Although many neuroscientists are trying to figure out how the brain works, Mark Changizi is bent on determining why it works that way. In the past, the assistant professor of cognitive science at Rensselaer Polytechnic Institute has demonstrated that the shapes of letters in 100 writing systems reflect common ones seen in nature: Take the letter "A"—it looks like a mountain, he says. And "Y" might remind one of a tree with branches. He also showed that across different languages most characters take three strokes to write out. That's because, he says, three is the highest quantity a person's brain can perceive without resorting to counting. But Changizi's theories aren't limited to writing. He also believes that primates developed the ability to see in color so that they could figure out if peers were sending emotional cues. He hatched that theory by comparing the light wavelengths given off by the facial skin of someone blushing to that of a person not flushed. The prolific Changizi recently published two papers: one that sets out to explain how our lexical systems evolved and another that suggests how the brain's visual system is adapted to anticipate the future a fraction of a second before we actually see it. (See related slideshow here.) Changizi spoke to ScientificAmerican.com about his newest research; what his forthcoming book, The Vision R(evolution): How the Latest Research Overturns Everything We Thought We Knew About Human Vision, has to do with superheroes; and what kind of scientist he is.

What's the goal of your research?
My goal is to understand the principles underlying the design of the brain or visual system or cultural artifact, like language or writing systems. I'm not as interested in the mechanisms per se. People like me make the point that you can't even study those mechanisms without having an idea what those mechanisms are trying to compute. So you have to have some opinion about what the design or function of those mechanisms are for to even do that. So, I am focusing on the function from a teleological [purposive] point of view. Of course it's unpacked with natural selection or cultural evolution.

Are you characterizing the functions of certain systems, so that other researchers can work on how a system performs its tasks?
It's certainly a consequence of my work that someone else will be in a better position to pose mechanisms when they know the big constraint of: "What is it that my mechanisms need to be computing?" But, that's not why I do it. I'm excited about the selection pressures undergoing why we see in color: What is color for? What is it optimized for? Only 1 percent of me is interested in the fact that it's implemented in the particular way it's implemented in some part of the brain. ... [My work] often makes some predictions about specific aspects of the mechanisms, but once that information is there, there could be infinitely many mechanisms that could carry out that function.

One of your more recent papers deals with the Oxford English Dictionary as an economically organized collection of the words in the English language? What is it about its organization that makes it so optimal?
If you gave definitions of all the words on the basis of some small set of atomic words, then you would have two levels of words: the bottom level, [a] small set of atomic words (between 10 and 50) and the other, roughly 100,000. That would be a very costly dictionary in terms of the size that's required. The signature of an optimally organized lexicon is: you instead take that small set of words and you use them to find a slightly larger set of slightly more complicated words, which are in turn used to build a slightly larger set of still more complicated words and so on. When you do that seven times, or so, that will then allow you to utilize the minimum amount of definition space to find the target words that you are really interested in defining in the first place.

6 Comments

1. 1. ReTech 09:05 PM 6/1/08

   I've gotta call snake oil on this one. The Changizi all appear as just what they are to me. Nothing bulges, nothing moves. I suspect he got a big grant to make them and just 'cuz he says that's what ppl are supposed to see, they do. So, perhaps, he won a grant on the power of suggestion, not illusion? Mark, go to night school and get better photoshop skills if you're going to continue with this, I found your illusions passe and your theories on color a bit protracted.

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2. 2. juankr 07:56 PM 6/8/08

   You possibly not up to the end are of value the work performed by you. Nevertheless, your article as is impossible by the way. Also it is very well put in the concept developed by me. Possibly, subjects of my site (http://www.spast.ru), on which work is presented (http://www.spast.ru/book/Inform/Inform.htm), can seem to you a little attractive if you wish to familiarise with it. Nevertheless, it is very pleasant, that in the future works to me on whom will refer.... Instead of to convince only to the thoughts. Your experience is important, not only for me but also for a science as a whole.
   By the way, whether you studied this mechanism at primacies? I think, that degree of a prediction at them should be even above, than at the person - using and other more developed mechanisms.
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3. 3. Steven Douglas 06:54 AM 8/25/08

   It's not snake oil. If done right, the brighter center should appear to expand outward in brightness. But this is also not an illusion. The nearer an object is, the brighter it is, and vice versa. Light waves, like gravity, are proportional to the square of the distance from one point to another. As you approach a point source of light, the number of photons reaching your eye from that given point increases as well. The only illusion, if it could be called that, comes from the fact that there is a gradation. In that respect it works like Christmas chase lights, because our eye will follow a single shade or color as if it were a fixed object. In this case, it's neighboring shades that are changing, which makes one ring appear to "move" outward as our eyes rapidly (and PHYSICALLY) approach.
   Incidentally, a simple zooming animation (wherein all the shades remain constant, but we make them larger), will not produce the same effect, because there must be a physical separation. A camera panning (not zooming, but actually moving) quickly to or away from this piece (on computer or paper) will produce the same effect.

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4. 4. Steven Douglas 07:16 AM 8/25/08

   Incidentally, image 6 of 10 has the same root explanation as the sphere with the center that appears to brighten outward upon a fast head bob forward, or physical approach of the eyes.
   
   The reason the lighter part of the rectangle appears tilted toward us is because this really is how light from physical objects works. As you approach a point source of light, the number of photons reaching your eye from that given point increases as well. Thus, we know on some level, (regardless of whether it is conscious or unconscious, the physics remains the same) that an object of uniform shade and hue will be "dimmer at a distance", and relatively brighter up close.
   
   This is similar to the "illusion" of 3D borders in windows. On your screen, look at any button or 3D frame, or your slider bar to the right of this page (assuming yours is 3D). The left and top edges will be light, and the right and bottom will be dark. That makes it come "out" at you. If you reverse this, the object will appear to be sunken in. The left or right components are really arbitrary, and can be shifted. It's the top and bottom edges that produce the illusion. Why? Since 99.99% of our direct lighting comes from above, our brains have come to expect this, and interpret objects accordingly.
   
   

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5. 5. sunnystrobe 11:36 PM 7/9/10

   Your theory, Mark, makes me blush! It is from a typically male perspective, because it leaves out the main evolutionary root of our colour vision: FOOD foraging! Which, for our nimble-fingered primate forefathers, must have been fruits & berries and the like, up in those ancestral trees! Females may well have been the main fruit pickers, and their much higher colour sensitivity bears witness to this survival factor. (Colour blindness is twenty times more common in males, who, in Neandertal times, found their own survival niche through hunting, when there was not much fruit picking possible, due to the Ice Ages.)
   I am constantly amused when I watch men at parties eating nothing but brownish-black meat slabs, thereby avoiding essential phytonuntrients from plant pigments. Eating a salad is considered 'unmanly'! Only when prostate cancer often strikes in middle age, tomato red lykopene seems to get back into the picture...
   For a science-based , yet light-hearted approach to our daily diet, view Colour Eating on youthevity.com

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6. 6. KennedyDA 03:57 PM 7/26/10

   "demonstrated that the shapes of letters in 100 writing systems reflect common ones seen in nature: Take the letter "A"it looks like a mountain, he says. And "Y" might remind one of a tree with branches. He also showed that across different languages most characters take three strokes to write out. That's because, he says, three is the highest quantity a person's brain can perceive without resorting to counting."
   
   Firstly, writing systems arose using the rebus principle whereby pictures of natural things were selected to represent sounds that were similar to their names in language. It was not so much the selection of natural forms per se but the phonographic rebus principle that drove the use of pictures, and the fact that only natural forms can be depicted by pictures. All current writing systems evolved by graphical simplification of the pictures.
   
   If you look closely you will see that the letters of the Roman and modern alphabets now bear almost no resemblance to pictures. Their linear forms arise from the execution of writing, simplicity for economy and most of the remaining attributes of shape arise logically from the simplest kinds of distinguishable graphical features.
   
   Graphical features that arise for perceptual facility include symmetry and orientation to the horizontal and vertical axes.
   
   I have this all worked out logically and you do not need to do any experiments.

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