Gallery of American types through 'performance art'; Men Inside; Voices of America. Solo performance pieces by Eric Bogosian.

One of the newest additions to the theater scene is ''performance art.'' At first glance, performance artists are often similar to traditional actors. But the performance artist rarely appears in plays written by other people, as the actor does. Rather, the performance artist is a firsthand creator like a painter or composer, using the stage as his or her medium.

Performance art can be offbeat and obscure. But sometimes it's just the opposite. Except for the irony running through his work, Eric Bogosian could be mistaken at times for a nightclub comedian - striding about the stage, cackling at his own jokes, racing through his routines quickly and aggressively. What separates him from a stand-up comic is the fierce vision behind his monologues, which often trace a razor-thin line between humor and horror.

Bogosian is presenting two of his solo pieces each Thursday through July 29 - at the Public Theater. The longer of the pair is ''Men Inside,'' a collection of one-man skits based on familiar-type characters, each given a wry twist. At the start, Bogosian is a carnival pitchman. Later he becomes a little boy, a lover, a street-corner tough guy, an ethnic father, a bored teenager, a derelict, and yes, a nightclub entertainer. And that's only a partial list, as Bogosian whips from one persona to another, some sketches lasting for several minutes, others only a few lines.

The second piece, ''Voices of America,'' is Bogosian's satire of contemporary radio. As such, it's a more wholly verbal work, relying on the performer's remarkably versatile voice. Moreover, at a time when many performers and playwrights bandy four-letter words casually, Bogosian uses them as metaphors for decadence and illiteracy he deplores. Though his words can be coarse at times, they are aimed toward a higher purpose.

A frequent film and video performer in addition to his solo activity, the busy Bogosian travels a great deal - he has toured the United States and Canada twice already this year - and keeps a relatively high profile among ''performance artists.'' His current show at the Public should boost his visibility and reputation yet further.