My Morning Jacket, Concorde 2, Brighton

As well as having the most puzzling name in music, My Morning Jacket have the distinction of being gloriously at odds with the current vogue for blustering garage rock. The Kentucky band's songs are long and unpredictable, their lyrics high on emotion. Listen to their third album (their first on a major label), It Still Moves, and it quickly becomes clear why they're adored by critics and have been repeatedly tipped as the next big thing. Their epic, multilayered songs dip into Sixties psychedelia, Seventies prog rock and old-time country. Echoing Neil Young's underwater wail, the 24-year-old singer, Jim James, has a voice to die for.

It's only when you watch the band perform that the confusion starts. Never have a band looked so different from the way they sound. With their shaggy, waist-length hair and inconspicuous get-up (despite the name, clothes aren't high on their list of priorities), My Morning Jacket come across as part-Eighties Scandinavian death-metal act, part-woolly mammoths. But it's not simply that they don't look the part.

In personality, too, they are an unprepossessing bunch and lack the charisma and electricity that are crucial to live performance. As with the drummer, Patrick Hallahan, and the bass-player, Two-Tone Tommy, James's face remains obscured by a thick curtain of hair. The only one brave enough to show his face is the well-shorn keyboardist, Danny Cash, though his gloomy expression hardly makes up for the rest of the band's coyness.

While it's refreshing to see a band high on music rather than adulation, for the rest of us it's an uphill struggle; that they don't even attempt a connection with their audience makes for a deeply uneven 90-minute set. My Morning Jacket spend much of the show locked in their own private reverie, so much so that sometimes you wonder if they know we're here at all. Aside from the odd strained: "You're a great audience", James says nothing and stands defiantly at the side of the stage, as if ready to make a speedy getaway.

That said, if you stare at the floor rather than the stage and concentrate hard enough, their music still has the power to move you. "Mahgeetah", a despondent ode to alcohol, and "Dancefloors" (not as chirpy as the title would suggest) send warm waves of delight throughout the crowd.

And when James dispenses with the rest of the band, picks up his acoustic guitar and launches into "Golden", we feel the full force of his talent. Magnified by reverb (an effect that has become as much a trademark for this band as their unruly locks), his voice is devastating in its bleakness, his lyrics racked with pain. My Morning Jacket are clearly a band with fierce passion and ambition, if only they could unlock it live.