Ahmad Hariri stands in a dim room at the Duke University Medical Center, watching his experiment unfold. There are five computer monitors spread out before him. On one screen, a giant eye jerks its gaze from one corner to another. On a second, three female faces project terror, only to vanish as three more female faces, this time devoid of emotion, pop up instead. A giant window above the monitors looks into a darkened room illuminated only by the curve of light from the interior of a powerful functional magnetic resonance imaging (fMRI) scanner. A Duke undergraduate—we’ll call him Ross—is lying in the tube of the scanner. He’s looking into his own monitor, where he can observe pictures as the apparatus tracks his eye movements and the blood oxygen levels in his brain.
Ross has just come to the end of an hour-long brain scanning session. One of Hariri’s graduate students, Yuliya Nikolova, speaks into a microphone. “Okay, we’re done,” she says. Ross emerges from the machine, pulls his sweater over his head, and signs off on his paperwork.
As he’s about to leave, he notices the image on the far-left computer screen: It looks like someone has sliced his head open and imprinted a grid of green lines on his brain. The researchers will follow those lines to figure out which parts of Ross’s brain became most active as he looked at the intense pictures of the women. He looks at the brain image, then looks at Hariri with a smile. “So, am I sane?”
Hariri laughs noncommitally. “Well, that I can’t tell you.”
True enough: On its own, Ross’s brain can’t tell Hariri much. But a thousand brains? That’s another matter…