Mental Cycles

A mental cycle is an arbitrary unit of “mental computing power” that is used to measure the mental costs of performing certain tasks. You can say finding the square root of 81 requires fewer cycles than finding the square root of 5329.  You can say a smart person has a lot of mental cycles, which means that they can think a lot. You can also say that a smart person uses their mental cycles very effectively, meaning that even if they’re slow, they have good heuristics around how to solve problems efficiently. Students who spend 10 minutes on a test that should have taken 60 are either geniuses or cheating. Teachers intuit possible explanations to quick test turnaround times with the implicit concept of mental cycles.

I think about mental cycles on a daily basis to make better decisions and know a bit more about the world. If we familiarize ourselves with the concept of mental cycles, we can discover some interesting observations.

Detecting Bullshit

Bullshit, in the context of this blog post, is noticing when people are thinking off the top of their heads. Besides body language and discourse analysis as signals in determining bullshit, there is some signal extracted from understanding the level of complexity in certain questions that would prevent people from figuring out an answer in 10 seconds.

If you know someone is thinking off the top of their head, you have to factor in the time humans take time to think through large complex problems and issues. You’re most likely want to distrust an answer from someone who hasn’t spend large amounts of time studying the healthcare system and why it’s messed up. They’re most likely wrong on some level, even if their conclusions coincidentally end up correct.

Nobody Really Thinks

“Never attribute to malice that which is adequately explained by stupidity” — Hanlon’s Razor

We strongly overestimate the amount of mental cycles people put into their actions, and because we do, we often attribute intentions behind actions. We judge ourselves by our intentions, but others by their actions. “Why did my friend read my Facebook message and not respond? She must be doing this to get back at me for making a comment about her haircut.”

The key insight in flipping this understanding on its back is that in order to give intention to every action, you would have to spend a stupid amount of mental cycles, like exhaustingly stupid.

Your friend probably has other things to spend mental cycles on besides giving you anxiety with a carefully executed social maneuver. In her mind, her mental cycles are spent on her priorities, like worrying about why HER friend hasn’t responded to her Facebook message.

You might admonish your friend for not being considerate, but I think understanding the limitations how much thoughtful care people can give each other in an urban 21st century environment should give you ample room for accepting that your friend is human. After all, it’s hard to say you’re doing any better.


You can use mental cycles as a proxy metric for understanding your epistemology. A conclusion you drew from 15 seconds of thinking is not as solid as a conclusion drawn from 15 days of thinking. Practicing this understanding means that you can begin to assign epistemic statuses to your beliefs (although raw computation is no substitute for raw data!).

A place in which this often comes up is in problem solving. “Oh, I spent 15 seconds thinking about whether this math problem is solvable. It’s been 15 seconds so it’s impossible to solve.”

YOU’VE ONLY SPENT 15 SECONDS HOW CAN SAY THAT? Mathematicians dedicate entire lives solving problems they aren’t sure are even solvable.


Even though the statement that fewer mental cycles spent -> less believable statements is generally true, the reverse statement is not true. Spending more mental cycles may not be the bottleneck in acquiring stronger epistemic understanding. Thinking more and believing more strongly in your sentiments is what we call “armchair philosophers.”

Rene Descartes believed in the mind-body duality that separates mind and body as separate entity. Although he has clearly thought a lot of the matter and his understanding is internally consistent, the moment you examine data from a scientific experiment on hormones in the body, you will understand that Descartes’ beliefs are wrong.

Idol Worship

On a higher-level, you also begin to understand that humans just think too slowly to be anywhere near perfect. People who are amazing at math don’t spend enough mental cycles to understand human relationships. A Nobel-prized political science professor will have a hard time understanding the primitives of the Linux kernel. Everyone is dumb on some level and that’s OK. No one is perfect or anywhere near well-rounded, and that upper ceiling is bounded by the finite resources of time and thinking power human biology has. I don’t think we should ever say someone “has life figured out.” You just have to pick and choose what you’re good at and what you’re okay with being okay at.

State of the World

Throughout my years in business, I discovered something. I would always ask why you do things. The answers that I would invariably get are: ‘Oh, that’s just the way things are done around here.’ Nobody knows why they do what they do. Nobody thinks very deeply about things in business.  — Steve Jobs

You’ll understand that on Earth, each individual only has a tiny sliver of knowledge about the world, and even grouped together, the things humans understand about the world are just tiny points of light in an otherwise completely dark room. Don’t go around assuming other people have it figured out. No one does, people just don’t have enough time and speed to know all the moving parts in the world. Using this knowledge means that if you begin looking in the dark corners in the room, you’ll often find new and exciting ways to making the world a better place.

Here’s the above section summarized in a series of pictures.


Mental cycles are a finite resource, and a resource you must fiercely protect. Imagine all the empty cycles you spin worrying about what people think about you, or how things could have been with your ex, or worrying about the future. Think what things are even worth your attention, what things are worth a fuck.

If you spend too much time “overthinking things,” I would prescribe therapy or meditation to help you not focus too much on negative or useless things. Thirty minutes of meditation a day is easily worth the upsides of being able to not spin empty cycles making yourself unhappy.

If you see opportunities to reduce cognitive load, take it! Use a to-do list instead of your mind for keeping track of tasks. Have a computer to computationally intensive tasks. Write things down.


Often times I cut meetings short to avoid bikeshedding, you just don’t want to waste mental cycles talking about decisions that don’t matter, have sensible defaults, or are deferrable to a later time (with more accessibility to information and experience). Less accessibility to information and experience means more mental cycles spent trying to find a good decision. Many creative careers are bottlenecks by mental throughput, and therefore you have to be careful of what you decide to think about.

Delegation of Thinking

Sometimes you’ll want to delegate mental cycles outside of your brain. For example, having someone make decisions for you on how you should dress. Doing the research yourself would require a lot of time and energy, so sometimes it makes a lot of sense to defer that decision to someone else.

Another controversial opinion with thought delegation is giving someone your vote. If you have confidence that the person you’re giving your vote to has similar values as you and spent time clearly thinking about policies and issues at hand, then even they would be better informed to vote on the good policies than I ever will be. My mental cycles could be better spent elsewhere.

References/Further Reading

On Computational Complexity

Think the idea of computational complexity is subjective speculation? There’s a whole branch of mathematics and computer science dedicated to the study of complexity and computability. For a solid application of complexity, I would watch this Youtube playlist on RSA encryption. The premise of a large part of security is making things hard for computers.

On Human Consciousness and Introspection

I really enjoyed reading The User Illusion, which makes some interesting claims about the nature of human consciousness.

On Habits and Productivity

On the description and prescription of habits, I recommend reading The Power of Habit by Charles Duhigg.

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