mariano sardón

As we read, our eyes move through the text making very hectic and quick movements (named saccades) and short movements for a little while on words called fixations.
These fixations are not distributed randomly, but its position and duration varies according to many parameters of the text, such as word length or frequency.
There is a strong evidence the eye movements reflect the mind activity and processing.
Sometimes we go back to review certain words before moving forward with the reading, this movement is called the repetition effect.
During fixation, the word being read is maintained on the fovea, where maximum sharpness is achieved just about 4 or 5 characters, and less clarity about 4 letters to the left and about 14 to the right. This is known as perceptual range.

So when we read, we don't look at every word in the text, but some of them are skipped.
Something that is evident in experiments did with readers in front of eye tracker devices, is that it is possible to guess the words that are in the parafovea since their length and the predictability of the word given by a strong textual context.

According to this, there are words that the eyes look partially and even in some cases are gone off.
For each text or book, there is one seen text and another unseen text at the same time. There is a read text and another guessed text.

Thus, we read the George Bataille's book The Story of the Eye in front of an eye tracker device. We cut the sheets where the eyes fixed and separate the parts of the text read from those parts of the text unread.
We finally obtain two different books, the read one and the unread one.