The Instagram post was effusive. "We were thrilled to welcome John Stamos to the Portrait Gallery this morning for a tour of our collection with Senior Curator of Photographs Ann Shumard," it gushed. "We hope you enjoyed your visit to the museum and Ralph Wolfe Cowan's portrait of Elvis Presley." Next to these words was an image of Stamos standing to the right of the painting, smirking over his shoulder. The post garnered more than 3,000 likes.

Many commenters sounded star-struck. “Wait til i tell my daughter uncle jesse was in our city,” wrote one. “Have mercy!” wrote another. But there was also an unsettling aspect of the picture that did not go unnoticed: “Why is he wearing sunglasses?” wrote one commenter. “Might be worth taking off the shades,” chimed in another.

This was not a one-time occurrence. The habit of donning dark lenses at exhibits appears to have taken hold across the art world. In February, Jane Fonda was among the stars who wore shades to the Frieze art fair in Los Angeles. In December, sunglasses invaded the VIP preview of Art Basel in Miami Beach, most notably on the face of Jennifer Lopez. (Alex Rodriguez had the decency to hold his in his hands.)

Wearing sunglasses indoors (save for medical reasons) can reflect a desire to mask one’s identity or emotions, and thus project coolness or aloofness. Sunglasses-wearers can look where they please without tipping their hats that they are gawking, or even paying attention — all of which may make sense for celebrities seeking a modicum of privacy.

But these days, non-celebs curating their lives on social media are wearing shades at museums as well. Last year, Yvonne Force Villareal, founder of New York consulting firm Culture Corps, posted a photo on social media of herself wearing sunglasses at the Renwick Gallery exhibit “No Spectators: The Art of Burning Man.” In July, Jonathan Blum, president of the entertainment company Cisneros Media, shared with his 46,000-plus Instagram followers a snap of him smiling from behind a pair of shades as he stood in front of a painting made up of vertical stripes in different hues by Gene Davis at the National Gallery of Art. In March 2018, the account of marketing group Destination DC, which had 146,000 Instagram followers, showed a photo of a visitor seated in front of a set of Mark Rothko paintings at the National Gallery wearing a baseball cap and sunglasses. “Picture-perfect framing” of Rothko’s work, read the caption. (Fonda, Villareal, Blum and Destination DC could not be reached for comment. The National Portrait Gallery and publicists for Lopez and Stamos declined to comment.)

Picture-perfect is the opposite of what artists and curators would say about museumgoers in dark lenses. Some liken looking at color field or abstract expressionist paintings through a pair of shades to sitting through a symphony in noise-canceling headphones.

Harry Cooper, curator and head of modern art at the National Gallery, hates sunglasses and wears them only when driving while facing the sun. “I guess I want to have an unfiltered view of the world to the extent possible, and that goes for art, too,” he told me. “I can’t imagine putting on sunglasses to look at art. It seems totally absurd.”

Archie Rand, a professor at Brooklyn College and a painter who has had more than 100 solo exhibitions, recalls a visit in 1987 to see 10 paintings at a Manhattan art gallery. Rand arrived to find the gallery owner fuming and railing about a curator and his entourage who had just viewed the art. “He yelled . . . that they were all wearing sunglasses and ‘How the f--- can you look at the color of a painting wearing f---ing sunglasses?’ ” Rand remembers.

The art world may have only itself to blame for the current scourge of sunglasses-wearing visitors, which has coincided with the rise of the art show as selfie opportunity. Museums, art fairs and galleries have now ingrained in visitors the habit of taking photos of themselves in front of art to the point that, with contemporary art in particular, the overriding axiom seems to be: Make it Instagrammable and they will come. And much as sharing photos from exotic vacations has long telegraphed being well-traveled, nothing signifies being cultured and hip better than posing in front of artwork.

Museums are catering “to a younger audience by hosting social events that are really ‘selfie’ extravaganzas, with the art as prop,” says Clarke Bedford, an artist who displays his sculptural installations, which he refers to as “self-made worlds,” outside his Hyattsville, Md., home. “Obviously cutting down the light alters the work both in [contrast] and color, and no one really interested in the art is wearing sunglasses.”

“I certainly don’t approve,” the color field painter Sam Gilliam says, laughing. “We call that voguing . . . where a person poses in front of a work and takes a photograph. It’s like the Oscars. The red carpet. They are beautiful places to be seen.”

To be fair, cash-strapped art institutions are merely doing what they can to broaden their appeal and, thus, expose more people to art. And perhaps it’s pedantic to gripe about visitors wearing sunglasses at museums.

To Rand, however, the sunglasses phenomenon is a disturbing symptom of a larger shift in the way people relate to visual art. Digital culture has led viewers to believe, erroneously, that they can absorb things immediately, he says: “Looking and thinking are not worth their time. Paintings were invitations for speculation and internal conversation. That is no longer the case.”

Menachem Wecker is a writer in Washington.