Pain tolerance selectively increased by a sweetsmelling odor. Psychol Sci 18: 308–311

ABSTRACT—Themechanism underlying reported analgesic effects of odors in humans is unclear, although odor he-donics has been implicated. We tested whether odors that are sweet smelling through prior association with tasted sweetness might influence pain by activating the same analgesic mechanisms as sweet tastes. Inhalation of a sweet-smelling odor during a cold-pressor test increased tolerance for pain compared with inhalation of pleasant and unpleasant low-sweetness odors and no odor. There were no significant differences in pain ratings among the odor conditions. These results suggest that smelled sweet-ness can produce a naturally occurring conditioned in-crease in pain tolerance. It is popularly believed that odors have the potential to influence human performance, behavior, and mood. Although many of these claims lack substantial scientific support, recent research has provided evidence that odors may modulate pain or pain tolerance in both humans (Marchand & Arsenault, 2002