Filtering sifts the action of a story through the point-of-view character’s senses. It tells the readers the sense the character uses and is followed immediately by showing what the character experienced with that sense.
1) He saw her step tiptoe around the lilac bush.
2) He felt his heart race.
Just show what happened rather than stating the sense the character used first, then showing it.
1) She tiptoed around the lilac bush.
2) His heart raced.
We should avoid filtering because…
1) The reader knows that everything shown comes from the point-of-view character’s perspective, so it must be something that the character can see, hear, feel, think.
2) When we state the sense used, we tell the reader something; when we show the sense being used, we paint a picture for the reader–we show them something.
3) By stating the sense used, then showing it, we are being repetitive. (so remember to RUE–Resist the Urge to Explain)
4) It makes the POV character a barrier between the reader and the story.
5) It minimizes the impact of the action by making the sensory verb (such as saw, heard, felt, thought) the main verb rather than the verb which shows the action.
6) It adds unnecessary words.