Abstract
Within dynamic events, the degree to which perceptual information is attended and later remembered varies over time. One cue that may lead people to attend to and encode perceptual information is the occurrence of a behaviorally relevant event, such as the appearance of a target in a stream of non-targets. However, target detection often interferes with concurrent, secondary task performance and therefore could reduce encoding of other information. In this study, we examined the dual-task interaction between detecting targets in a stream of non-targets and explicit memory for serially presented background scenes. For these experiments, participants monitored a black square in the center of a display for an occasional change in color (target event), while they encoded a long series of natural scenes into memory. Each scene was presented for 100msec with a 400msec interstimulus interval. Following the detection task, participants completed a recognition test that required them to distinguish between the old scene, a novel scene, and mirror-reversed versions of both scenes. Results showed that detecting a target event (i.e., color change to the central square) enhanced, rather than impaired, memory of the background scene that coincided with the target: Participants more accurately distinguished the old scenes from the new scenes, and the old scene from its mirror-reversed counterpart when it was previously presented with the target. However, accuracy was reduced for the scene that immediately followed the target. Follow-up experiments suggested that these effects diminished with longer presentation rates, and that the reduction in accuracy for scenes that followed the target was attributable to competition from the scenes that were presented with the target. Therefore, rather than resulting in interference, target detection facilitated secondary task performance. These data are consistent with the operation of a reward-based mechanism that globally reinforces perceptual information that coincides with behaviorally relevant events.
This study was supported in part by NSF 0733764 and NIH 071788.