LOS ANGELES – Whole Foods stores that have installed Amazon.com lockers are seeing a spike in shorter visits—providing an opportunity to boost sales through impulse buys and “low-consideration products.”

These “micro” visits, defined as three to five minutes in length, were up 11% at Whole Foods stores with lockers since the acquisition occurred in late August. Other groceries without lockers only saw a 7% spike.

The study, reported by inMarket and provided to Reuters News, looked at 98 stores around the country—76 of which had lockers. The study found that micro visits accounted for 9% of all visits to grocery sellers this year, but Whole Foods is behind the curve at 6.5%.

Shoppers can choose to have their orders sent to an Amazon locker for no additional cost—usually to avoid porch package lifters. Customers will then receive a locker number and unique code for the one-time pick-up. And while there, many may be tempted to buy a drink, eggs or a grab-and-go lunch. Whole Foods is keeping an eye on these impulse sales by placing products and self-service checkout options adjacent to the lockers.

“There's a serendipity and immediacy to the in-store experience," said Todd Dipaola, chief executive and founder of inMarket. "As good as delivery is getting - one-day delivery, sometimes one-hour delivery - that still can't compete with the one-second immediacy of being in store and picking up that avocado that I'm about to make guacamole out of because I thought about it in that moment.”

Amazon has already installed lockers in more than 300 7-Eleven stores. When the concept started taking shape in 2011, executives claimed it was a way for the c-store to stay relevant during the e-commerce boom.