The album Merriweather Post Pavilion, which was released in January, represented a new direction for the Brooklyn-based trio of musicians known as Animal Collective. The album was very well received by both critics and listeners (it got an astounding 9.6 on Pitchfork, if you must know), and it put the band firmly on the mainstream-alternative map with its unmistakable pop sound. "Pop" is a striking label to apply to a group of musicians whose screechy, experimental sound has historically conferred on them an image of avant-garde exclusivity. Nonetheless, nearly every track on Merriweather is seductively catchy, while several are even highly danceable.

During a show at the Prospect Park band shell in Brooklyn on Friday, Aug. 14, the three members of Animal Collective demonstrated that this newfound accessibility does not extend to their live performances. Earlier, the opening act, Black Dice, pounded the defenseless ears of the audience with a full hour of self-described "experimental electronica" that sounded like the soundtrack to Satan's inner monologue. Animal Collective took the stage alongside a bizarre, psychedelic, aquatic-themed art installation that elicited murmurs of delight from the crowd. But visual distractions aside, if fans hoped for something significantly more sonically agreeable than the headliner, they were sure to be disappointed.

The band's sometimes perplexing performance consisted of a single continuous set lasting 90 minutes, and much of that time was filled with vague melodies, ambient noise and the band's trademark dissonant fuzz. Discernable songs were few and far between; one had to really listen and wait patiently to discover a point at which the seemingly endless and mind-numbingly repetitive transitions might evolve into something better-formed. From a participatory angle, this organic approach to the music left much to be desired-a fact that was clear to anyone who, like me, attempted to tap his foot in time and soon got bored.

Such indulgence was particularly cruel during "Daily Routine," a song off of Merriweather that is distinguished by the soulful, drawn-out vocals at its conclusion, when singer Noah Lennox memorably repeats the line "just one sec more / in my bed." However, rather than playing it true to the song's recorded form, Lennox (a.k.a. Panda Bear) tantalized the audience by holding notes past their expected duration and extending the song by another two minutes. Voices in the audience shouted out the lyrics at the moment that they expected to hear them, while hands went up and fists pumped pathetically in the absence of any corresponding bass thump or chord. Some listeners obviously felt cheated, creating a palpable atmosphere of disappointment.

A similarly aggravating pattern of deconstruction and rearrangement followed with what should have been a crowd-pleaser, a recital of "Brothersport." Here, the lyrics were deliberately switched around, and the song structure was simplified in some sections but complicated in others. This made it unduly difficult to dance and nearly impossible to sing along. In consequence, people awkwardly tried to keep up with a song they had been eagerly looking forward to hearing all evening only to find that the music being played clashed with their expectations.

Time and again, the band made it a point to dangle a song or melody-a musical point of reference-only to take it away, displaying an almost sadistic refusal to conform to the recording. Often, such delayed satisfaction can bring spontaneous musical catharsis, particularly at live shows, but these gestures instead failed to inspire enjoyment or response. For instance, after teasing the drum riff to "Fireworks" for an interminable three minutes, whatever excitement was initially created had been completely used up with the unfulfilled anticipation that something might actually, eventually, begin. Only at a few moments did the group's experimentation beget something captivating, as during a vocal call-and-response buildup in the encore, "Guys Eyes."

Certainly, Merriweather Post Pavilion showed that Animal Collective is capable of crafting pop songs that are almost charitably catchy. But at this show, the trio expressed to its fellow Brooklynites a resolute refusal to be mimed, mimicked or predicted. If you'll pardon the cliché, they just simply won't allow themselves to be "put in a box," making their live performances something of a letdown.