Spatial offloading in multiple task monitoring

The role of working memory for task-order coordination in dual-task situations

Dual-task (DT) situations require task-order coordination processes that schedule the processing of two temporally overlapping tasks. Theories on task-order coordination suggest that these processes rely on order representations that are actively maintained and processed in working memory (WM). Preliminary evidence for this assumption stems from DT situations with variable task order, where repeating task order relative to the preceding trials results in improved performance compared to changing task order, indicating the processing of task-order information in WM between two succeeding trials. We directly tested this assumption by varying WM load during a DT with variable task order. In Experiment 1, WM load was manipulated by varying the number of stimulus–response mappings of the component tasks. In Experiment 2A, WM load was increased by embedding an additional WM updating task in the applied DT. In both experiments, the performance benefit for trials with repeated relative to trials with changed task order was reduced under high compared to low WM load. These results confirm our assumption that the processing of the task-order information relies on WM resources. In Experiment 2B, we tested whether the results of Experiment 2A can be attributed to introducing an additional task per se rather than to increased WM load by introducing an additional task with a low WM load. Importantly, in this experiment, the processing of order information was not affected. In sum, the results of the three experiments indicate that task-order coordination relies on order information which is maintained in an accessible state in WM during DT processing.

Prospective Memory Performance in Simulated Air Traffic Control : Robust to Interruptions but Impaired by Retention Interval

OBJECTIVE

To examine the effects of interruptions and retention interval on prospective memory for deferred tasks in simulated air traffic control.

BACKGROUND

In many safety-critical environments, operators need to remember to perform a deferred task, which requires prospective memory. Laboratory experiments suggest that extended prospective memory retention intervals, and interruptions in those retention intervals, could impair prospective memory performance.

METHOD

Participants managed a simulated air traffic control sector. Participants were sometimes instructed to perform a deferred handoff task, requiring them to deviate from a routine procedure. We manipulated whether an interruption occurred during the prospective memory retention interval or not, the length of the retention interval (37-117 s), and the temporal proximity of the interruption to deferred task encoding and execution. We also measured performance on ongoing tasks.

RESULTS

Increasing retention intervals (37-117 s) decreased the probability of remembering to perform the deferred task. Costs to ongoing conflict detection accuracy and routine handoff speed were observed when a prospective memory intention had to be maintained. Interruptions did not affect individuals' speed or accuracy on the deferred task.

CONCLUSION

Longer retention intervals increase risk of prospective memory error and of ongoing task performance being impaired by cognitive load; however, prospective memory can be robust to effects of interruptions when the task environment provides cuing and offloading.

APPLICATION

To support operators in performing complex and dynamic tasks, prospective memory demands should be reduced, and the retention interval of deferred tasks should be kept as short as possible.

Spatial ability contributes to memory for delayed intentions

Most everyday activities involve delayed intentions referring to different event structures and timelines. Yet, past research has mostly considered prospective memory (PM) as a dual-task phenomenon in which the primary task to fulfill PM intentions is realized within an ongoing secondary task. We hypothesized that these simplified simulations of PM may have obscured the role of spatial relational processing that is functional to represent and meet the increased temporal demands in more complex PM scenarios involving multiple timelines. To test this spatiotemporal hypothesis, participants monitored four digital clocks, with PM deadlines referring either to the same clock (single-context condition) or different clocks (multiple-context condition), along with separate tests of spatial ability (mental rotation task) and executive functioning (working memory updating). We found that performance in the mental rotation task incrementally explained PM performance in the multiple-context, but not in the single-context, condition, even after controlling for individual differences in working memory updating and ongoing task performance. These findings suggest that delayed intentions occurring in multiple ongoing task contexts reflect independent contributions of working memory updating and mental rotation and that spatial relational processing may specifically be involved in higher cognitive functions, such as complex PM in multiple contexts or multitasking.

Monitoring Multiple Deadlines Relies on Spatial Processing in Posterior Parietal Cortex

Proactively coordinating one's actions is an important aspect of multitasking performance due to overlapping task sequences. In this study, we used fMRI to investigate neural mechanisms underlying monitoring of multiple overlapping task sequences. We tested the hypothesis that temporal control demands in multiple-task monitoring are offloaded onto spatial processes by representing patterns of temporal deadlines in spatial terms. Results showed that increased demands on time monitoring (i.e., responding to concurrent deadlines of one to four component tasks) increasingly activated regions in the left inferior parietal lobe and the precuneus. Moreover, independent measures of spatial abilities correlated with multiple-task performance beyond the contribution of working memory. Together, these findings suggest that monitoring and coordination of temporally overlapping task timelines rely on cortical processes involved in spatial information processing. We suggest that the precuneus is involved in tracking of multiple task timelines, whereas the inferior parietal lobe constructs spatial representations of the temporal relations of these overlapping timelines. These findings are consistent with the spatial offloading hypothesis and add new insights into the neurocognitive mechanisms underlying the coordination of multiple tasks.