inhibition of return

n. Inhibition of return (IOR) is the second of two effects generally observed in a cue-response paradigm. In the cue-response paradigm, a cuing stimulus (a luminance change) is presented at a random location within a participant's gaze followed by a delay (either long or short) and finally a target (e.g., a letter). The participant's task is to indicate that the target has appeared or identify it in the presence of distractors. IOR is measured either as an increase in the amount of time necessary to detect a target or as a reduction in the accuracy with which a target is identified when that target is presented in a previously attended location after a delay of about a third of a second. This decrement in processing replaces the enhancement (faster or more accurate responding) in processing that typically occurs at attended locations prior to a third of a second.                       

- DGa