It was recently brought to my attention that most people don’t. I find that…literally impossible to believe.
So, do you have an inner monologue? Do you talk to yourself? Do you get lost for hours in your imagination? Just spend time thinking? When you read, is there a voice that reads the things or do you just…see the words or something.
The first "complicated process" that comes to mind is an algebra problem, and for things like that I often visualize what needs to happen. For example if a number needs to be subtracted to go on the other side I picture the number physically moving to the other side of the equation in my brain