A lot of us use our cellphones while shopping. And why not? Talking or texting or checking social media while you’re at the store is a great way to multi-task and buy back some time in your day.

Here’s why that’s not a good idea: Using your phone in any way that’s not related to your shopping trip, even listening to music, is distracting. Being distracted, research shows, can result in more impulse purchases or forgetting to buy things you wanted to get.

Mobile phone use not shopping related “negatively affects consumers’ ability to accurately carry out in-store shopping plans and is associated with an increase in unplanned purchasing,” according to a study published earlier this year in the Journal of the Academy of Marketing Science.

Researchers analyzed data gathered from more than 2,600 shoppers at various mass merchandise stores across the country. The study compared what shoppers said they were going to buy on their way into the store with what they actually purchased on their way out. During the exit interview, those shoppers were asked if they used their cellphones while in the store.

“Shopping-related” uses included: comparison shopping, scanning QR codes, looking at the retailer’s website or using the mobile app, using the calculator function, calling someone for help with a purchasing decision or accessing their shopping list.

“Shopping unrelated” uses were: talking, texting, checking or sending email, surfing the web, listening to music or playing games.

The major findings:

Those who used their phones for purposes unrelated to that shopping trip were 9 percent more likely, on average, to make unintended purchases than those who only used their phone for a reason that was shopping related.

Using a mobile phone in a shopping-related manner was also associated with a decrease in unplanned items by an average of 13 percent.

“It's kind of like it's a double-edged sword,” said Michael Sciandra, an assistant professor of marketing at Fairfield University and lead researcher on this study. “We’re not saying that phones are always bad in-store. We actually find evidence that using your phone in a way that's related to the shopping task — having a list or using a shopping app that helps you make better decisions — does help consumers stay away from unplanned purchasing and make better decisions. But with unrelated uses, negative consequences are more likely.”

Jeffrey Inman, a marketing professor at the University of Pittsburgh and a co-author of the study, says it’s all about distraction.

“We all tend to buy products that we didn't plan to buy. You get in the store and you see things that you've forgotten that you needed, like say laundry detergent which you don't buy that often. So those are fine,” Inman told NBC News BETTER. “It's the cookies and the ice cream and spur-of-the-moment impulse decisions that we need to try to keep under control. And those are the ones that tend to happen more often when people are distracted by their phones.”

MULTI-TASKING ISN’T AS EASY AS IT MAY SEEM

It’s estimated that half of all in-store mobile phone use is not shopping related.

The researchers found that most people don’t recognize the drawbacks to using their phones while shopping, and how distracting that can be.

During one-on-one interviews participants said they didn’t see any significant drawbacks to this behavior, and they disagreed with the notion that they lacked sufficient mental resources to focus on their shopping while on the phone.

Kit Yarrow, a consumer psychologist and author of "Decoding the New Consumer Mind", says most people don’t realize how vulnerable they are when they’re not paying attention.

“When we do other things, we're not really paying attention to how much money we're spending, and therefore, we're much more susceptible to mistakes and impulse purchases,” Yarrow told NBC News BETTER. “Spending money requires focus and when we're not focused, we're in danger, so multitasking while you're deciding what you want to buy is a mistake.”

ATTENTION HOLIDAY SHOPPERS

The average holiday shopper plans to spend $1,047 this year, according to the National Retail Federation’s 2019 Holiday Consumer Trends survey — 4 percent more than last year.

Impulse shopping can quickly bust your budget, and right now the retailers are doing everything they can to encourage unplanned purchases.

“People allow themselves to splurge during the holidays, so impulse shopping is a little more prevalent now than it is during the rest of the year,” said Miro Copic, a marketing professor at San Diego State University. “The minute you come off task, you’re susceptible to impulse purchases. If you can stay focused, you can stay pretty disciplined.”

There are always things to distract us while we’re shopping, whether it’s the flashy video display or free samples, but as the study authors note: “Given their ubiquity, mobile phones are quickly becoming the principal distractor for many consumers.”

Study co-author Sciandra worries that as we become even more connected to our phones, “this is something that’s going to become a little more problematic for many of us.”

THE BOTTOM LINE

So, how do you stay focused while shopping? Stay off the phone, unless what you’re doing is shopping related. This is not the time for long conversations, texting old friends, checking sports scores or social media, or even getting lost in some of your favorite music.

Study co-author Inman’s advice: If the phone rings and you need to take the call — stop, have your conversation and then get back to shopping.

“Think of it as texting while you're driving. It's not a good thing to do,” he said. “Don't try to multitask. It doesn't tend to work.”

HOLIDAY SURVIVAL GUIDE

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