Our Brains keeps Us 15 Seconds in the Past

Our eyes are continuously bombarded by an enormous amount of visual information – millions of shapes, colors, and ever-changing motion all around us.
For the brain, this is no easy feat.
On the one hand, the visual world alters continuously because of changes in light, viewpoint, and other factors. On the other, our visual input constantly changes due to blinking and the fact that our eyes, head, and body are frequently in motion.

To get an idea of the "noisiness" of this visual input, place a phone in front of your eyes and record a live video while you are walking around and looking at different things.
The jittery, messy result is exactly what your brain deals with in every moment of your visual experience.

Yet, seeing never feels like work for us. Rather than perceiving the fluctuations and visual noise that a video might record, we perceive a consistently stable environment.
So how does our brain create this illusion of stability? This process has fascinated scientists for centuries and it is one of the fundamental questions in vision science.

The time machine brain

In our latest research, we discovered a new mechanism that, among others, can explain this illusory stability.

The brain automatically smoothes our visual input over time. Instead of analyzing every single visual snapshot, we perceive in a given moment an average of what we saw in the past 15 seconds. So, by pulling together objects to appear more similar to each other, our brain tricks us into perceiving a stable environment.

Living "in the past" can explain why we do not notice subtle changes that occur over time.
In other words, the brain is like a time machine which keeps sending us back in time. It's like an app that consolidates our visual input every 15 seconds into one impression so that we can handle everyday life.
If our brains were always updating in real time, the world would feel like a chaotic place with constant fluctuations in light, shadow, and movement. We would feel like we were hallucinating all the time.

We created an illusion to illustrate how this stabilization mechanism works.

Instead of seeing the latest image in real time, humans actually see earlier versions because our brain's refresh time is about 15 seconds. So this illusion demonstrates that visual smoothing over time can help stabilize perception.

What the brain is essentially doing is procrastinating. It's too much work to constantly deal with every single snapshot it receives, so the brain sticks to the past because the past is a good predictor of the present.

Basically, we recycle information from the past because it's more efficient, faster, and less work.

This idea – which is also supported by other results – of mechanisms within the brain that continuously bias our visual perception towards our past visual experience is known as continuity fields.

Our visual system sometimes sacrifices accuracy for the sake of a smooth visual experience of the world around us. This can explain why, for example, when watching a film we don't notice subtle changes that occur over time, such as the difference between actors and their stunt doubles.

Read more at Science Alert