When do products (and money) literally make your mouth water?

"In multiple languages, the terms hunger and salivation are used metaphorically to describe desire for non-food items," writes author David Gal (Northwestern University). "But will people actually salivate when they desire material things?"

The answer, Gal found, is yes. In one study, for example, Gal examined whether people salivated in response to money. "Merely being exposed to the concept of money has been shown to have dramatic effects on behavior, and it has even been argued that money can be conceptualized as a drug in that it imitates the action of biological incentives in driving behavior," Gal writes. In the experiment, the author measured salivation by having participants put cotton dental rolls in their mouths while they gazed at pictures of money. He later weighed the rolls to measure the amount of saliva.

Before they viewed money, however, Gal primed the participants to feel powerful or to feel that they lacked power. "The main result of the experiment was that participants salivated to money (relative to baseline), but only when they were in a low-power state," Gal writes. "This suggests that people salivate to non-food items when those are items are desired to fulfill a highly active goal."

Next, Gal wondered whether men would salivate to high-end sports cars. Instead of looking at their perceived power, he induced some of the men to have a "mating goal," because prior research has shown that men who want to impress women purchase conspicuous luxury goods. Gal showed the men photos of attractive women and asked them to choose one they would like to date. Gal asked the other group of men to ponder a visit to the barber. The men with the active mating goal salivated more at images of high-end sports cars than the men who had been prompted to imagine getting a haircut.

"Why do people salivate to money and to sports cars?" Gal asks. "One possibility is the increasingly well-established finding that all objects of desire, whether biological or non-biological, activate the same general reward system in the brain. Salivation might merely be the consequence of the activation of this general reward system."