Mark Changizi
About Mark Changizi
Speech topics
YOUR SUPERPOWERS OF VISION
Mark Changizi, prominent neuroscientist and vision expert, addresses four areas of human vision and provides explanations for why we have those particular abilities, dispels commonly believed misperceptions about sight, and offers answers drawn from the field's most recent research.
Changizi focuses on four "why" questions:
- Why do we see in color?
- Why do our eyes face forward?
- Why do we see illusions?
- 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. Changizi shows that writing culturally evolved over time to look like something we’re already brilliant at recognizing: letters came to look like nature, thereby “tricking” our visual object recognition brains into becoming a reading machine, fundamentally changing what it meant to be human.
Books by Mark Changizi
“Expressly Human” (2022)
Over billions of years of evolution, animals have become increasingly sophisticated and increasingly sentient. In the process, they evolved emotions, which helped improve their odds of survival in complex situations. These emotions were, at first, purely internal. But at some point, social animals began expressing their emotions, in increasingly dramatic ways. These emotional expressions could accurately reflect internal emotions (smiling to express happiness)—or they could be quite different (smiling to cover up that you’re actually furious, but can’t tell your boss that). Why did once-stone-faced animals evolve to be so emotionally expressive—to be us? The answer, as evolutionary neurobiologist Mark Changizi and mathematician Tim Barber reveal, is that emotional expressions are our first and most important language—one that allows us, as social animals, to engage in highly sophisticated communications and negotiations. Expressly Human introduces an original theory that explains, from first principles, how the broad range of emotional expressions evolved, and provides a Rosetta Stone for human communication. It will revolutionize the way you see every social interaction, from deciding who gets the last slice of pizza to multimillion-dollar business negotiations, and change your definition of what makes us human.
“Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man” (2011)
The scientific consensus is that our ability to understand human speech has evolved over hundreds of thousands of years. After all, there are whole portions of the brain devoted to human speech. We learn to understand speech before we can even walk, and can seamlessly absorb enormous amounts of information simply by hearing it. Surely we evolved this capability over thousands of generations. Or did we? Portions of the human brain are also devoted to reading. Children learn to read at a very young age and can seamlessly absorb information even more quickly through reading than through hearing. We know that we didn't evolve to read because reading is only a few thousand years old. In Harnessed, cognitive scientist Mark Changizi demonstrates that human speech has been very specifically “designed" to harness the sounds of nature, sounds we've evolved over millions of years to readily understand. Long before humans evolved, mammals have learned to interpret the sounds of nature to understand both threats and opportunities. Our speech—regardless of language—is very clearly based on the sounds of nature. Even more fascinating, Changizi shows that music itself is based on natural sounds. Music—seemingly one of the most human of inventions—is literally built on sounds and patterns of sound that have existed since the beginning of time.
“The Vision Revolution: How the Latest Research Overturns Everything We Thought We Knew About Human Vision” (2010)
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.
“The Brain from 25,000 Feet: High Level Explorations of Brain Complexity, Perception, Induction and Vagueness (Synthese Library, 317)” (2003)
In The Brain from 25,000 Feet, Mark A. Changizi defends a non-reductionist philosophy and applies it to a variety of problems in the brain sciences. Some of the key questions answered are as follows. Why do we see visual illusions, and why are illusions inevitable for any finite-speed vision machine? Why aren't brains universal learning machines, and what does the riddle of induction and its solution have to do with human learning and innateness? The author tackles such questions as why the brain is folded, and why animals have as many limbs as they do, explaining how these relate to principles of network optimality. He describes how most natural language words are vague and then goes on to explain the connection to the ultimate computational limits on machines. There is also a fascinating discussion of how animals accommodate greater behavioral complexity. This book is a must-read for researchers interested in taking a high-level, non-mechanistic approach to answering age-old fundamental questions in the brain sciences.
At a glanceMark Changizi
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