Xu Jiaheng^1,2,3, Zuo Zhentao^1,2, Zhang Ruifan^1,2,3, Xue Rong^1,2, Zhou Tiangang^1,2,3; ¹State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, ²University of Chinese Academy of Sciences, Beijing, China, ³Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, China

Human visuospatial perception is profoundly influenced by the surrounding frame. For instance, in the frame effect (FE), the perceived positions of two physically aligned targets are shifted apart as if anchored in the moving frame (Özkan et al., 2021; Cavanagh et al., 2022). However, it remains unclear how the visual system attaches a target to the reference frame. Here, we hypothesize that the target is bound to the reference frame with the perceptual organization. In Experiment 1, a rectangular frame (width: 15°) moved back and forth below the fixation point, and two targets (white disks) flashed at the same spot but inside or outside the frame, depending on the motion path (horizontally covering 0° or -7.5° or -15° ± path length/2). This generated three organization conditions, both/either/neither inside the frame, across different path lengths. FE was quantified as the reported separation between two flashed targets. We found a systematically maximal FE in both-inside condition. Moreover, Experiment 2 yielded a maximum FE when the targets both flashed on a bar-shaped frame, compared with either-on and neither-on conditions, which collectively revealed a facilitation by the closure and connectedness organizations. To control the target’s distance to frame’s center (Shams et al., 2024), Experiment 3 varied distances while maintaining perceptual organization, and Experiment 4 fixed the distance but altered organization conditions. Both results confirmed that perceptual organization, rather than a certain distance, enhanced FE. In Experiment 5, we examined whether organization lacking a global configuration, e.g., color similarity, influence FE equally. The results failed to reproduce the pattern of the maximal FE when the targets were both isochromatic to the frame. Overall, these findings suggest that global perceptual organization, such as closure and connectedness, plays a significant role in frame-induced position shifts by binding the targets to the reference frame.

Acknowledgements: This project supported by Ministry of Science and Technology of China (2023YFF0714204, 2022ZD0211901), National Key Laboratory of Human-Machine Hybrid Augmented Intelligence, Xi'an Jiaotong University (No.HMHAI-202414), and the CAS (2021091, YSBR-068, 2024GZL003).