One article I read about repetitive cognition and autism, researchers defined thought perseveration and autism in this way. Quote, repetitive cognition is a tendency to perseverate on particular thoughts, often accompanied by difficulty disengaging with these thoughts. Repetitive cognition ranges from fixation on favorite topics or activities, whether actually doing these activities or merely thinking about them, to rumination, which is a perseveration on negative thoughts noted in typical activities. That's noted in typically developing individuals with depression, end quote. In children, cognitive perseveration often stems from some kind of anxiety or worry. So maybe a dog barked at them, or a door slammed, and it scared them, and now they feel like they can't stop thinking about it and how it could happen again. This is rumination, one particularly negative kind of thought perseveration. As an autistic adult, the kind of thought perseveration I catch myself doing most often is repeating conversations I've already had with other people in my mind. I know other people do this too. Sometimes I'm actively analyzing these conversations to try to figure out what I might be able to do better next time, but often they're just kind of looping through my mind for no particular reason other than my own anxiety about being socially awkward. Another common perseveration I notice in myself and in my kids is our total obsession with whatever book or TV show we're currently into. If I'm into a book, I am into the book. I will think about the characters, the plot, the little details constantly for weeks or months, constantly in the back of my head, even when I really need to be doing other things. As an adult, I understand that no one else around me particularly cares about this book, this one book that I happen to be stuck on, but that doesn't stop me from thinking about it all the time.