The experience of watching Deborah Hay perform her hour-long solo "Leaving the House" at the Washington Project for the Arts last night wasn't all like attending a dance concert. Instead, it felt as if one were on a field trip to an imaginary veld or pampa, observing some strange, fascinating creature -- obviously human but innocent of the constraints of civilization -- attuning herself to her surroundings and impulses.

Hay's appearance aided the illusion -- given the thick shrub of dark hair, her aboriginal face and tawny skin, the white halter and billowing trousers, she looked like a pre-Columbian Isadora, once again exploring movement from first principles, as an extrapolation from nature itself. When, now and then, her movement suddenly, briefly, took on a conventional "dancey" look, it was doubly startling.

Her current work gives little hint of her background -- childhood in Brooklyn, early tap and ballet, studies (and performance) with Cunningham, Judson Dance Theater experiments with structure and large groups. "Leaving the House," is, in fact, a solo version of a piece orginally staged with 37 dancers, but it's hard to imagine what it could be like without Hay's powerfully intensifying presence.

The work evolves in one continuous stream, passing almost imperceptibly from phase to phase as Hay modulates from spasmodic twitches to spongy hops, from brisk trotting to gingerly squats, from odd waggings of the head to inching along the floor chin first. There's a surprising range of dynamics, but like the mellow perucussion of Bill Jeffers' accompaniment (sometimes purely verbal), Hay maintains a softly cushioned, smoothly lubricated base to her movement. And she keeps you conscious of its internal properties -- when she stretches forth an arm, you feel with her the weight of the air molecule by molecule.

Hay and Jeffers will repeat their performance at WPA at 8 p.m. this evening.