It was the Hoover Dam of mental blocks. Pundits referred to it as a “brain freeze” or a “gaffe.” In Internet parlance, it was an “epic FAIL.” But to neuroscientists, what happened to Texas Gov. Rick Perry Wednesday night looked like something very ordinary, exacerbated by stress: a “retrieval failure.”

It happens more often as we age. But the brain scientists say it shouldn’t be seen as evidence of an intellectual deficit or some medical problem. Instead, they say, retrieval failures offer a glimpse into how the brain does and doesn’t work, not just in the skulls of presidential candidates but for everyone else, too.

It’s impossible to know what exactly was happening inside Perry’s head at the Republican presidential debate, and the pundit class will continue to debate whether it was a neurological hiccup or a telling sign of a candidate who doesn’t know his own policies. What’s certain is that, at a crucial moment, on stage, live on national television, Perry could not remember the name of one of the federal agencies he would like to abolish.

Once he started to flounder, he probably found himself entangled with unhelpful thoughts, suggested David Diamond, a behavioral neuroscientist at the University of South Florida. In a stressful moment like this, the mind turns to the consequences of the error, making an elegant recovery all the harder.

“Even though Rick Perry’s life was not being threatened, his brain was responding as if there was a lion in the audience about to pounce on him,” Diamond said. “He’s now got the media pouncing on him.”

The governor’s mental lapse did not occur in a vacuum. His previous debate performances have been widely panned, and he’s been sliding in the polls, fighting a perception that he’s not up to the job. He was speaking Wednesday night to an informed audience, one capable of understanding the nuances of policy. But he struggled with a talking point, opening himself to criticism that he doesn’t have the depth of knowledge expected of a presidential candidate.

It was unclear Thursday whether his candidacy could survive his blunder. But among brain scientists, at least, he’s getting a pass.

Jason Brandt, a professor of psychiatry and neurology at the Johns Hopkins University School of Medicine, said that he’s a die-hard Democrat but wouldn’t hold Perry’s flub against him:

“I think it’s unfortunate that it happened in a situation of such high visibility,” he said. “Whatever you want to call it, they happen, and happen at times of high anxiety in particular.”

Such mental blocks often involve the failure to retrieve a proper noun, the experts said. A proper noun is like a label: It represents a more complex concept. Patients with recurring, pathological problems retrieving a label are said to suffer from anomia. But it’s something that happens to everyone occasionally.

It happened to Perry in a particularly brutal fashion. For the better part of a minute during the GOP debate at Oakland University in Rochester, Mich., Perry tried to come up with a word: “Energy.” It was the third word in a list of three federal agencies he says he’d close if elected president. But although he named Commerce and Education, he couldn’t quite snag that third word from wherever it was hiding in his brain.

He pointed at his own head and laughed. Another candidate suggested that he was thinking of the Environmental Protection Agency, and Perry momentarily seized on that. But moderator John Harwood asked, “Seriously? Is EPA the one you were talking about?”

Perry acknowledged that it wasn’t.

“But you can’t — but you can’t name the third one?” Harwood said.

Perry made another spirited lunge at it.

“I would do away with the Education, the Commerce and — let’s see . . .

Retrieval failure, again.

The governor despaired.

“I can’t. The third one, I can’t. Sorry. Oops.”

It would be the oops heard round the political world.

Diamond said the structure of the brain is partly to blame for a retrieval error. Language centers are not particularly close to memory centers — it’s like New Jersey trying to communicate with China.

Diamond said retrieval failures often involve new information. In Perry’s case, he’s been governor of Texas for more than a decade but has been running for president for only a few months.

“When we forget words, when we forget names, it is new information that has just not established strong links in our brain,” Diamond said.

And yes, it’s getting worse for all of us, he said — not just because some of us are getting into the more advanced age brackets, where the brain literally shrinks and the rust metaphorically builds up, but because we’re all increasingly saturated with information.

“We are doing so much now, we’re multitasking perhaps at a higher degree than ever before,” Diamond said. “We get into work, and we’re handling e-mails, we’re going to all the Web sites, we’re processing more information now than ever before. We’re asking more of our brains than evolution ever prepared us to handle. So every now and then we just drop the ball.”

MIT neuroscientist John Gabrieli stresses that a retrieval failure is due to a mental block that has to be cleared away, somehow, before you can find the word you want.

“It’s not that you can’t get there, it’s that something’s blocking that, some other idea or word has come into your head. Until you clear that other thing, it’s hard to get back to that piece of information that you really know,” Gabrieli said.

Aileen Pincusof the Washington-based Pincus Group, which coaches people on public speaking, said a good rule for speakers is to avoid lists. Even a short list, like the one that Perry tried to offer, can be a trap.

“It was self-entrapment,” she said. And when Perry failed the first time, “he started the list again.”

Brandt counsels people who worry about memory slips to relax, go on to something else and wait. The memory will resurface soon enough.

“The more you try to focus on it, the deeper your hole gets,” he said.

But that common-sense strategy — retreat, relax, wait for the systems to reboot — wasn’t an option for Perry. When he couldn’t find the word “Energy,” he couldn’t just say, “Whatever.” All he could do was twist and writhe in his deepening hole.