I've never really thought about it until reading this about a week ago and set myself to the task of finding out how I think more, words or pictures.
I'd have to say I'm more pictures than words but I constantly have words and numbers running through my head- it isn't the same as when I'm thinking of something and concentrating or even daydreaming, it's hard to explain. Along with my thinking in pictures I also quite often have letters to represent what it is I'm thinking of and they are not just plain black and white alphabet letters, they are always fancy coloured swirley symbol style letters that kind of blend into the picture.
I have known for years that I am very much a visual learner so I'm sure this has a lot to do with my thinking in pictures and I am also good at math and love numbers and I am always reading something...
Others mentioned dreams...I also have very vivid sharp coloured dreams with a lot of detail...everything seems so real that I have had to confirm with others if things have happened or not...I don't like when those dreams happen and sometimes I get them more than once a week. On the plus side, I've 'seen' friends and family who are no longer with me and got to talk with them again
Ahh, brains and imaginations...