Eccentric vision: adverse interactions between line segments.

The paper deals with adverse interactions between line stimuli in eccentric vision. Both contrast threshold and just noticeable difference of slant have been measured for a test line as a function of the distance from a number of surrounding lines. Test lines were either parallel or perpendicular to the surrounding lines. It turns out that the interference affects both contrast threshold and j.n.d. of slant with a clear-cut oBspecificity. The surprising result is the extensive spatial range of the interference: between parallel lines it operates over retinal distances of about O+, degrees, where cp, is the eccentricity of the test line. Large-distance interference limits eccentric spatial &ion in daily life much more than classic visual acuity limits would indicate. and makes eccentric vision probably quite different from “unfocussed” foveal vision.