Discrete item-based and continuous configural representations in visual short-term memory

Abstract

ABSTRACTBoth discrete item-based and global configural information can be stored in visual short-term memory (VSTM). To characterize their contribution, the present study developed a dual-trace signal detection (DTSD) model consisting of a high threshold (HT) component for discrete item information and a continuous signal detection theory (SDT) component for configural information. We used an orientation change-detection task in which observers attempted to retain several orientations over a 1-s retention interval and then reported whether a cued item in the test array had the old or new orientation on a 6-point confidence scale. The resulting Receiver Operating Characteristics (ROC) curves were fit with the DTSD model, producing estimates of the two memory representations. In a series of experiments, we found that manipulations of configural encoding selectively affected the SDT component whereas the manipulation of item information selectively affected the HT component. Together these findings indicate that VSTM maintains a few discrete representations and continuous representation of configural information.