Darkside performing at Union Transfer

Before they called their electronics-and-guitar project Darkside, Nicolas Jaar and Dave Harrington used the word as a bit of private slang. In 2011, Harrington was playing guitar in the touring band for Jaar's celebrated electronic album Space Is Only Noise, when the two Brown University graduates started using darkside as an adjective or adverb.

"It entered the sublanguage at the end of the tour for things that were a little intense or noisy or a little bit crazy," says Harrington, from Los Angeles, where Darkside were on their debut tour. They'll be in Philadelphia on Thursday performing at Union Transfer.

"Darkside" became the name of the first song Jaar and Harrington created together. Then it became the name for their duo (although even that is flexible: Last summer they used the name Daftside to post a sly full-album remix of Daft Punk's Random Access Memories).

Psychic, Darkside's acclaimed debut album, is more dreamy than intense, more ambient than noisy, but it is a bit crazy in its wide-ranging creativity and its imaginative compositions. The 11-minute "Golden Arrow" opens the album with a gentle pulse behind a few shadowy chords, digital distortions, and disembodied voices before finally locking into a groove as it nears its midpoint, with guitar lines that burble out of the mix like thought bubbles. It sounds as if a song had been turned backward and upside down. "Paper Trails" takes Harrington's twangy guitar lead, somewhere between Bill Frisell and Mark Knopfler, and a murmured vocal and pairs them with a steady clap and a gradually morphing groove.

Psychic, which made many critics' best-of-2013 lists, is full of strange and subtle juxtapositions, the result of guitarist Harrington and laptop-whiz Jaar's seeking to surprise each other while collaborating.

"Nico has things that he likes, sounds and grooves, and I have ways of playing guitar and approaches, and we liked doing them at each other, and see where they lock up," Harrington says. "I mean, 'Paper Trails,' when you get right down to it, is kind of like a deep house/country song, and on paper that's a pretty bad idea. But for us, there are sounds we like, and we try to do them honestly and together."

For their highly touted live show, Jaar and Harrington take apart their songs and reassemble them. They are the rare electronic act that values in-the-moment improvisation.

"I've been an improviser my whole life," says Harrington, who also plays bass and keyboards. "I learned to play music from playing jazz. Playing with Nico, he shreds the computer like any great trumpet player, drummer, or piano player that I ever have improvised with; it's his instrument, in a very real way. I never feel like I'm playing along to a robot. We're doing it. He's sequencing stuff on the fly, we're doing guesswork about where the tune is going to turn next and land, and one of us will pull the rug out from the other. When it feels best to us is when we're on the edge of really pushing it as far as we can, moment to moment."