Cognitive scientist Mark Changizi looks through our eyes into our brains, exploring how our visual system works and why it evolved the way it has. To do that, he digs into optical illusions, the shapes of letters, and even our brain's ability to "see into the future" by generating images one-tenth of a second before they actually happen, thereby avoiding the delay between "seeing" and perceiving something. Scientific American interviewed Changizi about his latest research and his forthcoming book, The Vision R(evolution): How the Latest Research Overturns Everything We Thought We Knew About Human Vision. The online article also features a fun slideshow of optical illusions. From Scientific American:
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…
In the new work, you were able to sort optical illusions into categories based on four visual features that were being misperceived. What particular features are those?
There are four different domains of misperception: The first is illusions of size. The second is illusions of speed. The third is luminance, or contrast. The last is illusions of perceived distance. Now, there are different ways of affecting those kinds of misperceptions–the key features that are causing those illusions. For example, size differences within your visual field could cause misperceptions or illusions of speed.
So, does this work fit in with your forthcoming book, The Vision R(evolution)?
The book is about four stories about four of the big areas of vision: The first is motion, which is this perceiving the present stuff; binocular vision, which concerns the evolution of forward-facing eyes; color and luminance, which is like the skin work; and object recognition–this is a little bit more of a stretch–but it connects to the evolution of writing and reading. The four areas all have an evolutionary side to them. Furthermore, they all have a superhero angle to them. You can describe the perceiving the present stuff as future-seeing. People have proposed superheroes that see the future and, in a weak sense, we do, too. For the evolution of forward-facing eyes, I am arguing that it is for a kind of x-ray vision. It actually allows us to see through stuff–like when you hold up a finger vertically and you see through it instead of beyond it. For animals that are large and living in forested environments, there should be selection pressure for forward-facing eyes, because you can actually see more of your environment. For color vision, the cones that we have in our eyes–that [other] mammals don't–are evolved to see the oxygenation modulations in the blood, because we want to sense the emotions in others. We really have external-sensing equipment that…[is]…empathic in nature–mind reading and emotion-reading, like the annoying character in Star Trek, the empath. A bit of a stretch of the theme is spirit-reading, our ability to read the thoughts of the dead. Object recognition (reading and writing) has allowed us to read the thoughts of the dead. So, it's four different stories connected by these kinds of themes.