The eyes are one of the most amazing parts of the human body. Our eyes can perceive the ruby tones of a pomegranate, gaze up to the peak of Mount Everest, and follow speeding cars quickly enough to protect us as we cross the road. Though we do not always fully appreciate these abilities, a moment of thought reveals how extraordinary they are. Dr. Mark Changizi, Assistant Professor of Cognitive Science at Rensselaer Polytechnic Institute, goes a step further than simply thinking our eyes are remarkable. In his book. The Vision Revolution: How the Latest Research Overturns Everything We Thought We Knew About Human Vision, he compares four different aspects of our vision to four “superpowers,” shifting the lens for how we normally think about the human eye.
Changizi first discusses our ability to understand people’s emotions through changes in their facial color, a superpower he refers to as color telepathy. The need for this skill is one reason the author argues we have color vision at all: to easily observe the small changes in skin color, such as blushing, that reflect shifts in mood. While this claim is intriguing, Changizi’s evidence is often heavily anecdotal. For example, he writes that human skin is uniquely colorless, but explains this mainly by citing the lack of a word to describe the color “skin” in many languages. A full-color insert of figures and illustrations compensates in part for this shortcoming, however, and keeps the section entertaining.
In addition to color telepathy, Changizi also asserts humans have a form of X-ray vision ability. To see this ability in action, spread out your fingers: hold up your hand, and try looking past your hand with one eye closed, then the other. What you see is, obviously, much less than when both eyes work together. According to Changizi, this is what real X-ray vision is. Overall, this chapter is stronger than the first, continuing to include engaging asides while also referencing scientific studies to support the argument. Therefore, when the author claims that the advantage of seeing through clutter was the main driver of the evolution of our binocular vision, his argument feels more substantial.
The third chapter of the book deals with future-seeing, a fascinating explanation of why optical illusions work. True to the opening paragraph, illustrations of optical illusions are scattered throughout the chapter, maintaining the reader’s interest and demonstrating an effect of future-seeing. Changizi explains that our brains are constantly creating a perception of the future simply to keep up with the present moment, because of the time it takes to process visual input. To tie this theory back to the entertaining illusions, he suggests that they occur because we think the images are dynamic. As a result, our brains attempt to construct a future appearance that clashes with the static nature of the image. This section is perhaps the most successful in balancing entertainment with scientific thinking, because of the natural pairing of the optical illusions and future-seeing.
Spirit-reading, our last superpower, centers on an aspect of vision that is uniquely human: the ability to read. Many of us have struggled to perfect our nearly illegible handwriting, but perhaps fewer have wondered why letters look the way they do. Changizi suggests that letters model shapes found in nature in a way that makes them easy for our eyes to recognize. He found a strong correlation between the frequency of particular junctions in the natural world and the frequency of use for letters with similar-shaped junctions. For example, corners are easy to find, and so are Ls; on the other hand, crosses occur rarely, and so does the letter X. As one of the most technical chapters, the disconnect in this section between the scientific content and slightly artificial superpower terminology can be jarring, but the strength of the researched ideas makes it worth reading.
Overall, though the superpower theme can occasionally feel gimmicky, Changizi does an excellent job of writing about vision in an accessible way. The casual tone, frequent anecdotes, and informative illustrations make potentially complicated ideas easy for anyone to handle. Though the more scientific reader may be frustrated by the basic level from which he approaches his subject, his intriguing theories nonetheless give us a fresh perspective on how we see the world.