Spatial-filter selection in large-scale spatial-interval discrimination.

Abstract

Spatial-interval discrimination thresholds were measured for a pair of bars in the presence of other parallel bars placed far enough from the targets as to be outside the range of neural and optical blurring. Thresholds were elevated when the targets were embedded in an array of four parallel bars (two between and two flanking the targets), but not when there were only two parallels, whether the parallels were between the target bars or flanking them. The threshold elevation was larger with a 100-msec than with a 500-msec exposure duration. Attenuating the high spatial frequencies magnified the threshold elevation. The data indicate that the process responsible for spatial-interval discrimination automatically selects which spatial filters to use; it does not have to scan through all ranges of spatial filters.