Our eyes are constantly exposed to a great deal of visual information in the millions of shapes around us, such as color and ever-changing motion. Our visual input is constantly changing due to the constant movement of our eyes, head, and body, in addition to light, perspective, and many other factors; but despite this constant change, seeing doesn’t seem like a daunting task for us at all.
However, this task, which comes to us quite easily, is quite challenging for the brain, even if we are not aware of it. Instead of perceiving the visual fluctuations and pollution we see in any video, we actually get a more stable view. Let’s take a look at why and how the brain creates this visual stability, which is one of the fundamental questions of vision science.
Brain acts as a ‘time machine’ to eliminate visual noise
If you turn on your phone camera and put it in front of you and take a video while you’re constantly walking around looking at something else, you can understand what the “visual input noise” our brain has to deal with nonstop. In a new study, it was discovered that there may be a completely different mechanism behind our inability to perceive this visual noise.
Accordingly, our brain automatically corrects our visual input. Instead of analyzing each visual input one by one, we perceive the average of what we saw in the last 15 seconds in a given moment. This means that our brain ‘deceives’ us by putting together objects in our memory to look more alike, creating an illusion that we perceive a more stable environment.
Put simply, the brain acts as a time machine that constantly takes us back in time. In other words, the brain works like an application that combines our visual input into a single impression every 15 seconds so that we can cope with everyday life.
If instead it were our brains updating in sync with what we see, our perception of our surroundings would be no different from a video we shot. Due to the surrounding light, shadow and uninterrupted movement, we would perceive a chaotic environment with constant fluctuations and noise, which would make us feel like we were constantly in a hallucination.
We detect earlier versions instead of seeing in real time
To understand how this stabilization mechanism works, the researchers created an illusion.
Although the face on the left in the video is slowly aging over 30 seconds, it is difficult to discern the full extent of the change in age. In fact, according to us, the face ages much more slowly than it actually does. To test this illusion, the researchers watched the video with hundreds of participants, showing them close-ups of faces of varying ages in 30-second time-lapse videos.
When the researchers asked the participants at the end of the video to tell them the age of the face they saw, the participants were almost consistently accurate about the age of the face they had seen 15 seconds ago. This means that because our brain’s refresh time is about 15 seconds, people are seeing earlier versions instead of seeing the latest image in real time. So this illusion suggests that over time, visual softening can help stabilize perception.
In this case, it can be said that what the brain is actually doing is procrastinating. Because it’s too much work to constantly deal with every single snapshot it takes, the brain gets stuck in the past because the past is a good predictor of the present. In other words, we recycle the information from the past to the present, mainly because it is more efficient, faster and easier.
This illusion created by the brain has positive and negative effects.
This idea, supported by other research, of the mechanisms in the brain that continually direct our visual perception to our past visual experiences, are known as continuum areas.
Our visual system sometimes sacrifices ‘accuracy’ for the world around us to be a smooth visual experience. This may also explain why, for example, when watching a movie, we don’t notice subtle changes over time, such as the difference between actors and their stunt doubles.
On the other hand, the fact that our brain lags a little while processing our visual world has both positive and negative effects. While latency is an excellent mechanism to keep us from being bombarded with visual input every day, it’s hardly useful for situations where absolute precision is required.
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