Why do letters look the way they do?

Posted on by rwwiley
What do the shapes on the left all have in common? What about those on the right? (Pictured, from top: Roman, Greek, Hebrew, Arabic, and Devanagri scripts.)

When you look at this image, do you know what all of the shapes on the left have in common? How about the shapes on the right?

If you know how to read more than one of those languages, then you may think the answer is that they represent the same sound, or have the same name. While that’s not a bad answer, what would you think if I told you that what all of the shapes on the left have in common is that they all came from a drawing of an ox? And on the right, a drawing of a house?

The shapes above on the left originally were a representation of an ox, and those on the right a house! Can you see the resemblance?

This is true because of how many of the world’s writing systems evolved—through a process where the earliest written symbols were pictographic or ideographic. That basically means that the most ancient forms of writing represented an idea by drawing an image to represent it… the shape of an ox’s head to represent “ox”, or the outline of a house to represent “house”.

Although the details are lost to history, researchers do know that over time these shapes became abstracted away from their origins as obviously visual representations. Instead of a symbol representing a whole word or an idea, they started to represent the smallest units of human language: “phonemes”, the basic pieces of our words. It is this evolution that allowed a drawing of an ox, which was called “alep” or “alef” in ancient Semitic languages, to represent just the first sound of that word—and why the language you are reading right now calls this letter “A”!

A drawing of an ox’s head (“alep”) becomes more abstract, and stands in for just the first sound–“a”. If you turn this familiar letter, “A”, upside down, you can still see the ox’s head.

Of course, this evolution of what written symbols represent does not explain why our shapes look the way they do—while it’s pretty easy to see how an “A” looks like an ox, it’s not so obvious for other letters. And indeed, some letters (or entire writing systems, like Korean Hangul) never began as depictions of real objects. While it’s hard to say with certainty why the shapes of our letters are what they are, some fascinating research suggests a couple of probable factors that drove our distant ancestors to create the shapes that they did. 

In Mesopotamia, the cuneiform writing system was produced using a stylus on clay tables (top), whereas in Egypt hieroglyphs were carved into stone or inked onto papyrus (middle), and in China free-flowing forms developed with the use of brushes (bottom). Notice that early shapes (top rows) look like pictures of the actual objects, but with time (lower rows) they became more abstract–in both appearance and meaning.

One of those historical factors is the medium in which the language was written. If you’ve ever tried to sign your name on a painting using a brush, or chisel it into a sculpture, you know that the tools you use have a major impact on what you are able to create. Cultures that prominently used clay or stone to write were likely influenced by those media in a way that lead to very different types of shapes than those that used ink and brushes—and the advent of the printing press or, in more recent times, computers, lead also to fundamental changes in typography.

Intersecting lines and curves are all around us. Can you see the T’s, L’s, V’s, Y’s, etc., all over this scene?

Another possible factor that may explain the shapes of our letters comes from nature. Some researchers have argued that the prevalence of certain shapes across different languages, like L-shapes and T-shapes, are a reflection of what shapes we encounter naturally in our environment (Changizi et al., 2006). Think about how a tree trunk meets the ground to form an upside-down T-shape, or how the shoreline of a lake creates a C-shape. It turns out that such intersections which naturally occur more often are also more common in writing systems across the world and history (so for example, shapes like L are very common, but shapes like A are less so).

Watch a short clip of Hubel and Wiesel’s classic experiment.

One last clue as to why our shapes look the way they do comes from what we know about brain activity in response to viewing letter-shapes like this. In visual cortex (the occipital lobe), there are neurons that respond preferentially to certain types of stimulation, which we call “visual features”. Pioneering experiments by Hubel & Wiesel in the 1960’s helped pave the way for understanding this basic phenomenon. There are groups of neurons that become particularly excited when they see lines of certain orientations, for example responding much more to a line at 45° then a line at 0° (horizontal); other neurons may prefer lines that intersect each other like in an X; still others, to closed circles like O as opposed to open ones like C. This property of visual cortex most have evolved not for the purposes of reading, but rather for recognition of objects and scenes—and it is consistent with the possibility that our letters tend to use the same shapes as those we see frequently in our environment!

References/Further reading:

• Changizi, M. A., Zhang, Q., Ye, H., & Shimojo, S. (2006). The structures of letters and symbols throughout human history are selected to match those found in objects in natural scenes. The American Naturalist, 167(5), E117–E139.

• Hubel, D. H., & Wiesel, T. N. (1968). Receptive fields and functional architecture of monkey striate cortex. The Journal of Physiology, 195(1), 215–243.

• Daniels, P. T., & Bright, W. (Eds.). (1996). The world’s writing systems. Oxford University Press on Demand.

Writing or Reading Letters Backwards Is Not a Sign of Dyslexia

Posted on by rwwiley

Perhaps one of the most persistent misunderstandings of dyslexia is that one of its symptoms is perceiving letters as jumbled—especially as mirror-reversed, making letters like b/d and p/q especially challenging. However, the truth is that this is a very common thing for children to do when learning to read and write. With respect to dyslexia, its most common causes are unrelated to this mirror-reversal effect, or indeed to any difficulties with perceiving or producing single letters.

Screen Shot 2019-07-24 at 2.14.14 PM
The Roman alphabet is full of shapes that represent a different letter when reversed or rotated. This is a relatively unique property of our alphabet—most writing systems around the world have few shapes that are easily confused in this way, if any at all. Rates of dyslexia are high in English, especially compared to languages written in other scripts, but this has nothing to do with the shapes of the letters.

 

So, why do so many children write letters backwards? For adults for whom reading and writing is automatic and effortless, it is understandable that this seems like a funny, obvious mistake. But it turns out that the underyling issue is a difficulty with distinguishing between different perspectives of the same object. In a well-known anecdote illustrating this phenomenon (see Dehaene, 2009), it has been pointed out that  “a tiger is equally threatening when seen or left or right profile” (Rollenhagen & Olson, 2000)—meaning, it’s often helpful to immediately recognize something regardless of which direction it is facing! Thus, the theory is that vision has evolved so that, by default, we perceive shapes like b and d or as the same object. This surely is beneficial in most circumstances, with letters being a notable exception (challenge: can you even think of other shapes or objects that have different names depending on whether they are facing left or right?).

 

Maybe one of the most interesting aspects of this is evidence suggesting that learning to read and write a language like English helps us learn to tell apart left and right. For example, illterate adults are slower to detect a visual difference between shapes like p versus q, as are fluent readers of languages that do not have such shapes that are reversals of each other (see Pegado et al., 2014; Kolinsky & Fernandes, 2014; Danziger & Pederson, 1998).

arabicbackwards
In a recently conducted study (Wiley, 2018), even adults (perfectly literate in English) produced mirror-reversed shapes when being taught letters of the Arabic alphabet. In red are the correct orientations for the letters.

 

If you notice a child writing letters backwards, the good news is that this is common—in fact, most children will experience this a stage while becoming literate, and will cease to make such mistakes by around age 11. Of course, this leaves open the question of what are signs of dyslexia, and what might be its underlying cause or causes–you can read more about that here.

What makes an ‘A’ an ‘a’?

Posted on by rwwiley

How are we able to identify what an object is, just by looking at it? If you were to describe to a young child what the letter ‘A’ looks like, you might talk about it having three lines like a triangle, two of them leaning toward each other, etc. But do you think you could come up with a single description that explains why all of the shapes in the figure above are an uppercase ‘A’? Surely not—yet nonetheless, we can seemingly tell without effort that we are looking at a chart of the uppercase letter ‘A’, and not some other letter or shape. How do we do this?

Arguably the most straight-forward way would be for us to simply memorize each instance of the letter ‘A’ that we have seen, and “label” in our memory, so to speak, as examples of that letter. But consider all of the different ‘A’s we have seen—different fonts, different sizes, styles, different people’s handwriting—we would have to memorize thousands upon thousands of shapes for each letter! This burden on our memory would be inefficient to the point of absurdity, and this theory of letter recognition (called “template matching”) has largely become discounted.

Roman letter features
Fig. 2 taken from Fiset, D., Blais, C., Ethier-Majcher, C., Arguin, M., Bub, D. N., & Gosselin, F. (2008). Features for uppercase and lowercase letter identification. Psychol. Sci.

The best research on this question generally agrees with a theory called “feature matching”, which proposes that instead we memorize a (much smaller) set of features that describe the letter’s shape. This means we identify a letter by determining what its visual features are: lines, curves, intersections, etc., and comparing those features to lists in our memory. For example, when you read this letter ‘A’, visual processes in your brain determine that it is composed of two diagonal lines that meet in an L-intersection, a horizontal line that intersects them in two T-intersections, etc. The idea that our brains respond to such basic features is iwell-supported by scientific research (and arguably goes back to the cat experiments of Hubel & Weisel— check that out below!).

[youtube https://www.youtube.com/watch?v=IOHayh06LJ4?rel=0&w=560&h=315]

The upshot of feature matching is that a lot of the variability we see in fonts, size, etc., don’t matter—think of all of the ‘A’s in that figure that have in common those two diagonal lines and a horizontal line. Of course, some shapes that we consider to be the letter ‘A’ look quite different, and so it must be the case that we memorize a separate set of features to identify those ones—most obviously, the lowercase ‘a’ has very different features than the uppercase ‘A’ (two different shapes that share the same letter identity are called “allographs”; look out for Part 2 of this blog entry for more on that topic!).

The downside of feature matching is that it is not obvious what the features we actually use are—and so researchers remained challenged with determining this. One thing we do know is that expert readers, like you as you read this blog, pay attention to different features than do people who don’t have expertise (e.g., children, or second-language learners; see references). The most likely reason for this might be that experts have a better sense of what is or isn’t important—and when it comes to reading, what is most important is distinguishing between different letters. This means we become better are ignoring irrelevant features that don’t change the letter’s identity (think about some of the ‘A’s in the figure that have a lot of extra flourishes—you know that they’re not important, but someone just learning to read might not!).

Suggested reading: Hofstadter, D. (1995). On seeing A’s and As. Stanford Humanities Review, 4(2), 109–121. https://web.stanford.edu/group/SHR/4-2/text/hofstadter.html

References:
Wiley, R. W., Wilson, C., & Rapp, B. (2016). The Effects of Alphabet and Expertise on Letter Perception. Journal of Experimental Psychology: Human Perception and Performance, 42(8), 1186–1203. https://doi.org/10.1037/xhp0000213

Palmer, S. E. (1999). Vision science: Photons to phenomenology (Vol. 1). Cambridge, MA: MIT Press.

Gibson, E. J. (1969). Principles of perceptual learning and development. East Norwalk, CT: Appleton-Century-Crofts.

Fiset, D., Blais, C., Ethier-Majcher, C., Arguin, M., Bub, D. N., & Gosselin, F. (2008). Features for uppercase and lowercase letter identification. Psychol. Sci.

Courrieu, P., Farioli, F., & Grainger, J. (2004). Inverse discrimination time as a perceptual distance for alphabetic characters. Visual Cognition, 11(7), 901–919.

Is it true that we don’t look at every word when we’re reading? What are our eyes doing when we read?

Posted on by rwwiley

“Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.”

 

You’ve probably encountered that paragraph before (or, if you’re like me, a bunch of times—it seems to go viral every other year!). How true is this claim that “the human mind does not read every letter by itself, but the word as a whole”? The first part has some truth to it—we do not focus on each letter in a word as we read—but the second part is very misleading! It is a pernicious myth that we learn to read by memorizing words as a whole shape. And it’s easy enough to come up with examples where jumbling letters in this way is a real problem—calm becomes clam, blow becomes bowl, etc. So, what do we actually need to look at, when we’re reading?

 

As you’re reading this sentence, you might feel that your eyes are moving smoothly across it. In fact, when we read text, whether its on a printed page or a computer screen, our eyes more in a series of short jumps, called saccades. These saccades are very fast, around 20-35 milliseconds, and in between them our eyes fixate on the text. These fixations can be brief (150 milliseconds), or relatively long, say one half of one second.

 

So, what is it that we look at during these periods of fixation? It is true that we do not focus on every single word when we’re reading—this is more or less for two reasons. First, we’re able to perceive several letters within the fovea (the center of our gaze): in languages like English, which are written from left to right, we can see a few letters to the left of our fixation and maybe 12-15 to the right (in languages written from right to left, like Arabic and Hebrew, readers can perceive more letters toward the left of fixation that the right!). This means that during each fixation, we take in a few words at a time, unless there are very long words. When we saccade to our next fixation, we are able to skip over some words because we actually have already seen them. This means, of course, that one of the challenges of reading is remembering the words and letters you have recently seen (in working memory) and integrating them with new information, as you continue to saccade through the sentence.

 
visible_light_eye-tracking_algorithm

The second reason we do not need to fixate on every word is because we are often able to predict what words are going to follow—and we can use this ability to predict to speed our reading. This is often true of function words (words like “to”, “the”, and “do”), but also in sentences where the context leads to a very high probability for a certain word. Imagine that in one fixation you read “They sang Happy…”—you can guess that almost definitely the next word is “Birthday” (in fact, when we read sentences where we expect one word and it ends up being another, this surprise has consequences—it will cause us to slow down dramatically in our reading speed and often to double back and re-read!).

 

How do we know these things about reading? Mostly through the use of a machine called an eye tracker, which allows us to know (with very high temporal precision) where someone is looking. There are many videos online where you can see demonstrations of an eye tracker at work. This one in particular “How we read shown through eye tracking”) shows how we move our eyes from one line of text to the next—and how this is affected by the way that the lines are (or are not) justified!

 

Links:

“Eye movements in skilled readers”

“What eye movements during reading reveal about processing speed”

“How we read shown through eye tracking”