 Human visual performance varies significantly both across the visual field and around the polar axis. At the fovea, performance is highest, but decreases with increasing eccentricity. Additionally, performance is better along the horizontal than the vertical meridian and along the lower than the upper vertical meridian. However, these differences can be largely explained by cortical magnification, which scales stimuli according to their eccentricity and polar angle. When stimuli were scaled according to eccentricity, performance differences across the visual field were eliminated, but performance differences around the polar axis remained. These findings suggest that limits in contrast sensitivity across the visual field and around the polar axis are mediated by different anatomical and computational constraints. This article was authored by Michael Jigo, Daniel Tafdie, Mark M. Himmelberg, and others.