Hack 26. Get Adjusted
We get used to things because our brain finds consistency boring and adjusts to filter it out.
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.
In other words, it’s just another normal day in the world with my brain.
Our brains let us ignore any constant input. A good thing too; otherwise, we’d spend all our time thinking about how heavy our hands are, how exactly our T-shirts feel on our backs, or at precisely what pitch our computers are humming, instead of concentrating on the task at hand.
The general term for this process of adjusting for constant input is called adaptation. Combined with relative representation of input, adaptation gives us aftereffects. The motion aftereffect is a good example of a complex adaptation process, so we’ll walk through a detailed story about that here in a moment.
Both relative representation and the motion aftereffect are described in [Hack #25] . Simply put, how much “movement up” we perceive depends on the activation of up-sensitive neurons compared against the activation of down-sensitive neurons, not just the absolute level of activity.
Adaptation is a feature of all the sensory systems. You’ll notice it (or, on the contrary, most likely not notice it) for sound, touch, and smells particularly. It affects vision [Hack #25], too. If you stop to consider it for a moment, you’ll appreciate just how little of the world you actually notice most of the time.
Adaptation is a general term for number of processes. Some of these processes are very basic, are of short term, and occur at the level of the individual sense receptor cells. An example is neuronal fatigue, which means just what it sounds as if it means. Without a break, individual neurons stop responding as vigorously to the same input. They get tired. Strictly speaking, ion channels in the membrane that regulate electrical changes in the cell become inactivated, but “tired” is a close enough approximation.
The most basic form of memory is a kind of adaptation, called habituation. This is just the diminishing of a response as the stimulus that provokes it happens again. The shock of a cold shower might make you gasp at first, but with practice you can get in without flinching. It was neuroscientists using a similar kind of situationpoking sea slugs until they got used to itthat first demonstrated that learning happens due to changes in the strength and structure of connections between individual neurons.
2.15.1. In Action
Aftereffects are the easiest way to see adaptation occurring. You can have aftereffects with most thingssounds, touch pressure, brightness, tilt, and motion are just some. Some, like the motion aftereffect [Hack #25], are due to adaptation processes that happen in the cortex. But others happen at the point of sensation. The adaptation of our visual system to different light levels happens directly in the eyes, not in the cortex.
To see this, try adapting to a darkened room with both eyes and then walking into a bright room with only one eye open. If you then return to the darkened room, you will be able to see nothing with one eye (it has quickly adapted to a high level of light), yet plenty with the eye you kept closed in the light room (this eye is still operating at the dark-adapted baseline). The effect is very strong as you switch between having alternate eyes open and the whole lighting and tone of the room you’re looking at changes instantly.
Taken From : Mind Hacks
