The Weber relation for position is not an artefact of eccentricity.

We have measured the spatial threshold for discriminating the length of arcs falling on isoeccentric circles in the periphery out to 4 deg. The just-noticeable-difference rises with the arc length in the range 10-500 arc min, repeating the usual finding with foveally presented straight-line stimuli. Our results do not support a recent suggestion that the Weber relation is mainly due to greater positional uncertainty in the peripheral retina.