Acupuncture and placebo: Effects on delaying the terminating response to a painful stimulus

An experiment was performed to determine whether needles inserted into appropriate acupuncture points could delay onset of a pain-terminating response more than needles inserted as placebos into inappropriate points could. A heat source contained in a modified Hardy-Wolff-Goodell dolorimeter was used as a stimulus to produce pain on the posterolateral aspects of the left forearms of volunteer subjects. Subjects pressed a switch as soon as pain was experienced, and the latency between stimulus onset and response was measured to the nearest hundredth of a second. Response latencies were recorded before and after needling, which included electrical stimulation. Needles placed in specific acupuncture points called Ho-Ku and Wai-Kaun delayed onset of the pain-terminating response slightly more than needles inserted as placebos. Even with needles in appropriate acupuncture points, analgesia was slight and subjects still experienced pain.