No evidence for directional biases in inhibition of return

The phenomenon of "inhibition of return" (IOR) has been the subject of considerable research interest for nearly 30 years. Two reports claiming directional biases in IOR (Spalek & Hammad, Perception & Psychophysics 66:219-233, 2004, Psychological Science 16:15-18, 2005) were examined more closely, as such findings challenge the theoretical role attributed to IOR and imply that this purported mechanism for the facilitation of visual search would bias search in systematic ways. The data from two new experiments, as well as reanalysis of the original data, showed the reports to result from an unconventional method of calculating IOR that confounded visual field with target location. Although we found significant differences in target detection response times between the visual fields, directional biases were absent from all of the examined data when the conventional method of computing IOR was applied.