Benefits and costs of uniqueness in multiple object tracking: The role of object complexity

How do unique objects affect multiple-object tracking? Recent research has catalogued seemingly contradictory findings, varying from enhanced to impaired tracking performance. In this study, we explore the role of object complexity in this broad range of phenomena. In a series of three experiments, we demonstrate that unique objects of varying complexity can produce both costs and benefits on tracking performance. These experiments show that the key effects of uniqueness in object tracking are results of a tradeoff between tracking operation and processing of object identity information within the capacity limit of working memory.