Salivating for stocking stuffers

In the spirit of this season of holy consumption, I thought it appropriate to write about an article released earlier this year in the Journal of Consumer Research on salivating over material goods. Author David Gal, an economist at Northwestern University, proposes that when we covet an item, be it ice cream or an iPhone, we literally drool over it. He hypothesizes that this response mechanism is induced by our reward system, with desired material items stimulating the same pathways and neural regions as the hunger for food or other natural reinforcers do. This includes the striatum, amygdala and hypothalamus, areas involved in reward responses and homeostatic mechanisms such as hunger and satiety. Activation of these areas in response to salient stimuli signals that these items are rewarding and could be important for survival. Supporting this claim, in previous research the mesolimbic dopamine reward pathway is seen to light up in a similar manner for luxury items and sports cars, which are secondary learned reinforcers, as for natural incentives such as food and drugs. Taking this a step further, the physical outputs of this heightened reward arousal state can include the secretion of saliva, triggered by the sympathetic and parasympathetic nervous systems. Salivation occurs in response to cues for food or water as part of the natural metabolic system, preparing us for mastication and digestion. However, Gal claims that it is also a byproduct of the autonomal arousal system controlled via the hypothalamus, and that salivation can indicate any desired or salient stimulus, whether it be naturally rewarding, such as a member of the opposite sex, or a secondary conditioned reinforcer, like money or material goods.

Gal investigated this theory by presenting 169 undergraduate students with images of either money or mundane items, such as office supplies. While viewing the stimuli, participants were asked to keep cotton dental rolls in their cheeks and under their tongue to measure their saliva output. The weights of these cotton swabs were then compared to baseline measurements taken before the experiment to assess the increase in salivation due to the images presented. A second condition involved priming participants with feelings of either efficacy or helplessness by asking them to recall a time when they had felt either powerful or powerless. Gal hypothesized that money, symbolizing economic control, would be more coveted by those who felt they had little power, making it more desirable and rewarding than to those who deemed that they had greater power at the time of the experiment. Supporting this notion, only participants induced with feelings of powerlessness had significantly increased saliva output in response to the monetary cues. Individuals who felt powerful had no difference in salivatory rates when viewing the money images, nor was there a difference in saliva outputs in either power condition among participants in the control office supply group.

In a second follow-up study, Gal repeated the experiment using coveted luxury items in the place of raw currency. Gal exposed young men to images of sports cars, while also inducing in them the goal of winning a potential mate. He achieved this by presenting some participants with images of attractive women with whom they were to imagine going on a date with, while those in the control condition were to imagine having their hair cut. Men who viewed the sports cars as opposed to the mundane images had greater salivation rates compared to baseline ratings, but only when they had been primed with the goal of mating. The mating prime had no effect on saliva output in the control condition, and viewing the sports cars without the salient goal did not increase salivation rates on its own.

Importantly, increases in saliva production seem to be contingent upon the immediate rewarding value of the goods, only enhancing salivation rates when the presented stimuli were seen to help achieve a recently primed goal. This suggests that the triggering of salivation by reward cues is dependent upon the present desire or need for the item, much like the more visceral feeling of hunger in the presence of food.

So as you are finishing your Christmas wish-list this year, dreaming of drool-worthy duds and mouth-watering machines, perhaps rank your heart's desire on how quickly they'll come in handy and how moist your mouth feels afterwards. You'll be sure to find them more rewarding.

Happy holidays everyone!

(Thanks to Emily Barnet for this article.)

Dana Smith

PhD student in Experimental Psychology at the University of Cambridge