Plasticbrains is a term invented by Promethea to refer to a particular cluster of people who are disproportionately likely to be transgender. “Plastic” is a joking reference to BPAs, an endocrine disruptor in plastics, which some people have hypothesized is linked to transness. (There is no evidence that this is true, and “plasticbrains” is a joke.)

Common Traits of Plasticbrains

Plasticbrains people, as you can guess from the joke in the name, are disproportionately likely to be trans. However, not all plasticbrains people are transgender! While plasticbrains people are much more likely than baseline to be trans, many plasticbrains people are not transgender. It seems likely to me that half to two-thirds of plasticbrains people would not qualify as definitely cis, if you include “would transition in the glorious transhumanist future and but doesn’t want to now”, “happily only out as nonbinary to a few trusted friends”, “girl in the streets and dude in the sheets”, “socially dysphoric in very gendered spaces but otherwise fine”, “on hormones but not socially transitioning”, “I do not want to see or be seen by gender”, “??????”, and so on.

Plasticbrains people are most comfortable in situations with clear rules, consistently applied, which one can optimize within. This is probably why plasticbrains people are disproportionately represented in programming and math. Plasticbrains people often come up with clear and consistent rules for situations that don’t have them and then loudly insist that these rules are objectively correct. For instance, plasticbrains people often adhere to a specific philosophical school of ethics (egoism, utilitarianism, deontology, virtue ethics) instead of relying on intuitive morality. They often have odd political beliefs which they have worked out from first principles. (Anarchocapitalists and communists are both quite common. Even centrist liberal plasticbrains can generally explain to you why centrist liberalism follows from the basic principles of uncertainty and respect for experts.) But plasticbrains rules can apply to everything from programming languages (“Haskell is objectively correct”) to grammar (“prescriptivism is wrong and evil”) to social rules (“it is never morally wrong to make a request of anyone”).

Plasticbrains people often have a strong interest in optimization. Once they come up with a set of rules and goals, they will often try to optimize for their goals within their rules. Again, this probably explains their affinity for programming. This often leads to very strange behavior: for instance, plasticbrains people may adopt a variety of more or less evidence-based strategies for self-improvement, live on Soylent because that is the optimal way to save time and avoid cooking, or believe it is morally wrong to donate to the Red Cross because other charities use that money better.

There is no consensus among plasticbrains people what rules are actually the objectively correct rules. One would think that the fact that other plasticbrains people are going about saying “anarchocapitalism is obviously correct!” would make the plasticbrains communists think a bit, but as far as I know this has never happened. While in general plasticbrains people are pretty self-aware about their mental health issues, plasticbrains people are usually not self-aware about their rules. They can easily recognize that other plasticbrains people are adhering rigidly to their rules even in situations where there is more nuance, but then they will turn around and say “actually, lying is morally wrong and never justified and if you lie to people I will never interact with you again.” Occasional examples of plasticbrains people having nuance about their rules have been observed, but upon closer inspection these universally turn out to be plasticbrains people who have adopted “nuance exists!” as a rule. (I myself as I was typing this attempted to give “people in the developing world are exactly as important as people in the developed world, and the low level of foreign aid from developed countries is probably as bad as the Holocaust” as an example, but then my soul rebelled. Obviously, my own personal rules are just true.)

Plasticbrains people generally have engrossing and obsessive interests. These tend to be fairly intellectual interests, such as programming, linguistics, and history; however, obsessions with particular pieces of media are also common. The happiness of a plasticbrains person is directly correlated with how much time they spend talking about, collecting information about, or participating in their interest. Plasticbrains people often find other people’s interests to be just as interesting as their own interests, which leads to many happy plasticbrains friendships.

Plasticbrains people often have a hard time interacting with people who aren’t plasticbrains, although if they put time into developing the skill they can sometimes get pretty good at it. If a plasticbrains person has not put effort into the skill, then non-plasticbrains people will generally find them strange, off-putting, and uncomfortable to be around. This is possibly because plasticbrains body language tends to be unusual: for instance, they may come off as emotionless or robotic, or flap their hands when they’re happy or distressed. Plasticbrains people generally have a hard time understanding the behavior of non-plasticbrains people, but usually understand each other fairly well. That said, they have two consistent theory of mind failures which apply even to other plasticbrains people: “My Interests Are Interesting To Everyone And If They Aren’t Then I Clearly Have Not Explained Them Well Enough” and “My Rules Are Obviously Correct And If You Do Not Follow Them It Is Because You Are A Bizarre Moral and Intellectual Mutant.” If a plasticbrains person has adopted social rules that don’t work very well, this may also cause social failures.

Plasticbrains people tend to be introverted, but their level of social motivation ranges widely. Some plasticbrains people feel little to no desire to interact with anyone, while others enjoy regular social interaction. Some plasticbrains people may find interacting with certain people stressful and overwhelming in the same way they find loud noises stressful and overwhelming. Many appreciate quietly reading or writing in the same room as other people. Many plasticbrains people are very lonely, because their difficulties interacting with non-plasticbrains people makes it hard for them to fulfill their social needs.

Plasticbrains people usually have unusual sexualities. They are disproportionately likely to be bisexual. They are not disproportionately likely to be attracted the other assigned sex at birth, but the number of trans people means that many are lesbians or gay. Many plasticbrains people are asexual or low-libido or experience periods of asexuality. Plasticbrains people are often kinky. Many plasticbrains people enjoy and seek out casual sex. Some find touch much more rewarding than most people do, while others find it upsetting or painful.

Plasticbrains people typically find text-based interactions easier than verbal interactions. They like books. They are averse to phone calls. They may have entire relationships conducted solely over the Internet. While savant skills seem to be uncommon, hyperlexia is the most common.

Plasticbrains people combine neophilia with a strong aversion to change. Neophilia is the tendency to loathe tradition, easily become bored, and seek out novelty to the point that it becomes an obsession. Common areas for plasticbrains people to experience neophilia include art, literature, science, ideas, drugs, sex, and personal projects.

Interestingly, plasticbrains people also tend to dislike change. The specific ways in which they dislike change are very individual. For instance, one plasticbrains person may eat the same things for breakfast, lunch, and dinner every day, while another plasticbrains person may object to working anywhere other than their home office which has been set up to their specifications, and a third plasticbrains person may have a strict daily routine and be distressed by disruptions.

Plasticbrains people typically have difficulties with executive function. However, their difficulties span a wide range. Some may have relatively ordinary problems, such as procrastination, difficulty planning how long tasks will take, constantly forgetting why they walked into this room, and never knowing where they left their cell phone. Others may have deeper executive function problems, such as “sometimes I can’t stand up because standing up has too many steps.”

Plasticbrains people are typically quite smart and do well in academic fields. Many of them are autodidacts.

Plasticbrains people often have sensory issues. For instance, plasticbrains people may have trouble following a conversation that takes place in a noisy room or when the television is on. They may find car alarms, fireworks, the sound of people chewing, or other noises to be viscerally upsetting. They may be easily distracted by small sounds. They often find weighted blankets comforting.

Plasticbrains people fidget. They may chew on their fingers, their clothing, or random objects. They may pace. They often enjoy playing with Rubix cubes, tossing balls hand to hand, or playing with a toy designed for fidgeting. They sometimes move around a lot.

Possible Plasticbrains Traits

A high number of plasticbrains people I know are Jewish, but I am uncertain if Jewish people in general are more likely to be plasticbrains.

Anecdotally, it seems like many plasticbrains people tend to suffer from generalized shame disorder, but this trend may just be because people who have excessive shame tend to talk to me about it.

Plasticbrains people often experience anxiety and depression. It is unclear to me if this is a product of the underlying brain difference or the fact that plasticbrains people often have awful childhoods because children are much more likely to express their discomfort with plasticbrains people through bullying and assault.

I am uncertain whether plasticbrains people are disproportionately likely to have mood disorders other than depression and anxiety. While I certainly know many plasticbrains people who go through hypomania-like episodes, I am not sure if that is a central trait.

Plasticbrains and Autism

It is very common to refer to plasticbrains people as being autistic, and many of us have autism diagnoses. I tend to agree with the excellent Rethinking Autism (piratable here) that it doesn’t make sense to think of autism as a single condition, or even as a bunch of related conditions. Instead, we should think of autism as being something like fever: a symptom cluster with a wide variety of underlying causes, some of which lead to different associated symptoms. While some ways of treating fever work for all fevers, regardless of cause, it wouldn’t make sense to research fever as a single thing with a single etiology or call the flu a “fever spectrum condition”.

Not all plasticbrains people qualify for an autism diagnosis, or even any sort of diagnosis at all. Many autistic people are not plasticbrains. Even so-called high-functioning autistics are often not plasticbrains: for instance, Temple Grandin is definitely not. However, I expect that this cluster will turn out to have a single underlying cause. I expect (in spite of the name) the cause will turn out to be genetic, because it seems to run in families.