How Taylor Swift created 'Out of the Woods'

Out of the Woods isn't just a different-sounding song for Taylor Swift, it represents a whole new approach to songwriting for her.

Released this morning on iTunes and streaming at RyanSeacrest.com, Out of the Woods has massive, '80s-inspired production and an apprehensive melody that "sounds exactly like that frantic feeling of anxiety and questioning" in a fragile relationship, the singer told Good Morning America Monday.

But the second song made available from Swift's forthcoming album 1989, written and recorded with Jack Antonoff of fun. and Bleachers, is also the first Swift has written to a pre-existing track. "I tend to want to create something with my guitar or piano and bring it in, then we create the track from the ground up," Swift tells USA TODAY. "But with Jack, he has something very emotional about what he does when creating a track. I can kind of read that emotion as soon as I hear it, and we work very well that way."

Antonoff sent Swift an early version of the song, minus any lyrics or vocals. "I came up with that melody, the verse and chorus, in about 30 minutes and sent it back to him," Swift says. "Both of us were just freaking out."

When Swift got hold of the song, Antonoff says, "she wove this whole story that felt like it came from the outer space of your head."

The song's arrangement layers '80s and contemporary elements, especially when it comes to the synthesizers. "I used a Yamaha DX7 a lot on that song, which is so uniquely '80s, but then countered it with a super-distorted Minimoog Voyager in the chorus," Antonoff says. "That sounds extremely modern to me. It's that back-and-forth."

For one part of the track, he says, "I just chopped this piece of my voice singing and started looping it over and over. Then I started banging on some drums I had in the room and stomping on the floor and sampling all these sounds to make this big bombastic looping beat with the sample on top of it."

Antonoff says Out of the Woods is his favorite of the songs he and Swift have written together, which include the Golden Globe-nominated Sweeter Than Fiction, which appeared in the 2013 film One Chance.

Out of the Woods may never be a single for radio, Swift says, but she wanted people to hear it before the rest of 1989, out Oct. 27, because "I think it's the greatest example of the sound of this album."