What do you see now when you look around the room after studying that final shrimp loaded with potential? Do you see a quaint and charming room? Do those stains on the floor remind you of the little boy and reinforce your impression that this is a special place to host a party? Are you in a beautiful place, physically and mentally? What are you likely to remember about your evening?
Finally, consider all of the things you didn't notice that night. Is it possible that Carol was there after all, only a dozen steps away, and you somehow missed her entirely? A famous 1999 Harvard research study performed by Christopher Chabris and Daniel Simons colorfully demonstrates this point. Chabris and Simons showed their research subjects a video of six people passing basketballs around, three wearing white shirts and three wearing black shirts. The study participants were told to count the number of passes made by the players in white shirts, a task that required a high degree of concentration and focus.
The video contained a rather substantial wrinkle, a man in a gorilla costume. In the middle of the video, the gorilla walked to the center of the screen, thumped his chest, and then left. The gorilla's appearance lasted a full nine seconds, hard to miss.
But it wasn't hard to miss. Half of the research subjects failed entirely to notice the gorilla. For them, the gorilla was invisible. Engrossed in the counting task at hand, they missed it entirely. In their reality, the gorilla never existed.
Sight is much more than meets the eye. It is our thoughts, our memories, our emotions, our judgments, our experiences, our instincts. All of these aspects of who you are literally color what you see. And what you see shapes the contours of these diverse aspects of your life.
Numerous research studies have demonstrated as much. For example, estimates of a man's walking speed vary according to whether research subjects are primed to think about fast animals like cheetahs or slow animals like turtles. Similarly, interpretations of an ambiguous figure that can be seen as a woman's face or as a man playing a saxophone depend on whether people have been recently primed with the concepts of "flirtation" or "music." A hill appears more steep after the perceiver jogs vigorously for an hour, and the distance to a goal seems longer if the perceiver has strapped on a heavy backpack.
Additionally, sight is at work in these feedback loops even when your eyes are closed! Your visual cortex is hard at work as a mental air traffic controller when you are dreaming. When you experience memories you are playing them back through your visual cortex. Think about an elephant and, you guessed it, your elephant detectors in your visual cortex will fire.
More abstractly, we construct mental images of ideas or concepts. For example, we talk about the "image of success." What does that mean? Does your mind invoke the concept of success when you perceive an expensive car, a laughing child, both, neither? Conversely, when you imagine yourself achieving great success, do certain images come to mind?
Finally, what is it that you see, anyway? I said earlier that the photoreceptor cells of our eyes are tuned to respond to light. The full truth is more complicated. That light comprises a small sliver of electromagnetic radiation, a sliver we call "visible light." Electromagnetic radiation is characterized by the relationship between its wavelength and frequency, and it spans a vast spectrum that corresponds to a range of values for those properties. Our photoreceptor cells respond to electromagnetic radiation with a wavelength that falls in a particular, narrow range of values.
How tiny is that sliver? .00000000001 percent. As David Eagleman explains in his riveting TED Talk "Can we create new senses for humans?" we perceive only one ten trillionth of the electromagnetic radiation that floods our world. That's not much. And there's a lot of interesting information in the invisible spectrum, such as radio waves, microwaves, infrared, ultraviolet, X-rays, and gamma rays.
Is there anything magical about our microscopic sliver? No. Indeed, other animal species can see electromagnetic radiation outside the "visible spectrum." That is, they see electromagnetic radiation invisible to us humans. Change the tuning of your photoreceptor cells, even slightly, and you see a different world. Imagine a world in which you could see radio waves and microwaves, or X-rays and gamma rays. What does reality look like in that world? Which world is "right"?
Speaking of "right," is that even the goal? Is the human experience of sight optimized to render the information we perceive with accuracy? That may seem like an odd question, but Donald D. Hoffman, a professor of cognitive science at the University of California, Irvine, has spent three decades thinking about it. His conclusions are eye- opening. He summarizes them in his TED Talk "Do we see reality as it is?" which I encourage you to watch.
Hoffman posits that the purpose of our visual system is not to accurately portray some objective reality (if there is such a thing), but instead to create an experience that furthers the evolutionary goals of survival and reproduction. Put another way, our minds are less concerned with getting it "right" than they are with getting it "useful." The very point of sight, he argues, is to augment information, not represent it. In a recent interview published in 'The Atlantic', he explained: "Evolution has shaped us with perceptions that allow us to survive. They guide adaptive behaviors. But part of that involves hiding from us the stuff we don't need to know. And that's pretty much all of reality, whatever reality might be."
This excerpt ends on page 21 of the hardcover edition.