400-820-0859the fiddler crab's visual field托福tpo69听力原文翻译及问题答案，今天常春藤就来为大家分析这个问题。
一、the fiddler crab's visual field托福听力原文：
Professor: Okay so we've seen some examples of animals whose vision is very different from our own. Now I’d like to play around with this idea and animal’s visual perception,the way it sees the world has a profound effect on the way it behaves. And when we try to understand the behavior when animal whose perception is different from ours,where interpreting their behavior from our perspective. And for that reason,some of our current thinking about animal behavior,theories which have not taken perceptual differences into account,may be biased. So,before we get started,who can remind us of some of these differences,yes jack.
Student: Last week we talked about insects with compound eyes and well,I remember this picture in the book that show you how each eye was actually seeing hundreds of images of an object when we see only one.
Professor: I'm glad you brought up that example,because the animal I want to discuss today also has compound eyes and that’s the fiddler crab. The fiddler crab has been studied quite a bit by researchers interested in this connection between perception and behavior. One reason is that it's quite easy to observe,it lives out in the open on mud flats and has a very limited territory. In fact rarely leaves this mud environment. Now,the fiddler crab has an unusual way of seeing,as you notice from this picture,its eyes located on stalks that point straight up,this gives the crab a panoramic visual field.
Here let me show you what I mean,so the fiddler crab can see three hundred sixty degrees all around in every direction. And the end of each stalk is divided into about ten thousand little eyes. So,it has compound vision similar to what some insects have. Another unusual feature is that this crab’s vision is sharpest on the periphery on the outer edges of its visual field. Actually,this makes a lot more sense when you realize that is on the edge of its visual field on the ground,where the other crabs are likely to be,that they have to make the finest,distinctions,like between rival and mate. But even the sharpest part of the crab’s visual field isn’t all that great,it'd be like oh,imagine looking at a newspaper,and say you saw nothing but a blurry white object,maybe with a few black spots on it,ok.
Now another important thing,animals have to be able to see its predators. For fiddler crabs,the most important predators are typically birds and the very center of the fiddler crab’s field vision is,surprise,the sky. And here's the thing,the crab’s visual field is even blurrier in the center upon the sky than it is on the edges.
Student: But that doesn't make sense,if the center of the crab’s visual field is so blurry,then how can they ever defend themselves,I mean,how do you know they would,mistake,I don't know,something,anything,in the air for bird.
Professor: Well,this goes back to what I said earlier,we need to stop thinking from our own visual perspective and think about it from the animal’s point of view. Because everything it sees is blurry,the fiddler crab’s world view is very simple one,everything in the sky is assumed to be a predator and everything on the ground is assumed to be a crab. This is the most basic distinction that needs to make for its survival. So,what for us would be a disadvantage,blurry vision,actually turns out for the crab to be advantage to its survival. This way of seeing simplifies the way the crab needs to respond to whatever it sees.
Student: But how can we know that for sure.
Professor: Actually,researchers have proven it.Here’s what they did. They placed a cylinder on a mudflat inhabited by fiddler crabs,the crabs treated the object like another crab,fighting it,ignoring it or even sizing it up as a potential mate. But,when the same cylinder was tossed up in the air over the mudflats,all the crabs ran for the safety of their burrows. So you can see how the crab's behavior is affected by its vision and object on the ground,any object as long as it's on the periphery of its visual field is perceived as another crab. And that same object when seeing in the air,at the center of its visual field,is perceived as not a crab and therefore a potential predator.
二、the fiddler crab's visual field托福听力中文翻译：
教授：；好的，我们已经看到了一些动物的例子，它们的视力与我们的非常不同；现在我想谈谈这个想法和动物的视觉感知，它看待世界的方式对它的行为方式有着深远的影响；当我们试图理解感知与我们不同的动物的行为时，从我们的角度解释它们的行为；因此，我们目前对动物行为的一些思考，即没有考虑知觉差异的理论，可能存在偏见；所以，在我们开始之前，谁能提醒我们这些差异，杰克。
学生：；上周我们讨论了有复眼的昆虫，我记得书中的这张图片，它向你展示了当我们只看到一个物体时，每只眼睛实际上是如何看到数百个物体的图像的。
教授：；我很高兴你提到了这个例子，因为我今天要讨论的动物也有复眼，那就是招潮蟹；对感知和行为之间的这种联系感兴趣的研究人员对招潮蟹进行了大量的研究；一个原因是它很容易被观察到，它生活在泥滩上的开阔地带，而且领土非常有限；事实上，很少离开这种泥泞的环境；现在，招潮蟹有一种不同寻常的视觉方式，正如你从这张照片中注意到的，它的眼睛位于笔直向上的茎上，这给了蟹一个全景视野。
让我来告诉你我的意思，这样招潮蟹可以看到360度左右的各个方向；每根茎的末端被分成大约一万个小眼睛；因此，它有着与某些昆虫相似的复合视觉；另一个不寻常的特征是，这种螃蟹的视野在其视野外缘的边缘最清晰；事实上，当你意识到在地面上的视野边缘，其他螃蟹可能在那里，它们必须做出最好的区分，比如在竞争对手和配偶之间，这就更有意义了；但是，即使是螃蟹视野中最锐利的部分也不是那么好，它会像哦，想象一下看报纸，你只看到一个模糊的白色物体，可能上面有一些黑点，好吧。
现在另一件重要的事情是，动物必须能够看到它的掠食者；对于招潮蟹来说，最重要的食肉动物通常是鸟类，令人惊讶的是，招潮蟹视野的中心是天空；问题是，螃蟹的视野在天空中央比边缘更模糊。
学生：；但这没有意义，如果螃蟹的视野中心如此模糊，那么它们怎么能自卫，我的意思是，你怎么知道它们会错，我不知道，空中有什么东西，任何东西，对鸟来说。
教授：；好吧，这可以追溯到我之前所说的，我们需要停止从我们自己的视觉角度来思考，而是从动物的角度来思考；因为它所看到的一切都是模糊的，招潮蟹的世界观非常简单，天空中的一切都被认为是捕食者，地面上的一切都被认为是螃蟹；这是其生存所需的最基本区别；所以，对我们来说不利的是，视力模糊，事实证明，螃蟹对它的生存是有利的；这种视觉方式简化了螃蟹对所看到的一切做出反应的方式。
学生：；但我们怎么能确定这一点呢。
教授：；事实上，研究人员已经证明了这一点。下面是他们所做的；他们在有招潮蟹的泥滩上放置了一个圆柱体，招潮蟹把这个物体当作另一只螃蟹一样对待，与它搏斗，忽视它，甚至把它当作潜在的配偶；但是，当同一个圆筒被抛到泥滩上空时，所有的螃蟹都跑向它们的洞穴；因此，你可以看到螃蟹的行为是如何受到其视觉和地面上物体的影响的，任何物体只要在其视野的外围，都会被视为另一只螃蟹；同样的物体，在其视野的中心，当在空中看到时，被认为不是螃蟹，因此是潜在的捕食者。
三、the fiddler crab's visual field托福听力问题：
Q1:What is the purpose of the lecture?
A.To analyze the relationship between an animal’s visual perception and its body structure
B.To make students aware of potential bias in interpretations of animal behavior
C.To argue that human vision is inferior to the vision of certain animals
D.To evaluate methods researchers use to determine the characteristics of an animal’s vision
Q2:What feature does the professor describe as being common to both an insect and a fiddler crab?
A.They both have compound vision.
B.They both have a panoramic field of vision.
C.They both have eyes on stalks.
D.They both defend their territory in a similar manner.
Q3:According to the professor,what detail about the fiddler crab makes it easy to observe?
A.It remains close to its home.
B.It moves very slowly.
C.Its shell is easy to identify.
D.Its eyestalks can be seen from far away.
Q4:According to the professor,what is the most important distinction that a fiddler crab must make?
A.The distinction between mudflats and other surfaces
B.The distinction between predators and prey
C.The distinction between crabs and predators
D.The distinction between male crabs and female crabs
Q5:How would a fiddler crab react to a ball thrown in the sky above it?
A.As if the ball were a rival crab
B.As if the ball were a potential mate
C.As if the ball were a predator
D.As if the ball were potential prey
Q6:What does the professor imply when she says this:
A.Students should take notes on the point she is making.
B.Students should not be surprised by the fact she is citing.
C.She realizes that her statement contradicts what students have learned.
D.She is aware that her statement does not seem logical.
四、the fiddler crab's visual field托福听力答案：
A1:正确答案：B
A2:正确答案：A
A3:正确答案：A
A4:正确答案：C
A5:正确答案：C
A6:正确答案：D
