Consider the following sentence:
1. We talked about the fact that you slept for hours.
There are two possible interpretations for this sentence. One is where the PP for hours modifies the verb talked.
The other interpretation is where you slept for hours and we talked about it. The PP for hours must now be modifying the verb slept.
Something quite interesting happens if you move one of the DP/NPs to the beginning of the sentence.
2. The fact that you slept, we talked about for hours.
If the DP/NP the fact that you slept is moved to the beginning of the sentence, there is only one possible interpretation. We talked for hours. It doesn’t mean you slept for hours. A movement explanation can handle this quite simply by saying movement cannot take place out of certain islands.
It seems that DP/NPs are barriers to movement. Look at the following examples.