In images or language? If in languages are you just kinda talking in your head to yourself? Describing what you're seeing/doing or having a conversation with two you's bouncing ideas off of "one another"? Or are you thinking a conversation with you and someone else where you play both parts? Something else?

Discuss.

I always play out conversations with all sorts of people in my head, about all sorts of things. I usually have the imagery in my head to go with it, with a full scene/location, their face, their voice (in my head). I usually do it at nights when I'm trying to sleep... and it sometimes takes up to 30ish minutes to even realise I'm doing it, and sort of snap out of it... and by then I've made up my own story. It usually starts with something thats recently happened, or me talking to people that I feel like I have stuff I want to say/wish I could say.

Daydreaming basically...

I talk to myself in my head a bit, but not much more than most other people I don't think.

To answer your question, sort of (Philosophical stuff like this is never very compatible with my simple brain), I would say I think in languages... or at least in what my take on your question is.

Both.

Sometimes when I'm quite inspired, I start seeing/hearing things as if they were described in a book.

[Keeker]

Slowly.

Generally voices in my head, and sometimes I'll talk to myself, argue with myself, sing to myself, all while sitting next to the woman on the train who is peering over her Eat Pray Love book at me uncomfortably.
Sometimes I'll think with various music scores and riffs supporting my thoughts, depending on mood and direction.
If with images, it's almost like a movie or something in my head. Sometimes I'll have characters in a TV show talking for me, like my thoughts are a discussion panel of Peter Griffin, Dexter, and James Bond.
How I wish I wasn't exaggerating.

Voices i guess, but then its only one voice, and it is my own.

I think in words and images, but mainly word. I kind of talk to myself in my head...

I constantly think in images and alternate situations. Rarely words.

I constantly think in images and alternate situations. Rarely words.

Same, which makes it difficult for me at times to communicate my thoughts.

I hear music in images.

[Octillus]

I hear music in images.

Me too.

I hear music in images.

True for me, as well. Sometimes vibrant, sometimes vague, and sometimes just colors and hues with no shape.

I see a big chocolate cake constantly talking to me in my mind, I follow its orders.

[swervedriver]

Usually sitting down, resting my chin on the back of my right hand while my right elbow rests on my left knee. While naked.

Like all men, I think with my penis.

In a more genuine way, I tend to think in images and words, really. Depending on the situation it's different. Music also tends to conjure images in my head while I listen. I do talk to myself quite a bit, mostly when driving. Probably more than is healthy but being in a full-face helmet sort of puts you in a little bubble outside of the regular world so I just drift away into conversation as if someone else is there with me.