Yanina Tena Garcia¹, Bianca Baltaretu¹, Dominik Endres², Katja Fiehler¹; ¹Justus-Liebig-Universität Gießen, ²Philipps-Universität Marburg

Individual and ensemble perception are essential processes for effectively interacting with objects in our environment. Individual object perception focuses on the individuation and identification of single objects, while ensemble perception extracts summary information from groups of objects. The underlying mechanisms of these processes remain an active area of investigation, particularly regarding how they are influenced by the number of target objects and the duration of their presentation. Although previous studies have predominantly used simplistic stimuli, it is unclear how these findings extend to naturalistic settings. To address this question, we conducted a computer-based experiment in which participants were tasked with remembering and indicating either the position of a single object or the average position of all presented target objects within a naturalistic scene. We examined differences in individual versus ensemble perception across two key variables: scene set size (3, 6, or 10 objects) and encoding time (50, 100, or 800 ms). Our results show that encoding time had a similar effect on locating accuracy for both processes, with accuracy improving as encoding time increased. However, the set size manipulation had distinct effects: Individual perception showed higher locating accuracy for smaller set sizes, especially for longer encoding times. In contrast, ensemble perception was associated with reduced accuracy for smaller set sizes, especially at the shortest encoding time (50 ms). These findings suggest that individual and ensemble perception are differentially influenced by the amount of task-relevant information, highlighting the complementarity of their roles for real-world actions. We are currently applying two Bayesian models to explore whether individual and ensemble perception operate independently or are interdependent, as a way of gaining deeper insight into their underlying relationship.

Acknowledgements: German Research Foundation (DFG), project number 222641018 – SFB/TRR 135 TP A4