The evening Hanson got the skull, in April 2002, he grabbed a pair of calipers and struck out for a popular bar in an artsy Dallas warehouse district called Exposition Park. There he quickly scanned the room and spotted Kristen Nelson–a willowy blue-eyed brunette he knew casually–chatting with a guy at the bar. Hanson walked past once or twice, and they smiled at each other. Finally he walked up and said hello. "Can I measure your skull?" he asked.
Or maybe that's not exactly, or entirely, what Hanson asked. By the time of the AAAS conference and the unveiling of K-Bot in February, Hanson's robot-model instincts had borne fruit beyond his wildest hopes: He and Nelson were engaged. Not surprisingly, their "meet cute" story has seen its share of tellings and retellings; when the two recount the evening, they finish each other's sentences and expand upon each other's details. Hanson says he asked Nelson if he could measure her skull. She remembers it slightly differently:
"He asked, "Can I make you into a robot?'"
Can he make her into a robot? Can he make a robot into her? Should he even try? A month before Hanson and Nelson launched into barroom banter, Hanson had discovered that the almost universal answer from roboticists to that last question would be a resounding no: David Hanson should not try to make his robot look too much like Kristen Nelson, because to do so would mean risking a tumble into the depths of the Uncanny Valley.
In the late '70s, a Japanese roboticist named Masahiro Mori published what would become a highly influential insight into the interplay between robotic design and human psychology. Mori's central concept holds that if you plot similarity to humans on the x-axis against emotional reaction on the y, you'll find a funny thing happens on the way to the perfectly lifelike android. Predictably, the curve rises steadily, emotional embrace growing as robots become more human-like. But at a certain point, just shy of true verisimilitude, the curve plunges down, through the floor of neutrality and into real revulsion, before rising again to a second peak of acceptance that corresponds with 100 percent human-like. This chasm–Mori's Uncanny Valley–represents the notion that something that's like a human but slightly off will make people recoil. Here, there be monsters.
Breazeal, creator of Kismet, has, like many of her colleagues, taken both inspiration and warning from the Uncanny Valley. Kismet's gentle expression and enormous baby-blue eyes are designed to get the robot as close as possible on the acceptance curve to Mori's first peak, but it's so indisputably still a robot that there's no chance of it toppling over the precipice. To relate socially to a machine, Breazeal says, people must accept it. A mechanical human face that doesn't look quite right is "disquieting," she says. A realistic face that doesn't move right would be "doubly creepy."
Breazeal was the first to let Hanson know he was setting off into this uncharted territory. Hanson met her at a conference in early 2002 and struck up a conversation about robotic heads. "She seemed to totally reject the notion of reproducing the human face," he says. "I felt a little bit sad that this hero of mine would hold a view that was so opposite to my own. But I did feel defiant as well. And I felt a certain pleasure, like I was onto something."