Position and spatial frequency in large-scale localization judgments.

The frequency-channel model and the position, or "local-signs," model that have been proposed to account for hyperacuity (i.e. small-scale relative spatial localization) are examined in the context of large-scale relative spatial localization. As a basis for subsequent experiments, localization accuracy is measured over a large range of object separations, and previous findings that the "Weber fraction for localization" is constant are replicated. The effects on localization accuracy of both high- and low-spatial frequency components in the objects being localized are examined in some detail. Localization accuracy is found not to rely exclusively on either the high- or the low-frequency components. Neither the frequency-channel nor the position hypothesis as defined here is consistent with all of the observed results. However, with a slight modification, the position hypothesis can account qualitatively for all of the observed results, whereas no reasonable modification of the frequency-channel hypothesis appears able to do as well.