“Above all things,” Shakespeare wrote, “to thine own self be true.”

But that advice is getting harder to follow, experts say, as new technologies change the way we see and express ourselves.

“At the same time technologies are complicating identities, they’re making it easier to try out new identities,” points out Mitchell Resnick, a Massachusetts Institute of Technology professor. “Too often people talk about having an identity… But it’s more useful to think about making your identity, to think about identity as something you create.”

Resnick and fellow scholars, scientists and artists gathered this month at “ID/entity,” a one-day symposium sponsored by MIT’s Media Lab. There they discussed how our identities shape-and are shaped by-new technologies, from biotechnology and robotics to assistive technologies and virtual reality.

Among other highlights:

Judith Donath, a professor at MIT’s Media Lab, said that communication technologies speed the evolution of language and fashion-and “the Net is accelerating this trend, especially with language.” Trendsetting communities feel even more pressure to differentiate themselves with new slang and clothes, she explained. “What you have with fashion is this notion of obsolescence of information,” she said.

Harvard biology professor Walter Gilbert declared that gene research will rewrite the rules for individual identity. “At the current exponential rate of decoding, in 25 years everyone will be able to sequence their own genome for $300 and get the results on a DVD,” he said. “If a person’s genome is known, what does that mean?”

Trevor Darrell, who researches biometrics at MIT, is developing applications that go beyond traditional face, hand or iris recognition. He demonstrated a system to identify people by the way they walk; another to do it by the way they talk; and a third to spot suspicious behavior, such as someone walking up to the door of every car in a parking lot.

“We may soon have ubiquitous surveillance, where you can track people over a long time in public spaces and private spaces,” Darrell said. “We all want public anonymity for ourselves. But do you want it for your neighbor? Do you want it for your airplane seatmate?”

Deborah Hurley, director of the Harvard Information Infrastructure Project, said the U.S. has been slow to answer such questions. “In many countries, privacy is a human right,” she said. Some nations guarantee privacy in their constitution, in ways similar to the U.S.’s fourth and fifth amendment rights, she noted. But “U.S. citizens find themselves with very little protection for their personal information.”

Cynthia Breazeal, a researcher at the Media Lab, said her “affective” robot, Gizmo, behaves more like a “creature” than a tool. Gizmo reacts to a passerby with facial expressions and body language and responds to positive and negative feedback. “Many people loved R2D2 and C3P0, but they were bought and sold like property,” she said. As technology advances, “we have to ask whether these robots are creatures or tools.”

Inventor Ray Kurzweil described how a virtual humanoid has helped him learn more about his own identity. He showed a movie of himself and Raymona, a computer-generated female rock star that mimicked his voice and movements in real time. While Kurzweil sang and danced-with perhaps slightly more grace than the average computer genius-his alter ego performed on a screen behind him.

“These technologies, as they get more and more compelling, will give us the ability to explore the real nature of our identity,” Kurzweil told the crowd. “They will reveal that things we now think fundamental to our identity are more superficial than we realize.”

Photojournalist Peter Menzel proposed a way to extend one’s identity beyond the grave: artificial-intelligence headstones that simulate the deceased’s personality and converse with the living. “If you want to make sure your relatives are behaving how you want them to behave,” Menzel suggested, “you can require them to visit for a certain amount of time each month.”