Emsense Corp

Wearing electrode-studded headbands to track their brain waves, two subjects watched the campaign commercial on a monitor in front of them. Presidential candidate Hillary Rodham Clinton, clutching a microphone as she spoke to an approving crowd, promised that people in need would never be "invisible" to her. When the volunteers heard "invisible," the equipment registered a jolt of electricity in their frontal lobes. "It got their attention," said Brad D. Feldman, an analyst for EmSense Corp.