Is the Human Visual System Inefficient and Flawed?

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” The immediately preceding post might have you thinking that the human visual system is both inefficient and flawed. The fact that we cannot register what we see in our visual world suggests that the human visual system is a flawed one. Indeed, it will fail to detect a gorilla walking into a scene!

Before reaching this conclusion remind yourself that our species has managed to survive and prosper in a hostile environment. It is usually the case that the world around us is a stable and consistent one, and our brains work on this assumption. What is important is gathering information that is relevant to us. That’s what we need to focus on. We can ignore all the stuff that is of no value to us. A system that tried to process every scrap of visual information would be cumbersome and inefficient, and there is no need to process all the information available to us.

Dr. Van Der Stigchel writes “the system that uses less energy has an advantage in the evolutionary scheme of things. An efficient system makes the energy it does not use available to the system, and that is what our visual system also does. Although the retina catches the light from everywhere around us, only that information which is relevant to us is processed.”

Suppose when we went shopping in a supermarket we processed all the information we saw. Although we would know the brand and price of every product, that would cost us far too much energy.

Our visual system possesses a unique feature that allows it to present information very selectively: our continuous access to the visual world. All of the visual information that is available to us at any given moment is 100% accessible. All we need to do is to open our eyes and the information floods in. We can use the visual world as a kind of external hard drive. We do not need to store every single detail related to the external world in our internal world because all of the visual information is continuously available to us externally.

We only need to be able to recall internally to interact effectively with the external visual world where the relevant information is located in relation to our own location at any given moment.

Dr. Van Stigchel asks us to imagine the following: “we and a friend are walking down a busy street in town on our way to a coffee bar at the end of the street. There are people everywhere and neon signs flashing all around, At that moment, only certain aspects of the visual world are relevant to us: the coffee shop in the distance and our friends walking beside us. We are moving, so all of the information is moving too relative to our position. We use our eyes to access the visual world around us and note only the location of the information that is relevant to us. We would notice if the coffee bar suddenly disappears, our friend runs off, or if a screaming gorilla approaches because this information is relevant to us. We can afford to ignore everything else.”

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