As a person with ADHD, having conversations with single-thought people (my name for all you who only contemplate one thing at a time) can result in frustration and miscommunication, often without an obvious reason why. My whole life has been trying to figure out why others act like I'm a bad person simply for being myself. "You're so weird!" "Don't you know how rude you're being?" "Sometimes I think you do that on purpose." Despite all that hostility, I'm still trying to figure out the secrets of so-called normal communication, and I'm getting better every year.
"But Andy!" I'm sure you're saying, "what about the secrets of ADHD communication? I appreciate that you're trying to learn about us, but I want to learn about you too. Don't be stingy, now." I wouldn't dream of withholding such useful information, which is why I'm sharing this link I recently found. It's the best summary I've ever read, and pretty much describes my experiences spot-on, but I'll go ahead and add my own notes below.
Blurting Things Out - This has nothing to do with how little I respect the person I'm talking with. Instead, it has to do with the way my hardware runs. I can't count how many times I was about ready to say something, tried to my tongue for a few seconds, and then completely forgot what it was I was about ready to say (and this has happened for very important issues too). As many people with ADHD are well aware, thoughts are transient things. Any moment I'm thinking of something may well be the last, before it's lost forever to forgetfulness. Sometimes I manage to make it to a pen and paper in time. But often, I just say it, that way it gets out of my brain where I don't have to worry about it any longer. You may wonder what was so important about squirrels that it couldn't wait a minute? Well, let's just say that the fear of forgetting often overrides taking the risk to waste precious have decided that understand that yes, this cannot wait, it might be forgotten. Also, if I'm spending time contemplating what I'm about to say, I'm diverting my attention away from what someone else is saying in a conversation, and I've just completely missed it all. This is why I often just say what I have to say, then ask my conversational partner to continue where they left off.
Conversations that Go Everywhere - Apparently some people only think about one thing at a time. I never saw the point. After all, everything in life is interconnected (6 degrees of Kevin Bacon, anyone?), and drawing those diverse connections out into the open is an exciting way to learn new perspectives on familiar topics. I you really want to focus on one particular point, let me know. This doesn't mean I'll sit up straight and refuse to deviate (as if that were possible, ha!), but it does mean that I'll make sure to regularly touch base with that topic as we converse, especially if you bring it up again.
Monologues - If you don't like what I'm talking about, switch the topic. I probably won't notice if you don't find my thoughts engaging. I can't notice. I'm about as useful for reading conversational cues as my tone-deaf father is for reading music. The good news is, I rarely take a subject-change as a bad sign, and in fact could get excited because something new and different is now happening.
Extreme Defensiveness - I've been told I have this. Possibly. The author said it's because of years of being constantly criticized. I do know I'm tired of being told I'm a bad person simply because I am neurologically different. The best way to approach me is with the phrase "I know you may not be aware you're doing this..."
Poor Memory of Agreements or Incidents - I do my best, but I already have a long list of things I'm supposed to change about myself in order to fit in. Your item probably got lost down at the bottom. Just issue a gentle reminder, and I'll try to bump it up a bit.
Getting Lost in Conversations or Wildly Misunderstanding - I often get blamed as though I do this on purpose. It helps if you use really specific examples during conversations for me to help define the topic. In fact, tell stories, so I can form a vivid visualization of people acting out what you're trying to tell me. Also, ask questions. I do a lot of question-asking myself, and if they seem to be leading in the wrong direction, it's not because I'm trying to trip you up, it's because I'm trying to rule out what you're not saying to get a better grip on what you actually are saying.
There you go! Hopefully the article and my comments help you out. And if anyone has created a similar cheat-sheet for how single-thought people converse that is as good as this one, let me know. I've been looking for one for over 2 decades.