Abstract
Observers performed a speeded visual search for a target letter among an array of 12 letters that were embedded in visual noise. On a given trial, between 0 and 6 of the to-be-searched items appeared for a 2-second preview before the remaining items of the search array were exposed. The identity of the target letter was delivered aurally when the remaining digits appeared. A plot of RT by the number of previewed items shows a linear decrease in RT as the number of previewed items increases from 0 to about 3 items, at which point the function plateaus. The finding that the benefit of preview plateaus at about 3 items is consistent with the hypothesis that preview produces faster RTs by allowing observers to respond quickly from memory when the target item is held in VSTM. Thus, the benefit due to preview is capacity limited to roughly the same extent as VSTM.