From this thread:
I think that activity relations are easier to develop than duality for two reasons:Originally Posted by Joy
1.) It's easier to fulfill someone's hidden agenda with your first function than it is with your second. In a way this is because (going back to a theory I mentioned a while ago) in a way, the first function is who we are, and the second is what we do. The first function is default mode. It's what we're in which we're most confident. When in a confusing or difficult situation, it's the function we turn to. This also explains why activity relations are so enjoyable. It's fun when someone can't get enough of what you do best, especially when others don't encourage it as much (from my observations we usually have to filter our words/actions from our first function through our second and third to make sure we don't piss people off). Our activity partners readily admire our use of our first function, something which we enjoy getting sincere compliments on almost as much as our hidden agendas.
Perhaps an example of this would be myself and my massage therapist. We usually talk through my massages (lol), and she's often said that she loves the way I explain things. She said that even when there's a lot of complicated information that would require time and effort for most people to really understand, I explain it in such a way that allows even her to understand it, which (according to her) is saying a lot. "And not only can I understand it pretty easily, it's also an interesting way of looking at things."
2.) We'd rather ignore our 7th function when we can. Our 7th function isn't difficult, but it can be rather annoying when people want you to use it more than you already feel you should. The interactions between the third and seventh functions are largely how duals balance each other. We're likely to feel compelled to behave a certain way when it comes to our third functions because it's what's expected of us or what we're supposed to do. Our dual's tell us that it's not necessary, perhaps even in an irritable manner (it's their 7th function, after all). This doesn't necessarily immediately stop us from feeling compelled to behave that way or do a certain thing, and we end up going back and forth a little bit with our dual's until a solution is reached. Sometimes it's reached by our dual allaying our concerns, and sometimes it's reached by our dual conceding that we're probably right and we should be acting that way or doing that thing. This is probably the top cause of whatever friction there is in dual relations (the second is possibly our expecting our dual's first function to be infallible).
When we're interacting with our activity partners, they won't expect us to address things related to our 7th functions. Instead, they may expect us to address things related to our 8th (and their 3rd) functions. When people ask us to use our 8th function, it can be fun for a little bit, then seamlessly turn back to our 2nd functions (because we see them as being more important). Our activity partner appreciates that when they bring up their concerns related to their 3rd function, we entertain them briefly (can be sort of fun) and then in effect tell them that what's really important is the information related to their 5th function, the function that they have a greater need for fulfillment of than any other function (yet didn't realize it).
There are other reasons that activity relations are easy/enjoyable as well, of course, such as the dichotomies (we share the positivist vs. negativist and tactics vs. strategists dichotomies, yet one person is still an asker while the other is a declarer, which helps make for enjoyable conversation). Of course, there are also reasons that activity relations aren't as beneficial or stable as duality relations (such as temperament compatibility, which is a really big deal).