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Let’s talk about why your brain is lazy.
The short explanation is it’s lazy because it has to conserve energy as much as possible.
Energy in turn needs to be conserved because, even though your brain only represents about 2% of your total body mass, it burns through about 20% of your daily calories.
In other words, your brain’s an energy hog.
The reason it’s a hog is because it runs everything in your body, and keeping the human body running is, to put it lightly, a complex task.
Why is it so complex? Well, most of what you do is unconscious. Conscious thought only represents a small portion of the work your brain is doing.
For example, you don’t run your nervous system or maintain your internal organs with conscious thought. That’s all happening in the background, and all of it takes energy.
Your brain is never really turned “off” as a result, even when you think it is — it’s always busy managing something in your body.
This is why the whole “you only use 10% of your brain” myth is such a joke. Your brain is a constant hive of neuronal activity at all times, and it’s because the brain is busy running the whole system. This is true even when you’re asleep — so even if you think you’re idle and nothing is happening, your brain is busy running everything.
Anyway, because it’s so busy allocating resources all over your body, your brain has developed a long list of cognitive shortcuts as a means of saving energy.
Forgetting is the best example of a cognitive shortcut: your brain forgets most of what it encounters because it would be too energy-intensive to remember tons of useless data.
The brain is thus optimized to be, to borrow someone else’s terminology, a “change detector.”
Your brain’s lazy memory algorithm focuses on encoding new memories that are salient, and dropping everything that isn’t memorable.
For example, you’ll remember if, during your daily drive to work, a zebra steps in front of your car even though you live in a major metropolitan area. That’s such an unusual event that it’s guaranteed you’ll remember it — it’s so salient that your brain will encode it as a memory.
This is why repetition is important in learning: you need to tell your brain (through repeated exposures) that a given stimulus is worth the energy expenditures involved in remembering it.
Your brain does this in order to take note of environmental cues that could potentially influence your survival.
We suck up anything that’s unusual because big changes in our environment can be dangerous. A zebra running around in the street could be indicative of a problem at the local zoo, which in turn could mean there are dangerous animals running around that could eat you.
With all of these lazy shortcuts, your brain is making a trade-off of some kind. The brain is asking itself: “Is it worth pouring resources into this?” And if the answer is “no” then the brain doesn’t prioritize itself around that stimulus.
People get frustrated with these shortcuts, but they’re an indicator of a healthy brain. There are exceptions, like Alzheimer’s or CTE, but in general shortcuts like forgetting mean your brain is acting in accordance with its lazy nature.
The key idea to pull from all of this is that your brain does what it does for a good reason, and you won’t be able to learn or use your memory well if you don’t understand these internal dynamics.
Much of learning revolves around finding ways to use your brain’s built-in mechanisms for your benefit, but there will always be limitations. Don’t get frustrated, just accept that your brain will never be perfect.
To put this all in perspective: supercomputers that take up entire floors of industrial buildings can’t touch the capabilities of the human brain.
How is it that such vast amounts of electrical and computing power come up short when trying to handle tasks, like language, that we find trivial? This is one of the enduring mysteries of the brain. But it should clue you in to the fact that your brain, despite its laziness, is not as flawed as you might think.