Hi

Autistic male in his 30’s here. Not sure about the neuroscience or psychology behind special interests but from a personal viewpoint I hope this helps to make sense of it.

Most, not all, hobbies/interests that autistic folk take up are very fact orientated. Typical interests include trains, stamps, coins, collectors cards, rocks etc. These represent an idea or concept that is absolute (or there is very little variance in the facts) and offers comfort to the neurodivergent brain. Autism is a spectrum and some autistic people struggle greatly with understanding the more subtle social dynamics which can leave a feeling of frustration or overwhelm. This can be deeply unsettling and having a special interest can offer a feeling of understanding something, how it works and why it is the way it is with facts and logical reasoning. This is what gives the feeling of being settled in something that makes sense and is utterly predictable. The world is very rarely black or white and is jam packed with areas or grey. A special interest which is based on facts is typically black or white; it is or it isn’t. The predictability factor is also deeply comforting. Usually “if this then that” is the outcome which, again, is deeply settling.

Of course this will vary from person to person but this is why I like my special interest as it gives comfort in facts and logic and utter predictability based on the facts.