A woman in her early twenties sits alone in a small, windowless room at the University of Wisconsin's Health Emotions Research Institute in Madison. A bundle of spaghetti-thin wires draped over her head contains sensors that register the electrical activity of 128 brain sites as she watches photographic images flash by on a computer screen. A plump mushroom pops up for a few seconds, followed by a mangled body in a wrecked car and then a blooming rose.
Meanwhile, in a separate room, grad student Chris Larson watches the woman on a video screen and records the shifting pattern of electrical impulses in her brain. When a photo of a naked man and woman prompts a noticeable blip, Larson smiles. "Erotic pictures are the best," she says, for eliciting strong positive responses.
