Abstract
Crowding is a fundamental constraint on peripheral object recognition linked to variability in spatial precision at different visual field locations. Previous work has also demonstrated significant individual biases in perceived location across visual field locations. We investigated the relationship between observers’ inherent localization biases and the strength of visual crowding across different visual field locations, to determine whether these biases might be related to variability in the strength of crowding. We tested whether peripheral locations with larger apparent spacing between pairs of objects (in the absence of stimulus manipulation) are also associated with reduced crowding. In Experiment 1, crowding was measured at 12 locations at 8º eccentricity. Participants identified the orientation of a central clock stimulus (pointing up, down, left, or right) with two tangential flankers whose orientation varied randomly. We compared these results to participants’ perceived spacing (Experiment 2) at the same locations. Participants were shown pairs of Gaussian blobs separated by one of 6 randomly selected spacings and identified whether the spacing between them was larger or smaller relative to their average of all previously seen spacings. Perceived spacing was estimated for each location from the spacing producing 50% ‘larger than the average’ responses. We show large individual variability in critical spacing and perceived spacing at different visual field locations and a positive correlation between them. In locations in which participants have stronger crowding, perceived spacing was smaller, and vice-versa (r= 0.44, p < .001). These findings demonstrate that spatial heterogeneity in perceived spacing affects observers’ ability to recognize objects in the periphery. Our results support the idea that multiple mechanisms may contribute to individual spatial variability in the strength of crowding and add further evidence supporting the idea that early variation in spatial coding propagates across multiple stages of visual processing.