Does my brain live a little in the past? Yes, your brain does live a little in the past. It can't help it. The information it receives via your senses is always a little out of date.
Whether it’s light entering the retinas in your eyes, or sounds vibrating the hairs in your ears, it not only takes time for the data to arrive, but your brain then has to process it.
Unfortunately, data transmission in your brain is sluggish. Even your fastest neurons can only manage about 431km/h (268mph), which is a lot slower than copper wire at 1.08 billion km/h (669 million mph).
The result of this is that what you’re sensing now, actually occurred in the world around 100 milliseconds ago (about a tenth of a second).
These delays might not sound like much, but given that control of your body is similarly sluggish, interacting with the world poses a serious challenge. The solution your brain has engineered is to constantly anticipate what’s going on.
For this reason, your subjective experience of the world is a mix of an outdated sensory snapshot and a predictive best guess.
Usually, your brain does such a good job smoothing over these challenges that you don’t notice any of this. But there are some fun ways that the sensory guesswork can be made clear. One of them is how we’re unable to tickle ourselves.
This is because your brain is always anticipating the sensory consequences of your movements so that it can cancel them out.
Here’s another fun example. Have you ever stepped onto a broken escalator only to experience a weird wobble? This is down to your brain seeking to overcome the outdated nature of its incoming sensory information by making anticipatory posture adjustments.
When the escalator is functional, this works well and you stay on your feet. When the escalator is broken, your brain still makes the adjustments, but now they’re unnecessary, hence the wobble.
Not only is your brain living a little in the past in terms of out-of-date sensory information, but there’s also a fascinating sense in which it’s constantly back-dating experiences into the past.
This happens because of the jerky eye movements, known as saccades, that you’re making several times a second.
These eye movements are so rapid that they blur your vision, only you don’t see this because during each saccade your brain suppresses all visual input (life would be completely disorientating if it didn’t).
To smooth over these gaps, when your gaze lands on an object, your brain backdates your subjective experience of how long that object has been there – to about 50 milliseconds before you began your eye movement.
Given the stability of most objects in a visual scene, most of the time we don’t notice this back-dating process. But there’s a way it can manifest and that’s when your gaze lands on the second hand of a clock.
Have you ever noticed that when you first look at a second hand, it seems to hang there for too long? That’s because of this back-dating process, which makes it seem as if the second hand has been in its position for too long.
So, in short – yes, you might feel like you’re living in the now, but your brain, in some ways, is always playing catch-up!
This article is an answer to the question (asked by Karen Homer, Sunderland) 'Does my brain live a little in the past?'
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