Robert Longo, who is basically a painter, introduced his work in the still-young medium of performance art last night in the Corcoran Gallery's Atrium to an audience of about 300 persons in 150 seats. It was the world premiere of the complete trilogy "Empire," though two elements of the hour-long work, "Surrender" (1979) and "Sound Distance of a Good Man" (1978), have been around for some time.

In "Sound Distance of a Good Man," the earliest and -- I think -- the best segment, there is a large screen on which a still photograph is projected. On the screen, one of the carved lions from New York's 42nd Street Library looks off to stage right. He is one of the world's most complacent sculptured beasts, a look of smug serenity permanently fixed in its features.

Next to this figure, oriented toward stage left, is the face of a man looking upward (in agony? in supplication?), his chin thrust forward almost like the prow of a ship. In its harmonic sequences -- the rounded form of the man's hat merging into the blunt, angular form of chin and neck, his profile seems a slightly distorted mirror image of the lion's. What does this mean? Does meaning matter?

There is music -- Brian Eno's "Fullness of Wind" -- religious-sounding in an amorphous sort of way. At stage left, on a pedestal, stands a woman dressed and posed like a Renaissance statue. Slowly, the statue comes to life, moves slightly and sings, blending with Eno's music.

At stage right, two men, well-muscled and stripped to the waist, are locked in an unmoving embrace. The figures rotate slowly; they are mounted on a large turntable. As it rotates, they begin to move, ambiguity grows and then gives way to a new impression: What looked like an embrace is actually a frozen moment from a wrestling session. The wrestling continues with ever larger and more intense gestures; it begins to take on vicious overtones. Does it mean something that one of the men is black and the other white, or did it just happen in this performance? Are we supposed to think about it or just feel it? And why should we react the way the artist wants us to -- if he wants us to react in a particular way?

"Surrender" and the newest segment, also called "Empire," seemed anticlimactic and simple-minded in comparison. "Empire" opens with billowing clouds of smoke and concludes with a floor full of couples dancing. It was barely enough to keep me awake -- perhaps because I had managed to find a seat in the overcrowded hall after sitting on the floor through the first two numbers.

Performance art is like painting in its silent, objective modes of communication. It is like acting and mime in its use of the human body in motion (slow motion, usually, in Longo's work), but it does not use the kind of sequential logic found in real theater. It is like a frozen theatrical moment, slowly thawing, and its appeal to a painter is fairly obvious in a world where the artist must compete with New Wave rock and "Star Wars" special effects -- although Longo remains offstage throughout the performance. Unlike a painting, however, it makes fixed demands on the viewers' time -- demands that are not always justified by the interest or complexity of its contents.

The performance will be repeated tonight.