Eccentricity Advances Arrival to Visual Perception

We investigated temporal properties of visual perception as a function of eccentricity, that is, spatial position relative to the fovea. Our experiments were motivated by well-characterized non-uniformities in neuron distribution in the human eye and early visual pathways. These non-uniformities have been extensively studied in the context of spatial perception, while largely neglected in relation to temporal perception. In Experiment 1, participants fixated the rapid serial visual presentation letter stream and were instructed to report the letter which appeared simultaneously with a brief cue presented at different locations along the horizontal meridian. Participants exhibited a tendency to report earlier letters with more peripheral as compared to central cues, indicating that they misperceived differently located stimuli as simultaneous even though they were never presented together. Experiment 2 conceptually replicated the findings of Experiment 1. Experiment 3 further demonstrated that the effect is specifically due to eccentricity, and not the relative distance between the stimuli. We argue that such location-based misperceptions of simultaneity arise because transient stimuli at more eccentric locations advance to perception faster than stimuli at or near the fovea. Collectively, these experiments show, for the first time, how processing speed differences across the visual field translate into differences in perceived simultaneity. They also demonstrate, for the first time, location-based misperceptions of simultaneity for stimuli never presented together. Finally, Experiment 4 showed that greater eccentricity also increased the perceived duration of a stimulus compared to fovea. These results reveal the breadth of perceptual effects driven by temporal processing differences across the visual field.