To double space or not to double space?

Do you put two spaces after each sentence? Feel free to comment below! I never have– but maybe I should? Read on to find out…


An article recently appeared in the Washington Post with the title “One space between each sentence, they said. Science just proved them wrong.” It was prompted by a recent study, and is promoted (with this click-baitish title) as resolving one of those age-old debates: should there be two spaces, or a single space, in between sentences?

The TL;DR version? The story goes that historically, for legibility purposes, two spaces were always printed in between sentences. Like I’m now doing in this paragraph (although spoiler alert: I don’t normally double space, and don’t think it’s important!). Then along came the computer, creating an explosion of fonts and styles of typography (a topic for another day, but see some of the further reading below!). It was argued that while old fonts, which were all monospaced due to the constraints of the typewriter and printing presses (meaning, each letter had the same width), may have benefited from the double spacing, the new fonts created by computers were not constrained in this way. And it’s certainly true that most of our commonly used fonts nowadays are not monospaced (the most common exception is probably Courier).

People have strong feelings about this issue! Check out a post about it on this other cool blog:
People have strong feelings about this issue! Check out a post about it on this other cool blog:

The new study touted in the Wasingtion Post article (Are two spaces better than one? The effect of spacing following periods and commas during reading) reports that, using eye-tracking methods, it was found that indeed double spacing is better (read more about eye tracking here)! The reporting on this study is a good example of misleading science communication, however– a bit closer look at what the authors actually found, and you’ll see that you shouldn’t start double-spacing if you haven’t been! For those of you who do, the good news is, you may as well keep on doing it.

The best reason to not change your typing habits, based on this study? Probably none of us should ever change our behavior because of the results of one study! This is a basic, but crucial point. If you’ve ever read more than one article on a new finding about what you should or shouldn’t eat or drink, you know this frustration– science works best as compiling results, from different studies, fields, methods, researchers, and labs. So, if all you care about is whether this study has unequivocal evidence to start or stop double-spacing, you can stop reading here: it definitely does not.

So what did they find? This was the first study to directly examine whether single or double spacing is better, and as I mentioned, they used eye-tracking methods, so you can really get a lot of detailed information about how well people were reading. Are you surprised no one studied this before? Well in fact, there are dozens of studies that have looked at spacing, and that used eye-tracking– but they all looked either a t t h e s p a c i n g between letters, or the spacing between words– not just the spacing between sentences.

What did those studies might find, you ask? An amazingly mixed set of results! And what is one of the take-home messages? Two things are really important for determining how spacing will affect you: (1) whether you’re familiar with the spacing (so, you may read worse just because it unusual for you to read that way)!, and (2) which fonts were used in the study.


And sure enough, this new study on double-spacing had results that relate to both of those matters. First, remember that claim that double-spacing was better for monospaced fonts? Well, this study did indeed use a monospaced font (Courier!) and did not test any others. And secondly, and perhaps most crucially, they found a difference between people who normally single-spaced and those who normally double-space. While there was no effect on anyone’s comprehension of the sentences or their overall reading times, people who normally type with double-spacing (which was 21/60 people in their sample), did read more words-per-minute (WPM) when they read sentences with double-spacing, compared to single spacing. For those who normally type with single-spacing, they actually read a little bit fewer WPM in double-spaced paragraphs!

The upshot for the researchers was that they found all participants, whether or not they’re used to double-spacing, basically spent less time looking at the areas of the sentences around the periods, if there were two spaces. But again: this didn’t lead to better comprehension, or even to less time spent reading overall. So while it does seem that, at least for this one study and this one font, everyone may benefit from double-spacing, the benefit is limited to a short-term one: your eyes flow more evenly past the period and onto the next sentence, but this benefit doesn’t add up to anything in the context of the entire paragraph.

So as you can tell, I’m sticking to my single spaces!

Further reading:
The History of Typography – Britannica online

The Evolution of Typography

What makes an ‘A’ an ‘a’?

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!).

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.

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.

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?

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.


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!



“Eye movements in skilled readers”

“What eye movements during reading reveal about processing speed”

“How we read shown through eye tracking”



Why is English spelling so strange?

You may have had this experience before: you look at a word, and think to yourself “That can’t be how it’s spelled… is that right?” … that first R in February just looks wrong, sometimes. You may also have found yourself at some point asking your English teacher why something is spelled the way it is. If you got more than a response of “Because it just is.”– you’re lucky! Few people study orthography (the part of language concerned with letters and spelling), and fewer stills its history. However, we actually can find a lot of information about why words are spelled the way they are, by learning about their etymology—the chronology of a word’s form and meaning from its earliest (recorded) sources to current usage and spelling. It is a bit of a myth that English spelling is so strange because it is entirely random and arbitrary

The English language is a famous borrower—with roughly 200,000 words in the English lexicon (vocabulary), tens of thousands of words have been borrowed from several other languages, in particular Latin and French, which together account for half or more of the sources of modern English words. Other words are derived from Germanic languages, Greek, Spanish, Italian, Arabic, Chinese, you name it—and as a consequence of this global borrowing, there is added diversity in the spellings of words. This is because English orthography is relatively opaque: the relationship between letters and the sounds they represent is far from a perfect 1-to-1 mapping. For example, ‘K’ usually represents the phonological form (sound) /k/, a hard sound like in “kid”—but sometimes it’s read as /n/ like in “knife”, where it is part of the digraph (two letters that represent a single unit) ‘KN’. The letter ‘C’ is especially challenging—it can also represent the hard /k/, like the second ‘C’ in “circle”, but also the sound /s/, like the first ‘C’ in that same word! Or it can be part of the digraph ‘CH’, which can represent the sound /tS/ like in “choose”. And of course, there are those dreaded silent letters, like the ‘C’ in “indict”!

So, why is English spelling so irregular? It turns out that there is some method to the madness, which is beautifully described by D.W. Cummings in his book “American English Spelling”. The gist of it is, our spelling system as a whole is the result of a balance between competing ideas of what a words spelling should convey. You might think that the letters we use to spell a word should just tell us its sound—this is the phonetic demand. What would happen if we took this demand to the extreme, however? Should we spell the same word differently depending on the accent of the speaker—should “car” be spelled k-a-r for some of us but k-a-h for Bostonians? Should we spell homophones, words that have the same sound but different meanings, the same way—“two to many to count” becomes “too too many too count”? And how about the ‘S’ at the end of “cats” versus “dogs”—the first is pronounced as an /s/ but the second as a /z/ (say it aloud to yourself if you don’t believe me!)—should we write “It’s raining kats and dogz!”? A purely phonetic system, then, becomes problematic, because some sounds have multiple meanings, and because some words have multiple acceptable pronounciations.


Much of the oddness in our word spellings, then, comes from a desire to use the orthography to disambiguate meaning, or to give clues to the origin of the word (and, ideally, its definition). We want to spell “dogs” with an ‘S’ so that we consistently write our plural marker with that letter. For another example, although the ‘G’ in “sign” is not pronounced, it allows us to see its relationship with other words like “signature” (and not confuse it with “sine”!).

Admittedly, the system could be improved. Some of the oddities are no longer practically useful. Unless you speak Latin, the silent ‘C’ in “indict” or the ‘B’ in “debt” are not very helpful (they’re re-introduced nods to the original Latin “indictare” and “debitum”). In fact, several letters of the alphabet could probably be done away with entirely, if we were only willing to let go holdovers from their sources (for example, ‘X’ could be replaced with “ks” or “gz”). Ultimately, changes in spelling, like changes in language in general, occur continuously and naturally through social processes—what’s “here” today may be “gon tomarow”.


Links: “A Site for spellers, teachers of spelling and reading, and students of English words” Online etymological dictionary

Further reading: Chapter 1 in Cummings, D.W. (1988). American English Spelling. JHU Press: Baltimore.

Welcome to “The Writing Brain”

“Writing — the art of communicating thoughts to the mind, through the eye — is the great invention of the world. Great in the astonishing range of analysis and combination which necessarily underlies the most crude and general conception of it — great, very great in enabling us to converse with the dead, the absent, and the unborn, at all distances of time and of space; and great, not only in its direct benefits, but greatest help, to all other inventions. ” — Abraham Lincoln


It is difficult to imagine a world without written language. Although modern technologies do allow for communication across “all distances of time and of space” without written language (for example, cell phones), it surely would have been impossible for humans to develop such capabilities without written language. And despite, or perhaps because of, the ubiquitous nature of digital technology, written language is everywhere around us. And yet, anyone who can read this website probably takes their ability to do so for granted– once we learn how to read, it seems to come almost as natural as breathing.

But many of us may have found learning to read and write difficult as children; we certainly all know someone who had or continues to face such difficulties, and as teachers or parents are reminded of how this skill requires extensive practice. When someone says “I know how to read”, what is it she actually knows? How are we able to transform ink markings on a page (or black pixels on a screen!) into meaningful language? How can we best teach this skill? How is written language being changed by modern technologies? How do written languages differ around the world?

Welcome to “The Writing Brain”! These are the types of topics that will be covered on this website, through a mix of original blog posts and summaries of new research conducted across the range of fields that constitute Cognitive Science (including psychology, neuroscience, linguistics, and philosophy), with a focus on communicating the research to educators, in particular, and interested audiences in general.