The leftover effect: How shelf spacing between leftover products affects purchase intention of subsequent consumers

Product spacing on retail shelves can arise from either deliberate merchandising decisions or gaps left after customer purchases. While existing research consistently highlights the positive marketing effects of retailer-controlled spacing, the behavioral impact of customer-induced spacing among leftover products has yet to receive sufficient scholarly attention. Drawing on cue utilization theory and inference theory, we show across one field study and four experiments that customer-induced product spacing significantly lowers purchase intentions. This effect occurs through consumers’ leftover inference and perceived deficiency regarding these products. Importantly, this negative effect is weaker for high-reputation brands or low-variance products. These findings advance theoretical understanding of how environmental cues are processed in retail and provide practical recommendations for optimizing shelf layouts to minimize unintended sales losses due to such spacing.