People on the autistic spectrum have many traits that can be generalized, but they also display a variety of idiosyncrasies. I believe the latter arises from one of the most important traits of autism, a stereotypical tendency to mental fixations.
Understanding of how fixations work is best communicated in the language of behaviorism. In Skinner’s classic experiment, a mouse is trained to press a lever by randomly rewarding it with a pellet. Eventually, the mouse becomes addicted to pressing the lever and does so continually, at the expense of all other activities. Because the reward was random, the mouse can’t possibly understand why he’s pressing the lever; it must be pressed for its own sake. He’s probably thinking up theories about how pressing the lever is pleasing his mouse gods (or maybe not pressing it would anger them) while he does it.
This is a learned behavior. For example, maybe in the past I always wore a hat when I went to my grandma’s house, and every time I went to grandma’s I got to eat my favorite ice cream. Now, I just wear the hat because it reminds me of the good old days, and that makes me happy. Wearing the hat doesn’t do anything for my reproductive fitness because it doesn’t cause me to get ice cream, but now I wear it for its own sake. The association has nothing to do with the initial causality.
(Here keep in mind I’m making this up in my head, it’s not from reading proper science stuff.) A fixation occurs when the original neural pathway for some reward has decayed while the associated pathway has been strengthened. So, the mouse continues to get a dopamine reward for pressing the lever for a while (call it the pleasure of anticipation), but fails to get the dopamine reward of the pellet. Eventually the starvation causes frantic lever-pressing behavior because the brain is dopamine-starved, reinforcing the perverted (i.e. “disordered”, “in the wrong order”) behavior with diminishing dopamine returns long after it has become pathological, because the more general pellet-seeking pathway has degenerated.
Because of the process I’m describing here, I’d expect the tendency to develop fixations to be a general trait in all people with low time preference, who rely on anticipation of future rewards to motivate present behavior. This could explain all manner of fixations and particularly sexual ones, aka fetishes like homosexuality, BDSM, and transexualism. I would describe the personality trait which corresponds to the formation of fixations the “idiosyncrasy quotient”, by analogy to intelligence quotient, and expect that people on the autism spectrum have a right-shifted distribution on this trait.
This is of interest considering the fact that the more intelligent individuals with the Aspergoid condition are often inclined toward science or art, and that many if not most geniuses appear to be rather Aspergoid. It is a public secret that the world’s greatest minds tend to be sexual deviants, as expressed in sayings like “Once a philosopher, twice a pervert”, or Hoe groter de geest, hoe groter het beest (Netherlandic for “The greater the mind, the greater the beast”). When reading honest biographies of geniuses, one can not escape this fact. It is also something that may make one, secretly but with perverse delight, smile whenever one hears someone claim to be “the world’s smartest man” or have “the world’s highest I.Q.”.
Asperger’s 1944 article summarized
The same general tendency to fixations which predicts sexual fixations then predicts the intellectual and ideological fixations that we also observe in Asperger’s, as well as the tendency to personality disorders in general. Most notably, the diagnosis is often comorbid with ADHD, OCD, Tourette’s, and cluster A “eccentric” disorders.
Paranoid personality disorder: characterized by a pattern of irrational suspicion and mistrust of others, interpreting motivations as malevolent.
Schizoid personality disorder: lack of interest and detachment from social relationships, apathy, and restricted emotional expression.
Schizotypal personality disorder: a pattern of extreme discomfort interacting socially, and distorted cognitions and perceptions.
(More than likely I’m retreading old ground here, given that they’re already called personality “disorders”.)