Posts Tagged ‘book’

Daniel Lende from PLoS Blogs’ Neuroanthropology recently interviewed me about the relationship between culture, brain and nature, and the origins of language. See the interview here.

In my view, anthropology — and evolution and culture — are crucial to understanding neuroscience and our origins. …and so their “Neuroanthropology” blog (also by Greg Downey) will be one I follow closely.

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Recently I was interviewed by Pouria Nazemi, Science Editor of the Jam-e-Jam Daily Newspaper. Jam-e-Jam is the principal Iranian newspaper and is controlled by the government. In the wake of Iran shutting down its leading business newspaper last week and three pro-reform newspapers in October I thought this would be interesting to readers, since it appeared between these two events.

If your Farsi is up to par, here is the link (and pdf version here).   The interview was done via email in English so I have corrected some minor grammar but otherwise it is as we corresponded.  This originally appeared in English at ScientificBlogging.com .

By the way, before the piece appeared I didn’t realize that Jam-e-Jam was a major newspaper in Iran, much less the state-run newspaper. To my ears, and given that I do not know Farsi, the name sounds “light”, reminiscent of BoingBoing. Do not take this piece as an endorsement of the dictatorship!

Pouria Nazemi : Cognitive science is a new science that we hear more about every day.   Can you briefly describe what it is?

Mark Changizi : Cognitive Science likes to define itself at the intersection of many disciplines, including psychology, neuroscience, linguistics, philosophy and computer science. But, in reality, you’d be hard pressed to pin us down. …other than to say that we’re all interested in understanding the principles underlying thinking, seeing, and other complex brain powers.

Pouria Nazemi : The brain is an amazing thing. We understand the world around us using it but how much do we know about brain itself?

Mark Changizi : Not much – in fact, I wrote a recent blog story titled “We don’t know jack” (Does that translate well?!). There are many avenues for being pessimistic about what we know – or don’t know – about the brain, but one that I often focus on is our powers, or functions. If some alien stumbled upon a calculator or a stapler, would you say that the alien understood these artifacts if the alien did not know that calculators are for math and staplers are for binding paper together? The aliens can take apart, catalog, and watch the workings of calculators and staplers for eternity, and if they haven’t figured out their function, we will be confident they haven’t come to understand them.

We’re in a similar situation as these aliens for our brains. We’ve had significant successes in taking apart the brain and watching its mechanistic workings, but the problem is that much of what our brain can do – most of the functions it is capable of carrying out – are simply not known by us. We’ll be in a good position to make sense of all our mushy meat only when we have a good idea about the functions the meat was selected to implement. And in order to do that, we have to study the human animal in a more ecological setting – that is, we must understand not just the brain, but the complexity of the environment for which it evolved, and how the brain (and body) fit the environment (often) like a glove. For example, my own research often focuses on showing that we have powers no one has noticed. You can be sure that if I’m finding new powers, then there must be tens of thousands more!

Pouria Nazemi: According to Scientific American : “Although many neuroscientists are trying to figure out how the brain works, Mark Changizi is bent on determining why it works that way”; so do you think we can learn why the brain works by having a better understanding of its structure?

Mark Changizi : Another way of saying the same thing is that I want to reverse-engineer the brain. That’s what evolutionary types like me aim to do: figure out the principles governing our “design”.

Pouria Nazemi : When I read about you I find that you have many interesting experiments and theory from writing systems to optical illusions and similarity of brain and highway systems. So what is the main goal of your research in these categories?

Mark Changizi : The research on writing systems asks why our brains, which do not have areas specialized for reading, can read so well. Could it be that the symbols and letters used in writing systems have culturally evolved over time to have the shapes our visual brains are innately good at processing? And, what is our visual brain good at processing? The shapes from nature, in particular from objects strewn about in a three-dimensional world. Could letters have come to look like nature, explaining why we’re such capable readers? In fact, that’s what I found: the contour conglomerations found in natural scenes tend to be the same ones found in human writing.

The brain and highway systems research comes from earlier work of mine trying to explain why brains change in the way they do from mouse to whale. My research shows that much of the anatomical changes that occur as brains increase in size (and there are a lot) can be explained by brains “trying” to maintain a fixed level of total-brain interconnectivity. It struck me more recently that cities have some similarities to the cortex: cities lie on the surface of the Earth and the cortex is a flattenable sheet; highways serve a similar role to white-matter-projecting neurons in the cortex; and highway exits a similar role to synapses. With my understanding of brain scaling in hand, I wondered the extent to which city highway systems scale similarly to the brain as a function of size. To my surprise, there were deep similarities in the scaling laws.

Another major research direction concerns color vision, where I have shown that our kind of color vision is nearly optimal for detecting oxygenation changes in blood under the skin. That is, I have been able to provide evidence that color vision is for seeing the emotions and other socio-sexual signals on the faces (and rumps) of others.

Is there anything tying my research together? Yes and no.

“Yes,” in that I tend to focus on “design principles,” i.e., on the fundamental engineering principles explaining why it would have evolved in the first place. I also bring a similar style to my research directions, aiming for broad unifying theories, ones that are rigorous, ones that can be tested, and ones where I can actually do test. (Rather than many physics journals, say, which publish biological theories without any data.)

But, “no,” in the sense that I do not try to build an incremental program of research. I have always actively tried to remain aloof from previous research problems, and from research communities, so that I am psychologically open to stumbling onto new ideas. Thus the crazy suite of research directions I am embarrassed to admit to.

Pouria Nazemi : One of the most interesting things is your research about the brain’s ability to see into the future (1/10th second) so would you please explain more about that and if it is an ability we can hope to develop?

Mark Changizi: Well, you can’t actually see into the future. The point is that your brain has to anticipate a tenth of a second into the future – and generate a perception of it – because by the time it is done with its anticipating, a tenth of a second has elapsed, and so the anticipated future is of the present. That is, in order to at all times try to perceive the world as it is at that time – to “perceive the present” – the brain has to anticipate the near future.

My contribution here was to show how this simple idea is sufficiently rich that whole swathes of illusions can be explained as cases where the brain incorrectly anticipates the future.

Pouria Nazemi : many of us enjoy optical illusions.  You are studying illusions as a way to understand how our brain works. I think illusions are the result of some error in our mind.  Would you please explain more about how these tricks tell us about our brain.

Mark Changizi: Let me explain one specific case, the Hering illusion shown below, where the two vertical lines are parallel but appear to bow out. Radial lines like those in the illusion do occur very often in real life, in particular whenever you move forward. At these times, the objects in the world flow outward in your visual field away from a center point. In fact, they even often blur on your retina, because your retina is not an infinitely fast “camera”. So, when you fixate on the illusion, your brain sees all those lines emanating from that center point, and says, “When I usually see this kind of radial blur stimulus, it is because I’m moving forward in the direction of the center point.” (I don’t actually mean your brain is saying this! I only mean it has evolved to have mechanisms that figure out where the observer is headed on the basis of blur cues like this.)

Now the brain has a good guess as to where it is headed. Recall that it takes about a tenth of a second to build a perception from the retinal stimulation. The brain wants to generate a perception of the two vertical lines not as they actually projected onto the retina, but as how they will project a tenth of a second later, after the observer has moved forward toward the center a little bit. Think about how the look of two vertical poles, or the sides of a doorway, change their shape as you move forward. When far away they appear vertical in your visual field. But as you near them, to pass between them, they flow outward in your visual field, but do so most quickly at eye level. To see this, imagine walking through a tall cathedral doorway, where when you are close, the upper parts of the door look like they are approaching one another up in the sky (like railroad tracks). That is, when you move forward through a doorway, the sides of the doorway bow outwards in your visual field, just like you perceive the vertical lines in the illusion. You perceive them that way because that is how they would project in the next moment were you moving in the direction your brain has been tricked into thinking it is going. Of course, it is being tricked in this case, so it counts as an illusion. But in real life it typically encounters such radial-line stimuli only when it actually is moving forward toward the center, as I mentioned above.

Pouria Nazemi : Would you please explain about these categories of illusions?

Mark Changizi: The same explanation I just gave concerning the Hering illusion turns out to radically generalize. Radial lines are just one of seven cues I was able to identify for where the observer may be headed in the next moment. And it is not just the visual geometries that can distort in the next moment if you are moving forward; this is just one of four qualities that can distort in the next moment (the others concern speed, brightness contrast, and distances to objects). That is, I eventually realized that the explanation above extended to a 7 by 4 table of 28 predictions, the Hering-type classical geometrical illusions falling in just one of these 28 slots. And I provided evidence that the pattern of illusions predicted by this unified account was, in fact, the case.

Pouria Nazemi : Your recent well-received Book “The Vision Revolution” (that I didn’t have chance to get but would very much like to do) also is about our vision. Would you please tell us about the main focus of this book?

Mark Changizi: The book is about four “powers” of vision. Color vision is for sensing emotion, not for seeing fruit as it has been argued. Forward-facing eyes evolved for seeing better in cluttered forest environments, not for stereo-3D vision as it is usually argued. Illusions are the brain’s (failed) attempt at seeing the future…in order to perceive the present. And letter shapes have culturally evolved to look like nature, turning ancient illiterate visual areas in the brain into capable reading machines.

Pouria Nazemi : We understand our world by our brains. There is nothing out there that we can understand without our brains. Also, we know that our brain sometimes (like in optical illusions) have misunderstandings. Is it possible that some parts of the world that we think we understand are really the result of such misunderstanding? I mean, how we can talk about reality if each brain is that object that determines what reality is?

Mark Changizi: Our brain was selected to provide perceptions that help us survive and reproduce, whether or not those perceptions actually gave us a more objective view of our real universe. The brain could, instead, give us perceptions that are “useful fictions” (which is the term people often use). However, very often the most useful perception to have is the one that actually does truthfully represent the world. As liars know, it takes a lot of work to string together lies in such a way that there are not contradictions. And often the best way to predict the world and not get eaten is to see the world as it is. So much of what we experience is veridical. But not all. For example, as I discuss in The Vision Revolution, color (colors are not out there), stereo vision (we see a single view from a perspective where we have no eye), and illusions (we see a guess) are all cases where useful fictions are at work.

Pouria Nazemi : Your new study show similarity between human brains and highway systems. How can man-made structures can be similar to our brain that evolved during millennia?

Mark Changizi: The idea is that, in each case, there is selection pressure shaping the organization. For the brain it is natural selection, which consists mostly of lots and lots of animals being eaten. For cities, although being eaten does sometimes make the news, the selection pressure is mostly due to multitudes of political and economic forces over many decades, which serve to slowly “push” a city to have a more efficiently functioning highway design.

Pouria Nazemi : Is it possible that someday we can map our brains and understand completely how it works? And, if yes, how long will it take and what our the challenges along the way?

Mark Changizi: Yes. And I’d say hundreds of thousands of years, optimistically. Sorry for the pessimism. I mentioned some of the difficulties above. Another way to put things in context is to consider Caenorhabditis elegans, a little roundworm with 302 neurons, with about a thousand connections, and where we have nearly a “God’s eye view”. It is the most well understood organism on Earth, if not the universe. Despite everything we know about its details, we are a very long way from really understanding how the neural network relates to the complex sets of behaviors it carries out. (Probably because, I would say, we don’t completely understand its behavior.) Our brain has a wee bit more neurons than 302, and is the most complicated machine in the universe. We’re in for a long haul.

Pouria Nazemi : If such a thing happens, everything would change because we could program brains to do many different things. Can you tell us more about the effects of such theoretical mapping in human life?

Mark Changizi: As for programming brains, I have actually thought about that. I wondered whether it may be possible to create images that provoke the visual system to carry out computations. Our visual system would be the hardware, the image would be the software, and the output of the hardware when run on the software would be our perception itself. Why not put our visual brain to work, making it do complicated calculations, and yet it wouldn’t feel like work to us, because all those visual computations are done unconsciously? So I created a class of stimuli called “visual circuits” that can do this, albeit not very well at this point. Here is a Wired story on the research… http://www.wired.com/wiredscience/2008/07/scientists-sugg/

Pouria Nazemi : What is the next step in your studies?

Mark Changizi: For the last year or two I have been studying the origins of language and music. Like letters, I believe that the sounds of speech, and the sounds of music, culturally evolved to sound like nature. Too much to this story to get into here, but they will be the subject of my third book which I hope to finish by the end of the year: HARNESSED: How Language and Music Mimicked Nature and Transformed Ape to Man.

Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute, and the author of The Vision Revolution (Benbella Books).

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I was on the Lionel Show / Air America this morning, which was a blast!  Got to talk about my recent book, and about evolution, autistic savants, intelligent design, color, forward-facing eyes, illusions, and more. I really must get off the elliptical machine next time I do a radio show. Here’s the segment with me (or mp3 on your computer).

Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute, and the author of The Vision Revolution (Benbella Books).

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This first appeared on October 26, 2009, as a feature at ScientificBlogging.com

Later this evening I’ll be giving a talk to a group of astronomers on what its like to see like an alien. The beauty of this is that I can speculate until the cows come home without fear of any counterexamples being brought to my attention. And even if an alien were to be among the audience members and were to loudly object that he sees differently than I claim, I can always just say that the jury is out until we get more data, and then advise him not to let the door slam into his proboscis on the way out.

E.T. the extra-terrestrial

E.T.'s forward-facing eyes suggests its ancestors evolved in forests

Although it may seem wild-eyed to discuss the eyes of aliens, if we understand why our vision is as it is, then we may be able to intelligently guess whether aliens will have vision like ours.

And in addition to the fun of chatting about whether little green men would see green, there are human implications. In particular, it can help us address the question, How peculiar is our human vision? Are we likely to see eye to eye with the typical alien invader? Or does our view of the world differ so profoundly that any alien visual mind would remain forever inscrutable?

Let’s walk through four cases of vision that I discuss in my book The Vision Revolution and ask if aliens are like us.

Do aliens see in color like us?

Let’s begin with color. I have argued in my research that our primate variety of color vision evolved in order to sense the skin color signals on the faces, rumps, and other naked spots of us primates. Not only are the naked primates the ones with color vision, but our color vision is at the sweet spot in design space allowing it to act like an oximeter and thereby see changes in the spectrum of blood in the skin as it oxygenates and deoxygenates. (See the journal article.)

Aliens may be interested in eating our brains, but they have no interest whatsoever in sensing the subtle spectral modulations of our blood under our skin. Aliens will not see color as we do, and will have no idea what we’re referring to when we refer to “little green men.”

Little green men may not think they look green

This can take the wind out of many people, namely those who feel that their senses give them an objective view of the world around them. But evolution doesn’t care about objective views of the world per se. Evolution cares about useful views of the world, and although veridical perceptions do tend to be useful, little-white-lie perceptions can also be useful. We primates end up with colors painted all over the world we view, but our color vision (in particular the red-green dimension) is really only meaningful when on the bodies of others. Although we feel as if the objects in our world “really” have this or that color, no alien would carve the world at the color-joints we do.

Do aliens have forward-facing eyes?

How about our forward-facing eyes we’re so proud of? I have argued and presented evidence that forward-facing eyes evolved as an adaptation to see more of one’s surroundings when one is large and living in leafy habitats. Animals outside of leafy cluttered habitats are predicted to have sideways-facing eyes no matter their body size, but forest animals are predicted to have more forward-facing eyes as they get larger. That is, in fact, what I found. (See the article.)

So, would aliens have forward-facing eyes? It depends on how likely it is that they evolved in a forest-like habitat (with leaf-like occlusions) and were themselves large (with eye-separation as large or larger than the typical occlusion width). My first reaction would be to expect that such habitats would be rare. But, then again, if plant-like life can be expected anywhere, then perhaps there will always be some that grow upward, and want to catch the local starlight. If so, a tree-like structure would be as efficient a solution as it is for plants here on Earth. The short answer, then, is that it depends. But that means that forward-facing eyes are fundamentally less peculiar than our variety of color vision. Aliens could well have forward-facing eyes, but it would not appear to be a sure thing.

Do aliens suffer from illusions?

One of the more peculiar things our brain does to us is see illusions. I have provided evidence that these illusions are not some arcane mistake, but a solution to a problem any brain must contend with if it is in a body that moves forward. When light hits our eye, we would like our perception to occur immediately. But it can’t. Perception takes time to compute, namely about a tenth of a second. Although a tenth of a second may not sound like much, if you are walking at two meters per second, then you have moved 20 cm in that time, and anything perceived to be within 20 cm of passing you would have just passed you – or bumped into you – by the time you perceive it. To deal with this, our brains have evolved to generate a perception not of the world as it was when light hit the eye, but of how the world will be a tenth of a second later. That way, the constructed perception will be of the present. Although there is no room in this piece to describe the details, I have argued that a very large swathe of illusions occur because the visual system is carrying out such mechanisms. (See the paper.)

Are aliens buying books of illusions and “ooh”ing and “ah”ing at them like we are? If they are moving forward (and have non-instantaneous brains), then they probably are buying these books. This is because the optic flow characteristics that underlie the explanation of the illusions are highly robust, holding in any environment where one moves forward. Aliens are, then, likely to suffer from illusions. The illusions we humans suffer from, then, may not be due to some arcane quirk or mistake in our visual system software, but, instead, a consequence of running the efficient software for dealing with neural delays.

Is alien writing shaped like ours?

I have provided evidence that our human, Earthly writing systems “look like nature,” in particular so that words have object-like structure. And I have shown that for writing like ours where letters stand for speech sounds, letters look like sub-objects, namely object junctions. Certain contour-combinations happen commonly in natural scenes, and certain combinations happen rarely. I have shown that the common ones in such environments are the common letters shapes found in human writing systems. Culture has selected writing to have the visual shapes our illiterate brains can see, which is why we’re such capable readers. (See the paper, a popular piece, and an excerpt from The Vision Revolution on this.)

Would alien writing look like this?

In this light, would alien writing look like nature as well? It depends on how specific one is when one says “like nature.” If, say, our human writing looks specifically like a savanna – i.e., if our writing mimicked signature visual features of the savanna – then it would appear very unlikely that aliens would have our kind of writing. But what if human writing looks like a very general notion of nature, so general it is likely to apply to most conceivable aliens? In my research I have provided evidence that the “nature” that appears relevant for understanding the shape of human writing is, indeed, highly general: namely, “3D environments with opaque objects strewn about.” Although highly general, aliens could float in a soup of cloudy transparent blobs, which is a kind of “nature” radically different than the one that human writing looks like. But it does seem plausible that most aliens will be roaming around opaque objects in 3D, and if that’s the case, then (so long as their culture has selected their writing to harness their visual object recognition system) their writing may look similar to human writing. Alien writing, if thrown into a pile of samples across our human writing, might just fit right in!


So let’s take stock.

Would aliens have our color vision? No. Definitely not. Ours is due to our peculiar hemoglobin.

Would aliens have forward-facing eyes? Maybe. If they evolved in leafy habitats and were large.

Would aliens see our illusions? Probably.   If they move forward.

Would aliens have writing that looks like ours? Probably. If they live in a 3D world with opaque objects.

Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute, and the author of The Vision Revolution (Benbella Books).

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Kirsten Sanford

Kirsten Sanford (shown here) and co-host Justin Jackson (sorry Justin, you understand) of This Week in Science interviewed me last week about my research and my recent book, The Vision Revolution.

Here’s the interview, and I don’t start jibber-jabbering until about 33 minutes in.  Notice how they sucker-punch me right in the belly button. (That’s what they mean by “the kickass science podcast”.)

Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute, and the author of The Vision Revolution (Benbella Books).

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This is based on an excerpt from “Spirit-Reading”, the fourth chapter of The Vision Revolution.

The topic: How illiterate apes like us came to read.


Super Reading Medium

Communicating with the dead is a standard job requirement for a psychic such as the infamous medium John Edward of the television show Crossing Over who claims to be able to listen to what the deceased family members of his studio audience have to say. Hearing the thoughts of the dead would appear to be one superpower we certainly do not possess. Surely this superpower must remain firmly in the realm of fiction (Edward included). However, a little thought reveals that we in fact do this all the time. …by simply reading. With the invention of writing, the ability for the dead to speak to the living suddenly became real. (Progress in communicating in the other direction has been slower going.) For all you know, I’m dead, and you’re exercising your spirit-reading skills right now. Good for you!


Before the advent of writing, in order to have our thoughts live on after we had gone we had to invent a great story or catchy tune and hope that they’re singing it by the fire for generations. Only a few would be lucky enough to have a song or story with such legs (e.g., Homer’s Illiad), and at any rate, if our ancestors were anything like us, their greatest hits probably tended to include “ooh-la-la” and “my baby left me” much more often than “here’s my unsolicited advice” and “beware of milk-colored berries.” Getting your children to be your audio tape in this fashion is probably futile (and aren’t they just as likely to purposely say the opposite?), but at least it relies on spoken words, something readily understandable by future generations. The problem is getting your voice to last. Voices are just too light and insubstantial, like a quarterback finding an open receiver and throwing to him a marshmellow. Marshmellows are great to hold, but impossible to throw far. I suppose if you were to speak loudly enough during a heavy volcanic ash storm, ripples on the rapidly accumulating layers of ash might record your spoken words, one day to be recovered by clever archeologist decoders. However, much of what you’re likely to say in such circumstances will be unrepeatable in polite company.

What prehistoric people did successfully leave behind for us to read tended to be solid and sturdy, like Stonehenge or the moai statues of Easter Island. These were quarterback passes that got to the receiver all right, except that now the quarterback is throwing something that is uncatchable, like porcupines or anvils. Massive monuments are great if your goal is to impress the neighboring tribes or to brag to posterity. But if your goal is to actually say something that can be understood, this tact is worse than writing abstruse poetry, and literally much heavier. The only thing we’re sure of about such communications is that they had too much free time on their hands. Not the most informative spirit-reading.

The invention of writing changed spirit-reading forever. It also changed the world. Reading now pervades every aspect of our daily lives, so much so that one would be hardpressed to find a room in a modern house without words written somewhere inside. Lots of them. Many of us now read more sentences in a day than we listen to. And when we read we must process thousands of tiny shapes in a short period of time. A typical book may have more than 300,000 strokes, and many long novels will have well over one million. Not only are we highly competent readers, but our brains even appear to have regions devoted to recognizing words. Considering all this, a Martian just beginning to study us humans might be excused for concluding that we had evolved to read. But, of course, we haven’t. Reading and writing is a recent human invention, going back only several thousand years, and much more recently for many parts of the world. We are reading using the eyes and brains of our illiterate ancestors. And this brings us to a deep mystery: Why are we so good at such an unnatural act? We read as if we were designed to read, but we have not been designed to read. How did we come to have this super power?

Reading as a super power? Isn’t this, you might ask, a bit of an exaggeration? No, it really is super. To better appreciate it, when you next have the illiterate caveman neighbors over to the house—the ones who always bring the delicious cave-made bunt cake—wow them with how you can transmit information between you and your spouse without speaking to one another. …by writing and reading. They’ll certainly be impressed. It’s not your use of symbols that will impress them, however, because they leave symbols for one another all the time, like a shrunken head in front of the cave to mean the other is at the witchdoctor’s. And they have spoken language, after all, and realize that the sounds they utter are symbols. What will amaze them about your parlor trick is how freakishly efficient you are at it. How did your spouse read out the words from the page so fast? Although they appreciate that there’s nothing spooky in principle about leaving marks on a page that mean something, and someone reading them later, they conclude that you are just way too good at it, and that, despite your protestations, you must be magical shamans of some kind. They also don’t fail to notice that your special power would work even if the writer was far away. Or long dead. Their hairs stand on end, the conversation becomes forced, they skip dessert, and you notice that their cavekids don’t come around to throw spears at your kids any more. As the saying goes, one generation’s maelstrom is a later generation’s hot tub. We’re just too experienced with writing to appreciate how super it is, but not so for your cave neighbours.

We have the super power of reading not because we evolved to read—and certainly not because we’re magical in any way—but because culture evolved writing to be good for the eye. Just as Captain Kirk’s technology was sometimes interpreted as magic by some of the galaxy locals, your neighbors are falsely giving you credit for the power when the real credit should go to the technology. The technology of writing. And not simply some new untested technology, but one that has been honed over many centuries, even millenia, by cultural evolution. Writing systems and visual signs tended to change over time, the better variants surviving, the worse ones being given up. The resultant technology we have today allows meanings to flow almost effortlessly off the page and straight into our minds. Instead of seeing a morass of squiggles we see the thoughts of the writer, almost as if he or she is whispering directly into our ears.

The special trick behind the technology is that human visual signs have evolved to look like nature. Why? Because that is what we have evolved over millions of years to be good at seeing. We are amazingly good at reading the words of the dead (and, of course, the living) not because we evolved to be spirit-readers. Rather, it is because we evolved for millions of years to be good at quickly visually processing nature, and culture has evolved to tap into this ability by making letters look like nature. Our power to quickly process thousands of tiny shapes on paper is our greatest power of all, changing our lives more than our other powers. Literacy is power, and it’s all because our eyes evolved to see well the natural shapes around us and we, in turn, put those shapes to paper.

Good Listening

“How did your date go?” I asked.

“Great. Wow. What a guy!” she replied. “He listened so attentively the entire dinner, just nodding and never interrupting, and—”

“Never interrupting?” I interjected.

“That’s right. So supportive and interested. And so in tune with me, always getting me without even needing to ask me questions, and his—”

“He asked you no questions?” I interrupted, both eyebrows now raised.

“Yes! That’s how close the emotional connection was!”

It struck me that any emotional connection she felt was a misreading of his eyes glazing over, because her date was clearly not listening. At least not to her! I didn’t mention to her that the big game was last night during her dinner, and I wondered whether her date might have been wearing a tiny ear phone.

Good listeners don’t just sit back and listen. Instead, they are dynamically engaged in the conversation. I’m a good listener in the fictional conversation above. I’m interrupting, but in ways that show I’m hearing what she’s saying. I am also able to get greater details of the story where I might need them. In this case about her date’s conversational style. That’s what good listeners do. They rewind the story if needed, or forward it to parts they haven’t heard, or ask for greater detail about parts. And good communicators tend to be those who are able to be interacted with while talking. If you bulldoze past all attempts by your listener to interrupt you, your listener will probably soon not be listening. Perhaps he’s heard that part before and is tuning out now. Or perhaps he was confused by something you said fifteen minutes earlier, and gave up trying to make sense of what you’re saying. Good listeners require good communicators. My fictional friend above appears to be a good communicator because she dynamically reacts to my queries midstream. The problem lies in her date, not her, and I politely suggest he may not be the right one for her.

Even though we evolved to speak and listen, but didn’t evolve to read, there is a sense in which writing has allowed us to be much better listeners than speech ever did. That’s because readers can easily interact with the writer, no matter how non-present the writer may be. Readers can pause the communication, skim ahead, rewind back to something not understood, and delve deeper into certain parts. We listeners can, when reading, manipulate the speaker’s stream of communication far beyond what the speaker would let us get away with in conversation—“Sorry, can you repeat the part that started with, ‘The first day of my trip around the world began without incident’?”—making us super-listeners, and making the writer a super-communicator.

We don’t always prefer reading to listening. For example, we listen to books on tape, lectures, and talk radio, and in each case the speakers are difficult to interrupt. However, even these cases help illustrate our preference for reading. Although people do sometimes listen to books on tape, they tend to be used when reading is not possible, like when driving. When one’s eyes are free, people prefer to read stories rather than hear them on tape, and the market for books on tape is miniscule compared to that for hard copy books. We humans have brains that may have evolved to comprehend speech, and yet we prefer to listen with our eyes, despite our eyes not having been designed for this! Television and movies have an audio stream that is not easily interruptable, and we do like that, but now the visual modality helps keep our attention. And although students have been listening for centuries to the speech of their professors, until recently with relatively little visual component, anyone who has sat through years of these lectures knows how often one’s mind wanders. …how often one is not actually listening. Talk radio has some popularity, and tends to be more engaging than traditional lectures, but notice that such shows go to great lengths to be conversational, typically having conversations with callers, and often having a pair of hosts (or a sidekick), to elicit the helpful interruptions found in good listening.

Canned speech, then, tends to be difficult to listen to, whereas genuine, dynamic, interactive conversation enables good listening. There is, however, one kind of audio stream our brains can’t get enough of, where interruption is not needed for good listening, and where we’re quite happy not seeing anything. Music. Audio tapes that give up on communication and aim only for aesthetics are suddenly easy listening. The rarity of books on tape, and the difficulty with listening to canned speech more generally, is not due to some intrinsic difficulty with hearing per se. The problem is that speech requires comprehension—music doesn’t—and comprehension can occur most easily when the listener is able to grab the conversation by the scruff of the neck and manipulate it as needed so he can fit it into his head. Good conversation with the speaker can go a long way toward this, but even better listening can be achieved by reading because then you can literally pick up the communication with your hands and interact with it to your heart’s content.

Working Hands

Having a conversation is not like passing notes in class. Although in each case two people are communicating back and forth in turn, when passing notes you tend to do little reading and lots of wiggling—either wiggling your hand in the act of writing a note, or twiddling your thumbs while waiting for your friend to write his. Note-writing takes time, so much time that passing notes back and forth is dominated by the writing, interspersed with short bouts of reading. All the work’s in the writing, not the reading. Conversation—i.e., people speaking to one another—is totally unlike this. Speaking flows out of us effortlessly, and comes out nearly at the speed of our internal thoughts. That is, whereas writing is much more difficult than reading, speaking is not much more difficult than listening.

The reason for this has to do with how many people we’re communicating with. When we speak there are typically only a small number of people listening, and most often there’s just one person listening (and often less than that when I speak in my household). For this reason spoken language has evolved to be a compromise between the mouth and ear: somewhat easy for the speaker to utter, and somewhat easy for the listener to hear. In contrast, a single writer can have arbitrarily many readers, or “visual listeners.” If cultural evolution has shaped writing to minimize the overall efforts of the community, then it is the readers’ efforts that will drive the evolution of writing because there are so many of them. That’s why as amazing, as writing may be, it is a gift to the eye more than a gift to the hand. For example, a book may take six months to write, but it may take only six hours to read. That’s a good solution because there are usually many readers of any given book.

Is writing really for the eye, at the expense of the hands? One of the strongest arguments that this is the case is that writing has been culturally selected to look like nature, something we’ll see later. That’s a good thing for the eye, not the hand, because the eye has evolved to see nature—the hand has not evolved to draw it. Not only does writing tend to look like nature, but I have found that even visual symbols like trademark logos—which are typically never written by hand, and are selected to be easy on the eyes—have the fundamental structural shapes found in nature. And note that for some decades now much of human writing has not been done by hand, but instead has been done by keyboard. If the structures of letters were for the hand, we might expect that now that our hands tend to be out of the picture, the structures of letters might change somewhat. However, although there are now hundreds of varying fonts available on computers, the fundamental structural shapes have stayed the same. Shorthands, however, have been explicitly selected for the hand at the expense of the eye, and shorthands look radically different from normal writing, and I have shown that they have shapes that are not like nature. I have also taken data from children’s scribbles and shown how the fundamental structures occurring in scribbles are unlike that found in writing and in nature. Finally, one can estimate how easy a letter is to write by the number of distinct hand sweeps required to produce it (this counts sweeps resulting in strokes on the page, and also sweeps of the hand between touchings of the paper), and such estimates of “motor ease” do not help to explain the kinds of shapes we find in writing.

Could culture really have given no thought whatsoever to the tribulations of the hand? Although selection would have favored the eye, it clearly would have done the eye no good to have writing be so difficult that no hands were willing to make the effort. Surely the hand must have been thrown a bone, and it probably was. The strokes in the letters you’re reading, and in line drawings more generally, are quite a bit like contours in being thin, but there is an important difference. Real world contours occur when one surface stops and another starts, like the edge between two walls, or the edge of your table. Usually there is no line or stroke at all (although sometimes there can be), but a sudden change in the nature of the color or texture from one region to the next. The visual system would therefore probably prefer contours, not strokes. But strokes are still fairly easy to see by the visual system, and are much easier for the hand to produce. After all, to draw true contours rather than strokes would require drawing one color or texture on one side of the border of the intended contour and another color or texture on the other side. I just tried to use my pen to create a vertical contour by coloring lightly to the right and more darkly to the left, but after a dozen tries I’ve given up. I won’t even bother trying to do this for an “S”! It’s just too hard, which is why when we try to draw realistic scenes we often start with lines as contours, and only later add color and texture between the lines. And that’s probably why writing tends to use strokes. That we use strokes and not true contours is for the benefit of the hand, but the shapes of our symbols are for the eye.

Harness the Wild Eye

You’d be surprised to see a rhinoceros with a rider on its back. In fact, a rider would seem outlandish on most large animals, whether giraffe, bison, wildebeast, bear, lion, or gorilla. But a rider on a horse seems natural. Unless you grew up on a farm and regularly saw horses in the meadows, a large fraction of your experiences with horses were likely from books, television and film where the horses typically had riders. Because of your “city-folk” experiences with horses, a horse without a rider can seem downright unnatural! In fact, if aliens were observing the relationship between humans and horses back when horses were our main mode of transportation, they may have falsely concluded that horses were designed to carry humans on their backs. But, of course, horses aren’t born with bridles and saddles attached, and they didn’t evolve to be ridden. They evolved over tens of millions of years of evolution in savannas and prairies, and it is only recently that one of the primates had the crazy idea to get on one. How is it that horses could have become so well adapted as “automobiles” in a human world?

Horses didn’t simply get pulled out of nature and plugged into society. Instead, culture had to evolve to wrap around horses, making the fit a good one. Horses had to be sired, raised, fed, housed, steered, and scooped up after. Countless artifacts were invented to deal with the new tasks required to accommodate the entry of horses into society, and entire markets emerged for selling them. Diverse riding techniques were developed and taught, each having certain advantages for controlling these beasts. The shapes of our homes and cities themselves had to change. Water troughs in front of every saloon, stables stationed through towns and cities, streets wide enough for carriages, parking spaces for horses, and so on. That horses appear designed for riders is an illusion due to culture having designed itself so well to fit horses.

Just as horses didn’t evolve to be ridden, eyes didn’t evolve for the written. Your eyes reading these words are wild eyes, the same eyes and visual systems of our ancient preliterate ancestors. And yet, despite being born without a “bridle,” your visual system is now saddled with reading. We have, then, the same mystery as we find in horses: how do our ancient visual systems fit so well in modern reading-intensive society?

Eyes may seem like a natural choice for pulling information stored on material, and indeed vision probably has inherent superiorities over touch or taste, just as horses are inherently better rides than rhinos. But just as horses don’t fit efficiently into culture without culture evolving to fit horses, the visual system couldn’t be harnessed for reading until culture evolved writing to fit the requirements of the visual system. We didn’t evolve to read, but culture has gone out of its way to create the illusion that we did. We turn next to the question of what exactly cultural evolution has done to help our visual systems read so well.

From the Hands of Babes

You might presume that a two and a half year old girl couldn’t have much to say. If I were struck on the head and reduced to infant-level intelligence for two and a half years, I’m fairly sure I wouldn’t thereby have a flood of stories to tell you about. None, at least, that are not considerably degrading. But there she is, as you well know if you’ve seen these creatures, talking up a storm. A little about the few things that have happened to her, but mostly about things that never have, and never will: princesses, dragons, Spongebob, Stegosauruses. She’s five now and there’s been no let-up. She’s talking to me as I write this!

I just gave her a piece of paper and crayons, and although she’s just begun trying her hand at writing—“cat,” “dug,” “saac” (snake), “flar” (flower)—she’s been putting her thoughts and words to the page for a long time now. By drawing. Children are instructive for the invention of writing because they invent their own writing through pictures. Through the work of Rhoda Kellogg in the mid-twentieth century we know that children world-wide draw very similar shapes, and follow a similar developmental schedule. Since they are not designed to draw, these similarities are, in a sense, parallel discoveries about how to ably communicate on paper; on how to write. Sir Herbert E. Read, an early 20th century professor of literature and arts, encountered Rhoda Kellogg’s work late in his life, and wrote the following:

It has been shown by several investigators, but most effectively by Mrs. Rhoda Kellogg of San Francisco, that the expressive gestures of the infant, from the moment that they can be recorded by a crayon or pencil, evolve from certain basic scribbles towards consistent symbols. Over several years of development such basic patterns gradually become the conscious representation of objects perceived: the substitutive sign becomes a visual image. … According to this hypothesis every child, in its discovery of a mode of symbolization, follows the same graphic evolution. … I merely want you to observe that it is universal and is found not only in the scribblings of children but everywhere the making of signs has had a symbolizing purpose—which is from the Neolithic age onwards. [from Herbert Read, “Presidential Address to the Fourth General Assembly of the International Society for Educational Society for Eduation through Art.” Montreal: Aug 19, 1963.]

Aren’t children’s drawings just that, drawings? It’s certainly true that sometimes children are just trying to depict what they see. Those are “mere” drawings. But often their drawings are primarily aimed to say something—to tell a story. When my daughter brings me her latest drawing, she usually doesn’t brag about how real it looks (nor does she tell me about its composition and balance). Sure, sometimes she asks me to count how many legs her spider has, but usually I get a story. A long story. For example, here is a Cliffs Notes version of the story behind her drawing in Figure 1: A house with arms and eyes; the windows have faces; it is a magic house; there is a girl holding a plate of cream puffs; two people are playing with toys at the table but a tomato exploded all over the toy; there are butterflies in the house. Her drawing is intended to communicate a story, and that sounds an awful lot like writing.

But if she’s truly writing, then she’d have to be using symbols. Is it really plausible that small children are putting symbols on the page before they learn formal writing, as Rhoda Kellogg and Herbert Read believe? I think so, for consider that most of their drawings have only the barest resemblance to the objects they are intended to denote. Look again at nearly any of the objects in my daughter’s drawing in Figure 1. An attempt at realism? Hardly. We find similar kinds of symbols when even adults draw cartoons—adults who could draw realistically if they wished. These cartoon symbols, like those in the first row of Figure 2a, are ridiculously poor renderings of objects. You have surely seen similar visual signs out and about in culture. Although you’ll probably have no trouble knowing what animals the drawings are intended to symbolize, your dog would have no idea what those (or my daughter’s) drawings are supposed to be. They get their meaning by convention more than by resemblance. We’re so used to these conventions that we have the illusion that they look like the animals they refer to, but other cultures often have somewhat different conventions for their animals. For example, I find it difficult to tell what kind of animal I’m looking at in many of today’s Japanese cartoons for kids, some of them shown in the second row of Figure 2a.

The same is true for sound. We in the United States say “ribbit” to refer to the call made by a frog, and after growing up with that as the symbol for frog calls it can be hard to appreciate that frogs don’t sound at all like that. In fact, people from different cultures use different sound symbols to refer to frog calls, and each person is initially convinced that their sound resembles frogs. Algerians say “gar gar,” Chinese say “guo guo,” the English say “croak,” the French say “coa-coa,” Koreans say “gae-gool-gae-gool,” Argentinians say “berp,” Turks say “vrak vrak,” and so on. Just as in children’s drawings, the sound “ribbit” is a symbol for the call of the frog, not a real attempt to resemble or mimic it.

Children’s drawings communicate stories with symbols. That sure sounds like writing to me. Or at least the barest beginnings. If these little whippersnappers are so smart that they can spontaneously invent writing largely on their own, perhaps it couldn’t hurt to look into the kinds of symbols they choose for their writing. And the answer is so obvious that it may be difficult to notice: children draw object-like symbols for the objects in their writing. Their drawings may not look much like the objects they stand for, but they look like objects, not like fractal patterns, not like footprints, not like scribbles, not like textures, and so on. The same is true for the cartoons drawn by adults, as in Figure 2a. And we find the same so-obvious-it-is-hard-to-notice phenomenon for animal calls: although there are lots of different sounds used for frog calls, they are all animal-call-like. All those frog calls sound like some possible kind of animal. What might this phenomenon mean for writing?

Word and Object

Is the strategy of object-like drawings for objects mere child’s play? Apparently not, because it’s not just in kids’ drawings and cartoons that you find this, but among human visual signs generally. Most non-linguistic visual signs throughout history have been object-like, such as those found in pottery, body art, religion, politics, folklore, medicine, music, architecture, trademarks and traffic (see Figure 2b for a small variety). And computer desktop icons are not only object-like in appearance, but can even be moved around like objects. Much of formal writing itself has historically been of this objects-for-words form, such as Egyptian hieroglyphs, Sumerian cuneiform, Chinese, and Mesoamerican writing. Modern Chinese is still like this, used by nearly half the world. In these writing systems we find drawings with the complexity of simple objects and used as symbols to refer to objects, and also to refer to adjectives, adverbs, verbs and so on. (See Figure 2c for several examples.) Object-like symbols for objects—that trick’s not just for kids.

Is there something beneficial about drawing objects for the words in writing? I suspect so, and I suspect that it is the same reason that animal-call symbols tend to be animal-call-like: we probably possess innate circuitry that responds specifically to animal-call-like sounds, and so our brain is better able to efficiently process a spoken word that means an animal call if the word itself sounds animal-call-like. Similarly, we possess a visual system designed to recognize objects and efficiently react to the information. If a word’s meaning is that of an object (even an abstract object), then our visual system will be better able to process and react to the written symbol for that object if the written symbol is itself object-like. Figure 3b shows a fictional case of writing with object-like symbols for words (and single strokes are shown for “function words” like ‘the’ and ‘in’). To begin to grasp why this strategy might be good, consider two alternative strategies besides the objects-for-words one.

First, rather than drawing objects for words, we could be lazy and just draw a single contour for each spoken word. Writing “The rain in Spain stays mainly in the plain” would then look something like that shown in Figure 3a. Shorthand is somewhat akin to the lazy approach, with some words having single stroke notations. Shorthand is great for writers with fast-talking bosses, but is notoriously hard to read and has not caught on for writing. Kids also don’t think it’s a good idea—there’s not even a single lone contour in my daughter’s drawing in Figure 1. One reason it’s not a good idea is that there are just not enough distinguishable stroke types for all the words we speak. Coming up with even 100 easily distinguishable stroke types would be tricky, and that would still be far below the tens of thousands that would be needed for writing.

There is also a more fundamental difficulty, and it has to do with the fact that the part of your brain doing the visual computations is arrayed in a hierarchy. The earlier stages of the hierarchy deal with simpler parts like contours, higher areas deal with simple combinations of contours, and eventually at the highest regions of the hierarchy full objects are recognized and perceived. The problem with using single strokes to represent spoken words like in Figure 3a is that the visual system finishes processing the strokes far too early in the hierarchy. The visual system is not accustomed to word-like (e.g., object-like) interpretations to single strokes. Single strokes are typically not perceived at all, at least not in the sense that they make the list of things we see out there. For example, when you look at Figure 4 you perceive a cube in front of a pyramid. That’s what you consciously notice and carry out judgements upon. You don’t see the dozen contours in quite the same sense. Nor do you see the many object corners and junctions (intersections of contours). You don’t say, “Hey, look at all those contours and corners in the scene.” Our brains evolved to perceive objects, not object-parts, because objects are the clumps of matter that stay connected over time and are crucial to parsing and making sense of the world. Our brains naturally look for objects and want to interpret stimuli out there as objects, so using a single stroke for a word (or using a junction for a word) is not something our brains are happy about. Instead, when seeing the stroke-word sentence in Figure 3a the brain will desperately try to see objects in the jumble of strokes, and if it can find one, it will interpret that jumble of strokes in an object-like fashion. But if it did this, it would be interpreting a phrase or whole sentence as an object, something that is not helpful for understanding a sentence: the meaning of a sentence is “true” or “false,” not any single word meaning. Using single strokes as words is, then, a bad idea because the brain is not designed to treat single contours as meaningful. Nor is it designed to treat object junctions as meaningful. That’s why spoken words tend to be written with symbols having a complexity no smaller than visual objects.

How about, instead, letting spoken words be visually symbolized by whole scenes, i.e., via multiple objects rather than just a single one? Figure 3c shows what “The rain in Spain…” might look like with this “scene-ogram” strategy. Quite an eye full. These are akin to the drawings found in some furniture assembly manuals. The problems now are the opposite to those before. First, the natural meaning of scene-ogram images is more like that of a sentence, like “Take the nail that looks like this, and pound it into the wooden frame that looks like that.” Secondly, the fact that there are objects as part of these complex symbols is itself a problem because now the brain wants to inappropriately make meanings out of these, and yet these objects are now just the building blocks of a written word, having no meaning at all.

In sum, the visual system possesses innate mechanisms for interpreting object-like visual stimuli as objects. Because spoken words are the smallest meaningful entities in spoken language, and often have meanings that are at the object level (either meaning objects, or properties of objects, or actions of objects), it is only natural to have visual representations of them that the visual system has been designed to interpret, and to interpret as objects. By drawing objects for spoken words—and not smaller-than-object visual structures like contours or junctions, and not larger-than-object visual structures like scenes—the visual system is able to be best harnessed for a task it never evolved to do. (See Figure 5.)

Object-like symbols might, then, be a good idea for representing words, but are the object-like symbols we find in culture a result of cultural evolution having selected for this, or might it instead be that they are just a left-over due to the first symbols having been object-like? After all, the first symbols tended to be object-like pictograms, even more object-like than the symbols in Figures 2b and 2c. Perhaps our symbols are still object-like merely because of inheritance, and not because culture has designed them to be easy on the eye. The problem with this argument is that writing tended to change quickly over time, especially as cultures split. If there were no cultural selection pressure to keep symbols looking object-like, then the symbol shapes would have randomly changed over the centuries, and the object-likeness would have tended to become obliterated. But that’s not what we find. Culture has seen to it that our symbols retain their object-likeness, because that’s what makes us such good readers. It is interesting, though, that even the first symbols were on the right track, before cultural evolution had time to do any shaping of its own. Although, given that even small children codgeon onto this, it’s perhaps not too surprising that the first scribes appreciated the benefits of object-like drawings for words.

The Trouble with Speech Writers

The brain prefers to see objects as the symbols for words, and kids and much of the world have complied. Such writing is “logographic” (symbols for words), and doesn’t give the reader information on how to speak it, which is itself a great benefit, for then even people who speak different languages can utilize the same writing system and be able to communicate via it. That is, logographic writing systems can serve as universal writing systems bringing together a variety of spoken languages into harmony and friendship, Tower-of-Babel style. Japanese speakers, for example, have no idea what a Chinese speaker is saying, but can fairly well understand written Chinese because Japanese speakers also use Chinese writing (which is of the objects-for-words kind).

Brotherhood and peace may be nice, but there er jus some thangs ya cayant do when writin’ with objects. For one thing, you can’t communicate how to say those words. …including putting a person’s accent down on the page. A Japanese person may be glad to be able to read Chinese content, but he will be totally unprepared to actually speak to anyone in China. The kind of writing you’re reading at the moment is entirely different. Rather than symbols for spoken words, the basic symbols are letters saying how to speak the words. You’re reading “speech-writing.” Speech-writing allows us to put Tom Sawyer’s accent on paper, and it allows non-speakers of our language to obtain a significant amount of knowledge about how to speak among us by reading at home. Such a learner would have an atrocious accent, of course, but would nevertheless have a great start. A second important advantage to speech-writing is that one can get away with many fewer symbols for writing. Rather than one object-like symbol for each of the tens of thousands of spoken words, one only needs a symbol for each of the dozens of speech sounds, or phonemes, we make. That’s a thousand-fold reduction in the number of written symbols we have to learn.

I have no idea whether the merits of speech-writing outweigh the benefits of logographic (symbols-for-words) writing, but there have been hundreds of speech-writing systems over history, many in use today by about half the world’s population. And when culture decided to go the speech-writing route rather than the logographic route, it created for itself a big dilemma. As we’ve discussed, the best way to harness the natural object-recognition powers of the visual system is to have spoken words look object-like on paper. But in speech-writing the symbols are for speech sounds, and written words will consist of multiple speech sound symbols. How can our written words look like objects if written words no longer have fundamental symbols associated with them? If symbols are for fundamental speech sounds, then the look of a written word will depend upon the letters in it. That is, the word’s look will be due to the vagaries of how the word sounds when spoken. Had it been spoken differently, the written word would look different. If the look of a word depends on how speakers say the word, it would seem that all hope is lost in trying to make written words look object-like in speech-writing.

There is a way out of the dilemma, however, and although no individual may have conceived of the idea, culture nevertheless eventually evolved to utilize this solution. The solution is this: If written words must be built out of multiple symbols, then to make words look object-like, make the symbols look like object parts. That’s what culture did. Culture dealt with the speech-writer dilemma by designing letters that look like the object parts found in nature, object junctions, in particular. That way written words will typically be object-like, so that again our visual system can be best harnessed for reading.

Because the geometrical shapes of letters vary considerably across fonts (and across individuals), but do not typically much change in their topology (see Figure 6a), a topological notion of shape is the apt one for studying letter shape. It is also apt because the geometrical shape of a conglomeration of contours in a scene changes with the observer’s viewpoint whereas the topological shape will be highly robust to viewpoint modulations. Figure 6b shows three simple kinds of topological shape, or configuration: L, T and X. Each stands for an infinite class of geometrical shapes having the same topology. Two smoothly curved contours make an L if they meet at their tips, a T if one’s tip meets anywhere along the other (except at the tip), and an X if both contours cross each other. Whereas Ls and Ts commonly occur in the world—as corners and at partial occlusion boundaries as displayed in Figure 6b—Xs do not. And, indeed, Ls and Ts are common, but Xs rare, over the history of human visual signs and nearly a hundred writing systems (see the red squares in Figure 6e). Figure 6c shows four configuration types that are similar in that they each have three contours and two T junctions. Despite these similarities, they are not all the same when it comes to how commonly they can be found in nature. While three of them can be caused by partial occlusions and are thus fairly common, one of them cannot, and is thus rare in nature. Their commonness over the history of writing also shares this asymmetry, the rare-in-nature configuration also rarely occurring among human visual signs (see the green diamonds in Figure 6e). Finally, Figure 6d shows five configurations having three strokes that all meet at a single point, or junction, and one can see that some of these require greater coincidental alignments in the world for them to occur, and are accordingly expected to be rarer in nature. And measurements show that writing over history mimics this relative frequency distribution (see the blue circles in Figure 6e).

Commonness in the world drives commonness in writing. Culture appears to have, over centuries, selected for written words that look object-like, thereby harnessing the natural powers of our visual system, allowing us to read with remarkable efficiency.

This excerpt also appeared at Semiotix.

Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute, and the author of The Vision Revolution (Benbella Books).

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Originally a piece in ScientificBlogging, October 2, 2009…

Dear Hugh Hefner:

Ever wondered  why you’re rich?   Yes, yes, you’re a savvy businessman who succeeded where thousands have failed.   But there are deeper reasons underlying why your business model works at all. When one digs deeply enough one finds that color – yup, the stuff of rainbows and Crayola – is at the core of your success. Without hue, there’d be no Hugh.

To see why you should be giving thanks to the existence of color, let’s start with something closer to your home; nakedness.   Although mammals tend to be furry-faced, some of us primates had the chutzpah to lose the hair on our faces, and often on our rumps. And we humans are nearly naked all over, something you may have noticed.   If we humans weren’t so bare, we would probably not wear robes. And then there would be no reason to disrobe.

If there were no bare skin, there would  be no Hefner as we know it.

Now  let’s delve deeper and ask why some of us primates got bare in the first place. One feature that distinguishes the primates with bare faces from the furry-faced ones is color vision. The naked primates can see in color, but the furry-faced ones cannot.   Color goes with nudity. Why?

As I have argued in my research, our color vision is a distinctive kind of color vision, one that is specialized for detecting the color changes that happen in skin due to the physiological changes in blood (e.g., oxygenation). Most varieties of color vision – like that in birds, reptiles and bees – do not have this extraordinary capability. Our color vision is for seeing blushes, blanches, red rage, sexual engorgement and the many other skin color changes that occur as one’s emotion, mood, or physiology alters. Color is for seeing embarrassment, fear, anger, sexual excitement, and so on.

Our primate ancestors once had furry faces, and one was born with our style of color vision, able to detect the peculiar changes in our underlying blood physiology. Although the faces this ancestor looked at were  furry, some skin would have been visible, such as around the eyes, nostrils, lips and any lighter patches of fur. This ancestor would have been born an “empath,” able to see the moods of others. Color vision of this kind would thus spread over time.

And once it spread, animals could then have evolved to “purposely” signal colors indicating their mood, and then bare skin would have evolved to have more canvas for signaling. Many of our skin color changes are indeed “purposeful,” i.e., not simply inevitable consequences of our underlying physiological state. For example, Peter D. Drummond has shown  that peoples’ faces blush more on the side which people can see.

You might be wondering  why, unlike the other primates who mainly have bare faces and rumps, we humans are so naked all over.  It might be that, although we don’t consciously notice it, we color signal over our entire canvas.  If all our bare spots are for color signalling (setting aside the palms and the bottoms of the feet) then we should not be naked in places that viewers would not tend to be able to see.

Well, there are three places on the body that are difficult to observe; the top of the head, the underarms and the groin. And notice that, as expected if bare skin is for color signaling, these three spots are the universally furry spots on humans.

The only complication here is that the groin does occasionally become dominated by bare skin rather than fur, namely when  the genitalia engorge. But at these times there is often another person involved in a behavior wherein the groin is, ahem, no longer difficult to see.

Bare skin really may be for looking at! And it is worth  looking at because it often signals something to the viewer. But the viewer can only see these signals if they have our special kind of color vision.

No color vision, no nakedness. No nakedness, no Hugh Hefner.

Or, no hue, no Hugh.

And now the real point of my writing: Because of the dependency of your enterprise on the evolution of color, it would only be natural to bring some diversity to those apocryphal parties at the mansion … by inviting an evolutionary neuroscientist.

Just have your people call my person.

Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute, and the author of The Vision Revolution (Benbella Books).

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Other people have an accent, but not me. And this is not just because I have no accent. I wouldn’t have an accent even if I had one!

Accent is a strange thing (as is my reasoning style). No matter the accent you get stuck with – southern, New Yorker, or my valley girl rendition – you feel as if it is the other accents that sound accented to you. Your own accent sounds, well, unaccented, like vanilla, corn flakes, or white bread. Arguments about which person “has an accent” don’t tend to be productive; just a lot of pointing and reiterating the pearl, “No, you’re the one with the accent.”

And it is not just accent where we find ourselves behaving badly. We do the same for skin color. Most people feel that their own skin color is fairly uncolorful, and difficult to accurately name. Why are our perceptual systems like this? Here’s what I said about this in The Vision Revolution.

    “Why would we evolve to perceive our own skin color as uncategorizable and uncolored? How could this be a useful thing? Consider an object with a color that is highly categorizable—say an orange. If I place 100 oranges in front of you, there will actually be some variation in their colors, but you won’t pay much attention to these differences. You will subconsciously lump together all the different hues into the same category: “orange.” Ignoring differences is a central feature of categorization. To categorize is to stereotype. When a color is uncategorizable, however, the opposite of stereotyping occurs. Rather than lumping together all the different colors, you appreciate all the little differences. Because our skin color cannot be categorized, we are better able to see very minor deviations in skin color, and therefore register minor changes in others’ skin color as they occur.”

Unfortunately, this fine discrimination around one’s own skin color (or accent, or the taste of your own saliva, for that matter) has an unintended consequence: it can lead to racism.

Race and skin color.

Could racism really be a side effect of highly efficient perceptual mechanisms? I’m afraid so. Here’s an excerpt from The Vision Revolution where I discuss why…

    If our skin color is so uncolored, why do we use color terms so often to refer to race? Races may not literally be white, black, brown, red or yellow, but people do perceive other races to be colored in the general direction of these fundamental colors, which is why color terms are used at all. So, what is all this nonsense about uncolored skin?
    To answer this, one must remember that it is only one’s own skin that appears uncolored. I perceive my saliva as tasteless, but I might taste a sample of some of yours. I don’t smell my nose, but I might be able to smell yours. Similarly, my own skin may appear uncolored to me, but a consequence of being designed to perceive the changes around baseline is that even fairly small deviations from baseline are perceived as qualitatively colored, just as a 100 degree temperature is perceived as hot. An alien coming to visit us would find it utterly perplexing that a white person perceives a black person’s skin to be so different from his own, and vice versa. Their spectra are practically identical (see Figure 3). But then again, this alien would be surprised to learn that you perceive 100 degree skin as hot, even though 98.6 degrees and 100 degrees are practically the same.
    Therefore, the fact that languages tend to use color terms to refer to other races is not at all mysterious. It is consistent with what would be expected if our color vision is designed for seeing color changes around baseline skin color. Whereas your baseline skin color is uncategorizable and appears uncolored, skin colors deviating even a little from baseline appear categorizably colorey.
    Skin color is probably a lot like accents. Rather than asking about the color of your skin, let’s now ask, What is the accent of your own voice? The answer is that you perceive it to have no accent. But you perceive people coming from other regions or countries to have an accent. Of course, they believe that you are the one with the accent, not them. This is because we are designed to ably discriminate the voices of people in our lives who have the same accent (or non-accent) as ourselves. We need to discriminate between different people’s voices, and we also need to discriminate the inflections in the voice of a single individual. A consequence of this is that our own voice and those typical of our community are perceived as non-accented, and even fairly small deviations away from this baseline accent are perceived as categorizably accented (e.g., country, urban, Boston, New York, English, Irish, German and Latino accents). Because of this, people find it difficult to recognize people by voice when they have an accent. People also find it more difficult to discriminate the tone or emotional inflections of the speaker when the speaker has an accent.
    In talking about your perception of your own skin color earlier, for simplicity I was implicitly assuming that the community you have grown up around shares approximately the same skin color. For most of our evolutionary history this was certainly the case. And even today most people are raised and live among individuals largely sharing their own skin color, but by no means always. If you are an ethnic minority in your community, your skin color may differ from the average skin color around you, and your baseline skin color may well end up to be different from your own. If this were the case, then you may in principle perceive your own skin to be colored. For example, if you are of African descent but living in the U.S., then because the baseline skin color of the U.S. leans toward that of Caucasians, you may perceive your own skin to be color-ey. Similarly, if someone with a Southern accent moves to New York City, he may begin to notice his own accent because the baseline accent of his community has changed (but his accent may not much change).

    One implication of all this is that our perception of the skin color of various races is illusory, and these illusions are potentially one factor underlying racism. In fact, it leads to at least three distinct (but related) illusions of racial skin color. To understand these three illusions, it is helpful to consider these illusions in the context of perceived temperature.

    First, as noted earlier, we perceive 98.6 degrees to be neither warm nor cold, yet we perceive 100 degrees as hot. That is, we perceive one temperature to have no perceptual quality of warmth/cold, whereas we perceive the other temperature to categorically possess a temperature (namely hot). This is an illusion because there is nothing in the physics of temperature that underlies this perceived qualitative difference between these two temperatures. For skin there is an analogous illusion, namely the perception we have that one’s own skin is uncolorful but that the skin of other races is colored. This is an illusion because there is no objective sense in which your skin is uncolorful but that of others is colorful. (Similarly, there is no objective truth underlying the perception that one’s own voice is not accented but that foreign voices are.)

    A second consequent illusion is illustrated by the fact that we perceive 98.6 degrees as very different from 100 degrees, even though they are objectively not very different. This is closely related to the first illusion, but differs because whereas the first concerns the absence versus the presence of a perceived categorical quality, this illusion concerns the perceived difference in the two cases. The analogous illusion for skin is the perception that your own skin is very different from that of some other races. This is an illusion because the spectra underlying skin colors of different races are actually very similar.

    And third, we perceive 102 degrees and 104 degrees as very similar in temperature, despite their objective difference being greater than the difference between 98.6 degrees and 100 degrees, the latter which we perceive as very different. For skin colors, we lump together the skin colors of some other races as similar to one another, even though in some cases their colors may differ as much as your own color does from either of them. For example, while people of African descent distinguish between many varieties of African skin, Caucasians tend to lump them all together as “black” skin. (And for the perception of voice, many Americans confuse Australian accents with English ones, two accents which are probably just as objectively different as American is to English.)

    As a whole, these illusions lead to the false impression that other races are qualitatively very different from ourselves, and that other races are homogeneous compared to our own. It is, then, no wonder that we humans have a tendency to stereotype other races: we suffer from perceptual illusions that encourage this. But by recognizing that we suffer from these illusions, we can more ably counter them.

How much of the human tendency toward racism is explained by these perceptual mechanisms? I don’t know, but I would not underestimate the power of such illusions, for they fundamentally affect – or color – how we see the world and the people in it.

Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute. This research on the evolution of color – and other work of his on the origins or writing, illusions and stereo vision – are the topic of his new book, The Vision Revolution (Benbella Books).

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Originally a piece in ScientificBlogging, September 17, 2009…

Reading pervades every aspect of our daily lives, so much so that one would be hardpressed to find a room in a modern house without words written somewhere inside. Many of us now read more sentences in a day than we listen to. Not only are we highly competent readers, but our brains even appear to have regions devoted to recognizing words. A Martian just beginning to study us humans might be excused for concluding that we had evolved to read.

But, of course, we haven’t. Reading and writing is a recent human invention, going back only several thousand years, and much more recently for many parts of the world. We are reading using the eyes and brains of our illiterate ancestors. Why are we so good at such an unnatural act?

Here I describe recent evidence that, although we have not evolved to be good at reading, writing appears to have culturally evolved to be good for the eye. More specifically, recent research supports the exciting hypothesis that human visual signs look like nature, because that is what we have evolved over millions of years to be good at seeing. This ecological hypothesis for letter shape not only helps explain why we are such good readers, but answers the question, Why are letters and other visual signs shaped the way they are?

The Variety of Visual Signs

Given the tremendous variety of visual signs over human history, it may at first glance seem that there could be no simple answer to the question, Why are visual signs shaped as they are? After all, we have been making visual signs for at least 40,000 years, starting with tool decorations and cave paintings. The evolution of ornamentation, art, painting, and other non-linguistic visual signs (i.e., signs not part of language) has gone on unabated, diversifying into millions of non-linguistic symbols used over the ages, and occupying nearly all aspects of our lives, including pottery, body art, religion, politics, folklore, medicine, music, architecture, trademarks and traffic.


Writing (i.e., visual signs distinguished by use as a means of visually recording the content of spoken language) has also undergone an evolutionary explosion in variety. The earliest writing appeared several thousand years ago, and occurred independently in Sumer, Egypt and China (and much more recently in the Americas). These earliest linguistic visual signs were pictograms, evolving later to logograms (where a character denotes an object, idea or action), and a single logographic writing system (such as Chinese or Linear B) can have many thousands of distinct visual signs. It wasn’t until about 2000 years ago in Egypt that phonemic writing was invented and used, where each character stands for a constituent of speech rather than having a meaning as in logographic writing. Many hundreds of writing systems have evolved and diversified from this ancestor (e.g., Latin, Arabic, Avestan, Mongolian, Phags-pa), varying widely in geometrical shape and style, and in the aspects of speech the characters represent (e.g., alphabets represent consonants and vowels, abugidas represent just consonants, and syllabaries represent syllables).

Amongst both non-linguistic and linguistic signs, some visual signs are representations of the world—e.g., cave paintings and pictograms, respectively—and it is, of course, not surprising that these visual signs look like nature. It would be surprising, however, to find that non-pictorial visual signs look, despite first appearances, like nature. Although writing began with pictograms, there have been so many mutations to writing over the millenia that if writing still looks like nature, it must be because this property has been selectively maintained. For non-linguistic visual signs, there is not necessarily any pictorial origin as there is for writing, because amongst the earliest non-linguistic visual signs were non-pictorial decorative signs. The question we then ask is, Why are non-pictorial visual signs shaped the way they are?

Previous efforts at answering this question have primarily concentrated on the differences. In particular, some of the shape differences among different (non-pictorial) visual signs are due to the kind of writing implement used, whether impressions in clay tablets with a blunt reed, rounded writing on leaves, or the physical details of a modified feather-tip point. Little attention has been devoted to uncovering the similarities, however, and as we will see here, there are deeper visual regularities that hold across human visual signs, independent of the writing mechanism (regularities that are also found in nature). It is as if someone had noticed that throat size causes male and female voices to sound differently, without noticing that male and female speech possesses a critical deeper regularity, namely that they utter the same set of phonemes, morphemes, words and sentences as one another (within a single language speaking community). We will find that, despite superficial differences in their shapes, visual signs appear to possess similar underlying “visual phonemes.”

The Shapes of Visual Signs

Uncovering deeper visual regularities that might govern visual signs is crucial in any attempt to explain why visual signs are shaped as they are, and, in turn, to explain why we are so good at reading. After all, we cannot explain why visual signs are shaped as they are if we do not first determine how visual signs over history are, in fact, shaped! A difficulty in trying to find such regularities is that it is not straightforward to describe how even a single letter is shaped, for a single letter can undergo considerable distortion (e.g., from person to person, or from font to font) without losing its identity. How can one hope to scientifically address the kinds of shapes found among visual signs, when it is awkward to even rigorously say what the shape of a single letter is?

To solve this problem I decided to use a topological notion of shape, where the details of the geometry do not matter, and what matters is only the manner in which strokes intersect, or join, with other strokes. A straight line, a C and an S have the same topological shape because each is topologically just a single stroke. L, T and X are the three distinct kinds of topological shape having two strokes. For example, a V has the same topological shape as an L because each consists of two strokes meeting at their endpoints. This notion of shape will be helpful later in measuring the shapes of nature, because while geometrical shape can change quickly as a function of a person’s viewpoint, topological shape is more viewpoint invariant, providing a more robust characterization of the shapes in nature. This topological notion of shape is not merely useful, but possesses psychological justification as well: experts in psychology (e.g., Irving Biederman’s work on intermediate-level representations) and computer vision believe that our visual systems may represent shape in a topological manner.


In earlier research I had shown (along with my collaborator Dr. Shinsuke Shimojo) that letters have on average three strokes, and this average does not vary as a function of the number of letters in the writing system. Because of this, I considered topological shapes with three or fewer segments, in particular the 36 topological shapes that can be drawn with three straight lines (even though each topological shape covers curvy geometrical shapes as well). In addition to a single-stroke, and L, T and X, there are five three-stroke configurations having a single junction (i.e., a single point of intersection of the strokes) exemplified by Y, K and Y. There are 11 configuration types having three segments and two junctions, exemplified by characters such as ] (or, equivalently, Z), 1, F, I, p, and ≠. Finally, there are 16 topological shapes with three segments and three junctions, such as D and A.

With these 36 kinds of topological shape primitive in hand, we (Dr. Shinsuke Shimojo, and two Caltech undergraduate students, Qiong Zhang and Hao Ye) set about rigorously measuring how common these shapes occur among visual signs. We began by measuring from three distinct classes of non-pictorial visual sign: phonemic writing systems (non-logographic), Chinese characters (logographic), and non-linguistic symbols. The set of phonemic letters were taken from about one hundred phonemic writing systems over history, and the topological shape of the entire letter was measured (if it was one of the 36 types in our repertoire). For Chinese characters and non-linguistic symbols, the signs typically have more than three strokes, and we measured all the topological shapes that occur as part of the whole sign.

What we discovered is that the shapes across these three very different kinds of visual sign are similar. For example, Ls and Ts are in each case common, but Xs rare. And across the 32 different kinds of topological shape with three segments, these three classes of visual sign highly correlate with one another. For example, Ys tend to be common relative to Õs, Zs and Fs more common than1s, and Hs more common than ps. That is, despite the seemingly unrestrained variability in shape among these visual signs, they in fact possess a similar topological shape “signature.” Now we are in a position to more meaningfully ask why visual signs are shaped as they are. Namely, why do visual signs have this signature?


They don’t get this signature by chance. For example, if one were to randomly place strokes onto the writing surface, the most common two-segment topological shape would be X. Ts would be rarer because they require a coincidental alignment of one endpoint along the edge of another. Ls, in turn, are even rarer because they require the double-coincidence of two endpoints touching. Among the topological shapes with two or three junctions, the shapes with more Xs will be more common in a randomly generated sign, and the shapes with more Ls the rarest; e.g., ≠ is the most common topological shape with two junctions, and Z the least common. This is not at all the case for the visual sign signature, where Ls and Ts are more common than X, and where, for example, ≠ is actually much rarer than Z. Another mechanism for the random generation of visual signs would be the act of scribbling, which is similar to the random-stroke case just mentioned, except that for scribbles Ls are now common, not rare. That is, for scribbles Ls and Xs are much more common than Ts, leading to a distribution of topological shapes unlike that of human visual signs.

[Figure 4 to be put near here.]

Designed for Reading or Writing?

Thus far, we have seen that human non-pictorial visual signs appear to possess a characteristic signature, and we have seen that this signature is not a result of chance. Before attempting to explain this signature, a natural first question is, Does this signature appear to be good for the eye, or good for the hand (or any other writing mechanism)?

There are at least two reasons for expecting that visual sign shapes are designed (by cultural selection) for ease of reading, not ease of writing. First, visual signs are written once, but can be read many times. Second, writing speed is typically limited not by the motor system, but by the time taken for the writer to compose the sentence; that is, writing is not like talking, where we can talk effortlessly without feeling as if we are composing our thoughts.

Shorthand is an example kind of visual sign that violates both of these reasons—it is typically not read more than once, and it is written without the writer having to compose the sentences (instead, the boss is orally dictating). Accordingly, shorthand is designed for the hand at the expense of the eye. We measured the topological shapes across six different shorthand writing systems, and found that their topological shapes are radically different from that found in visual signs more generally.

In contrast, consider trademark logos, which are designed to be seen at the expense of being written (they are, in fact, typically not written at all). We discovered that trademark logos possess the same shape signature found in visual signs.

That is, when we look at signs we know are designed for the eye at the expense of the hand, the signature matches the general signature we saw earlier, but when we look at signs we know are designed for the hand at the expense of the eye, the signature is altogether different.

As further support for this, we found that the visual sign shape signature correlates well with the number of angles in the shape (a measure of visual complexity), but does not correlate at all with the number of hand motions required to write the topological shape (a measure of motor complexity).

Together this makes a strong argument that the topological shapes of visual signs have been selected for reading, not writing.

Natural to the Eye

The topological shapes of non-pictorial visual signs are, then, for the eye, not the hand. But we are still left with the question, Why does the eye like these shapes? Here is where the evolutionary, or ecological, hypothesis enters into the story. Because over millions of years of evolution our visual systems have been selected to be good at processing the conglomerations of contours occurring in nature, I reasoned that if visual signs have culturally evolved to be easy to see, then we should expect visual signs to have natural topological shapes.


Where are these topological shapes in nature? What were conglomerations of strokes for visual signs are now conglomerations of contours for natural scenes. Contours are the edges of objects (as seen by the eye), not, of course, strokes in the world. For example, an L occurs in the world when exactly two edges of an object meet at their endpoints, like an elbow. A T occurs in the world when the edge of an object goes behind another object in the foreground. A Y occurs, for example, at the inside corner of a rectangular room. We measured how common these and the other topological shapes occur in natural scenes, and were stunned to find that nature possesses the shape signature we saw earlier for visual signs. That is, visual signs are shaped like nature, confirming our ecological hypothesis for the shapes of visual signs.

If visual signs look like nature, one might first suppose that the shape signature of nature depends significantly on which natural environment one considers. However, to our surprise, we found that the shape signature is highly robust, differing hardly at all whether we measured images of ancestral environments (e.g., tribal villages, savannas) or urban environments (buildings, walkways). Because of the robust topological notion of shape we used in our analysis, any environment with opaque objects strewn about will tend to have the same shape signature. This underlies why the diverse kinds of visual sign have a similar signature despite the diverse environments from which they spring, and one may speculate that aliens might for this reason possess visual signs that look reminiscent of our own.

changizi_sciblog_topographyOfLanguage_figs_Page_07We have been considering visual signs generally, but let us now specifically consider letters in phonemic writing system, for there is an additional question one might have about letters. We saw a moment ago that letters look like natural object junctions. Our ecological hypothesis expects letters to look natural, but why natural junctions? Why not have letters shaped like natural single contours? Or, alternatively, why not have letters shaped like whole objects? Instead of one stroke or a dozen strokes, letters in fact tend to have about three strokes (independent of the size of the writing system), and thus are at an intermediate level between edges and objects.

The answer may lie in the following pair of facts: (i) we wish to read words, not letters; and (ii) we have evolved to see objects, not object-junctions. In this light, we expect culture to select words to look like objects, so that words may be processed by the same area in visual cortex responsible for recognizing objects. Logographic characters (e.g., Chinese) and non-linguistic symbols do tend to be more object-like, possessing many more than three strokes. For phonemic writing, however, there are severe limits to how closely words can match natural objects, for the manner in which letters combine is determined by speech. However, by having letters shaped like natural object-junctions—rather than natural contours or natural whole objects—written words become combinations of natural junctions, and thus more similar to objects and more easily processed by our visual system.


Evolution by natural selection is too slow to design our brains for reading, and so cultural selection has come to the rescue, designing (without any designer) visual signs for our brains. Because our visual systems have evolved to be good at perceiving natural objects, cultural evolution has created non-linguistic symbols, logographic symbols, and written words in phonemic writing that tend to be built out of object-junction-like constituents, and are thus object-like. In particular, this explains why letters tend to have around three strokes and have the topological shapes they do. We expect that these insights will be useful in designing optimal alphabets or visual displays.

Because culture is capable of designing for the eye, the visual signs of our culture are a fingerprint of what our visual systems like. Akin to the linguistic study of the auditory productions humans make, the “visual linguistic” study of the visual productions people make is a currently under-utilized tool for vision research. There is every reason to believe that the study of visual linguistics will aid traditional lab experiments on vision and brain design as much as linguistics has supplemented lab experiments on cognition.

changizi_sciblog_topographyOfLanguage_figs_Page_09Mark Changizi is a professor of cognitive science at Rensselaer Polytechnic Institute. This research – and other work of his on the evolution of color, illusions and stereo vision – are the topic of his new book, The Vision Revolution (Benbella Books).

[A relevant ScienceDaily piece.]

Short Bibliography:

Biederman I & Cooper EE (1991) Priming contour-deleted images: evidence for intermediate representations in visual object recognition. Cognitive Psychology 23: 393–419.

Changizi MA & Shimojo S (2005) Character complexity and redundancy in writing systems over human history. Proceedings of the Royal Society of London B 272: 267-275.

Changizi MA (2006) The optimal human ventral stream from estimates of the complexity of visual objects. Biological Cybernetics 94: 415-426.

Changizi MA, 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: E117-E139.

Changizi MA (2009) The Vision Revolution (Benbella Books, Dallas).

Daniels PT & Bright B (1996) The World’s Writing Systems. New York: Oxford University Press.

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By Mark Changizi   

As a young man I enjoyed listening to a particular series of French instructional programs. I didn’t understand a word, but was nevertheless enthralled. Was it because the sounds of human speech are thrilling? Not really. Speech sounds alone, stripped of their meaning, don’t inspire. We don’t wake up to alarm clocks blaring German speech. We don’t drive to work listening to native spoken Eskimo, and then switch it to the Bushmen Click station during the commercials. Speech sounds don’t give us the chills, and they don’t make us cry – not even French.


But music does emanate from our alarm clocks in the morning, and fill our cars, and give us chills, and make us cry. According to a recent paper by Nidhya Logeswaran and Joydeep Bhattacharya from the University of London, music even affects how we see visual images. In the experiment, 30 subjects were presented with a series of happy or sad musical excerpts. After listening to the snippets, the subjects were shown a photograph of a face. Some people were shown a happy face – the person was smiling – while others were exposed to a sad or neutral facial expression. The participants were then asked to rate the emotional content of the face on a 7-point scale, where 1 mean extremely sad and 7 extremely happy. 

The researchers found that music powerfully influenced the emotional ratings of the faces. Happy music made happy faces seem even happier while sad music exaggerated the melancholy of a frown.  A similar effect was also observed with neutral faces. The simple moral is that the emotions of music are “cross-modal,” and can easily spread from sensory system to another. Now I never sit down to my wife’s meals without first putting on a jolly Sousa march.

Although it probably seems obvious that music can evoke emotions, it is to this day not clear why. Why doesn’t music feel like listening to speech sounds, or animal calls, or garbage disposals? Why is music nice to listen to? Why does music get blessed with a multi-billion dollar industry, whereas there is no market for “easy listening” speech sounds?

In an effort to answer, let’s first ask why I was listening to French instructional programs in the first place. The truth is, I wasn’t just listening. I was watching them on public television. What kept my attention was not the meaningless-to-me speech sounds (I was a slow learner), but the young French actress. Her hair, her smile, her mannerisms, her pout… I digress. The show was a pleasure to watch because of the humans it showed, especially the exhibited expressions and behaviors.

The lion share of emotionally evocative stimuli in the lives of our ancestors would have been from the faces and bodies of other people, and if one finds human artifacts that are highly evocative, it is a good hunch that it looks or sounds human in some way.

…continue reading at Scientific American

Mark Changizi is Professor of Cognitive Science at RPI, the author of The Vision Revolution (Benbella, 2009) and The Brain from 25,000 Feet (Kluwer, 2003).

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