We rely on maps to tell us where we stand. This isn't so difficult when it comes to placing ourselves among mountains and rivers -- these we can see. But get inside our heads, to our mental maps, and the landmarks slip away.

It's just this type of psychological terrain -- marked by past, present and future, as well as experience -- that the best artists in "On the Line: Machines, Maps and Memory," on view at the District of Columbia Arts Center, dig into. The inconclusive, often untranslatable answers these six artists come up with reveal just how difficult it is to break out of individual experience. Many of the pieces here feel so personal that they're illegible to almost anyone but their maker. Yet still there exists in them a desire to connect. If the obsessive artworks in "On the Line" show us anything, it's just how unmoored our lives have become and how we yearn -- often futilely -- to know where we stand.

Let's start with Andy Holtin, who devised portable gadgets for the insecure. In one way or another, his trio of objects -- simple wooden contraptions not bigger than a shoe box -- purport to measure location in place and time. "Personal Cartography I: The Earth-Center Locator" amounts to a low-tech, conceptual global positioning system. Text accompanying the piece promises to show users the center of the Earth if they look through a hole in the device's top, below which a pendulum swings. While Holtin's object may do what it claims, you'd see about the same thing if you looked down between your feet. The piece is like a neurotic's reassurance device, one that willfully forgets that it's not the Earth's center that moves, but us.

Another of Holtin's works marks the passage of time. In a little box, paper is marked by a pencil as it rolls from one spool to the other. The accompanying text reads, "This act confirms the existence of a then, a now, and a later." But there's a catch: We are responsible for advancing the paper. A device intent on seeking outside confirmation of existence depends, maddeningly, on us.

But even relying on ourselves doesn't ensure satisfying answers. Jennifer Swan tracks her movements and locations, creating makeshift maps. Yet they look indecipherable to you and me, and probably to her as well. Her "Existence I" charts places she's lived and for how long. Good luck making out a country or a state: Just as soon as a familiar profile emerges -- Italy's boot or Florida's panhandle -- the silhouette fades and lines overlap lines. The result is a map that tells us nearly nothing. The work underscores the uniqueness of personal experience. One person's map is another person's doodle.

And then there's Andrew Krieger. Seemingly defying categorization, his drawings and three-dimensional constructions register aspects personal, political and sociological. I peg him as a less crotchety creative cousin to legendary artist William Wiley, whose drawings look like visual streams of consciousness. Krieger shares with Wiley the instinct of an inventor on a quest to make sense of the world. He's also an adept draftsman, one who makes lines of just a hair's breadth feel robust.

Each of Krieger's drawings depicts what looks to be an invention, albeit a low-tech, childlike one. Yet whatever Krieger might have been thinking when he drew these doesn't translate. How would we use his weather observation platform? Why would we want to? Like so much of "On the Line," Krieger's works proffer solutions for problems we barely understand.

McLean Project for the Arts

A mixed creative bag is on view at McLean Project for the Arts, where four artists contribute to the final show of outgoing director of exhibitions Deborah McLeod, who recently moved to Chestertown, Md.

Me, I'm inclined to set out food and water for Sue Papa's sculptures. She's created a brood of organic bodies out of ceramic that I could almost swear were breathing. Though not exactly animals -- they remind me more of plants, albeit ones out of Dr. Seuss stories -- they certainly feel alive. Maybe they're doodads or whatchamajiggers. Some might have popped off a Miro canvas. Whatever they are, Papa's remarkable ability to imbue inert clay with life is reason enough to see this show. When you go, you'll meet an enigmatic group: Some are free-standing on tripod legs, others hang on the wall, and one leans against it like an old man. Each is finished with unusual glazes that make for peculiar surfaces and textures.

Adjacent to Papa's works hang the botanical prints and paintings of Tanja Softic. These are decorative pieces, often using stylized floral motifs of the kind Victorians enjoyed. Many have inset imagery of lungs or pelvic bones, so at times it seems as if a botanist and anatomist switched sketchbooks. Several of Softic's pictures include silhouettes of fighter jets and warheads in addition to the botanical imagery, though the intention of such juxtapositions remains unclear.

Artist-partners Sharon Fishel and Jeffrey Smith derive their artworks from the same source, but their end products couldn't be much different. In the darkroom, the artists expose leaves and flowers against photo paper, making sharply silhouetted images called photograms, which become the basis of their works. Fishel turns the silhouettes into paintings, manipulating her oils so that it looks as if tissue paper had been adhered to the canvas. The works are pretty but forgettable. Smith, on the other hand, makes large-scale, black-and-white, oil and wax works on paper that resemble giant Rorschach tests. In his inkblot-like works, silhouettes of flowers and fish and deer emerge. Keep looking and you'll keep finding.

On the Line at the District of Columbia Arts Center, 2438 18th St. NW, Wednesday-Sunday 2-7 p.m., 202-462-7833, to May 30.

Sharon Fishel/Jeffrey Smith: Two Natures, Sue Papa: Protology and Tanja Softic: Several Inquiries Into Origins at McLean Project for the Arts, 1234 Ingleside Dr., McLean, Tuesday-Friday 10 a.m.-4 p.m., Saturday 1-5 p.m., 703-790-1953, to June 5.

Andrew Krieger's "Weather Observation Platform in Deep Ellum," at DCAC.Sue Papa's "Scope," on view at McLean Project for the Arts.