What language do deaf people think in?

I think deaf people can see letters and are taught sign language, and so they associate those letters with images, feelings, and impressions just as hearing people do. So in that sense, they wouldn't really be exempt from thinking in a language like English, Spanish, etc.

If you were deaf AND blind, however, that would be the real question, because you wouldn't be able to associate anything sensory with your language, except for the hands as they are forming sign into someone else's hands. In that instance, I think those people may be thinking at a deeper level than language. Maybe just pre-verbal emotions, visceral instincts, etc. Interesting question.

the same language they learned to read

ASL unless they are taught another language first. Ever heard of lip reading?

I think in English.

I read in English

I write in English

I dream in English

I've always sorta guessed that they think by seeing written words in their head

What ever language they learned to sign in (signing is not universal).

namaste

Mind same time

Good question! No answer.

Sign language

Braille. <}:-})