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).

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