CAN WE ATTEND TO LARGE AND SMALL AT THE SAME TIME

Evidence from several sources suggests that visual attention is tuned to stimulus scale. This tuning impairs performance when the observer m ust attend to more than one scale at a time. In experiments originally designed to measure the bandwidth of attention to stimulus scale, we have found tasks in which observers show no attentional tuning for sca le. In separate blocks, observers located or identified targets in arr ays of elements, either numbers in arrays of letters or static squares in arrays of flashing squares. Each display contained two arrays, eit her of the same scale or of different scales. The accuracy of locating the target element was lower in mixed-scale than in single-scale disp lays, but the accuracy of identifying the target was unaffected by a m ixing of scales within the same display. This holds for both high-leve l discriminations-numbers vs letters-and low-level discriminations-sta tic vs flashing. Thus, at least for identifying, one can attend to lar ge and small at the same time. The difference in bandwidth between ''w hat'' and ''where'' implies that stimulus identification is not depend ent on prior localization.