SAN DIEGO (FOX 5/KUSI) -- With the holiday season at its peak, millions of Americans have been hitting the stores — both in person and online — to take advantage of deals, while securing gifts for family and friends. Uma Karmarkar, associate professor, an associate professor with a joint appointment at UC San Diego’s Rady School of Management and School of Global Policy and Strategy. (Photo courtesy of UC San Diego) During the shopping frenzy of this year's Black Friday to Cyber Monday, an estimated 197 million people in the U.S. made purchases, according to the National Retailer Federation. Consumers spent a record $33.6 billion on Black Friday alone. But what makes people open their wallets? What happens in the brain when we decide to buy something and why do we often feel an irresistible urge to splurge? Dr. Uma Karmarkar, an associate professor at UC San Diego’s Rady School of Management and School of Global Policy and Strategy, explored these questions through her research in neuroeconomics. This field blends neuroscience, psychology and economics to understand how people make decisions, especially in the realm of consumer behavior. San Diego shoppers race to snag last-minute gifts Dr. Karmarkar, who holds a Ph.D. in neuroscience from UCLA and a second Ph.D. in consumer behavior from Stanford, sat down with UC San Diego Today to explain the science behind shopping. How do we make purchasing decisions? Neuroeconomics research often involves experiments where people make choices or evaluate options, often while undergoing brain scans using functional magnetic resonance imaging (fMRI). This technology helps track brain activity and reveals which areas of the brain are activated when consumers are faced with buying decisions. When shopping, a key area of the brain, the ventral striatum, lights up when shoppers see things they like, even before they decide to buy them, the associate professor explained. Once we start considering whether or not to make a purchase, additional brain circuits become involved in weighing factors like price and value. "These liking-and-paying brain processes are similar across in-person versus online shopping," said Dr. Karmarkar. "But other research suggests there are factors such as the presence of other people, or interactions with physical products and displays that can create differences between being in a store versus looking at a webpage." Physical stores can provide sensory experiences that trigger more intense brain activity — such as handling products or interacting with salespeople — while online shopping may evoke different neural responses, influenced by the absence of these physical cues, the neuroscience researcher explained further. The influence of neuromarketing According to the associate professor, companies are keenly aware of these brain processes and increasingly rely on neuroeconomics to optimize their marketing strategies. For example. Dr. Karmarkar’s research has provided insight into how online shopping experiences can be tailored to maximize consumer engagement. She found that when recommended products are thematically consistent — such as suggesting matching sweaters when browsing one — consumers are more likely to make a “sweater-specific” purchasing decision. If you see related products, like sweaters with other sweater options, you feel more engaged with the idea of buying a sweater," she said. "But if you see unrelated items, like jewelry or home goods, research shows shoppers become distracted and the likelihood of making a purchase decreases. Sustainable shopping choices While shopping may offer immediate rewards, Dr. Karmarkar suggests that consumers can seek satisfaction in more sustainable ways. The same brain areas that respond to the reward of buying new things also react to other pleasurable experiences, such as self-care or discovering something "new to me" — whether it's a vintage item or a sustainable alternative. "So beyond necessities, we have options for treating ourselves in different ways, including more sustainable ones. It doesn’t have to be a sacrifice — maybe a massage is a more sustainable option than a product made out of non-recyclable plastic," the associate professor explained. "Another facet of this is newness — we like novelty and new things." She believes consumers are starting to realize that "new to me" can be just as rewarding as buying a brand-new product as, in some cases, the reward comes from the novelty of the experience, not necessarily from a physical object. How to shop more mindfully To help consumers make better decisions, Dr. Karmarkar recommends being more intentional about shopping by planning ahead, setting a budget and defining your goals before you start shopping. She says impulse purchases are often the result of not having a clear plan, so shopping lists can be a helpful tool. She also suggests stepping back and considering alternative uses for your money. Ask yourself what else you could do with your time and money. If the product still feels like the right choice after evaluating other options, then it may be a good purchase, she explained. Dr. Karmarkar’s work is helping to shape our understanding of the complex psychological and neural processes behind shopping, helping both consumers and companies navigate the tricky landscape of decision-making. As we push forward during the busiest shopping season of the year, understanding the science of spending could lead to smarter, more intentional purchases — and perhaps a more sustainable future. To learn more about Karmarkar’s research, check out her video, Your Brain on Shopping, or her interview on The Neuroscience of Marketing with Poets and Quants.