The role of visual short-term memory in object-based attentional selection

The present study investigated the relationship between object-based attention and visual short-term memory (VSTM). Three claims were investigated: (a) spatial attention and spatial STM share similar processing resources; (b) object-based attention and object STM share similar processing resources; and (c) both sets of processing resources are dissociable. Although the first claim is well established, the latter two claims are less established due to limited empirical evidence in the literature. Specifically, studies that provided evidence for the latter two claims (Matsukura & Vecera, 2008; Tan, 2008) employed an object-based attention task (Duncan, 1984) with no spatial component that heavily engaged object STM. These issues were addressed in the present study using a dual-task paradigm with different combinations of attention tasks and memory tasks. The different attention tasks used could engage spatial attention, object-based attention, or both. Similarly, the different memory tasks used could engage spatial STM, object STM or both. Experiment 1 was designed to address the issue of a lack of spatial component in the object-based attention task by including a spatial version of the object-based attention task used in previous studies. The results in Experiment 1 were consistent with all three claims that were investigated. Experiment 2 was designed to address the issue of heavy engagement of object STM by the object-based attention task by using a different object-based attention task (Egly et al., 1994). The results in Experiment 2 were not entirely consistent with all three claims. Specifically, while there was some support for the first two claims, the third claim was not supported. Overall, the findings in the present study suggest that the interaction between object-based attention and VSTM is complex and further studies are required to fully describe the relationship