[Spread of inhibition of return in visual search]

For conducting efficient visual search, it is important to inhibit spatial attention from reorienting to previously examined distractors. Several studies have proposed that this inhibition can be associated with object-based inhibition of return (IOR). The present study examined whether the spread of IOR across an object's surface affects the performance of visual search or not. If the spread of IOR occurs in visual search, unexamined targets and distractors linked with the previously attended items would be inhibited. We found that the spread of object-based IOR results in the increases of error rates in the target present trials and the decreases of reaction times in the target absent trials. These results indicate that participants made "absent" responses before examining all items if object-based IOR spread over unconfirmed items. We discuss the function of object-based IOR in visual search and also deal with how visual search is terminated.