Does unattended information facilitate change detection?

Changes between alternating visual displays are difficult to detect when th e successive presentations of the displays are separated by a brief tempora l interval. To assess whether unattended changes attract attention, observe rs searched for the location of a change involving either a large or a smal l number of features, in pairs of displays consisting of 4, 7, 10, 13, or 1 6 letters (Experiment 1) or digits (Experiments 2 and 3). Each display in a pair of displays was presented for 200 ms, and either a blank screen (Expe riments 1 and 2) or a screen of equal luminance to the letters and digits ( Experiment 3) was presented for 80 ms between the alternating displays. In all experiments, the search function for locating the larger change was sha llower than the search function for locating the smaller change. These resu lts indicate that unattended changes play a functional role in guiding foca l attention.