Abstract
The binding problem is one of the core issues in working memory (WM), and has been explored extensively. Recent studies suggested that retaining bindings in WM requires more object-based attention than retaining constituent single dimensions. While human beings have evolved unique capabilities of quantity processing, no study so far has explored the attentional mechanism of retaining quantitative-dimension bindings in WM, which may be endowed with a unique attention mechanism. The current study aimed to explore whether extra object-based attention is required in retaining quantitative-dimension bindings in WM via a dual-task paradigm. Participants were required to memorize feature dimensions or the bindings between two dimensions in a change detection task. Critically, a secondary transparent motion task was added to compete for object-based attention with the memory array. If object-based attention plays a pivotal role in retaining bindings in WM, the secondary task would lead to a larger impairment for bindings relative to constitute dimensions (selective binding impairment). Line’s length and circle’s area were used as the representatives of quantitative-dimensions, while colors and locations were used as qualitative-dimensions. We found that the secondary task did not lead to a selective binding impairment for bindings containing quantitative-dimensions (Experiments 1 and 5 length-color, Experiment 2 length-location, and Experiment 3 area-color), which is against the bindings without quantitative-dimensions (Experiment 4 color-location; as well as ample previous studies). The results suggested that retaining quantitative-dimension bindings in WM is a passive process, and does not require extra object-based attention relative to the constituent single dimensions.