Why are letters shaped the way that they are?

In a new study forthcoming in the May 2006 issue of The American Naturalist, Mark A. Changizi and his coauthors, Qiang Zhang, Hao Ye, and Shinsuke Shimojo, from the California Institute of Technology explore the hypothesis that human visual signs have been cross-culturally selected to reflect common contours in natural scenes that humans have evolved to be good at seeing.

"[We] analyzed one hundred writing systems, Chinese characters, and non-linguistic visual signs, and found that these very different types of human visual signs possess a similar shape structure," explain the researchers.

Comparing human visual signs to natural scenes, the researchers demonstrate a high correlation between the most common contour combinations found in nature and the most common contours found in letters and symbols across cultures. For example, contours resembling an "L" or "X" are more common in both human visual signs and natural scenes than anything resembling an asterisk (*).

The researchers also examined motor and visual skills and the shapes that are easiest to see and form. They make a strong case that the shape signature for human visual signs is primarily selected for reading, at the expense of writing.

From University of Chicago

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March 30, 2006