One of the art world's most controversial exhibitions takes place every two years at the Whitney Museum of American Art in New York City. The eagerly awaited and avidly debated Biennial, as it is known, attempts to take the pulse of contemporary art in the United States.

This is a conversation between two heads, molded from silicone, in one of the galleries at the Whitney Museum. Loaded with the software that their creator, Ken Feingold, calls "artificial pseudo-intelligence," the duo carries on a rather nuanced discussion. The artist suggests that the heads could be replacement parts for humans, reflecting how far civilization can go in efforts to create ever more human-like machines.

The chief curator of the Whitney Biennial, Lawrence Rinder, says the dialogue he wants viewers of the exhibit to have is not very different from the conversation the heads are having. "The heads are talking with each other about what it means to be conscious, what it means to be alive, although they are not really alive, but they appear to be," he says. "One of the strong under-currents of this exhibition is artists' exploration of these fundamental questions of existence, of knowledge, of consciousness, of community. So, I hope that viewers will be engaged with the exhibition on that level, as well as simply enjoying it. I think there is a lot of very entertaining work here."

To make the Biennial truly reflective of the wide range of artistic practices that are flourishing in the United States, Mr. Rinder and his team traveled throughout the country. He says it is hard to define what constitutes art in today's United States. But he believes one of the country's great strengths, its diversity, is reflected in the exhibition. "In terms of the tones, I'd say, there is kind of a double-sided quality," he says. "On the one hand, there are works that are even somewhat melancholy, reflective of questions of life and death and the essential nature of being a human. And then there are other works, on another hand, that have an exuberance that borders on an almost manic quality, unrestrained optimism and unfettered creativity in the face of all the trials and tribulations of life in the beginning of the 21st Century."

The current biennial is the largest since 1981. It has a large component of new and experimental art forms, including sound and performance art. Viewers can spend hours watching film and video-projects. Veteran filmmaker Ken Jacobs is among the artists whose work is shown at the Biennial. "Really amazing things happen with video, with film, and I am very grateful that the Whitney pays attention to this area of the arts, the cinema, and the play between 2- and 3-D [dimension]," he says.

For the second time, the Biennial has devoted a special section to Internet-based art, displayed on computers that are constantly connected to the world-wide-web.

Christiane Paul, who curated this part of the exhibit, says that the Internet has become an inspiring medium for a surprisingly large number of artists. "Internet art, obviously, is an art that is created for the Internet and uses the Internet as a medium. So, it is interactive, it is customizable (can be customized), and it makes use of the connectivity of the network. Many artists use scripting languages, such as HTML. Many of the projects are software that has been written by the artists."

For the first time the Whitney Biennial is showing art works outside the museum. A number of sculptural projects are on view on the nearby lawns of Central Park. And in Soho, in downtown New York, a group of artists has recreated the legendary 1920s Paris salon of Gertrude Stein and Alice B. Toklas.