Don’t drink coffee and shop, researchers warn

Researchers recently discovered a surprising effect of caffeine on shopping. The international team recommends that “consumers trying to control impulsive spending should avoid consuming caffeinated beverages before shopping.”

The reason? They have discovered that caffeine impacts what consumers buy, and how much they spend when shopping. Caffeinated products such as coffee, tea, energy drinks and the like are popular choices for drinking before or during the shopping experience, be it in person or online.

Their research has been published in the Journal of Marketing.

The researchers ran three experiments in retail stores. They note that shopping while drinking caffeinated beverages or right after drinking caffeinated beverages “ is further facilitated by the increasing prevalence of coffee shops and also with some retail stores having in-store coffee bars and offering complimentary caffeinated beverages.”

What the research team discovered was that shoppers who drank a cup of complimentary caffeinated coffee before walking around in the stores spent about 50 percent more money and bought nearly 30 percent more items than shoppers who drank decaf or water.

“Caffeine, as a powerful stimulant, releases dopamine in the brain, which excites the mind and the body. This leads to a higher energetic state, which in turn enhances impulsivity and decreases self-control,” said lead author Dipayan Biswas, the Frank Harvey Endowed Professor of Marketing at University of South Florida.

“As a result, caffeine intake leads to shopping impulsivity in terms of higher number of items purchased and greater spending.”

The research team set up an espresso machine at the entrances of a retail chain and home goods store in France and a department store in Spain. When they arrived, about 300 shoppers were offered a choice of coffee with 100 mg of caffeine, or decaf or water. After they were done with their purchasing, they shared their receipts with the researchers.

The researchers discovered that shoppers who had a caffeinated beverage purchased a significantly higher number of items and spent more money compared to those who had decaf or water.

They wrote: “The results of a series of experiments conducted in the field (at multiple retail stores across different countries) and in the lab show that consuming a caffeinated (vs. non-caffeinated) beverage before shopping enhances impulsivity in terms of higher number of items purchased and higher spending.”

The impulsivity spurred on by caffeine not only increased spending, but it also impacted the types of items shoppers bought. The researchers wrote: “This effect is stronger for ‘high hedonic’ products and attenuated for ‘low hedonic’ products.”

What does that mean? Individuals who drank caffeinated coffee bought more non-essential items than the other shoppers, such as scented candles and fragrances. On the other hand, there was negligible difference between the two groups when it came to practical purchases, such as kitchen utensils and storage baskets.

In addition to the experiments in stores in Europe, the researchers arranged for a fourth experiment, this time in a lab. They were able to replicate the results of the field experiments.

There were 200 business school students in the lab study. The researchers divided them into two and offered them caffeinated and decaffeinated coffee before asking them to pick items from a list of 66 options for purchase.

The business school students who drank the caffeinated coffee selected more items considered to be impulsive purchases, such as a massager, while the decaf group members chose more practical items, such as a notebook.

“While moderate amounts of caffeine intake can have positive health benefits, there can be unintended consequences of being caffeinated while shopping,” Biswas said.

“That is, consumers trying to control impulsive spending should avoid consuming caffeinated beverages before shopping.”