The more straightforward realism seems, the more it is prone to complications. Beyond the art world — in schoolrooms, prisons, amateur art classes, and psychiatric wards — depiction of the human form is the primary impulse of people who feel the urge to make art. But it is also a persistent strand of the artistic vanguard, even in a century —like the last one — marked by expressionism, abstraction, and recurring claims that mimesis is obsolete.

While the desire to render people is essentially primal, the revival of realist styles entails sophistication — technically, if you are going to pull it off without looking anachronistic, and conceptually, if in fact mannerism is part of your intent. Often, significant contemporary realism is pulled by competing forces: innocence and savviness.

Many young artists (Philip Akkerman at BravinLee Programs and Delia Brown at D’Amelio Terras, for instance) exploit realism as much for the frisson of transgression as for the energy it generates within their work. But this is also a good moment to think about realism because of shows by veterans of the 1960s revival of perceptual realism, artists who consciously sought to extend, rather than simply challenge or bypass, the achievements of Abstract Expressionism.

The key figures of that movement were Alex Katz, Philip Pearlstein, and Alfred Leslie. Mr. Katz is the subject of a museum loan exhibition at the Park Avenue Bank that examines his early work of the 1950s, and Mr. Pearlstein has a show of new work that extends the line of inquiry he established in the 1960s. Mr. Leslie, meanwhile, is also the subject of a historical show, spanning between 1964 and 1990. Sylvia Sleigh’s exhibition is a reassessment of an artist — now in her 90s — that focuses on her work of the 1970s.

Mr. Leslie had enjoyed early success as an abstract painter, first working gesturally in a robust style akin to Willem de Kooning’s, and then moving into rough, drippy collage-based paintings that recalled Robert Motherwell and Robert Rauschenberg. Then in 1964–65, Mr. Leslie underwent a radical change of heart with a series of fullfrontal portraits rendered with precisionist finesse.

In a catalog essay, David Elliott argues against reading these works as a rebuttal of modernism. He suggests that the New York School was more than abstract painting: It included poets, musicians, and other experimenters with whom Mr. Leslie’s realism was consonant. Even during his abstract phase, Mr. Leslie was engaged in experimental filmmaking — he made “Pull My Daisy” (1959) with Robert Frank and Jack Kerouac — that relates to his later figurative painting. And from a formal perspective, the paintings adopted strategies from Abstract Expressionism, namely materiality, directness, and scale. The show at Ameringer Yohe includes Mr. Leslie’s earliest surviving realist figure paintings of the 1960s, group figure compositions of the mid-1970s, and large-scale nude drawings from 1989 and 1990.

Mr. Leslie’s style is extraordinarily diverse. At times he veers toward photographic realism. “Linda B. Cross” (1967) employs harsh lighting in which the face is spotlit, the mammoth lower body plunged into an almost drastic chiaroscuro. “Judy Tenenbaum Early in Pregnancy” (1966–67) has a contrastively symbolist feel: The head is fully work and in color, while the body is more ethereal and generalized, in a chalky miasma. “Jane Elford” (1967–68) has a slightly Northern Renaissance grotesqueness in the leer of drooping facial features. The later group figure compositions, like “Birthday for Ethel Moore” (c. 1977), bring various baroque masters to mind, including Caravaggio and de la Tour.

This diversity gives conceptual edge to Mr. Leslie’s realism, which would exhaust his interest by the early 1990s. In the portraits, it is as if he is testing, in each work, the limits of different genres. This gives the work a unique intellectual energy, and with it an alienating severity and stiffness. Unlovable works, they do demand to be noticed.

Despite her marriage to the critic Lawrence Alloway, Ms. Sleigh’s realism is less concerned with its own stylistic implications. On first impression, her work seems blessed by an unaffected naïveté. This arises from avoiding the kind of academic tropes embraced by Mr. Leslie, such as single-point perspective, and from a slightly nutty, primitive ambition to capture each petal, blade, and body hair. An “outsider” sensibility contrasts charmingly with evidently insider subjects, as in “Lawrence and Betty Parsons at Horton’s Point,” (1963), which depicts her husband and the well-known art dealer.

Her bucolic scenes of nudes in the open air recall the self-consciously anachronistic later works of André Derain, while Henri Rousseau could be quoted in the painting “Reclining Nude: Paul Rosano” (1977). Her penchant for seating nudes in the classic modernist pieces that furnished her home, from Rosano in a Jacobson chair from 1971 to “Max Warsh Seated Nude” (2006), the one contemporary work, in an Eames lounge chair. She makes a justified historical case for naïve realism as literally and metaphorically embraced by vintage modernism. The critical fortunes of Messrs. Pearlstein and Katz have been intertwined since Irving Sandler jointly identified them with what he termed the “new perceptual realism.” But where Mr. Katz uses perception to build a painting, Mr. Pearlstein paints in order to use perception. He is optically obsessed, with no love to spare for paint itself. At times it seems that the “paint originals” might be jettisoned once they have been photographed: The only value of the paint was to realize the image.

This is not to say for a moment, however, that Mr. Pearlstein is a photo-realist. He revels in distortions that only become apparent to an eye trained on the highly suggestive shapes of limbs in space and the shadows they create, with patterns and objects chosen to test the gaze and tease the picture surface.

The new body of work includes old favorites among its motif: toys, furniture, models, and kinds of relationships whose reality is exclusively bound to the studio “set-up.” If there is a dichotomy in contemporary realism between a naïve belief that you can capture reality and astute awareness of the relativity of style, Mr. Pearlstein has it both ways. He is a mannerist when he arranges his sets up his models and props and positions his easel, a primitive thereafter.

Leslie until April 21 (20 W. 57th St., between Fifth and Sixth avenues, 212-445-0051); Sleigh until May 10 (557 W. 23rd St., between Tenth and Eleventh avenues, 212-645-1100); Pearlstein until April 28 (541 W. 25th St., between Tenth and Eleventh avenues, 212-242-2772).