| Popis: |
Crowding refers to the inability to recognize objects in clutter, setting a fundamental limit on object recognition. Here, we investigated the processing level at which crowding occurs by exploring the type of crowding errors (global, local, or both). Twenty-seven observers estimated the orientation of a target when presented alone or surrounded by flankers (local shapes). Flankers were aligned to create an illusory rectangle (enhanced global configuration) or misaligned (reduced global configuration). We analyzed the error distributions by fitting probabilistic mixture models. Results showed that often participants misreported the orientation of a flanker instead of that of the target. Interestingly, in some trials the orientation of the global configuration was misreported. These results suggest that crowding occurs simultaneously across multiple levels of visual processing and crucially depends on the spatial configuration of the stimulus. Thus, crowding might be characterized as a bottleneck of visual object identification at different levels of representation. |
