Width discrimination for band-pass stimuli

There is a disagreement in the literature about whether the discrimination function for width is a continuous or a segmented function of target size (Hirsch & Hylton, 1982; Mayer & Kim, 1986). We determined the Weber fraction for width for difference of Gaussian (DOG) luminance distributions. Data for seven different standard widths were collected simultaneously. Although the value of the Weber fraction varied with target size, there was no evidence for any discontinuities in the discrimination function, either in the fovea or at 2.0 deg eccentricity.