The influence of dual-task load on redundant signal processes

Current technology and workplace environments are designed to enable people to attempt multiple tasks simultaneously. Consequentially, people divide their limited attentional resources among many competing demands. In some recent work, Morey et al. (2018) found the limited processing capacity to redundant targets in a peripheral task did not change depending on the difficulty or presence of a dual-task. Nonetheless, it is unknown how 1) the introduction of, or increased difficulty of, a second task may change how people combine multiple peripheral targets (e.g., in parallel or serial) and 2) processing efficiency may depend on both the salience of peripheral targets and the presence/difficulty of a second task. In this work, we use systems factorial technology to investigate the cognitive processing mechanisms of redundant visual targets in isolation and in the context of an easy or difficult multiple object tracking (MOT) task. We manipulate the degree of MOT demands: track 0, 1, or 4 dots, and the salience of peripheral red target squares (easy, difficult). We find limited-capacity parallel-OR processing of redundant targets but the degree of limited processing capacity depends on the demands of the MOT (0, 1, or 4 dots) and the salience of the dual-targets (low/high). Our data suggest that the structure for how people process multiple peripheral cues does not change depending on the overall attentional demands of the task(s); however, the extent that people benefit from redundant information may depend on how difficult it is to perceive the targets and external task demands.