Psychology says shoppers who drink coffee before heading into a store may spend more than they planned; Biswas et al.’ s 2022 experiments found caffeinated shoppers bought more items and spent more

That grande latte on the way to Target may be doing more than waking you up. According to the study, ‘Caffeine’s Effects on Consumer Spending,’ published in the Journal of Marketing by Dipayan Biswas of the University of South Florida and eight co-authors, people who drink a caffeinated beverage before shopping end up buying more items and spending more money than people who don't.

The team conducted a few experiments, three in real retail stores in France and Spain, and two in lab settings with university students in France and the US. The pattern, they found out, was the same in every case.

What the researchers actually did
The Journal of Marketing study was not a survey that asked people to guess how they would behave. In an experiment in France, roughly 500 shoppers entering a home-goods store were offered either caffeinated or decaffeinated 50 mL espresso before shopping. The caffeinated drink contained about 100 mg of caffeine, and staff checked their receipts as they left.


On an average, coffee drinkers bought 2.16 items for about 27 euros, compared to the decaf group, which bought 1.45 items for about 15 euros. In a second experiment, shoppers at a department store in Spain were served coffee or plain water, and then sent off on a two-hour shopping trip. The coffee group averaged nearly 70 euros, versus around 40 euros for the water group.

Why a cup of coffee nudges you to buy more
The study says the effect is not simply that caffeine makes people more reckless. It comes down to what the researchers call energetic arousal, that jittery, alert, wired feeling that caffeine produces. Statistical tests revealed that it was this heightened arousal, and not general alertness or overall mood, that connected coffee drinking to increased spending. The researchers say the mechanism is not simple alertness: caffeine boosted energetic arousal, a state of feeling energized and excited that can narrow attentional capacity and increase impulsivity.

In one of the experiments, the researchers found no difference in overall mood between the coffee and no-coffee groups, which helped them rule out feeling happier as the true explanation. In another experiment, shoppers who had coffee did feel more pleasant overall, but statistical testing revealed that it was arousal, not this extra pleasure, that drove the extra spending.

It matters more for the fun stuff, less for the practical stuff
This is the part that might sound familiar to anyone who has wandered into a home goods store “just to look.” The Journal of Marketing study found that the effect of caffeine was much stronger for what researchers call “high-hedonic” products, those bought mainly for fun or pleasure, such as candles, decor or gift items, and weak or non-existent for practical, “low-hedonic” items. In Study 4a, the lab experiment was preregistered and used a 2×2 design crossing beverage type with product set; 221 participants were analyzed after one unusual case was excluded. The study found that coffee drinkers chose significantly more high-hedonic items than water drinkers, but the difference in low-hedonic items was not statistically significant. So that hit of caffeine seems a lot more likely to make you buy scented candles than paper towels.

The caffeine amounts were pretty ordinary
No one in these experiments was drinking anything extreme. The caffeinated drinks used in the experiments contained about 30 to 100 milligrams of caffeine, roughly the amount in a small cup of coffee or tea or a can of soda. For context, the FDA says most healthy adults can safely have about 400 milligrams of caffeine daily, so this is just one normal coffee trip, not an energy-drink binge.

The results were also published in a press release from the American Marketing Association, which reported that the pattern held across countries, types of stores, and even different caffeinated beverages, including tea, in one of the lab experiments.

Should you actually worry about this
Probably not in the coffee-is-costing-you-money sense. The effect was less pronounced for people who already drink a lot of coffee daily, more than two cups a day in two of the experiments, so if you're already a two-cups-a-day person, an extra espresso before Target probably won't move the needle much, the Journal of Marketing study found. This is also one line of research, not a settled fact about human behavior. The effect sizes, while statistically real, were measured in specific stores with specific products.

That said, if you're someone actively trying to rein in impulse spending, this is a really useful low-effort tip. If you are trying to curb impulse spending, consider skipping the pre-shopping latte or going in aware that caffeine may nudge you toward unplanned purchases.

The bottom line
Coffee isn't the villain here, and nobody's suggesting you give it up. But next time your “quick trip” to Target turns into a full cart, it might not just be the store lighting or the sale signs drawing you in. According to the researchers, it could be, in small part, the caffeine talking.