Yale School of Management

Shop Till You SHOP?!
Study Shows Shoppers Don't "Drop" -- They Just Keep On Shopping

Ravi Dhar
A new study of shopping behavior by researchers at the Yale School of Management and Duke University explains why some consumers may buy more than they intend.

In their study, Ravi Dhar and Uzma Khan of the Yale School of Management and Joel Huber of Duke University, demonstrate that consumers who purchase one item are more likely to continue shopping and buy more. Taking a metaphor from physics, the authors term this propensity to buy the “shopping momentum effect.”

The shopping momentum effect arises out of a shift in consumers’ thinking that occurs when they move from browsing to buying. Browsing is characterized by deliberation—consumers evaluate whether or not to purchase the item—which acts as a mental hurdle to buying. Buying involves thoughts of implementation: consumers have decided to purchase and think about carrying it out. Once an initial purchase is made, the momentum of the psychological impulse to buy drives the purchase of subsequent items, even if they are unrelated.

In the study, the authors demonstrate the shopping momentum effect by comparing consumers’ likelihood of purchasing a target item while manipulating the purchase incidence for an initial item. Among the findings: the shopping momentum effect is more likely to occur when the first item purchased is utilitarian such as an umbrella, a snow blower, or back-to-school supplies. The effect is less likely to occur if the consumer considers the first item to be a guilty pleasure.

While the study shows that consumers, with the exception of compulsive shoppers, are largely unaware that one purchase they’ve made affects another, retailers have long recognized the value of the shopping momentum effect as evidenced by tactics to induce a first purchase such as attractive prices or holiday specific items. For retailers hoping to cash in, the study suggests the most effective means of initiating a first purchase: a highly desirable item such as a seasonal or emergency good at reasonable prices.