Mother! Photo: Paramount Pictures

Last weekend, Darren Aronofsky’s Mother! divided critics, audiences, and Jennifer Lawrence’s diaphragm. But in the process, it also joined one of the most select clubs in Hollywood: the list of movies that have earned an F from CinemaScore.

For those of you not in the habit of following the industry response to films, CinemaScore is a company that exit polls moviegoers’ opinions on opening night. It’s been around since 1979, and according to research analyst Harold Mintz, it’s been storing its data since 1986 — or 30-plus years of audiences reacting to movies. Like grade-school or the signs you see in restaurant windows, CinemaScore’s grades range from A+ to F; an example of a recent film to earn the coveted A+ rating is Girls Trip, with Spider-Man: Homecoming and Leap! delivering solid As. If you want to put Mother!’s achievement in perspective, none of the other movies currently listed on the CinemaScore home page have less than a B- score; it’s a significant enough event that Paramount felt the need to respond.

How select is that company? Vulture asked Mintz just how many films have received Fs since ’86. His answer was 19; here’s the complete list, published in full for the first time:

Alone in the Dark

The Box

Bug

Darkness

The Devil Inside

Disaster Movie

Doctor T and the Women

Eye of the Beholder

Fear Dot Com

I Know Who Killed Me

In the Cut

Killing Them Softly

Lost Souls

Lucky Numbers

Mother

Silent House

Solaris

The Wicker Man

Wolf Creek

“CinemaScore has an algorithm,” Mintz explains. “A long time ago, we tweaked and analyzed until we came up with what we thought to be the absolute right system. Obviously I can’t share that. That’s the McDonald’s secret sauce,” he laughs. “But if you have 100 ballots, even if you divided it evenly, and had 20 As, 20 Bs, 20 Cs, 20 Ds, 20 Fs — in school, that’s a C. In our curve, it’s a lot worse; a B in school is more equivalent to a C in our terms. When you start getting Bs with CinemaScore, it affects the algorithm and curve a lot harder than it does in school. If you have 20 percent Cs, 20 percent Ds, 20 percent Fs — imagine how bad that is.”

A+s are plentiful compared to Fs, Mintz says — they average about two a year, versus the 19 Fs in 31 years (though both are extremely rare). But all genres are not treated equally by respondents. It’s pretty obvious that, of the movies to receive Fs, horror is disproportionately present. In the year of Split, Get Out, and It, that might seem strange; horror is practically keeping the box office afloat, particularly in the realm of films that cost less than nine figures.

“Until the last year or two, a great score for a horror film would be a B-, even when they’re good. There were no As until The Conjuring [an A-] came out,” Mintz says. “Get Out got an A-, and did very well box-office-wise. The trend is changing a little bit. For the longest time, most horror films were Cs and lower. An F in a horror film is equivalent to a B- in a comedy. There’s no science to that, exactly.”

Mintz suspects that a rising quality in the genre is responsible for this change. Most of the straight-up horror films on the list of Fs wouldn’t surprise anyone, and for much of the past few decades, those were the types of movies that made up the majority of the form: starlet-driven, teen-oriented schlock that would lure in audiences opening weekend based on stars and serving a need, then give way to the next one. Sure enough, Mintz says that these films tended to deliver low multiples, meaning the overall gross in relation to the opening weekend. This is generally thought of as CinemaScore’s main utility: If a movie delivers a poor CinemaScore on opening night, it’s a bad sign for word of mouth, and it suggests that a low multiple is likely. If it delivers a high CinemaScore, it’s the opposite, and with the higher CinemaScores for horror, Mintz has seen a corresponding increase in multiples, with movies like The Conjuring franchise delivering unheard-of-for-the-genre 3.0 multiples. (Get Out has managed a staggering 5.3 multiple. Among movies opening this year in wide release, only Hidden Figures did better, with Baby Driver about equal, thanks to inflation from its Wednesday opening — although both of those films made $10 million less than Get Out did opening weekend.)

Of course, horror isn’t the only type of film to earn an F CinemaScore. Another type of movie features prominently on the list: let’s call it “Misleading Auteurism.” These are movies made by prominent, often Oscar-nominated directors that investigate risky and controversial subject matters and receive both praise and pans. But because of how the movie industry works — the name of a director alone not being enough to get most people to go see something — they tend to be marketed as more straight-ahead genre films, resulting in a whole bunch of misled and pissed-off audience members. (If you can explain the F given to the more or less unremarkable Richard Gere rom-com Dr. T and the Women, which is mostly notable for having been directed by Robert Altman, we’re all ears. Disaster Movie’s presence seems a bit more logical.)

Solaris, In the Cut, and Bug were directed by Oscar winners Steven Soderbergh, Jane Campion, and William Friedkin, respectively; The Box by cult hero Richard Kelly, maker of Donnie Darko; and Killing Them Softly by Andrew Dominik, who made the modern classic The Assassination of Jesse James by the Coward Robert Ford. (Mother!, meanwhile, is the seventh film by Aronofsky, who was nominated for Best Director in 2011.) But on the surface, all of these movies can scan as your average multiplex entry, especially in comparison to much of their filmmakers’ other work: They feature stars (George Clooney, Meg Ryan, Ashley Judd, Cameron Diaz, Brad Pitt, and Jennifer Lawrence, respectively), and they fit within existing genres (sci-fi, thriller, horror-thriller, sci-fi–thriller, crime, horror).

But underneath the conventional trappings, these are all films of ambition and, if not necessarily complexity, at least an unconventional approach to their material. Solaris is a sci-fi movie that defies the form at all turns, from a creative mind, Soderbergh, who delights in subverting expectations; Bug is a disturbing work from the pen of Tracy Letts, who would collaborate again with Friedkin in 2011 on the similarly bonkers Killer Joe; In the Cut is defiantly sexual; The Box becomes increasingly complicated and outré as it goes on, culminating in a fable of moralism; and Killing Them Softly is more a European-inflected riff on a gangster movie than an actual gangster movie, punctuating its philosophizing, political reflection, and character studies with bursts of violence.

What these movies have in common is that they take on the cloak of a genre and then refuse to give the audience what they expect from that genre, a feat that Mother! — which was marketed largely as a horror movie — perpetrates gleefully. If CinemaScore’s list of Fs has a major lesson, it’s that audiences do not like to be fooled in this way. (Trey Edward Shults’s It Comes at Night and Robert Eggers’s The Witch are recent examples of this phenomenon as well; both received very positive reviews and then D and C- CinemaScores, respectively, when they turned out to defy the horror genre’s parameters.)

It’s also an observation reinforced by the current state of the film industry, in which the most successful movies tend to be the most easily understood, based on preexisting property, and part of ongoing franchises and narratives. While it’s surprising that Paramount made Mother! at all, it’s hardly shocking that viewers received it like they did.