Abstract
Goals: In everyday life we remember stimuli and events in the absence of effortful encoding. However, tests of visual short-term memory (VSTM) typically require subjects to engage in an effortful encoding and maintenance process. In the absence of such attention and effort, does anything enter VSTM? If VSTM is closely linked to attention, then excess attentional resources should pull unattended items into memory stores. Methods and Results: Participants were shown a screen of stimuli containing target items, designated by a white underline cue, and distractor items. They were instructed to remember only the cued items over a short delay interval. At test, participants performed a same/different judgment. The different judgments could be either a completely new item, or one of the distractor items. The results show that at setsize 2, there were more false-alarms when distractor items were used as lures, suggesting that participants involuntarily encoded all items on the memory task. This was not found at setsize 4. Conclusions: These findings show that at small setsizes unattended information gets into VSTM suggesting that there is a tight linkage between visual attention and memory. When there is excess attentional capacity, such as at setsize 2, non-target items enter VSTM. When there is no excess capacity, such as at setsize 4, non-target items do not enter VSTM.