An unplanned shopping spree has more psychological implications than might first meet the eye.

New research finds that consumers who purchase a new item that doesn’t fit in with their existing possessions, will often embark on a shopping spree to rectify the situation rather than simply returning the item.

The problem starts with the purchase of a new item, particularly one among designer product lines, luxury branded items, or consumer goods of high-end design. Once home, these items – graced with what researchers call “salient design elements,” such as a unique pattern or interesting color scheme – can look out of place when compared with other possessions. The most obvious solution to this aesthetic mismatch would be to return the item to the store.

But instead of making a return, consumers who were surveyed said they would make more purchases in an effort to try to surround their designer purchase with other luxury items and restore aesthetic harmony, according to marketing professors Vanessa Patrick of the University of Houston and Henrik Hagtvedt of Boston College, whose study is forthcoming in the Journal of Marketing Research. In fact, this additional string of purchases may represent a far larger expenditure than the initial purchase.

"When we buy something with unique design elements and it doesn't fit, it frustrates us," Hagtvedt said. "This is because design has intrinsic value. So rather than returning the item, we actively seek ways to make the item fit, often by making complementary purchases. This has financial implications that may have been entirely unforeseen when the consumer made the initial purchase."

"In talking to people, it turns out that this is a pretty common occurrence," Patrick said. "We buy something we really like – after all what could be so wrong in purchasing a cute purple sweater or a unique little side table for the hallway? But, we take it home and that's when it happens…these items become really hard to give it up…so we buy more. And before we know it, we have purchased matching necklaces, shoes and bags, to go with the purple sweater or paintings, new wallpaper and new lighting to accommodate the unique side table."