Since the stories are very different it can be confusing to focus on the differences. Here is what is similar about them.
In Psycho, Marion metaphorically tries to
fix what she has done by working out the figures of what she has spent. She then crosses in
in front of a mirror where she is partially reflected. She flushes the ripped up figures
down the drain, steps into a cubicle, and is
joined by another figure. She
screams. After she falls dead, the camera closes in on her eye and
lap/dissolves to the drain. The story of Marion Crane is not what Psycho will be about. Marion Crane is finished.
Compare this to Brokeback. Ennis metaphorically tries to fix what is happening between himself and Jack
by fixing Jack's truck. As Jack leaves, we see Ennis in Jack's rear view mirror -- the equivalent of being
reflected and
going down the drain at the same time. Ennis steps into an alley and doubled over with cramps, and is also joined by another figure. He
screams. As he doubles over, we hear "forgive us our trespasses" --
the audio equivalent of a lap dissolve as the story shifts to Ennis's wedding. Any promise of a future between Jack and Ennis, effectively goes down the drain here as we. The romance of Brokeback mountain is not what Brokeback will be about. The romantic promise of Brokeback is also finished.
Very different stories, but similarities
can be found.
....
In Psycho, the "Adam's apple" shot is very pronounced as the camera goes below eye level and looks up at Norman's throat as the detective Arbogast questions him.
In Brokeback, the camera stays put, but Heath's head is cocked back at an awkward angle to expose his throat as he sits on the bed. Alma is working her "charms" with "no more loney places". The interesting feature of this awkward head tilt seems to be his exposed throat (the frontal lump on a man's throat is commonly referred to as the "Adam's apple").
....
I don't know if Annie Proulx had any Hitchcock elements in mind when she wrote the short story, but many curious coincidences keep popping up:
One of the scenes that was cut from Brokeback was pulling a VW microbus out of a lake. This would also parallel a remarkably similar scene in Psycho - Marion's car being dredged from the swamp. Presumably, James Schamus wrote this scene and it was cut because it didn't work. Strange that it would also find a parallel a scene in Psycho.