Parafoveal identification asymmetry in a lateral masking effect

The degree to which the identification of a parafoveally presented letter target was impaired by being flanked by a foveal or peripheral nontarget at a target-mask interval of zero, 75, or 150 msec, was examined. Peripheral placement of the nontarget was more disruptive than foveal placement, and this asymmetry was significantly more pronounced at a 75-msec interval than at either of the other two. This finding is consonant with explanations of the asymmetry based on target visibility rather than on criterion or response factors.