Abstract
The primary tenet of object-based theories of attention is that observers have access to all features of attended objects. In studies of visual short-term memory (VSTM), memory for arrays of color-shape conjunctions present no additional cost compared to memory for arrays of color features (Luck & Vogel, 1997). However, in dynamic settings, such as multiple-object tracking (MOT), maintenance of target locations may prevent storage of surface features, like colors. We investigated whether colors could be stored in dynamic objects with a VSTM / MOT dual-task paradigm. On each trial, participants encoded colors of three out of ten dots in a visual display (VSTM task). Colors were removed and participants attentionally tracked three target dots (MOT task). Either the same dots were used in the VSTM and MOT tasks (Within-objects condition) or different dots were tracked (Between-objects condition) while VSTM dots remained stationary. If object-based attention supports tracking, there should be less dual-task interference in the Within-objects condition. This hypothesis was confirmed, as the Within-objects condition produced higher percent correct in the VSTM task (t(12) = 2.2, p<0.05) and MOT task (t(12) = 4.1, p<0.01) compared to the Between-objects condition. Additionally, Cowan's formula (2001) revealed greater retention of information in the Within-objects condition (K = 4.1) than the Between-objects condition (K = 3.4). These results provide a first step towards confirming whether the key property of object-based attention, access to all object features upon selection, is common to visual memory and attention to dynamic objects.