The idea of computer-generated representations of (possibly nonexistent or dead) people has been around since at least the 1980s, when William Gibson penned his famous cyberpunk novel Neuromancer. But what's special about these virtual humans or avatars, in contrast with other representations of people? Bailenson cites their realism---that is, their photographic, behavioral and other qualities that make them seem a lot like us---and describes how the rather primitive brains of real humans fail to distinguish between conspecifics and mere virtual representations thereof, as they fail (in some ways) to mark the difference between real pits and virtual ones.

Along with audience members, Ken and John press Bailenson on whether virtual humans and places should be considered real---in physical, social, and other senses. Is virtual reality a way to escape from reality, a way to break our "addiction" to reality, or a part of reality itself when it is coherent with the rest of our perceptions and activities?

Much of the discussion concerns the costs and benefits of using virtual reality. For the optimist, virtual reality offers a wealth of treasures: Potential immortality (sans consciousness, perhaps) through avatars that mirror the behavioral patterns of their users; more effective teachers, through new kinds of social interaction (like making eye contact with multiple students at once) that are physically impossible in the real world; and the treatment of phobias, chronic pains, and social problems by exploiting the phenomenon of presence. For the pessimist, virtual reality is a veritable garden of sin: Virtual crimes go unpunished due to lack of definition and regulation and also due to vague notions of what it is to count as a person; sexual activity is rampant, constituting around 85% of what goes on in virtual communities like Second Life; and for some, like video games, virtual reality promises to keep children from playing outdoors while simultaneously inuring them to violence.

• Roving Philosophical Report (seek to 6:44): Zoe Corneli takes a trip to Professor Bailenson's Virtual Human Interaction Lab at Stanford, where researchers build virtual environments for use in psychological experiments. According to Bailenson, these allow us to see whether (and, if so, how) the human condition is different in virtual worlds from the human condition in the real world. To get a taste of what he means, Zoe tests out a virtual environment called the "pit room". Intriguingly, she gets a fright, even though she believes the pit room to be virtual! This illustrates the phenomenon that virtual-reality researchers call presence, wherein users in some sense feel that they are "in" a virtual world.

• Sixty-Second Philosopher (seek to 49:58): Ian Shoales considers the ethical status of so-called "trolls" and "griefers" -- individuals who, for the sake of what they call "lulz", vandalize and disrupt organized activity in virtual communities like Second Life, for instance by taking on the appearance of giant walking penises and floating through your virtual living room while your avatar tries to watch a movie.