“As you read in this way, you think about how the choices the author made and the techniques that he/she used are influencing your own responses as a reader”.
When you read you need to determine the impact the writing has on you, mainly as a reader so you get an understanding on how to impact your own readers. This gives you insight on two sides of the coin, one being the writers and the other being the readers. If you have that understanding on how the writer impacted you during your reading you can bring that over to your own writing. For example not only taking into account things like word choice and tone but comprehending why the author chose to sort their writing in a specific matter can also increase the impact of your writing.
OK