Mind

Hacks 3-33 The puzzle that is vision lies in the chasm between the raw sensation gathered by the eyelight landing on our retinasand our rich perception of color, objects, motion, shape, entire 3D scenes. In this chapter, we'll fiddle about with...

When we talk about "visual processing," the natural mode of thinking is of a fairly self-contained process. In this model, the eye would be like a video camera, capturing a sequence of photographs of whatever the head happens to be looking at at...

The rest of your visual input is low res and mostly colorless, although you seldom realize it. Your vision isn't of uniform resolution. What we generally think of as our visual ability, the sharpness with which we see the world, is really onl...

Perception exists to guide action, and being able to act is key to the construction of the high-resolution illusion of the world we experience. The other hacks in this chapter could give the impression that seeing is just a matter of your brai...

Coating the back of each eye are photoreceptors that catch light and convert it to nerve impulses to send to the brain. This surface, the retina, isn't evenly spread with receptorsthey're densest at the center and sparse in peripheral vision [H...

During each movement, vision cuts out. Despite the fact that the eye has a blind spot, an uneven distribution of color perception, and can make out maximal detail in only a tiny area at the center of vision, we still manage to see the world a...

We are able to effortlessly distinguish between the past, present, and future. Yet, subtle illusions show that our mental clock can make mistakes. You only have to enjoy the synchrony achieved by your local orchestra to realize that humans mu...

Shifting attention often means shifting your eyes. But we're never fully in control of what our eyes want to look at. If they're latched on to something, they're rather stubborn about moving elsewhere. It's faster for you to look at something new...

Looking at shadows is one of many tricks we use to figure out the shape of objects. As a trick, it's easy to foolshading alone is enough for the brain to assume what it's seeing is a real shadow. This illusion is so powerful and so deeply ingrai...

Shadows get processed early when trying to make sense of objects, and they're one of the first things our visual system uses when trying to work out shape. [Hack #20] further showed that our visual system makes the hardwired assumption that li...

We use all together in vision and individually in visual design and real life. Our ability to see depth is an amazing feature of our vision. Not only does depth make what we see more interesting, it also plays a crucial, functional role. We u...

A major challenge for our vision is the reconstruction of a three-dimensional visual world from a two-dimensional retinal picture. The projection from three to two dimensions irrevocably loses information, which somehow needs to be reconstructed ...

This is a journey into the code the visual system uses to work out how far away things are and how fast they are moving. Both of the variablesdepth and velocitycan be calculated by comparing measurements of object position over time. Rather than ...

Why, when the train stops, does the platform you are looking at out the window appear to creep backward? The answer tells us something important about the architecture of the visual system and about how, in general, information is represented in ...

My limbs feel weightless. I can't feel my clothes on my body. The humming of my laptop has disappeared. The flicker of the overhead light has faded out of my consciousness. I know it all must still be happeningI just don't notice it anymore. ...

The motion aftereffect [Hack #25] shows that motion is computed in your brain separately from location. For instance, becoming accustomed to the moving surface of a waterfall causes you to see stationary surfaces as moving the other way, althou...

How quickly we can act is slow compared to how quickly things can happen to usespecially when you figure that by the time you've decided to respond to something that is moving it will already be in a new position. How do you coordinate your slow ...

The moral of this story is that if you want people to see moving objects, make them brighter or darker than the background, not just a different color. Motion is important stuff for the brain. Information about movement gets routed from the ey...

We've all seen optical illusions in which parts of a completely static picture appear to drift and swirl. One of the most famous examples is Professor Akiyoshi Kitaoka's rotating snake illusion (Figure 2-25), commonly passed around via email, bu...

Reducing the imaginary distances involved makes manipulating mental objects easier and quicker. Mental imagery requires the same brain regions that are used to represent real sensations. If you ask someone to imagine hearing the first lines ...

Typically, the more important something is, the deeper in the brain you find it, the earlier in evolution it arose, and the quicker it can happen. Avoiding collisions is pretty important, as is closing your eyes or tensing if you can't avoid t...

Neural signals are always noisy: the timings of when they fire, or even whether they fire at all, is subject to random variation. We make generalizations at the psychological level, such as saying that the speed of response is related to intensit...