In the past several years photographers Claire Felicie and Lalage Snow have independently published pictures of soldiers taken before, during, and after their service in Afghanistan. It’s easy to project one’s own beliefs about the war, and war in general, onto these portraits; still, they offer fascinating portrayals of how people can change. I wasn’t expecting the frequency with which the soldier in the final, “after” photo looks much younger than he had before the war. During their service the soldiers typically looked focused and grim, but afterward they often looked as if they’d been knocked off-balance, slightly lost, questioning.

The same desire to know how our experiences change us, and whether these interior changes can be read accurately from our faces or whether we can hide them, motivates most of the best portraits in the National Gallery of Art’s exhibit “The Serial Portrait: Photography and Identity in the Last One Hundred Years,” on display through December 31. The exhibit is a collection of series, each one following the same subject through the years—or, in the more gimmicky series, simply through many costume changes.

The exhibit seems to divide into three parts. The final section shows recent work in which photographers try on various personae: Gillian Wearing wears incredibly unsettling masks to look like famous self-portraits by Diane Arbus and Robert Mapplethorpe; Nikki S. Lee dresses up as a “yuppie” or a “lesbian” and embeds herself briefly in some urban subculture in a combination of art and sociological tourism. The images in this section create a hall of cultural mirrors: What do you think of what Lee thinks of what other people think of lesbians? These pictures represent anxiety about identity, but they rarely get beyond their originating idea. They’re headlines, not stories.

The middle section explores experimental approaches to the portrait, especially the self-portrait. Ilse Berg catches herself in mirrors or portrays herself only in shadow. Lee Friedlander catches himself reflected in a shop window, or, cheekily, appears as the looming shadow on the back of a blonde woman’s head. Francesca Woodman dissolves from her portrait like a ghost, or stands, monumental and faceless, portraying a caryatid. Blythe Bohnen swings her head from side to side, or in circles, to create weird time-lapse images in which the top face looks young and the bottom face looks older, or the features collapse into a mass of putty. Some of these experiments focus on the act of photography, while others simply exploit the possibilities of the camera for manipulating images. Some of these images are funny and others creepy, occasionally even haunting.

But by far the best section of the exhibit is the first one. This section best justifies the title “The Serial Portrait,” since here the artists really do follow their subjects over years and even decades. Time gives these portraits immense poignance, and the various non-naturalistic techniques used by the artists work to enhance the underlying human story, rather than being experimental for its own sake.

So Alfred Stieglitz photographs first Georgia O’Keeffe, then Rebecca Salsbury Strand. The early O’Keeffe portraits in this show—which offer only a tiny hint of the huge catalog of Stieglitz portraits of O’Keeffe—emphasize her hands, with delicate fingers crooked carefully like a Degas dancer’s legs. She’s associated with feminine fabrics and tools: buttons, thimbles, bedclothes. We see her teasingly toying with the shoulder strap of her thin white nightgown. A less domestic and more mystical side of intimacy is suggested by a 1918 portrait of her nude torso, dark and sculptural. In 1930 we see her in public for the first time. Her clothes look like priestly robes, concealing the shape which was revealed to us by the previous portraits, and she stands in front of one of her own paintings with a canny, assessing gaze. She looks older: Her face is lined and thinned, her eyelids droop, and there are smile lines around her turned-down lips. Her eyes are shadowed, and her whole face conveys a sense of the weight of her public persona.

That portrait was taken after Stieglitz had already begun photographing Rebecca Salsbury Strand in the nude. His 1922 underwater portrait of her is voluptuous, even a bit overdone—is she really squeezing her own breast for the camera?

To complete the set there are more portraits of Rebecca by her own husband, Paul Strand. She’s much less glamourous in his pictures. A photo from their first year of marriage shows her with a level expression, direct and ready for the future, very slightly tilted to the left to soften the sense of confrontation. Strand’s 1922 nude portrait of her is one of the best pictures in the show: She’s shown waist to calf, in a highly angular pose which emphasizes the jut of her hipbone and the bend of her knee. The angles give her a sense of uniqueness and personality, even though we can’t see her face. By 1932, shortly before the couple’s divorce, Strand is pointing the camera up at his wife from below as she glowers into the distance. Her brow is furrowed, her hair pulled back from her prominent forehead, and she’s in a stiff white blouse with one hand at her hip holding a cigarette, just barely visible at the edge of the frame. She’s looking out of the frame, away from the photographer, with deep wariness. A whole novel has played out in this first room of the exhibit.

There are gentler portrayals of the changes of married life, however. Harry Callahan also photographed his wife at various stages of their marriage. In 1945 she’s direct and windblown, seeming amused. Then he gives her a tender, extremely intimate portrait, a minimalist and delicate picture of her face and arms in which the photograph seems composed out of thin, lilting brushstrokes. She gets older, and he puts her in a variety of different settings—superimposing her nude body over a French field, or posing her in the water with her eyes closed and her long dark hair streaming down.

But Emmet Gowin, influenced by Callahan, crafts the exhibit’s best narrative of a good marriage changing over time. His first portrait of his wife Edith, taken in 1963, is purely lovely and would be almost too pretty-pretty, too magaziney, if not for the formal element of a leafy shadow which caresses and frames her face. In 1967 she’s a bright nude, one eyebrow lifting, spreading her arms: Here I am! In the next pictures she gets older, smaller; a heaviness gathers at her jowls. No more nudes. But for the last portrait, 2002′s “Edith and Moth Flight,” Gowin used an ultraviolet light and a long exposure to capture a blurred, glowing image of Edith in front of Ferris wheels and confetti streamers showing the paths of fluttering moths. It’s a tender image, recollecting childhood evenings and softening the lines carved by time. The moths, instead of seeming like gimmicks, add to the fairylike, dreamlike feeling of the portrait, the sense that we have stepped out of time.

One big wall of the show is dedicated to Nicholas Nixon’s portraits of a family of sisters, starting out tough and cool and even judgmental but gradually becoming gentle and affectionate as the years pass. That gentling brought on by age and experience is also present in several of Milton Rogovin’s fascinating portraits of poor and lower middle class people, mostly in Buffalo, NY. His camera watches a class of girls in their First Communion dresses turn into moms: some happy and proud, others subdued and watchful. Samuel P. “Pee Wee” West starts out in 1974 as a normal, happy-seeming young dude hanging around in front of a store, but by 1985 he’s gaunt and lost. West says that photo “actually changed my life,” prompting him to quit drinking. He went back to the bottle after six months—his 1992 portrait is just rough, sad and lonely, not even fully dressed—but he pulled himself together and formed what the exhibit calls a drug and alcohol prevention program for youth. The logo from that program is visible on the jacket hanging up behind him in his last portrait, from 2002; in that photo you can see that he’s had a hard road, but he’s gained weight and self-awareness. He seems much more present. A lot of Rogovin’s portraits give this sense of hope against the odds.

The first wall caption for the exhibit gives us some bafflegab about how the show highlights “a modern understanding of identity as inherently mutable.” But the questions of how much we can really change ourselves and how much we can change the way others see us are much older and more interesting than that. The best works in this show suggest that marriage, aging, family bonds, addiction, and hope can all change us more than “modernity” ever has.

Eve Tushnet is a freelance writer in Washington, D.C. She blogs at http://www.patheos.com/blogs/evetushnet/