01 May 2020

Scent and Food Choice

Oh, but they smell so good (photo
from www.eatthis.com/unhealthiest-foods-2018/).
Welcome back. A few months ago, I almost reviewed a study of how scents (aromas) affect our choice of food. Now that most people are under stay-at-home orders, captive to scents and possibly snacking too much or on all the wrong things, it’s time for me to follow through.

The background for the study is that marketers, who usually rely on visual and auditory cues, are increasingly adopting ambient scent. This is occurring in a range of venues, and food-related scents are common, such as cotton candy, popcorn and caramel apples in theme parks, cinnamon sticks, rosemary or heated cilantro in restaurants, and chocolate and baked bread in supermarkets.

Researchers affiliated with South Florida and Louisiana State universities set out to determine if and how such ambient scents influence children’s and adults’ food choices. For added significance, they focused on the scents of indulgent (unhealthy) and nonindulgent (healthy) foods.

In the course of their study, the researchers conducted a series of tests--2 in a middle school cafeteria, 1 in a supermarket, 4 in the lab. The basis for their testing hypotheses is cross-modal sensory compensation, which they describe in some detail and I’ll summarize.

Olfactory and Gustatory Trade-Off
Neuroscience has identified brain regions where inputs from our sensory systems (visual, olfactory, auditory, gustatory and haptic) combine, interact and influence one other.

Reward values (subjective pleasantness) assigned to sensory system stimuli by the brain’s reward centers are dependent on a number of factors, such as prior experience. For gustatory (taste) stimuli, high-calorie, high-fat and high-sugar (indulgent) foods tend to have the highest reward values.

Although the reward centers discriminate among stimuli intensity, they do not distinguish among stimuli of different sensory systems. Because the olfactory (smell) and gustatory systems are strongly interconnected, foods do not have to be eaten to activate reward centers.

Going further, the researchers posit that sufficient exposure to ambient scents of indulgent, unhealthy foods can satisfy the brain’s reward mechanism, reduce the desire to consume indulgent foods and enhance the preference for healthy foods. In contrast, scents of healthy foods or the lack of an ambient scent will have no effect, because of their lower reward value.

The researchers point to studies that show prolonged exposure to a certain scent can induce satiation and reduce the desire for products with that scent.

Testing Cross-Modal Sensory Compensation
I’ll review 2 of the study’s 7 tests and wrap up with a third to illustrate what was done and the outcomes.

Middle school--Testing in the cafeteria of a middle school with about 900 students, the researchers used an ultrasonic scent nebulizer to produce ambient scents of pizza and apple on two separate days. A third day was the control, with no ambient scent. Students’ entry was deliberately slowed to longer than two minutes to prolong the ambient scent exposure.

Cafeteria items were coded as healthy or unhealthy before testing. Of the total number of items sold on each day (over 2,800), the lowest percentage of unhealthy items was sold on the day with the ambient scent of pizza, 21%, compared to 37% on both the apple scent and control days.

Middle-school student choice of healthy and unhealthy foods after being exposed for longer than two minutes to pizza, apple or no ambient scents (from journals.sagepub.com/doi/full/10.1177/0022243718820585).
Supermarket--Testing in a supermarket one Saturday afternoon, research assistants used a nebulizer to expose incoming shoppers to either chocolate chip cookie or strawberry scents, while offering them a $10 gift card if they would turn in their shopping receipt (minus credit card info) at the exit. The recruitment process ensured prolonged exposure.

Purchased products were coded as healthy, unhealthy or neutral/nonfood. Of the total number of items purchased, the percentage of unhealthy items was lower and of healthy items higher with the cookie ambient scent than with the strawberry ambient scent. The proportion of neutral/nonfood items was similar with both scents.

Supermarket shopper purchases of healthy, unhealthy and neutral/nonfood items after being exposed for longer than two minutes to cookie or strawberry ambient scents (from journals.sagepub.com/doi/full/10.1177/0022243718820585).
Wrap Up
All tests confirmed that prolonged exposure to the indulgent, unhealthy food scent sufficed to overcome the initial craving.

In one of the four lab tests, for example, participants exposed to the cookie scent for less than 30 seconds chose the unhealthy food twice as often as when they were exposed for longer than 2 minutes (45% vs 22%).

Bottom line: If you wait it out, there’s a good chance you’ll reach for the healthy stuff. Thanks for stopping by.

Study of cross-modal compensation effects in Journal of Marketing Research: journals.sagepub.com/doi/full/10.1177/0022243718820585
Article on study on TIME magazine website: time.com/5506851/how-to-stop-eating-junk-food/

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