Abstract
Visual short-term memory (VSTM) and attention have been found to have a similar capacity limit of four items. VSTM capacity limits are usually investigated with the change detection paradigm, in which participants have to detect a change between two visual arrays separated by a brief interval (e.g., Luck & Vogel, 1997). Attentional capacity limits have been revealed with the multiple object tracking (MOT) task, in which participants have to attentionally track a number of moving identical items in a display of identical distractors (e.g., Pylyshyn & Storm, 1988). Last year at VSS, Alvarez & Cavanagh (VSS 2004) reported studies using the MOT paradigm and demonstrated that twice as many items could be simultaneously attended when they are displayed in the two visual fields as when they are all presented within the same hemifield. The goal of the current study was to examine whether the number of items that can be concurrently encoded into VSTM also increases when the items are split between the two fields. Two tasks were used, namely a color and spatial location change detection task, in which the items were displayed in two different regions located either in separate hemifields or in the same hemifield. The data revealed an interesting pattern of results, as only the capacity of spatial location VSTM appears to increase with the separation of the items between the two visual fields. These findings support the view of VSTM as a chain of capacity limited operations where the process of stimuli spatial selection, which dominates in both spatial location VSTM and MOT, may occupy the first place and show independence between the two fields.