Anyone with access to digital media or a television can see what Michael Bloomberg’s presidential campaign is trying to do. The former New York mayor has spent at least $350 million on campaign ads, according to a CNN analysis, which has allowed him to effectively blanket the market, since his competitors do not have the resources necessary to match those levels of spending.

And as the ads kept rolling by, Bloomberg saw his numbers rise in national polls, enough to secure his place in Wednesday’s debate in Nevada, and the next one on February 25 in South Carolina—two states where he’s not even on the ballot, thanks to his late entry into the race.

Yet experts say that existing research about how political advertising works on the audience concludes that ads usually only make a minor difference: A 2016 study co-authored by political scientists Seth Hill, Lynn Vavreck and Alexander Coppock found that political advertising has a very small effect on a candidate’s favorability and voter choice. And what little effect it does have decays rapidly.

Bloomberg’s marketing blitz, however, is not usual—in fact, experts who spoke to Slate described it as unprecedented. No other candidate has ever tried the kind of saturation campaign currently underway, so Coppock said he doesn’t know of anyone who’s tested what such a barrage might do.

In his own work, Coppock said, he’s conducted experiments where he randomly assigned people to watch one, two, three, six or zero pro-Democratic advertisements. “Six works better than two or three,” he said, “but I don’t know when it stops working.”

Bloomberg is effectively running that experiment in real life. At least 2 billion Bloomberg ads have been displayed by Google and Facebook this year, according to the Washington Post. And currently there are at least 185 Bloomberg-funded video ads circulating.

Coppock couldn’t recall a time when a candidate burst onto the scene and dropped such an incredible volume of advertisement in a short period of time. Vavreck pointed to Rudy Guiliani who skipped the early primaries in 2008 and Steve Forbes who funneled $69 million into both of his presidential bids in 1996 and 2000. But neither of them did this kind of ad blowout.

“Here in Pennsylvania, I think there was a Bloomberg ad during every single commercial break—or at least it seemed like it,” said Dr. Michael Platt, a neuroscientist at the University of Pennsylvania who studies how humans make decisions, about Wednesday’s debate. “I’ve never seen anything quite like that. That’s pretty remarkable saturation.”

But what happens within a human’s literal brain when they are seemingly inundated by political advertisements?

There isn’t a straightforward answer on that, either.

“There’s not a particular brain area or something that lights up…in a meaningful way that’s distinct for advertising versus other kinds of messaging,” said Uma Karmarkar, a neuroeconomist who studies consumer behavior.

Being exposed to new information over and over again does, among other things, make it easier to recall. It’s a consumer psychology phenomenon referred to as top-of-mind awareness and it’s possible that’s part of the reason Bloomberg has been rising in the polls lately. Names that would normally be well-positioned in a voter’s mind—such as Joe Biden or Elizabeth Warren or Bernie Sanders—are being pushed back a bit by Bloomberg’s dominance in the media market.

An equivalent comparison would be something like a Geico advertisement, a fairly common occurrence you’re likely to not have missed if you consume any type of media.

“If you ask someone just about insurance, they’re very likely to come up with Geico even if it’s not a brand that they would consider,” said Karmarkar. “In part, because that mental association is so strong at this point that it’s one of the easiest names to retrieve regardless of whether you have a positive or negative thought about it.”

It doesn’t hurt that Bloomberg’s video ads, from a marketing perspective, are well done. “They’re very effective at telling a story. They’re really brief, which if we’ve learned one thing from the neuroscience of advertising, keeping something short and simple is critical,” said Platt, who watched about 10 of the videos online.

And the commercials, as constant as they may seem, are spaced out and varied across program breaks, which can prolong Bloomberg’s “rising period” and temper how quickly people lose interest, explained Mark Changizi, a cognitive scientist from the Human Factory, a research lab that merges brain science and technology. The variety of ads within the campaign also helps forestall repetition blindness—when people see something so much that they begin to tune it out. Bloomberg’s ads are similar in theme and structure, but the topic varies in each piece of media. One ad can be about education while the next one you see is about the economy. It’s enough to keep you interested while it hammers away on the message that Bloomberg is the guy whose name you need to know.

Essentially, this is why our Southern Nanas know who the former mayor of New York is even though they have never lived anywhere near the city. Dr. A.K. Pradeep described the hierarchy by which our brains pay attention: motion, where something literally catches the eye; novelty, or unexpected newness; error, when something is inaccurate or out of place or otherwise causes your brain to pause and try to understand; and ambiguity because humans love a little enigma.

The Bloomberg ads are playing with these in real time. “When you see Bloomberg saturate, it’s not just for saturation,” said Pradeep, the CEO of machineVantage, a neuromarketing firm. “There’s actually a little method to the madness in that they’re trying to figure out what constitutes motion, what constitutes novelty, what kinds of error are permissible, and what kinds of ambiguity is allowed so that they could sharpen their campaign better because they’re going against Trump who uses these instruments almost on a daily basis.”

Along with the constant message-testing, the variety and quantity of the ads may also be conveying a message that Bloomberg, despite his late arrival in the race, is an active contender. “Part of what he’s accomplished is more than just persuasion,” said Vavreck. “He has communicated to people that he’s a candidate in this race and that he’s a serious candidate. Every candidate has to do that in some way. Bloomberg is doing it in this really unusual way—but it worked.”

Still, human choice is incredibly complicated and all the experts agreed that a candidate being “top of mind” doesn’t necessarily translate to someone flipping the lever for them in the voting booth. Persuading someone off their political preference is hard in general. And once your brand is in front of them, you have to build up trust in it. It’s possible that once people start really thinking about whether Bloomberg is the candidate for them, the marketing and outreach will matter less than the ordinary elements voters consider when deciding on a political candidate.

“It isn’t all about campaigning. It isn’t all about effort,” said Vavreck. “It’s about message and mission and capabilities—all of that stuff gets wrapped up into how people are making up their minds.”

Platt concurred: “You can’t use advertising to literally force somebody to buy something. You can’t force somebody to vote for someone just by making them more omnipresent through advertising.”