For online retailers, the goal is not only to get customers to buy. It is getting them to buy more. Even on impulse.

“Impulse shopping involves making unplanned purchases with little deliberation that’s typically associated with feelings of guilt or regret afterward,” says Sarita Schoenebeck, Ph.D., an associate professor at the University of Michigan’s School of Information.

For many Americans, impulse shopping is pretty common, according to a recent survey by the research firm DAC. The survey shows that 88% of Americans admit to impulse buying, spending on average about $81 every time they shop.

In addition, DAC reports that, “Americans make around 156 impulse purchases a year, spending up to $5,400 annually, or $324,000 over their lifetime.”

Schoenebeck was a co-author on a study led by doctoral student Carol Moser that examined the strategies retail websites use to entice shoppers to buy impulsively.

For the study, the researchers looked at the websites of the top 200 online retailers like Amazon, Target, Macys and As a result, they identified 19 common features used to prompt consumers into making unplanned purchases.

Those features fell into several categories.

Creating Urgency

Online retailers often gather real-time data to determine what shoppers are buying and how much stock is left. They then use that data to push marketing messages such as “Only 10 left in stock. Order now.” or “Forty-five people are looking at this product.”

A majority of the websites also featured limited-time discounts to encourage shoppers to buy while a few websites utilized order deadlines for shipping and messages like “Lock in your discount now.”

“Features that present a sense of urgency or high demand motivate people to purchase right away,” Schoenebeck says.

Promoting Social Influence

“Social influence is a widespread theory that describes how people tend to do things that they see other people doing,” Schoenebeck says.

“It’s easy to design social influence into sites,” she says. “It’s intuitive that if you see other people doing something, you’ll want to do it, too.”

Of the 200 sites they examined, 192 contained social influence features, she says. The social influence features included product ratings, customer reviews and bestseller tags.

“High ratings are a kind of social influence showing that if most people liked this product, you probably will, too,” says Schoenebeck, “and that’s something that can be quantified and manipulated.”

Building Perceived Physical Proximity

Several of the online retailer sites showcased large, interactive images of merchandise to enhance customers’ perceived proximity to the products, the study says.

Many retailers, for example, have added zoom functionality to their websites so shoppers can get a closer look at the merchandise just like they would in a brick-and-mortar store.

Further, a lot of e-commerce sites feature 360-degree photography so customers can view products online at all angles. Meanwhile, other functions let shoppers manipulate photo images to preview items in different colors and shades.

These kinds of online interactions with products allow for more engagement and greater feelings of attachment to products, Schoenebeck says.

“It’s similar to going into the department store and deciding that something looks nice,” she says. “After that, a customer feels more invested in the product.”

Moreover, retailers also seek to give shoppers a sense of temporal proximityto merchandise, telling customers that the product they want could be in their hands in just hours or a few days. Retailers do that by offering same-day delivery, store pickup, quick add-to-cart buttons and quick checkout buttons.

Keeping Shoppers Shopping

Once shoppers buy one product, retailers use website features designed to encourage shoppers to make even more purchases before leaving the site. It is what the study calls “shopping momentum.”

Shopping momentum features include add-on product recommendations, discounted shipping with minimum spent, as well as discounts for add-on products and auto-reorders.

Moreover, e-retailers also frequently engage in strategies such as curated product collections and similar product recommendations to keep shoppers browsing their websites.

Lowering the Risk

Some of the most popular features to ease shoppers’ fears about buying online are discount offers, member rewards programs, discount promo codes, returns and refunds and third-party seals or endorsements.

“The least common features included entry into a sweepstakes with a purchase, displaying a countdown clock for limited-time product availability, quick check-out buttons, discounts for the first purchase made on the site, virtual dressing rooms, and showing that social media friends have purchased the product,” the study says.

Less than 3% of websites used these features, the study says.

For the second part of the study, the researchers surveyed online shoppers who admitted to making impulse purchases.

Many of the participants had bought items such as clothing, shoes, housewares, beauty products and electronics online, Schoenebeck says.

The researchers then asked the participants what strategies they used to control their spending and the kinds of tools they wish they could use to help them avoid buying on impulse.

Some suggested tools to track their spending. They also expressed their desire for a tool that would show that a purchase was equal to, for example, “10 specialty coffees” or one that estimated how many hours they would have to work to pay for the item.

Some even proposed tools that would compel them to take a pause before hitting the “Buy” button and ask, “Do I really need this?”

But at the end of the day, retailers are not likely to add website tools that discourage impulse shopping, the researchers say.

“Further,” they write, “some design features that encourage impulse buying are also integral to the user experience.”