THEORETICAL NEUROBIOLOGIST: In his work, Mark Changizi attempts to determine why our brain works the way it does.
COURTESY OF RENSSELAER POLYTECHNIC UNIVERSITY

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.