Distributing versus focusing attention in visual short-term memory.

Visual short-term memory (VSTM) is traditionally considered a robust form of visual memory resistant to interference from subsequent visual input. This study shows that the robustness of VSTM depends on the way attention is allocated in VSTM. When attention is distributed across multiple memory items, VSTM for these items is vulnerable to interference from subsequent input, including passively viewed images and the postchange testing displays. Yet attention can readjust its focus in VSTM on the basis of an attentional orienting cue presented long after encoding. When attention is oriented to a particular memorized item, the memory is resistant to subsequent interference. This effect, however, is eliminated when the subset of items demanding focal attention exceeds one, suggesting that orienting attention in VSTM is less flexible than orienting attention in perception. We propose that the robustness of VSTM is influenced by whether attention is focused or distributed in VSTM.