Foveal vision in reading.
Foveal vision in reading.
This picture shows the acuity of foveal vision in reading (during
one eye stop).
The lower line of text simulates the acuity of vision with the relative
acuity percentages
(Hunziker, H.-W., (2006). Im Auge des Lesers.)
To do a test close one eye, fixate the upper line at
the fixation point and try to read the words to the right and left without moving your eyes.
The result should be similar to the incrementally blurred lower line of
text - except that you never have the impression of a blurred text. The
reason: Your visual perception is already the result of a massive computational
analysis made by your brain. Your system "knows" that the upper
line is not blurred, so you don't see it as blurred. But the difficulty of recognition increases with the distance from the fixation point.
While foveal vision works like a magnifier, peripheral vision
is your data compression. It allows your biological computers to determine
where to find the relevant information. From this they calculate in milliseconds
all the necessary muscle commands for bringing your foveal system into
position. This happens 3 to 4 times per second. And automatically the compressed
data of your peripheral system are recalculated to compensate for the eye
movements. Your foveal system uses roughly 50% of the visual nerves for transmitting the information of the 100% acuity spot (approx. 1/10'000th of your total visual field).