Additional product displays in supermarket aisles—so-called secondary placements—are intended to encourage impulse purchases. However, a new study by Mathias C. Streicher of the University of Innsbruck shows that excessive use of secondary displays narrows the aisles, reducing in-aisle browsing and sales. In real-world field experiments, sales rose by about 11.5 percent after removing secondary displays from a congested aisle, even though fewer products were on display overall.
For decades, supermarkets have relied on secondary placements—additional product displays in the middle of the aisle—in hopes for boosting sales. Over a 12-week period, a team led by Mathias C. Streicher of the University of Innsbruck’s Department for Management and Marketing compared shopping behavior in the same supermarket aisle, with and without these displays. Their observations show a clear trend: After removing the in-aisle fixtures, customers stopped more often and engaged more with the shelves. “Both the stop rate and product interactions increased, and the number of product contacts multiplied in our measurements,” Streicher said.
Another key finding: Shopping carts amplify the downsides of additional displays. By expanding shoppers’ peripersonal space—the area perceived as near space—carts make narrow aisles feel even tighter. People with carts are more sensitive to spatial constraints, which can have stronger negative downstream consequences for these customer group as compared to basket shoppers. “With shopping carts, customers are more sensitive to spatial crowding, which further amplifies the negative effects of secondary fixtures placed somewhere in the aisle,” Streicher concludes.
“Our findings do not mean that secondary fixtures or placements are inherently ineffective,” said Mathias C. Streicher, academic director of the Retail Lab at the University of Innsbruck. “Used strategically, they can lift sales of specific items and generate slotting fees from brand manufacturers.” Still, the Innsbruck team finds that excessive use of in-aisle displays is common in practice. The problem becomes acute when extra displays disproportionately increase perceived crowding; at that point, the drawbacks outweigh the benefits for total sales. “Supermarkets can counter this by systematically identifying bottlenecks, for example, through customer surveys and observation,” Streicher said. “Our results show that, in this case, less can be more.”
Methodologically, the study, now published in PLOS One , combined supermarket field experiments with laboratory tests. The latter isolated the psychological mechanism: confined spaces reduce perceived control, directly affecting purchasing behavior and product interactions.
Publication: When Merchandise Crowds the Aisle and Carts Crowd the Shopper: Joint Effects on Sales. Mathias C. Streicher. PLOS One 2026 DOI: 10.1371/journal.pone.0346492
PLOS One
Experimental study
When Merchandise Crowds the Aisle and Carts Crowd the Shopper: Joint Effects on Sales
22-Apr-2026