But it does maintain many of the characteristics of dialogue. We may imagine an exchange with someone else, or we may just talk to ourselves. But that doesn’t mean it’s not a conversation. Our minds contain many different perspectives, and they can argue or confer or talk over each other.
I can confirm the claim that people talk to themselves more when others are present. There have been a few occasions when I am home but my wife does not know it, and I am in the basement or in the yard, and note that she does not talk to herself, not a word. Yet when I call out and identify myself, within a few minutes I hear her start in, usually in the ways mentioned in the article - to criticise her own actions or to recite things that she needs to remind herself of. I don't know if I speak more when others are nearby, or when I am listening to the radio or a podcast. I suspect so. But I know that I can speak when there is no one else present. I bring them with me quite well. When I used to smoke, and would go outside by the driveway to have a cigarette, my sons would observe "There's Dad out arguing with liberals again." When I take extended walks I will sometimes turn off a podcast in order to imagine a further conversation branching off from something that I said, and that frequently results in me talking to someone. When they were young, my children would ask when observing me in the car, "Who are you talking to?" Unfortunately for them, I would answer. "I am accepting the Nobel Prize for Literature," or "I'm arguing with your mother. This time I'm winning." They learned quickly not to ask.
At the hospital, sometimes when nurses are giving report they will say "Jason was observed talking to unseen others throughout the shift." I have to clear my throat and remind everyone that this is not necessarily as bad a sign as they are implying. "Some of us speak to unseen others quite a bit." People smile and acknowledge. Yet it is true that it is an especial sign of those hearing voices, and at least worth noticing.
That we can discuss things within our heads would seem a powerful argument in favor of the existence of free will. Fernyhough discusses the inner conversation specifically in terms of moral decisions, and while he notes that most decisions are instantaneous, gut-feeling results, others are more of a process. Even if those various fragments are mostly an elaborate ruse we engage in, with our decisions largely predetermined, the very nature of interaction brings in an element of competition between voices that can create differing outcomes.