Reading in the Brain and Mirror Writing
Stanislaus Dehaene has a new book entitled Reading in the Brain: The Science and Evolution of a Human Invention and he has been kind enough to publish chapter summaries and all color figures here.
From Chapter 7, a discussion of how mirror reading is thought to be a loss of generalization ability (recognizing that b is related to d, for instance) that occurs as children grow older. At left, Orton's original thought that mirrored letter mistakes resulted from a failure to inhibit the perception in the opposite hemisphere; at right, the current theory that mirror 'mistakes' occur from the retention of a generalization ability rather than a real mistake. The generalization ability is a good thing for young children because it helps them recognize their parents and their world from different angles.
In our own family, I remember being surprised when our then young son brooded over how to write the letter "f"... he said, "f, f, f,... oh that's right, it's a flipped over 'j' with a line through it." Huh? I hadn't even thought about the relationship between the letter 'f' and 'j' before that. To this day both he and Brock are able to read words backwards more quickly than me. There are advantages to this mirror ability (as well as disadvantages of course) - usually in the ability to rotate objects and perceive from different angles (like Tesla turning an apparatus around in his mind), and not surprisingly, we often see this talent among the spatially-talented dyslexics that we see. Our loss of mirroring ability is therefore more of a 'mistake', likely reflecting the same process that we discussed in The dark side of expertise.
In the figure at right, the bar graph shows how mirroring is common condition in children below the age of 8 years. Above the graph, the writing observations of Cornell that 5 year old children are more like to write their name backwards when not given enough room for left-to-right writing. Lissie and Meggie were sisters. Lissie was 5 and Meggie, 6.
Below, an example of Leonardo Da Vinci's mirror writing.
For more from Dehaene on mirror writing: Why do children make mirror errors while reading? pdf