When a man has butterflies in his stomach, how fast are their wingbeats? Does anger or anxiety have a greater effect on stomach contractions? Medical researchers trying to answer these questions have been hampered by difficulty in observing what goes on inside the gut. Last week a team of U.C.L.A. psychologists studying automatic nervous reactions announced a compact solution to the problem: a plastic-coated magnet no bigger than a small medicine capsule.
In the psychology lab a student volunteer washed down the magnet with water, then lay down on a bed, fully dressed and in no discomfort. Beneath the bed was a...