 120 度是双眼视觉区域，两侧各 40 度是单眼视觉区域[3]。
  3. 双眼加和作用使得两只眼睛能够相互弥补对方看不清的部分[4]。
  4. 双眼视觉形成的视差可以辅助产生精细的深度知觉，进而产生立体视觉[5] 。

双眼视觉通常伴随着视觉的融合，尽管两只眼睛中的图像并不相同，但是视觉在融合后可以产生单一的整体感觉[5]。 其他与双眼视觉有关的现象包括utrocular discrimination，优势眼，双眼竞争。如果双眼视觉除了问题，可以寻求视轴矫正师医治。

视场和眼动

鸽子（Pigeon）和猫头鹰（鸮，xiao）（Owl）的视野范围比较。

对于被捕食者来说，他们的眼睛通常长在头的两侧，这样他们就能够拥有尽可能宽的视野，比如兔，水牛和羚羊。这些动物的两只眼睛通常能够独立转动，这样可以增加视野范围。某些鸟类，即使保持眼睛不动，也可以实现360度的视野。而捕食者的眼睛通常位于它们头部前方，这样可以产生双眼视觉和立体视觉。比如人，鹰，狼和蛇。然而还有一些捕食者，尤其是某些大型动物，如蓝鲸和虎鲸，它们的眼睛却位于头的两侧。还有些动物并不是严格意义上的捕食者，如果蝠和某些灵长类，它们的眼睛是面向前方的。这些动物通常需要精细的深度视觉来帮助它们提高抓取水果或者树枝的能力。

双眼前视动物的两只眼睛通常是联动的。当两只眼睛水平运动时，英文叫做 version。当两只眼睛朝相反的方向运动时叫做聚散，如果眼睛都朝鼻侧转动，叫做汇聚，如果都朝颞侧转动，叫做发散。还有些动物，比如人（尤其是外斜视患者），还有椋鸟，它们的眼睛既可以将两只眼睛转到两边形成宽广的视野，也可以将两只眼睛汇聚形成立体视觉。一个很显著的例子是变色龙，它们的每只眼睛可以独立的像炮塔一样上下左右自由转动，然而，当它们在捕食的时候，却可以将两只眼睛汇聚到一个物体上形成立体视觉。


双眼加和

主条目：双眼加和

双眼加和是指双眼一起对某种视觉刺激的反应阈值要低于单只眼睛。主要有两种形式：第一，在试图看清一个模糊信号时，两只眼睛相比一只眼睛由于接收的能量更多，所以具有统计学上的优势。从数学上看，双眼对于单眼的优势差不多相当于根号2，大约1.41倍[來源請求]。第二，视皮层的某些细胞在接受双眼同时输入时，细胞的发放会比分别给予单只眼睛视觉输入时发放的总和还要强。使用双眼比单眼有1.41倍的优势，这种现象还叫做神经加和现象。

双眼相互作用

除了双眼加和现象，两只眼睛之间最少还在三个方面存在相互作用：

  • 瞳孔直径：射入一只眼睛中的光线会影响到双眼的瞳孔直径。这一点很好检测，在身边找一个朋友，当他的一只眼睛（A）睁着的时候，另外一只眼睛（B）的瞳孔比较小，但是当眼睛（A）闭上的时候，眼睛（B）的瞳孔就会放大。
  • 聚焦和辐辏：聚焦是指眼睛的聚焦状态。如果将一只眼睛（A）睁着，闭上另外一只眼睛（B），当用眼睛（A）注视一个近处的物体时，闭上的那只眼睛的聚焦情况和睁开的那只眼睛相同。另外，那只闭上的眼睛（B）还会将其焦点指向眼睛（A）注视的物体。有研究表明，两只眼睛依靠反射弧来实现同步聚焦和辐辏。

Utrocular discrimination

Utrocular discrimination is the ability to tell, when both eyes are open, to which eye a monocular stimulus was shown.[6]

双眼单视

主条目：双眼单视

Once the fields of view overlap, there is a potential for confusion between the left and right eye's image of the same object. This can be dealt with in two ways: one image can be suppressed, so that only the other is seen, or the two images can be fused. If two images of a single object are seen, this is known as double vision or diplopia. Fusion of the images from the two eyes is considered to be separate from stereopsis for at least two reasons. First, some disorders of binocular vision, such as strabismus can spare fusion but abolish stereopsis. Second, the depth of an object either much nearer to or farther from where the eyes are fixating can be accurately judged despite the images of the object appearing double.

Fusion of images occurs only in a small volume of visual space around where the eyes are fixating. Running through the fixation point in the horizontal plane is a curved line for which objects there fall on corresponding retinal points in the two eyes. This line is called the empirical horizontal horopter. There is also an empirical vertical horopter, which is effectively tilted away from the eyes above the fixation point and towards the eyes below the fixation point. The horizontal and vertical horopters mark the centre of the volume of singleness of vision. Within this thin, curved volume, objects nearer and farther than the horopters are seen as single. The volume is known as Panum's fusional area (it's presumably called an area because it was measured by Panum only in the horizontal plane). Outside of Panum's fusional area (volume), double vision occurs.

优势眼

主条目：优势眼

由于每只眼睛都可以向大脑传输一幅图像，因此就有可能将潘农融合区内外的物体排列到一起。有一个检测优势眼的简便方法：将一个水杯放在房间的远处，在一张白纸上掏一个指甲盖大的小孔，将白纸放在眼前约20厘米的位置，透过小孔去看水杯。此时盖上一只眼睛，如果盖上的这只眼睛看不到水杯，就表明这只眼睛是优势眼。通常情况下，人们通常用来瞄准的眼睛就是优势眼。

立体视觉

主条目：立体视觉

Stereopsis is an ability to make fine depth discriminations from parallax provided by the two eye's different positions on the head. There are two sorts: quantitative stereopsis, in which the depth seen is very similar to the actual depth of the object being judged, and qualitative stereopsis, in which the depth is correctly nearer or farther than the fixation point but the amount of depth does not grow with distance of the object from the fixation point. Quantitative stereopsis holds for small distances from the fixation plane (approximately within Panum's fusional area); qualitative stereopsis holds for larger distances from the fixation plane (outside of Panum's fusional area). Eventually an object can be moved so far from the fixation plane that there is no sense of depth of the double image– instead they appear to be on the fixation plane.

Allelotropia

Because the eyes are in different positions on the head, any object away from fixation and off the plane of the horopter has a different visual direction in each eye. Yet when the two monocular images of the object are fused, creating a Cyclopean image, the object has a new visual direction, essentially the average of the two monocular visual directions. This is called allelotropia. The origin of the new visual direction is a point approximately between the two eyes, the so-called cyclopean eye. The position of the cyclopean eye is not usually exactly centered between the eyes, but tends to be closer to the dominant eye.

双眼竞争

主条目：双眼竞争

When very different images are shown to the same retinal regions of the two eyes, perception settles on one for a few moments, then the other, then the first, and so on, for as long as one cares to look. This alternation of perception between the images of the two eyes is called binocular rivalry.

双眼视觉异常

To maintain stereopsis and singleness of vision, the eyes need to be pointed accurately. The position of each eye in its orbit is controlled by six extraocular muscles. Slight differences in the length or insertion position or strength of the same muscles in the two eyes can lead to a tendency for one eye to drift to a different position in its orbit from the other, especially when one is tired. This is known as phoria. One way to reveal it is with the cover-uncover test. To do this test, look at a cooperative person's eyes. Cover one eye of that person with a card. Have the person look at your finger tip. Move the finger around; this is to break the reflex that normally holds a covered eye in the correct vergence position. Hold your finger steady and then uncover the person's eye. Look at the uncovered eye. You may see it flick quickly from being wall-eyed or cross-eyed to its correct position. If the uncovered eye moved from out to in, the person has exophoria. If it moved from in to out, the person has esophoria. If the eye did not move at all, the person has orthophoria. Most people have some amount of exophoria or esophoria; it is quite normal. If the uncovered eye also moved vertically, the person has hyperphoria (if the eye moved from up to down) or hypophoria (if the eye moved from down to up). Such vertical phorias are quite rare. It is also possible for the covered eye to rotate in its orbit. Such cyclophorias cannot be seen with the cover-uncover test; they are rarer than vertical phorias.

During the cover-uncover test, a person with some phoria will notice a brief episode of double vision or diplopia after uncovering the eye. This is a normal consequence of the eye's being briefly misaligned. If the diplopia is enduring, that is considered a disorder.

The cover-uncover test can also be used for more problematic disorders of binocular vision, the tropias. In the cover part of the test, the examiner looks at the first eye as he or she covers the second. If the eye moves from out to in, the person has exotropia. If it moved from in to out, the person has esotropia. People with exotropia or esotropia are wall-eyed or cross-eyed respectively. These are forms of strabismus with amblyopia. When the covered eye is the non-amblyopic eye, the amblyopic eye suddenly becomes the person's only means of seeing. The strabismus is revealed by the movement of that eye to fixate on the examiner's finger. There are also vertical tropias (hypertropia and hypotropia) and cyclotropias.

另外参见

查看维基词典中的词条「双眼视觉」。

参考文献

  1. ^ Harper, D. (2001). Online etymological dictionary. Retrieved April 2, 2008, from http://www.etymonline.com/index.php?term=binocular
  2. ^ 簡志忠，《附錄B》，http://cslin.auto.fcu.edu.tw/bioassist/eyetrack/paper3/3-14.htm，發表日期不明。（中文）
  3. ^ Henson, D.B. (1993). Visual Fields. Oxford: Oxford University Press.
  4. ^ Blake, Randolph; Fox, Robert. The psychophysical inquiry into binocular summation.. Perception & Psychophysics. 1973, 14 (1): 161–85. doi:10.3758/BF03198631.  已忽略未知参数|month=（建议使用|date=） (帮助)
  5. ^ 5.0 5.1 Wheatstone, Charles. Contributions to the physiology of vision.—Part the First. On some remarkable, and hitherto unobserved, phænomena of binocular vision. Philosophical Transactions of the Royal Society of London. 1838, 128 (0): 371–394. doi:10.1098/rstl.1838.0019. 
  6. ^ Blake, Randolph; Cormack, Robert H. On utrocular discrimination. Perception & Psychophysics. 1979, 26 (1): 53–68. doi:10.3758/BF03199861.  已忽略未知参数|month=（建议使用|date=） (帮助)

扩展阅读

  • Scott B. Steinman, Barbara A. Steinman and Ralph Philip Garzia. (2000). Foundations of Binocular Vision: A Clinical perspective. McGraw-Hill Medical. ISBN 0-8385-2670-5.
  • 液晶快门眼镜

外部链接

检索自“https://zh.wikipedia.org/zhwiki/w/index.php?title=双眼视觉&oldid=20791140”