Dimension-based visual attention modulates dual-judgment accuracy in Duncan's (1984) one- versus two-object report paradigm

Four experiments, adapting the object-judgment paradigm developed by J. Duncan (1984), examined the relationship between object-based and domain-based mechanisms of visual attention. The experiments demonstrated a cross-domain cost, in terms of accuracy, when observers made dual color-form judgments to one or two overlapping objects presented briefly, relative to within-domain, dual-color and dual-form judgments. This domain-based selection effect was additive to an object-based effect, a cost of making dual judgments to separate objects, as reported by J. Duncan (1984). The pattern of object- and domain-based effects points to a capacity limitation in how multidimensional features are bound into a coherent object representation, consistent with the dimension-weighting account of H. J. Miller, D. Heller, and J. Ziegler (1995), which postulates that there is a limit to the total selection weight available to be allocated to an object's dimensions.