The Park Bench performances involved planting email and video-conferencing kiosks in New York City subway stations with the goal of encouraging people from diverse neighborhoods to communicate with one another.

Art critics at the Village Voice considered Park Bench so innovative that they put the project on a published list last year of the "51 (or So) Greatest Avant-Garde Moments" of the last couple of centuries.

This summer, Sobell and Hartzell launched Web Seance, a project they see as a natural outgrowth of Park Bench. It's a series of live online performances (or is it social experiments?) that attempt to explore the phantom-like qualities of the online world.

The Web Seance project was commissioned by the Banff Centre for the Arts, an arts institution in Alberta, Canada, known for its support of new media artists. The third installment takes place Wednesday, at 3 p.m. CMT, and the fourth takes place 28 July.

Sobell said Web Seance deals with the same essential concepts as those explored in Park Bench.

"Park Bench was about breaking ghetto boundaries, bridging communication gaps, using technology to bring us closer to respectful understanding of our differences, unfettered by bureaucracy through art," said Sobell. "Web Seance is still yet another instance of these precepts."

Diverse elements are used to create eerily beautiful, but perhaps nonsensical, multimedia collages that appear on the Web Seance home page during the live performances.

The performances take place at both the Walter Phillips Gallery in Banff and at the office of Suzerain, a New York Web development firm. They involve live audiences gathered around computer terminals and a large projection of the Web Seance home page.

The key elements of the Web collages are "brainwave drawings," live heartbeats (of live participants) streamed via RealProducer, and a question-and-answer interface backed by a chatterbot programmed to respond to certain words and text patterns typed in by those who log onto the Web Seance site during performances.

A shareware program called dadadodo collects stories that Web participants submit and deconstructs the text. The program then borrows phrases from each to create a series of new, grammatically correct collaborative sentences, meant to read like a narrative of sorts scrolling across a segment of the screen.