Outstanding scientific yet understandable book about human vision

Magic Eye, Indeed!! | The Vision Revolution: How the Latest Research Overturns Everything We Thought We Knew About Human Vision | Mark Changizi

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	• The Vision Revolution: How the Latest Research Overturns Everything We Thought We Knew About Human Vision Mark Changizi BenBella Books, 2010 - 240 pages average customer review:based on 8 reviews view larger image
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highly recommended

From Evolution to Abstraction

Mark Changizi's application of evolutionary biology to the analysis of vision is brilliant and provocative. As an art historian, I am particularly interested in the chapters on "Color Telepathy" and "Spirit-Reading." Of course, color is a central concern in art history, but I was also fascinated by Changizi's argument for the centrality of flesh color to our perception of color in general. It recalls a passage from the Romantic critic William Hazlitt's essay, "On Gusto," about the variegated flesh color in Titian. Analyzing flesh color in real life, Changizi points out how much it changes from moment to moment, depending on blood, oxygenation level, and emotional states, notwithstanding the fixed amount of pigmentation.

His discussion of contours and combinations of contours as models for written signs is equally fascinating. Here, he sets off speculation about two issues. Is the basic repertory of signs for contours related in any way to the neural wiring of the retina and the brain, which preferentially recognizes certain shapes and alignments: horizontals, verticals, diagonals (as per the pioneering research of David Hubell & Margaret Livingstone)? And could this "machine code," so to speak, of vision be related to abstract forms in art? This last question is of particular interest in relation to Cubism and abstract painting. Perhaps their basic vocabulary is in some way related to the "natural" structure of vision.

A book that constantly provokes new reflections, not just about vision, but about life and culture.

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Outstanding scientific yet understandable book about human vision

If you were to do nothing more than glance at the chapter names, you would consider this book to be a collection of occult dung powder. Old, stale, and reworked so often that it is dried up. The chapter titles are:

*) Color telepathy
*) X-ray vision
*) Future-seeing
*) Spirit-reading

However, that first impression would be a significantly wrong impression, Changizi has written such a fascinating and scientifically sound book that it remains interesting, even when you disagree with his conclusions.
The chapter "Color telepathy" describes how humans are often able to "read" a person's thoughts and diagnose the state of their health by interpreting slight changes in skin color due to the level of oxygenation in the blood. In this area, his reasoning is sound and Changizi points out that colorblind doctors have been demonstrated to be at a significant disadvantage when attempting to visually diagnose a patient. Where his reasoning breaks down is when he argues that Homo sapiens evolutionarily acquired color vision so that they could use changes in skin color to learn what other people were thinking. In my opinion, this position is untenable.
In general, predators try to blend into the environment as much as possible so that they can get as close as possible before they move in for the kill. Having an acute sense of color vision would allow the relatively defenseless human to spot the stalking predator much earlier than if they were colorblind. Although Changizi's position has some merit, the value of color vision in spotting predators is a much stronger argument for it being evolutionarily selected.
The chapter "X-ray vision" has nothing like the powers of Superman to see through solid objects, the point is quite different. In this context x-ray vision is a consequence of having two eyes with some distance of separation between them, allowing for the brain to receive two offset images. A consequence is that if a sufficiently slim object obstructs your view, while one eye may not be able to see a segment of the visual field, the other eye can, allowing you to "see through" the object. Changizi also convincingly argues why humans and other creatures evolutionarily kept both eyes pointing forward, gaining stereovision when looking forward while losing some ability to see behind them.
Chapter 3, "Future-seeing" is not ESP-style precognition but the processing similar to what we do when we catch a ball. As we prepare for the catch, our minds generate a prediction where the ball will be when it arrives, in other words we must compute the future position of the object. Several years ago, I read a book about baseball where it was stated that when a baseball is pitched at 90 miles per hour, it is physically impossible for the human eye to follow the trajectory for the last several feet. To hit the ball the batter must compute the best estimate as to where the ball will be when it crosses home plate.
In chapter four, "Spirit-reading", the author describes the role of written language, how it was developed and how it is used by the dead or otherwise distant to communicate detailed information to others. Once again, Changizi's analysis is sound; his description of minimal strokes and more complex ideograms as methods of communication was easy to follow and convincing.
It is clear that Changizi is an expert on the concept of how humans use vision to understand their literal place in the world and cope with the dynamic nature of their environment. As optical illusions demonstrate, human vision is a very complex apparatus and in this book Changizi clarifies a great deal in language that is accessible to everyone.

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Magic Eye, Indeed!!

Changizi has a light & amusing style, so that one might at first, undervalue him. But noting the citations & reference, plus doing the exercises he mentions, show one that the eye-ball is even more magical than one has ever imagined.

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Exploring, interpreting eye-brain synergy

Human brain has picked, in terms of senses, vision to be its favorite - if you consider the number of neurons connected. Perhaps it is the complexity of image processing that requires such tight coupling or perhaps the evolutionary trends on this lane determined that vision could be the deciding factor in spotting opportunities and danger, getting killed or staying alive. Or perhaps both evolutionary and computational needs converge at the eye-brain integration.

I wish the font of the book (printed edition) was better and was more evenly spaced -which would have made for a better reading experience. Also, the author would have reached a lot more mainstream audience by making the style more conversational - as he does in some sections later in the book (see "My Supercomputer Is Running Slowly" in the "Future-Seeing" chapter) but not early enough. Such changes would have catapulted this book to the "Freakanomics - Outliers" level. These, though, are relatively minor points when you think about the expanse of topics presented in this book and great care given to the color pictures, photographs, charts and other artifacts.

This book is both interesting and educational and provides an optimistic note in the realm of vision research, especially for anyone frustrated with funding cutbacks in such research areas. There are many practical applications that can be drawn from this book and the work highlighted and recommend this book highly.

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Changizi is a genius, but this book is not for everyone

Changizi is undoubtedly a genius, and he writes well, being particularly adept at analogies. Still, Changizi is detailing all the evidence for his conclusions, and some of it is not very interesting.

The most unintuitive conclusion is that our eyes have evolved to detect small variations in flesh color. Yet Changizi is very convincing, particularly because of Figures 14 and 15, which show that 2 of our color cones detect almost the same wavelengths, specifically the wavelengths needed for detecting small variations in flesh color! It is not clear whether this adaptation is primarily for detecting illness, or a person's true emotion, but I would have to go with the latter, and therefore this finding supports those evolutionists who emphasize social interaction as a primary driver in human evolution.

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In The Vision Revolution: How the Latest Research Overturns Everything We Thought We Knew About Human Vision, Mark Changizi, prominent neuroscientist and vision expert, addresses four areas of human vision and provides explanations for why we have those particular abilities, complete with a number of full-color illustrations to demonstrate his conclusions and to engage the reader. Written for both the casual reader and the science buff hungry for new information, The Vision Revolution is a resource that dispels commonly believed perceptions about sight and offers answers drawn from the field?s most recent research.

Changizi focuses on four “why? questions:
1. Why do we see in color?
2. Why do our eyes face forward?
3. Why do we see illusions?
4. Why does reading come so naturally to us?

Why Do We See in Color?
It was commonly believed that color vision evolved to help our primitive ancestors identify ripe fruit. Changizi says we should look closer to home: ourselves. Human color vision evolved to give us greater insights into the mental states and health of other people. People who can see color changes in skin have an advantage over their color-blind counterparts; they can see when people are blushing with embarrassment, purple-faced with exertion or the reddening of rashes. Changizi?s research reveals that the cones in our eyes that allow us to see color are exquisitely designed exactly for seeing color changes in the skin. And it?s no coincidence that the primates with color vision are the ones with bare spots on their faces and other body parts; Changizi shows that the development of color vision in higher primates closely parallels the loss of facial hair, culminating in the near hairlessness and highly developed color vision of humans.

Why Do Our Eyes Face Forward?
Forward-facing eyes set us apart from most mammals, and there is much dispute as to why we have them. While some speculate that we evolved this feature to give us depth perception available through stereo vision, this type of vision only allows us to see short distances, and we already have other mechanisms that help us to estimate distance. Changizi?s research shows that with two forward-facing eyes, primates and humans have an x-ray ability. Specifically, we?re able to see through the cluttered leaves of the forest environment in which we evolved. This feature helps primates see their targets in a crowded, encroached environment. To see how this works, hold a finger in front of your eyes. You?ll find that you?re able to look “through? it, at what is beyond your finger. One of the most amazing feats of two forward-facing eyes? Our views aren?t blocked by our noses, beaks, etc.

Why Do We See Illusions?
We evolved to see moving objects, not where they are, but where they are going to be. Without this ability, we couldn?t catch a ball because the brain?s ability to process visual information isn?t fast enough to allow us to put our hands in the right place to intersect for a rapidly approaching baseball. “If our brains simply created a perception of the way the world was at the time light hit the eye, then by the time that perception was elicited—which takes about a tenth of a second for the brain to do—time would have marched on, and the perception would be of the recent past,? Changizi explains. Simply put, illusions occur when our brain is tricked into thinking that a stationary two-dimensional picture has an element that is moving. Our brains project the “moving? element into the future and, as a result, we don?t see what?s on the page, but what our brain thinks will be the case a fraction of a second into the future.

Why Does Reading Come So Naturally to Us?
We can read faster than we can hear, which is odd, considering that reading is relatively recent, and we?ve evolved to process speech for millions of years. Changizi?s research reveals that language has been carefully designed to tap in to elements of the visual processing center that have evolved for tens of millions of years. Visual signs of all languages are shaped like objects in nature, Changizi says, because we have evolved to see nature easily. “People have noticed letters in nature for some time, and there are artists who have a spent a lot of time photographing Latin letters in natural scenes or on butterfly wings,? Changizi says. “For example, if you look at an upper corner of the room you are in, you will see three contours meeting at a point, making a shape close to that of a ‘Y.?“ The Vision Revolution expands upon how our ancestors found the shapes of Latin letters and delves into how visual signs can have similar shapes even though their inspirations come from very different environments.

In addition to these four areas, The Vision Revolution explores other phenomena such as cyclopses, peeking and many more you hadn?t even thought to wonder about. Changizi shows how deeply involved these evolutionary aspects of our vision are in why we see the way we do—and what the future holds for us.

“…to understand how culture interacts with vision, one must understand not just the eye?s design, but the actual mechanisms we have evolved,? Changizi says, “for culture can tap in to both the designed responses of our brains and the unintended responses.?

The Vision Revolution is a book that finally gives attention to what before has been largely neglected by other works on human vision—a book that looks at the “why.?

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