When Mirror Writing is Normal

Thanks to Dr. Dan Press for a fascinating video he shot of his son (and our grandson) Ethan showing the concept of mirror invariance advanced by Stanislas Dehaene.  You may vaguely recall the name Dehaene, about whom we blogged in December 2010.

Dr. Dan found a wonderful article by Dehaene written for Cerebrum titled Inside the Letter Box: How Literacy Transforms the Human Brain.  Here’s what Dehaene wrote about mirror invariance, as related to reading acquisition, as demonstrated in the video below:

Early on during reading acquisition, most children generalize across mirror images to such an extent that they are able to read and write their first words independent of orientation. Just ask any 5- or 6-year-old child to write his or her name next to a dot located near the right side of the page. Most of them will unhesitatingly solve the problem by writing from right to left. This mirror competence slowly disappears during reading acquisition, but it remains present in illiterate people who, contrary to literates, exhibit no cost at all in recognizing a learned object in mirrored form. Indeed, illiterate people find it extraordinarily hard not to see “b” and “d” as identical shapes. The breaking of this spontaneous mirror invariance is one of the important outcomes of literacy. 

So here we go, with Dan doing the Dehaene experiment on Ethan, who just turned 5 years old (that’s little sister Eva being vocal in the background):

As you can see, when Daddy prompts him to write his name next to the dot on the right, Ethan performs a perfect mirror sequence of the capital letters.  When he then directs him to write his name next to the dot on the left, the mirror effect is gone.  Ethan is just at the beginning phase of learning to read, and we anticipate that as he does (as predicted by Dehaene’s research) the mirror effect will progressively diminish.  This is a huge concept for developmental optometrists to be aware of in terms of the persistence of mirror writing – even in the form of reversals – as related to reading acquisition.

If you’d like to read further about the topic, here is a nice article from Frontiers in Psychology that is part of a research series on the impact of learning to read on visual processing.

Reading Pathways



2 thoughts on “When Mirror Writing is Normal

  1. Nice sharing Dan! I wonder if it also has more to do with dual tasking. 18 mo. old will try to go into the door of a car even though it is only a toy. Thus they are looking at “what you do with a car door” and also lack awareness of size of door as related to one’s self. In this example, Ethan appears to write letters normally from L to R starting at both points. But you’ve asked him to start at a different point…thus he is thinking about letter construction of writing, and not paying attention or generalizing to the direction of the letters as per normal L to R direction. Thus not monitoring both at same time. I think we see a lot of behaviors in these youngsters that appear abnormal simply as they haven’t automatized multiple aspects.

  2. When I was a 2nd grade teacher, back in the 70’s when children were still learning how to write their letters in 1st and 2nd grade (think of that difference in the last 40 years!), I saw this all of the time. I never worried about it, even then, because I understood that the child couldn’t plan ahead how much space his/her name would take and started writing the letters on the left side. What stroke is first for an “E”? A straight line. It shows how they do not ‘see’ the letters as a whole yet, let alone the name. They have them learned as a bunch of separate strokes.

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