Research shows that shopping while hungry makes people buy more than just food

It's almost lunchtime. You are hungry, but decide to stop at an office supply store before eating to pick up a few items. New research by USC Dornsife's Norbert Schwarz, Provost Professor of Psychology and Marketing, shows that your hunger will lead you to buy considerably more of those binder clips than if you had visited the store after lunch.

Binder clips may be the least of your worries. One of the studies showed that hungry shoppers spent more than 60 percent more and bought more non-food items than less hungry customers.

While many studies have shown that shopping while hungry leads people to buy much more food than they usually would, Schwarz and his fellow researchers probed the question: are hungry people also more likely to acquire non-food items that cannot satisfy their hunger?

In a paper recently published in the Proceedings of the National Academy of Sciences, Schwarz, along with lead author Alison Jing Xu, assistant professor at the University of Minnesota's Carlson School of Management and Robert S. Wyer, Jr., visiting professor in the Chinese University of Hong Kong's Department of Marketing, found that hunger does promote the acquisition of non-food items—including binder clips.

However, their research shows that this is not because non-food items suddenly become more desirable when we are hungry.

"We found that the desire to get food may more generally plant the idea of 'getting stuff' in your mind, which increases the likelihood that you'll also be attracted to products that won't satisfy your physical hunger," Schwarz said.

In other words, the researchers maintain that biologically based motivation—the desire to eat—can affect seemingly unrelated behaviors. So, when a hungry shopper is tempted by things to buy, the internal message "I want food" becomes simply "I want."

This conclusion was drawn from the results of five research studies conducted by Schwarz, Xu and Wyer, which found that hunger appears to increase the likelihood that people acquire things that catch their attention, and that something could be pretty much anything—from stationery to flat-screen televisions.

In two of the studies, the participants were asked to evaluate binder clips from a well-known office supply company and were told they could then take home as many as they wished.

In the first study, 89 undergraduates were asked how hungry they felt. In the second, researchers controlled the hunger of 63 undergraduates by instructing some of them to take part in a "taste test" of a loaf cake before asking them to evaluate the binder clips.

The findings showed the students' hunger levels did not affect how much they liked the binder clips. But the hungry students nevertheless took 50 percent more of the clips than those who ate the cake or had reported feeling full.

Although hungry people experience increased liking or attraction to food, they do not experience increased attraction to non-food items. "Our research showed that hungry people just wanted to acquire binder clips, not that they suddenly desired them," Schwarz said.

In another study, the researchers approached 81 customers as they were leaving a large department store. With the shoppers' permission, the researchers scanned their receipts and asked them to fill out a questionnaire that included a question on how hungry they felt.

The results showed that the shoppers who reported being hungry had spent 64 percent more money and had bought more non-food items than the store's less hungry customers. This was true even after accounting for factors such as mood and length of time spent in the store.

"People who reported they were hungry bought more non-food related 'stuff' and spent more money on it," Schwarz said, adding that the research team had been surprised by the size of the effect.

They are now expanding their research on this topic, Schwarz said.

"At this point we know if you are hungry you will acquire more things, but what about the other way round?" he said. "If you set off on a shopping trip with the goal to acquire non-food items, such as a dress or a book you really want, you also have 'getting stuff' on your mind. So are you then also more likely to pick up other items that are irrelevant to the categories you actually want?"

Although it sounds counter-intuitive, because one might think a person going shopping for a particular item will not pay attention to anything else, the fact the person has put "getting stuff" on his mind may cause him to buy other things along the way, Schwarz noted.

"If it is true that wanting to get product X also makes me pick up other products, then probably the more I want to get a certain product, the more I may acquire other items," Schwarz said.

Schwarz believes the research may have wider implications.

"If a motive such as hunger creates a final goal in your mind—eating—that makes you acquire other things along the way to reaching that goal, then such spillover effects may exist in many other domains of life," he said.

"If you have a goal to save money and that is on your mind, you may find yourself saving a lot of things other than money as you pursue your goal. If a goal requires you to be very choosy, you may be choosy in unrelated domains as well.

"Although at the moment we only have the hunger data, there is no reason to believe that the spillover effect of a motive into unrelated domains is limited to hunger. And that is why we think this research is exciting."

In the meantime, the lesson seems clear: if you want to save money, avoid shopping while hungry. Otherwise you may end up spending money on items you don't want or need.