Each Dehaene moment listed below from chapter 3 of Reading in the brain: the new science of how we read, is in an intentional order. Stanislas Dehaene, well-known French neuroscientist, lays out his theory of how our brain learns to read. This blog about chapter 3 is a follow-up to the previous blog because there was more than one Dehaene moment and all felt important.
Extra Dehaene Moment #1: Back to the Letterbox
The brain’s letterbox, located in the left hemisphere, is in charge of written word recognition and is located in the same area of all people around the world – regardless of the language (alphabetic vs logographic) and regardless of the directionality of how we read (left to right or right to left).
The letterbox “exquisitely [adapts] its hierarchical architecture to the specific requirements of each writing system.” (Dehaene, 2010, p. 100) How do we know this? Using fMRI results, research shows how certain neurons respond to certain categories of objects: faces, objects, numbers, letters, animals, tools, etc… Recognizing the written word comes from the 10 million year old area of the brain “whose specialty … has been the visual identification of objects.” (Dehaene, 2010, p. 125)
Dehaene speculates that there is a “neuronal hierarchy that supports visual word recognition”. (Dehaene, 2010, p. 151) And with the next extra Dehaene moment, we build toward his hypothetical neuronal pyramid.
Extra Dehaene Moment #2: Proto-letters
Many of the neurons in our visual system respond to preferred shapes: circles, asterisks, curved lines, straight lines, and all of their varied intersection points. Dehaene calls these intersection points proto-letters. Preferences to these shapes have been shown to be deeply embedded in the brains of macaque monkeys. (Photos: Dehaene, 2010, p. 137-138)
The junctions of certain shapes and objects are repeated in nature. The shapes, regardless of their size, distance, lighting, or viewing angle, always have the same junctions present. When the object has a curve or hole, the shapes J and 8 are formed.
The parts of many geometrical and mathematical shapes, as well as the curves of heads or bowls, “lay dormant in our brains for millions of years, and [they] were merely rediscovered when our species invented writing and the alphabet.” (Dehaene, 2010, p. 139)
Extra Dehaene Moment #3: Non-accidental properties
Non-accidental properties were a huge Dehaene moment for me. He defines non-accidental properties as a visual scene that is “unlikely to occur accidentally”. (Dehaene, 2010, p. 138) Another explanation for non-accidental properties is shapes, objects, and geometrical shapes that are invariant. Invariant, according to the Oxford Languages’s dictionary, is “never changing” and “a function, quantity, or property which remains unchanged when a specified transformation is applied”.
To further explain his point, Dehaene gave the example of throwing many matches on the floor. What are the chances that the pile of matches consistently form the letter F or T or Y? Highly unlikely. However, the brain sees the shapes and lines of many objects in the world. Each time the brain sees a coffee cup, the same invariant properties and junctions are present regardless of the angle, direction, lighting, or distance of the coffee cup from the eye.
Our brain has evolved to know that if an object contains a hole that its “projection on the retina will probably include a closed O-shaped curve.” (Dehaene, 2010, p. 138)
Extra Dehaene Moment #4: More on non-accidental properties
OMG-this Dehaene moment on non-accidental properties is amazing! Our brain does not store all objects seen in nature and in the world. Instead, the brain “extracts a sketch of their non-accidental properties as well as their organization and spatial relations.” (Dehaene, 2010, p. 138) We pull that shape out as a series of invariant, never changing 3D cones, sticks, circles, and junctions to create the complete object.
Our brain’s ability to recognize an object is based on how many of the object’s non-accidental properties and junctions are present. Remove too many of the non-accidental properties and junctions and we are unable to identify the shape. Leave the non-accidental properties and junctions intact but remove all other parts and we are able to identify the object.
In the far left column, too many non-accidental properties and junctions were removed and the object is not identifiable on its own. However, the center column retains non-accidental properties and junctions and the object, therefore, is identifiable. (Photo: Dehaene, 2010, p. 140)
Cover up the columns with your hands and ask someone to individually identify the objects on the far left. Can they?
Extra Dehaene Moment #5 – Plasticity
As I mentioned in my previous blog summary about chapter 3, the brain’s plasticity allows us to repurpose these shape and contour invariants (these circles, sticks, and angles) to learn how to read letters in writing. “Neurons learn to respond to new visual combinations….[and] some neurons learn to fire exclusively for combinations that appear frequently.” (Dehaene, 2010, p. 142)
Kaboom. Another big Dehaene moment that put several different puzzle pieces together. We must train our brain to recognize these invariant shapes (circle + stick = the letter d). As we train our brain to recognize the circle + stick = the letter d, then those neurons begin to connect and work in tandem. “Neurons that fire together, wire together.”
The plasticity in our brain’s letterbox allows us to recycle those neurons and have them fire in a way that can then match the letter d to the sound /d/. Kaboom – another Dehaene moment fits the piece into the puzzle.
Extra Dehaene Moment #6 – Cortical Connectivity
What is cortical connectivity? It is when the brain’s neurons fire together in a synapse so fast that the pathway is smooth and efficient – like a super highway. It becomes automatic. We don’t even think about it. We can’t “unthink” it. Listen to someone say “elephant” without picturing an elephant in your head. You can’t unthink those two stimuli (hearing the word and picturing the elephant).
“…how each neuron responds [visually] depends on the particular visual events to which we are exposed…[and] a repeated succession of two images are quickly extracted and stored in our cortical connections.” (Dehaene, 2010, p. 144) Bam, Batman, that is another big Dehaene moment.
What two images is he talking about? Two images that are invariant and have non-accidental properties. Two images that never change in nature. Two images that our evolutionary brains are already tuned into: sticks, circles, curves, junctions, etc… Kaboom – a Dehaene moment
Circle + stick = the letter d
Extra Dehaene Moment #7 – A pyramid of neurons
Dehaene hypothesizes about a neuronal hierarchy pyramid that allows one to read with efficiency and accuracy (after learning how–reading is not natural to the brain). At the bottom of the pyramid, neurons detect lines. The neurons determine if it is a letter T or X or F, for example. The next level up on the pyramid has contour detectors which determine the directions of curves as well as circles.
The next two levels up look at letters and shapes to sift through all of the possibilities and narrow it down to the exact letter. One level up from this – and the pyramid is becoming more narrow, yes? – are bigrams. Bigrams are the strings of letters that go together such as the example of “E to the left of N” with some tolerance of variables. Examples of this tolerance of variables are hen, fern, mean, and rent. All of those are E to the left of N and our brain is okay with these variables.
However, put too many unrelated letters in there and our brains slow down: hein, feorn, meun, and reant. Our brain is confused.
Dehaene and his colleagues reason that this pyramid exists. They have never seen bigrams and current technology does not allow this yet.
Extra Dehaene Moment #8 – Bigrams
Dehaene moment #7 proposes and defines a bigram as “an ordered pair of letters such as “E left of N.” (Dehaene, 2010, p. 1554). A bigram pays attention to and tolerates other letters being inserted between the “E left of N”. The code of reading can handle deleting a few letters and is not sensitive to flip flopping two consecutive letters: badge / bagde.
Case in point: the company French Connection UK (FCUK). Our brain instinctively flip flops them back and we are shocked when we see someone wearing that company’s sweatshirt!
The bigram also does not change with font, size, distance, or lighting. The code of reading can tolerate some letter deletions and flipflopping of two consecutive letters. Consider the sentence: I can “raed snetneeces in which the psoitoin of ltteers is mxeid up.” (Dehaene, 2010, p. 156)
The brain can adapt to some variance of placement of letters, strings of letters, and spacing but not all. If any of those variables move beyond the tolerance point of the brain’s letterbox, even a skilled adult reader will return to sounding out simple words in a sentence.
Extra Dehaene Moments – Final Thoughts
I truly believe that each Dehaene moment is showing us how a systematic and explicit approach to reading is the critical key for our learners. The plasticity of the brain’s letterbox is capable of learning to read. Let’s do some self-reflecting and then begin a conversation with someone around the science.
Are your reading conversations grounded in a vast body of science? Do your conversations include the 5 pillars of reading: phonemic awareness, phonics, fluency, vocabulary, and comprehension? Do your conversations move colleagues and administrators away from outdated pedagogy that is not beneficial to all students?
This marks the end of chapter 3 of 8 chapters in Dehaene’s book. Check out my YouTube Channel: L’Essentiel French Resources and watch the video versions of blogs or consider starting back at the beginning of my blogs and his book:
- #1 Introduction: 3 Important Wow Moments
- #2 Chapter 1 (Part 1): Amazing Ideas
- #3 Chapter 1 (Part 2): 4 Big Considerations
- #4 Chapter 2 (Part 1): the Brain’s Amazing Letterbox
- #5 Chapter 2 (Part 2): 10 More Memorable Moments
- #6 Chapter 3 (Part 1): Neuronal Recycling
My name is Lisa with L’Essentiel French Resources – join me again soon! This book is FUN!
Resources:
Dehaene, S. (2021). How we learn: Why brains learn better than any machine…for now. Penguin Books..- Dehaene, S. (2010). Reading in the brain: The new science of how we read. Penguin Books. (I receive a commission if you purchase either Dehaene book from Amazon.)
