Does "inhibition of return" occur in discrimination tasks?

When attention is drawn to a location and then withdrawn, responding to a stimulus at that location may be slower than to one at a new location. This "inhibition of return" (IOR) has not been reliably demonstrated in tasks that require discrimination of targets from nontargets. The present experiments replicated IOR in detection and localization tasks only when target/non-target discrimination was not also required. When discrimination was required, a consistent same-location advantage occurred for repeated targets. Changed targets may, however, induce a bias toward opposite responses. The results cast doubt on IOR as a general attentional phenomenon.