Processing multiple visual objects is limited by overlap in neural channels

Cohen, Konkle, Rhee, Nakayama & Alvarez

High-level visual categories (e.g., faces, bodies, scenes, and objects) have separable neural representations across the visual cortex. Here, we show that this division of neural resources affects the ability to simultaneously process multiple items. In a behavioral task, we found that performance was superior when items were drawn from different categories (e.g. two faces/two scenes) compared to when items were drawn from one category (e.g. four faces). The magnitude of this mixed-category benefit depended on which stimulus categories were paired together (e.g. faces and scenes showed a greater behavioral benefit than objects and scenes). Using functional neuroimaging (fMRI), we showed that the size of the mixed-category benefit was predicted by the amount of separation between neural response patterns, particularly within occipitotemporal cortex. These results suggest that the ability to process multiple items at once is limited by the extent to which those items are represented by separate neural populations.


Significance Statement

Human cognition is inherently limited: only a finite amount of visual information can be processed at a given instant. What determines those limits? Here, we show that more objects can be processed when they are from different stimulus categories than when they are from the same category. This behavioral benefit maps directly onto the functional organization of the ventral visual pathway. These results suggest that our ability to process multiple items at once is limited by the extent to which those items compete with one another for neural representation. Broadly, these results provide strong evidence that the capacities and limitations of human behavior can be inferred from our functional neural architecture.

Cohen, M., Konkle, T., Rhee, J., Nakayama, K., & Alvarez, G. A. (in press). Processing multiple visual objects is limited by overlap in neural channels. Proceedings of the National Academy of Sciences