Multiple-Object-Tracking Supported by Parvocellular, Magnocellular, and Koniocellular Pathways

Our study explores the differential contributions of the parvocellular, magnocellular, and koniocellular pathways to the task of multiple-object-tracking (MOT). Observers viewed moving stimuli designed to isolate these pathways. For the parvocellular pathway, red on green isoluminant stimuli were used; yellow on blue isoluminant stimuli were employed for the koniocellular pathway; and fast flickering discs on a red-green checkerboard background were adopted to isolate the magnocellular pathway. We also included a condition that allowed all visual pathways to participate for comparison. Observers’ performance was measured while we manipulated two critical variables: the minimal inter-item distance and the motion speed of the moving objects. These manipulations allowed us to assess how spatial and temporal processing demands impact tracking accuracy across different visual pathways. Results reveal distinct pathway sensitivities in supporting attentional tracking: Koniocellular pathway exhibited marked sensitivity to both speed and spatial proximity. As object speed increased and inter-item distance decreased, a significant drop in tracking accuracy was observed. This suggests a pronounced limitation in the koniocellular pathway’s ability to process rapidly moving and closely spaced stimuli. Magnocellular pathway demonstrated a higher sensitivity to spatial proximity. Reduction in inter-item distance substantially impaired tracking accuracy, underscoring this pathway's limitation in spatial in spatial resolution during motion perception. Parvocellular pathway showed a pattern similar to that observed when all visual pathways were engaged. Here, rapid object motion combined with reduced inter-item distance led to only a slight decrease in tracking accuracy, suggesting a more robust processing capability under high temporal and spatial demands. This research contributes to our understanding of how different visual pathways support the complex and attentional demanding task of MOT, with results highlighting the unique processing characteristics and their relations to attention of each pathway.