Going to the store with a list in hand is a way to stay on track when shopping, but human nature often intervenes and consumers tend to make unplanned purchases that were clearly not on the list.

What can I do to make your shopping experience better over the long-term, as opposed to just this one shot?

This behavior has been researched extensively, but a recent study sheds new light on the phenomenon. NACDS.org caught up with an author of the study, University of Notre Dame marketing researcher Timothy Gilbride, to find out what spurs unplanned purchases.

Q: What did your study uncover?

A: Our research found that over the course of a shopping trip, the probability that shoppers will buy an unplanned item increases over time. When consumers are first starting to shop, there’s a 40-42 percent chance they will purchase an unplanned item, but by the end of the shopping trip—the longer they are in the store—that likelihood increases to 55 percent. Once they have made all the deliberations about what to get, they have depleted all their mental resources and are more amenable to making an unplanned purchase than when they first walked into the store.

Q: What does this information reveal to retailers about shoppers?

A: We found that when shoppers purchase a planned item that isn’t very fun—like toilet paper—their next purchase is more likely to be unplanned, more of a splurge. This is called the licensing effect, which says that when you do something that you don’t really want to do, but that’s good for you, that builds up your self-esteem and you give yourself permission to do something a little naughtier after that.

Q: How could this information potentially affect technology that tracks consumer behavior?

A: If consumers are using shopping apps, and the app notes a planned purchase of a carton of eggs, then with this information, the app could offer the consumer a coupon for something unplanned, like a half-gallon of ice cream. That’s how, in a real-time way, with technology, some of the results could be used by retailers.

Q: What do you see going forward?

A: Retailers are starting to take a longer view of seeing their relationships with consumers as something more than just transactional. They recognize that consumers could potentially have a relationship with the store for as long as they live in their current houses. This will prompt the retailer to ask, ‘What can I do to make your shopping experience better over the long-term, as opposed to just this one shot?’ I think leveraging the data and recognizing these sorts of behavior patterns are a step in that direction.