Special interests are extremely intense. Like, “doesn’t talk about anything else” intense. This will be mentioned later but is deserving of its own category because its so much.

Autistic people are made fun of for our special interests - even if they’re “normal”, “acceptable”, and “age appropriate” interests. We are made fun of for them, and if we get excited about them are nearly always told to shut up or are yelled at because “you’ve said that before”. I’ve never met an autistic who wasn’t told to shut up when infodumping.

Very common in special interests is an extreme protectiveness. This often stems from the above - we don’t want people we don’t like to like our SpIns. That doesn’t mean we stop people from liking them - this usually only extends to people we dislike or are for some reason uncomfortable around and family members, who often are the ones who tell us to shut up.

Yes, people like to know things about interests. But autistics often can’t stop. We repeat ourselves about them, and because of the social aspects mentioned above, we know people think we’re annoying. But we can’t stop. We store the information and when it comes up its like they’re kicking over the file cabinet.

Special interests are (not named) literally a part of the diagnostic criteria for autism. From the DSM-V directly: Highly restricted, fixated interests that are abnormal in intensity or focus

Note: abnormal in intensity or focus that means that if “everyone” has special interests, they aren’t ‘abnormal’ in intensity or focus, because that’s everyone.

In the examples, directly from the DSM-V, specifically referring to interests: excessively circumscribed or perseverative interests (circumscribed=restricted perseverative=repeat insistently/redundantly)