Eyes on the Brain

A neurobiologist explores the amazing capacity of the brain to rewire itself at any age

Does Reading Give You A Headache?

Why printed text causes eyestrain.

Last year, I had a student who always turned in assignments late - if at all. When I asked her what was wrong, she said, “When I read, the words on the page seem to scream and pulse at me.” This statement is not as strange as it may first seem because many people experience significant visual discomfort when reading. Some of this discomfort may result from the overall pattern that the print makes on the page. Dark lines of print are separated by white spaces between the lines creating a pattern of black and white stripes, much like the pattern below.  BUT don't look at this picture if you're prone to migraine headaches or visually induced seizures.

 

Wilkins A. Visual Stress. Oxford Univ. Press, 1995.

If you enlarge this figure so the circle is about 4 inches in diameter and look at it from a normal reading distance, you might find it unpleasant to view. Parts of the figure may appear to shimmer or flicker, the lines may appear to curve or blur, and you may see colors or shapes among the lines. These are illusions of color, shape, and motion. 

 People who experience eyestrain and headaches while reading see more illusions in the above figure than people who are comfortable readers.  See here.  Some are helped by placing over the page a card with a slot that allows only a few lines of print to be seen at a time. As they read, they move the card with its slot down the page. Newspapers (the old fashioned, paper kind) reduce visual discomfort by breaking up the text into many paragraphs that are displayed in narrow columns.

In the figure above, the number of illusions seen depends upon the spacing of the stripes. Similarly, reading discomfort varies with the amount of white space between lines of print. Increasing the distance between the lines of print generally increases clarity and comfort. So, electronic readers may be very helpful to those who find reading unpleasant if the spacing between the lines can be adjusted.

 The figure of the black and white stripes above reminds me of many op-art paintings. In a post next week, I’ll discuss why these paintings may create illusions of color, motion, and shape and what they may then tell us about reading discomfort.

 

Susan R. Barry, Ph.D., is a professor of neurobiology in the Department of Biological Sciences at Mount Holyoke College and the author of Fixing My Gaze (June, 2009).

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