SLOW LEARNERS: The Pixies needed four or five years to become exceptional.

Hell, when the group started in 1986, they barely played well enough to hammer out their songs on stage. That was shortly after Thompson, an anthropology major, dropped out of college to form a rock band, apparently after digging up the demon Pazuzu and becoming possessed. Early on, Thompson, Kim Deal, Joey Santiago, and David Lovering were passionate little devils when they took the stage at Boston area clubs like the Rat and T.T. the Bear’s. But they lacked the blend of technique and panache that makes a rock band — even a primitive punk-rock band — good, not to mention the precision that acoustic arrangements demand. The truth about the Pixies is that though it took them just two albums and an EP to become influential, they needed four or five years of playing to audiences to become true performers. And then, after their 1992 tour, they broke up.

So it’s odd that a pair of DVDs capturing the reunited band in semi-acoustic and acoustic performances would be released within the past month. Pixies Acoustic Live at Newport (Eagle Rock Entertainment) is fascinating, even when the framework for their songs turns weak. Pixies — Live at the Paradise in Boston (also on Eagle Rock) is hideous and uncomfortable until Thompson puts down his acoustic guitar and hefts a Fender Telecaster to join his mates in plugged-in-ville. Then it’s exceptional — an electric Pixies concert that captures the group’s balance of musical passion and mad lyric prophecy. And for those curious as to why the Pixies are playing together again at all, there’s loudQUIETloud; A Film About the Pixies (MVD Visual), a behind-the-scenes documentary about their reunion that’s the finest of these releases.

What’s best about the Newport show is that its 22 tunes set Thompson’s lyrics in sharp relief. Biblical imagery bumps bellies with dark absurdism and contemplations on fate with absolute sonic clarity during their performance on stage at the famed Rhode Island folk festival on a sunny August 2005 day. The summery setting adds some innocence to a set list that’s a fan’s dream. Alterna-hits like Deal’s vocal feature “Gigantic,” “Monkey Gone to Heaven,” “Where Is My Mind?”, and “Wave of Mutilation” are balanced by thornier numbers like “Gouge Away,” “Subbacultcha,” and “River Euphrates.” The well-directed multi-camera shoot puts you right in the midst of the Pixies, and that makes it easy to see Santiago and Thompson exchange half-bemused/half-resigned glances whenever the usually bellowing guitar lines don’t make the transition to tinnier acoustic tones. When an audience member shouts for the group to jam, Thompson replies, “We’ve never jammed.” But a few songs later, on “River Euphrates,” he shoots Santiago a sly look and they do just that. Deal appears as nonplussed as ever behind her blimp-sized mariachi bass. Lovering has it easiest; his instrument’s always acoustic, and as usual he provides the Pixies’ pounding heartbeat with methodical grace.

Pazuzu’s curse is in effect during the early portion of Live at the Paradise. The band are off-balance: Thompson’s acoustic-guitar playing is lackluster, and Santiago seems reticent to blast over the frontman’s strumming. So the rocket fuel the audience is craving the moment the band take the stage is missing. The Pixies’ reunion was still very much a novelty at this point, and expectations for this semi-secret home-town show were high. Slow tempos and muffed song starts deflate the occasion, even if they seem a bit calculated on Thompson’s part. Maybe it was the cameras, since the group also have that deer-in-the-headlights look until Thompson straps on his Telecaster.

As any nervous club musician can tell you, there are two brands of courage: liquid and sonic. When Thompson begins to rumble through his amplifier on “Gouge Away,” he and Santiago provide a potent flaming double shot of the latter. And the Pixies find their wings, delivering the kind of rock-and-roll orgy they grew into before calling it quits.

Good as the Paradise concert becomes, fans may get a bigger turn-on from the disc’s bonus show: a 1986 set from T.T. the Bear’s. It’s bootleg quality, so the sound and the look aren’t as impressive as Thompson’s hair, and his thinness, and the pleasure of witnessing the Pixies when they were truly tiny.

LoudQUIETloud is an impressive little beast. Besides giving fans a chance to see Thompson in his skivvies, Steve Cantor and Matthew Galkin capture the band on stage at their best, thriving in the just-reignited spotlight during their first returning tours of Europe, Canada, and the States. Although the filmmakers’ contention that the Pixies are among the most influential bands of all time is dubious, they get into their subjects’ craniums with unforced effectiveness. Deal comes off as the most soulful and complex. (“She needs something to do besides making poetry, snowflakes, and sleeping all day,” her mom says of the reunion.) And who knew that after the band broke up, Lovering became a struggling, couch-surfing magician?

Incidental music by Daniel Lanois fills in the quiet spaces. Since the Pixies aren’t Chatty Cathys, there are lots of these. Then again, on the early comeback tours, the band had much to brood about. Deal was one year sober; Lovering’s dad was dying of cancer; Santiago and his wife had another baby on the way; Thompson was struggling with an impasse in his solo career. LoudQUIETloud is also a wake-up call to all the dipshits who slag bands like the Who for reuniting to harvest a cash crop on tours. Terrific as they are, it’s obvious early on that the Pixies are back in it only for the money. Frank Zappa would be proud!