Eye Movement and Several Faults in Reading
Suppose you do this experiment with a friend.Get hold of a book with a large page size and lines that run right across the page.Get your friend to hold the book up and to read it with the top of the book just below his eye level.This means that you can watch the movement of his eyes as he reads the page.If you do this，you will see that your friend’s eyes do not make a continuous forward sweep.Instead，they progress by little ’jumps’moving，then stopping，as they progress along the line.This kind of jumping movement is called a saccadic movement（跳跃）.
There has to he this starting and stopping movement because the eye can see only when it is still motionless.Every time the eye pauses it sees a phrase or even a sentence then jumps to the next part of the line and so on.
There is another interesting fact about eye movement.If you record the eye movements of someone who is reading，you will notice that，from time to time，the reader goes back and looks again at something he has read before；in other words，he regresses（回视）an earlier part of the text，probably because he realizes he does not understand the passage properly.Then he comes back to where he left off and continues reading.At one time，it was though that regression was a fault，but it is in fact a very necessary activity in efficient reading.
There are several different kinds of faults in reading，which are usually more exaggerated with foreign language learners.The most common one is that most people read everything at the same slow speed，and do not seem to realize that they can read faster or slower as required.Other people say the words to themselves，or move their lips-these habits slow the reader down to something near speaking speed，which is of course much slower than reading speed.Another habit that can slow you down is following the line with your finger，or with a pen.

What phenomenon can you see in the experiment mentioned at the beginning of the passage?（）