The Vision Revolution: How the Latest Research Overturns Everything We Thought We Knew about Human Vision
by Mark Changizi. Benbella Books, 2009
Ever wanted to feel like a superhero—able to read people’s emotions, see through objects and predict the future? Well, you’re in luck. According to Mark Changizi in The Vision Revolution, you can already perform all these feats—thanks to the exceptional power of your two eyes.
Changizi, a cognitive scientist at Rensselaer Polytechnic Institute, approaches the field of vision from a different perspective than most scientists do: he is interested not in how our eyes work but in why they work the way they do. Why, for instance, did primates evolve color vision, whereas other animals did not? Changizi argues that color vision did not evolve to help us pick out edible leaves or fruits—a theory that has held ground for decades—but rather that we began to see greens, blues, reds and yellows because doing so helped us to distinguish among hues of skin. Skin color changes slightly when we are happy, angry, embarrassed or sick, and our primate ancestors’ ability to detect these subtle changes helped them socially.
In case overturning one venerable hypothesis isn’t enough, Changizi offers more: for instance, our eyes face forward to help us see “through” objects, he argues. The fields of vision from each of our eyes overlap, so one eye can sometimes see behind an object when the other eye cannot. This overlap allows us to see layers in front of us. What is more, our eyes predict the future, he says. Imagine a game of catch: by the time your eyes process the sight of a ball a meter away flying toward you, it will already have passed you. We tend, then, to perceive moving objects as farther along their trajectories than they really are—a quirk that explains why so many visual illusions work the way they do, Changizi suggests.
Throughout the book, Changizi peppers his explanations with quick, fascinating visual exercises that help to drive his points home; these exercises are useful because his writing ranges from clear and engaging (and even quite funny!) to dense and somewhat abstruse at times. And although Changizi’s ideas sound radical—they are—he bolsters his arguments with evidence from many disciplines, among them neuroscience, evolutionary biology, medicine and linguistics. Still, the book leaves the reader feeling skeptical: Changizi’s theories are appealing and logical, and he backs them with good circumstantial evidence; however, as with any evolutionary theorizing, the ideas are also nearly impossible to prove correct—or incorrect. One thing is certain: The Vision Revolution will make you wonder the next time you notice someone blush, catch a ball or finish reading a magazine page.