Figure 1.

Schematic of experimental trials: visual search and VSTM search (top) used in experiment 1 (a) and experiment 2 (b). In visual search trials, a single item was initially presented in the center of the screen, followed by an array of two or four peripherally located items. Participants were asked to search for the initial item within the second array and indicate whether the item was present (50%) or absent (50%). In VSTM search trials, an array of two or four peripheral items was initially presented, followed by a single centrally presented item. Participants were asked to search for this item within the previously presented array now maintained in VSTM. In both types of search, the delay between presentation of the first and second items varied between 800 and 1300 ms. Sensitivity measures (d′) and mean response times (milliseconds) in target-present trials across the two types of search tasks (visual and VSTM) and two types of search load (two-item and four-item) were measured (bottom). Error bars represent SEM.