Movies are blurring fact and fiction on purpose. What does that do to the audience?

I, Tonya and the Sundance heist film American Animals are just two recent examples.

Nonfiction and fiction have always bled into one another on the big screen — movies based on true stories, documentaries with staged scenes — but these days it feels increasingly difficult to separate the two, and sometimes not really worth the effort.

Take Errol Morris’s recent Netflix docuseries Wormwood, which is about half interviews with the son and acquaintances of a man who died under suspicious circumstances, half dreamlike reenactments of the mental state of the man (played by Peter Sarsgaard) before he died.

The reenactments are so pervasive and extensive — there are whole scenes with scripted dialogue, rather than just representation of something an interviewee is describing — that Wormwood feels like a truly hybrid work, not easily characterized as anything at all.

Or consider I, Tonya, which hinges partly on “irony-free, wildly contradictory, totally true interviews” — according to the film’s title cards — that screenwriter Steve Rogers conducted with Harding and her ex-husband Jeff Gillooly. The interviews are included in the movie, but Harding and Gillooly don’t appear in the film themselves.

Instead, it’s their characters, played by Margot Robbie and Sebastian Stan, doing the talking, and their accounts conflict with one another by design. So we’re connected to what “really” happened, but still a level or two of abstraction away from “reality.”

These are just two recent examples among many. But if you’ve watched a movie in the last few years, chances are you’ve seen one that could fall into the category of blurred realities. If this year’s Sundance Film Festival selections in both in the documentary and narrative sections are any indication, films that push the boundaries of reality are a trend here to stay.

Do those boundaries even matter? When a film is well executed, the question of whether it’s “fiction” or “nonfiction” can seem utterly irrelevant. Good storytelling is good storytelling, and if it gets its point across, who cares?

There are a few reasons to think about the distinction between fiction and nonfiction, not least because so much of American culture today seems to operate on smoke and mirrors, sleight of hand, and outright falsehoods.

But another, less politically fraught reason is that blurring fiction and nonfiction well can push the audience in ways that one or the other might not accomplish alone. Ultimately, the result can be more effective storytelling.

There’s something disorienting — and exhilarating — about the mixing of fiction and nonfiction, performance and “reality” (though of course, you can argue that everyone who appears on camera is performing). It messes with the paradigms through which we’ve been trained to consume stories.

When we’re told a movie is “fiction,” we assume that what we’re watching is at most a reenactment of reality, not that we’re actually watching the events themselves. These are actors, playing parts; even if what they’re doing is creating an exact replica of the original story, it’s still a copy of the original. (And of course, movies based on true events often alter or embellish their source stories, to varying degrees, for reasons of artistry, clarity, or storytelling cohesion.)

In contrast, when we listen to an interviewee or a watch a series of unscripted events in a documentary, we assume we’re seeing roughly what we would have seen if we had been there to witness the events presented or discussed. If you watch Frederick Wiseman’s documentary about the New York Public Library, then actually go to the New York Public Library, you see what his camera saw.

The difference comes in the relationship between us — the viewers — and what we view. With nonfiction and documentary, what we’re watching exists in our space-time continuum. We could bump into these people we see onscreen on the street, or visit these places. With fiction, we know we’re watching a constructed version of reality. It may be very like our own, but it isn’t our own.

When those lines are blurred, though, the effect is disorienting even when it’s subtle. Watching Wormwood, we move back and forth between our own universe and the one Morris has constructed, which makes us feel disjointed from reality and unsure of what really happened — just like the movie’s main interviewee, who’s spent his life pulling apart layers of lies about his father’s death.

Experiencing I, Tonya, we wonder not only how much of what the characters are saying onscreen matches up with the filmmakers’ real-life interviews, but because the two main characters’ accounts differ from one another, we are left wondering how much of the movie’s action matches reality, too.

It’s no surprise that at a film festival like Sundance, which encourages independent artists who push the relatively staid boundaries that the larger movie industry draws around its big-budget projects, truth and fiction would blur over and over again.

One of the 2018 festival’s most talked-about films, The Tale, is something close to, but not technically, a documentary. Writer and director Jennifer Fox (who traditionally works in the documentary genre) called it “pure memoir” and gave her 13-year-old self a writing credit on the film. In the documentary category, Robert Greene’s Bisbee ‘17 mixes interviews with performance to cast a dreamlike spell over a real town’s confrontation of its real history.

One of the festival’s most commercially viable movies to mix the real and the constructed is American Animals, a kind of a heist film and one that I’m still not sure shouldn’t be categorized as a documentary.

Directed by Bart Layton, American Animals tells the story of four young men in Lexington, Kentucky, who decide they’re going to pull off one of the most insane heists in American history, by stealing James Audubon’s Birds of America from the library at Transylvania University; that book alone is worth $20 million, and maybe they’ll pick up some other rare books along the way, like a very old copy of Charles Darwin’s On the Origin of Species.

Why bother? They’d like the money, of course. But basically, they’re just bored and frustrated with their seemingly dead-end lives. Pulling off a heist will make them feel like they’re living in a movie, and that’s got to be better than their ordinary existence.

This seems like the formula for a straight-ahead heist movie based on a true story, but American Animals has something else on its mind. “This is not based on a true story,” the title card declares at the beginning of the film. Then the words “not based on” fade out.

So, wait, it is a true story? Yes. It did happen. The actual subjects of American Animalsappear in the film as interviewees, and they’re introduced in a visual format that resembles a traditional documentary, centered in the frame and speaking directly to the camera.

Most of the film, however, feels more like a typical scripted movie, with Evan PetersBarry KeoghanJared Abrahamson, and Blake Jenner playing the young men as they plot and try to execute their heist, figuring out how they’ll neutralize the librarian (Ann Dowd) who guards the rare books.

The movie doesn’t simply cut back and forth between interview and scripted re-enactment. Again, the lines get blurry. Sometimes the scripted sections change slightly based on different interviewees’ recollections; at one point, the real person and the movie-actor version of him sit in a car conversing.

Unfortunately, American Animals is not as clever as it seems to think it is. By the end of the film, it’s not clear that it has harnessed the power of its own narrative devices, which could stand to more effectively explore the illusions of grandeur and the boredom of the over-entertained. It loses steam and ends with the vague sense that there’s somehow less to the story than the sum of its parts.

There’s a kernel of something interesting in the film, and it’s the movement between performance and “reality” that makes it work. The young men who attempted the heist in real life did it largely because they wanted to feel significant, to feel caught up in a narrative like the ones they watched in movies.

Now they are part of a real movie, and yet they’re wiser, and older. As we watch them talk about both the excitement and shame that accompanied their actions, we grasp the moral import of their behavior in a way that more standard heist movies, caught up in the excitement of the caper, rarely do.

The presence of the “real” people, in addition to their actor counterparts, grounds the film for the audience. So we can’t pretend this is just entertainment or ignore the fact that their choices had a social cost.

It’s a heady distinction. Ultimately, American Animals succeeds more if you think of it as a documentary with lots of reenactment, rather than as a fictional film. As part of a broader move toward hybrid storytelling, it’s instructive: In a culture that has experienced “reality” through mediated means for so long that we are often rendered immune to the human toll of the stories we tell, there may still be a way to shake loose our calcified ethical compasses.

Challenge the paradigm of the viewer, and they may just be startled into seeing their own reality in a new way.