As you said, images ("films") are always flowing off of other objects and contacting our body. Our body is able to perceive these films differently in different parts of the body (the nose will smell, the eye will see, the brain will visualize).
It seems to me that repeated contact with these images/films produces an automatic expectation (basic stereotype) of objects and object-interactions that we can access in our mind by focusing on them -- and these stereotypes are the basis of our thought and speech.
Epicurus says (38a) "Seeing [for ourselves] the primary thought for each word, and in no way needing proof, is necessary – if We are to have [something] to which we will refer what is investigated, uncertain, or judged."