In the past year alone, more people have probably seen an Andy Warhol Screen Test than during the entirety of their initial circulation. In 1970, the artist removed the 472 tests that he had filmed from 1964 to 1966—along with all of his other moving image works—from public view. Restored versions of a smattering of the Screen Tests were first screened at MoMA in 1995. The museum showed 28 of the tests at MoMA Queens in 2003, and the Museum of the Moving Image staged a retrospective of Warhol's films in 2007. Now "Andy Warhol: Motion Pictures" arrives at MoMA (on view through March 21) after stints in Berlin, Rio, Buenos Aires, and Moscow, among other places. The show brings together 13 of the Screen Tests with other early silent Warhol films, including Kiss, Eat, and Sleep (all 1963), and Empire (1964). These museum shows, taken with a successful tour of wistful yet anodyne Dean & Britta concerts set to the films, has introduced these beguiling moving portraits to a new generation of media consumers. But what are they seeing?

The basics: each Screen Test was shot at 24 frames per second on a 100-foot roll of 16mm film, with a recording time of 2 minutes and 45 seconds. Each is intended to be played back at a silent film speed of 16fps, attenuating the duration to an oneiric four minutes. Each one ends with a white camera flare and a flurry of white dots from the perforated leader at the end of the roll. Since the tests' welcome resurrection, critics, curators, and scholars have put forth a number of illuminating—but now overly rehearsed and rotely repeated—readings in the contexts of Warhol's interest in stillness, seriality, the aesthetics of boredom, the relation of these works to early film, and the artist's well-known obsession with celebrity.

The current show at MoMA, however, seeks to tease out the relationship between the selected films and Warhol's myriad takes on portraiture, specifically his automatic photo booth and silkscreen portraits. Hence the museum's decision to "hang" the Screen Tests in a single room, as enormous (seven-by-nine-foot) DVD loops, side by side, the films' heavy black frames at once recalling the masking of conventional cinema theater screens and the classical means of showcasing easel paintings. The selections are a mix of the expected—Baby Jane Holzer does some lascivious tooth-brushing, white paste running down her chin; Dennis Hopper sings along to a song we can't hear; Lou Reed and Allen Ginsberg eye each other intently from across the gallery—and surprising, including Donyale Luna, the first African-American cover model, presumably using the reflection of her own image in the lens to performatively primp her hair, smooth her eyebrows, and caress her cheeks with talon-nailed fingers.

While the formal relationship of the tests to Warhol's portraiture is obvious, it is also worth considering their differences. The Screen Tests are neither voyeurism nor vérité. These are exhibitionist films on a glacial scale, presented expressly for the camera. Some performances were coaxed by Warhol, who would flatter subjects with admiring exclamations of "Isn't he terrific! He's doing it!" Others claim that Warhol would simply switch on the bright light, turn on the camera, and walk away, leaving subjects to confront the apparatus on their own terms. Each Screen Test's subject possesses an agency and elasticity unavailable to those depicted in still portraits.

Entering the gallery, visitors are confronted with an 86-minute excerpt (why an excerpt?) of Sleep, projected at monumental size. Warhol's then-lover, the poet John Giorno, snoozes away, flanked by Blow-Job and Robert Indiana and his mushroom in Eat on opposing walls. A temporary 50-seat theater has been set up in the rear of the exhibition, where Kiss, a compilation of 13 couples kissing, some heterosexual, some homosexual, assembled over the course of several months. Between Sleep, Blow-Job, and Kiss, the presence of gay icons such as Sedgwick, Japanese actress Kyoko Kishida, and queer theorist Susan Sontag, one would think the subject of the artist's homosexuality would be noted—but it is left there, evident but unremarked upon. The theater will also host special screenings of the full five-hour, 21-minute Sleep and the eight-hour Empire.

In a curious curatorial decision, a Screen Test of Ethel Scull, a Warhol patron and one of the first great collectors of pop and minimal art, is shown on an actual 16mm loop outside  the exhibition. Projected onto a tripod screen that would not look out of place in a 1970s elementary school classroom, Scull's visage is impassive, and aside from a brief lick of the lips, she displays none of the shades-sporting vivacity captured in Warhol's colorful silkscreen grid portrait of her a year earlier. The film is gray, grainy, distant, and obviously an "old media" thing. The projector whirs loudly and insistently, and the pairing of apparatus and image hammers home the filmic-ness of the whole enterprise.

This is in stark contrast to the churchly silence of the main gallery, where the other 12 screen tests play in quiet perpetuity, the faces disappearing and reappearing in glamorous eternal return. The look of these digital transfers is sharp (except for some weird artifacting marring the cheekbones of otherwise handsome composer Gino Piserchio), with the contrast far more pronounced than with their celluloid sister outside.

The cognitive dissonance between the filmed and digitized tests throws up a thorny matrix of curatorial concerns. Preserving artworks, after all, not only entails extending the life of and caring for their physical materials, but also relates to maintaining an experiential sense of said work. So how far should a museum go toward replicating—or providing information regarding—a film's original screening conditions? The limits are clearer when considering discrete objects like a single painting. The museum would never replace, say, one of their Rothkos with a poster, and tell visitors that it was the same piece of art. Preserving and displaying mechanically reproducible artworks, on the other hand, is a trickier proposition.

That 16mm loop serves as a kind of synecdochic shoulder shrug for the exhibit, as if to say, what else can we do? It is understandable that the museum would find the digital versions of the Screen Tests easier to handle, but the difference in viewing experiences is marked. Warhol himself readily embraced new moving image technologies—employing video for his dual-screen Outer and Inner Space (1965), replacing his trusty Bolex with the Auricon's larger magazine for the filming of Empire. He was also enthusiastic about varied screening conditions, showing the Screen Tests on the walls at the Factory, mobilizing his silent film material as part of the Exploding Plastic Inevitable, and screening compilation reels at the New York Filmmaker's Coop. As pointed out by Callie Angel in her meticulous catalog raisonné of the Screen Tests, Warhol, business-minded as ever, even conceived of making personalized 8mm prints of individual tests and selling them as TV-like "Living Portrait Boxes" for $1000 a pop. And yet to acknowledge the differences in screening and reception practices by inference only comes off as an institutional shortcoming.

MoMA's noble but confused preservation strategy provides a funhouse-mirror reflection of Warhol's intentions. For Warhol, too, the issues of collection, preservation, and display are anchoring principles of the Screen Tests. As MoMA's Glenn Lowery has said, the Screen Tests make up "a visual almanac" of New York City's demimonde. That's certainly true, but more than anything else, the Screen Tests read as an attempt by the notoriously mercurial and distant Warhol to keep his friends close at hand. He would flatter them by screening their tests at Factory parties, and he would shoot particular subjects numerous times. The MoMA exhibition, by design and necessity, cannot show you all 10 of the screen tests Holzer took for Warhol, for instance, but it's more than a little interesting to know that he not only insisted on shooting her again and again, but that he would also mark certain films as "bad"—meaning that the tests, conceived as a whole, can hardly be understood as a savant's compulsive interest in seriality. Warhol's attention to detail is similiarly evident in the various compilations he made of the Screen Tests, such as The 13 Most Beautiful Boys (whose fey and flirtatious name is an apparently purposeful contrast with Warhol's censored 13 Most Wanted Men project for the facade of the New York State Pavilion at the 1964 World's Fair), The 13 Most Beautiful Women, and Fifty Fantastics and Fifty Personalities. These assemblages were designed to woo potential collectors, and their subjects far exceeded the numbers announced by their fan-magazine titles. For example, 47 different tests were included in various iterations of Women, indicating that it was an ongoing and mutating project, to be updated and added to as superstars-on-the-rise took a seat on that Factory stool.

So we've established that both MoMA and Warhol were intently focused on issues of preservation. But what about the elements of his work that cannot be preserved, either by intent or by institution? For one, there is the unavoidably unrecoverable shock of the new: screenings of Sleep and Empire in Los Angeles and New York, respectively, were met with box-office riots, wherein outraged—not bored—viewers assailed theater managers with refund demands. Another is the screening conditions. Even with a theater specially provided for screenings, one doubts that few people will stay for all eight hours (the duration of the museum's opening hours) of Empire, when there are plenty of other art attractions to distract them. Viewing these works in a museum obviates the kind of focus a moviegoer brings to a theatrical projection (Warhol himself quite famously never stuck around to see his cinematic readymade play to conclusion). Indeed, by buttressing Sleep with Blow-Job and Eat, the museum shatters the kind of cinematic confrontation offered by the single-screen experience these works once provided. Rather than provoke viewers to confront their boredom, by noisily shifting their weight in their seats, deciding to breach etiquette by leaving the theater, etc., they can simply look to their right or left, or politely move along to the next room. It diffuses the films' power to challenge cinematic conventions in favor of a sampling that demands much less of the viewer, and suppresses Warhol's radical intentions.

Furthermore, the Screen Tests were almost never shown as loops. When projected, they arrived one after the other, each face emerging out of the white miasma of the one previous. The effect was impermanence, rather than recurrence. This encouraged a kind of close scrutiny that the looped video versions shown at MoMA dismiss—you can always come back to one or another, in medias res.

Another unpreservable aspect of the Screen Tests is that a number of them, together with the silent films, were also shown as part of Warhol's Exploding Plastic Inevitable. The EPI was a traveling, assaultive multimedia project, consisting of still slides, strobe lights, multiple, simultaneously projected films, and dance routines, all backed by thunderously cacophonous performances by the Velvet Underground. Media historian Gene Youngblood described the experience as a "hellish sensorium." Putting the lie to arguments regarding Warhol's unmotivated approach to filmmaking, the artist planned and screen-tested specific individuals to screen at the EPI. MoMA's displayed tests of Lou Reed and Nico were such cases, with the latter's Screen Test featuring unexpected smash cuts and zooms, ostensibly to further the disorienting effect when used in the EPI. The tests were edited together into several different rolls to be shown during the happenings. The EPI transformed these quiet studies into visual weapons designed to confuse, collapse, and reorient the senses. The link to Warhol's portraiture here disintegrates, and provocatively complicates interpretations of Warhol's work across diverse media. The EPI was not about contextualizing relationships between art practices, but eradicating those differences to create an art that was unabashedly not commercial, and not for sale as a piece. It was an affront to art-historical notions of medium specificity, and incapable of being wholly preserved. While Ronald Nameth's impressionistic 1966 documentary on the EPI captures some of the event's energy and is loaded with a bevy of time-bending editing effects, the result is quite beautiful—not a sensory maelstrom. Unlike portraiture of any stripe, the EPI was not merely a perceptual experience, but a bodily one. As one advertisement asked: "Do You Want to Dance and Blow Your Mind with The Exploding Plastic Inevitable?"

Finally, the MoMA exhibit only indirectly recognizes the profound influence these works have had on both avant-garde and popular filmmaking. Thomas Struth's long video portraits, Josh Melnick's time-shifting captures of New York straphangers, Douglas Gordon and Philippe Parreno's polymedia footballer profile Zidane: A 21st Century Portrait (2006)—not to mention countless YouTube submissions of starry-eyed webcammers—all owe a pronounced debt to Warhol. Online, the museum is encouraging people to submit their own screen tests, which are then automatically monochromed and slowed to mimic the originals. Great fun, of course, and while Warhol would undoubtedly celebrate the way the Internet has fulfilled his "famous for 15 minutes" prophecy, the museum's digital intervention mistakes his opportunism for populism, and replaces his groundbreaking project of using film as a tool for community-based filmmaking with a crowd-sourced narcissism that provides instant nostalgia for all.