Comparing costs in time-based and event-based prospective memory

Effects of delay and reminders on time-based prospective memory in a naturalistic task

The current study examined the effect of a delay on naturalistic time-based prospective memory (PM) tasks. Two experiments were performed to compare PM performance on a texting task with delays of 1 to 6 days after an initial session. In the first experiment, half of the participants were asked to repeat their response with the same delay to test whether requiring a second response (i.e., a repeated PM task, such as taking medication at the same time each day) would affect time-based PM performance. In the second experiment, participants were given an implicit or an explicit reminder several hours before their time to respond to examine the effect of type of reminder on this PM task. The results of both experiments showed a significant decline in PM performance between the 1-day and multi-day delays. Repeating responses (Experiment 1) had no effect on accuracy of the PM task, but in Experiment 2, explicit experimenter-initiated reminders significantly increased time-based PM performance compared with implicit reminders. These results are discussed in the context of previous studies that have tested delay effects on time-based PM and current theoretical descriptions of time-based PM.

Keeping the Time: The Impact of External Clock-Speed Manipulation on Time-Based Prospective Memory

Several studies have suggested that time monitoring is important for appropriate time-based prospective memory (TBPM). However, it is still unknown if people actively use internal timing processes to monitor the approaching target time, and whether they do so by tracking the duration between clock digits, or by counting and matching the numerical progression of clock ticks' digits with the target time. Therefore, in the present study, we investigated whether a manipulation of the external time affected time monitoring and TBPM performance. In two experiments, participants performed two identical TBPM tasks: a first TBPM block with no clock-speed manipulation followed by a second TBPM block, where the clock-speed was manipulated as faster or slower (experimental conditions) or normal (control condition). The results showed that only participants in the slower clock condition increased time monitoring in the second compared to the first TBPM block (d = 0.42 and 1.70); moreover, particularly in Experiment 2, participants in the faster clock condition checked the clock significantly less frequently than participants in the slower clock (d = -1.70) and in the control condition (d = -0.98), but only during the 4th minute. No effect was found for TBPM performance. Overall, results suggested that people tracked the target time by counting and matching the numerical progression of clock ticks' digits with the target time. The findings are discussed considering the most recent theoretical advancements about the relationship between time perception and TBPM.

The promotional effect of prosocial motivation on time-based prospective memory

Time-based prospective memory (TBPM) is the ability to remember to do a planned task at the right time. In social interactions, people are often motivated to do things for others, which reflects an important factor that influences prospective memory, namely prosocial motivation. According to the motivational cognitive model, prosocial motivation promotes TBPM by paying more attention or adopting more effective strategies. This study explored the effect of prosocial motivation on TBPM under different time-monitoring conditions within the motivational cognitive model framework. One hundred and thirty-one university students participated in this experiment that adopted a 2 (groups: control, prosocial motivation) × 2 (viewing time conditions: limited, unlimited) between-subjects design. The results revealed that the prosocial motivation group had better TBPM performance than the control group under both limited and unlimited viewing time conditions. At the same time, compared with the control group, the prosocial motivation group consumed more internal attention and utilized more strategies under both viewing time conditions, and their external attention was more effective. In addition, the external attention of the prosocial motivation group was higher only when time-monitoring was unlimited. The results of this study further extend knowledge of the motivational cognitive model and expand its scope of application, which has theoretical significance.

The processing mechanism of mixed prospective memory: Changes in internal and external attention

While time-based prospective memory (TBPM) includes only time cues, mixed prospective memory (MPM) is a special form of prospective memory including both time and event cues. Depending on the classification of the clarity of time cues, MPM can be divided into time-period MPM and time-point MPM. While the time cue of the latter is a definite time point, the time cue of the former is a vague time period. As such, MPM and TBPM may have different processing mechanisms due to the additional event cue. This study aimed to investigate whether there are differences in the processing mechanisms between TBPM and the two types of MPM. A total of 240 college students were recruited to participate in the experiment. They were randomly assigned to a TBPM group, time-point MPM group, time-period MPM group, and baseline group. We adopted the performance of ongoing tasks to reflect internal attention indirectly and the frequency of time checks to measure external attention. The results showed that in terms of prospective memory, time-point MPM had the best performance, followed by time-period MPM, while TBPM had the worst performance. In relation to ongoing tasks, the two types of MPM had a better performance than TBPM in some stages, although worse than the baseline. In addition, the two MPMs evoked a lower time monitoring frequency than TBPM under different monitoring conditions. These results suggested that, compared with TBPM, MPM reduced both internal and external attention consumption and achieved better prospective memory performance. Internal attention consumption displayed dynamic changes for both types of MPM, and the time-point MPM had higher internal attention effectiveness than the time-period MPM. These results support the Dynamic Multiprocess Theory and the Attention to Delayed Intention model.

Assessing time-based prospective memory online: A comparison study between laboratory-based and web-based testing

Prospective memory (PM, i.e., the ability to remember and perform future intentions) is assessed mainly within laboratory settings; however, in the last two decades, several studies have started testing PM online. Most part of those studies focused on event-based PM (EBPM), and only a few assessed time-based PM (TBPM), possibly because time keeping is difficult to control or standardise without experimental control. Thus, it is still unclear whether time monitoring patterns in online studies replicate typical patterns obtained in laboratory tasks. In this study, we therefore aimed to investigate whether the behavioural outcome measures obtained from the traditional TBPM paradigm in the laboratory-accuracy and time monitoring-are comparable with an online version in a sample of 101 younger adults. Results showed no significant difference in TBPM performance in the laboratory versus online setting, as well as no difference in time monitoring. However, we found that participants were somewhat faster and more accurate at the ongoing task during the laboratory assessment, but those differences were not related to holding an intention in mind. The findings suggest that, although participants seemed generally more distracted when tested remotely, online assessment yielded similar results in key temporal characteristics and behavioural performance as for the laboratory assessment. The results are discussed in terms of possible conceptual and methodological implications for online testing.

Prospective Memory and Regional Functional Connectivity in Subcortical Ischemic Vascular Disease

Objectives: Patients with subcortical ischemic vascular disease (SIVD) often have prominent frontal dysfunction. However, it remains unclear how SIVD affects prospective memory (PM), which strongly relies on the frontoparietal network. The present study aimed to investigate PM performance in patients with early stage SIVD as compared to those with Alzheimer's disease (AD) and to older adults with normal cognition, and to explore the neural correlates of PM deficits. Method: Patients with very-mild to mild dementia due to SIVD or AD and normal controls (NC) aged above 60 years were recruited. Seventy-three participants (20 SIVD, 22 AD, and 31 NC) underwent structural magnetic resonance imaging (MRI), cognitive screening tests, and a computerized PM test. Sixty-five of these participants (19 SIVD, 20 AD, and 26 NC) also received resting-state functional MRI. Results: The group with SIVD had significantly fewer PM hits than the control group on both time-based and non-focal event-based PM tasks. Among patients in the very early stage, only those with SIVD but not AD performed significantly worse than the controls. Correlational analyses showed that non-focal event-based PM in SIVD was positively correlated with regional homogeneity in bilateral superior and middle frontal gyri, while time-based PM was not significantly associated with regional homogeneity in any of the regions of interest within the dorsal frontoparietal regions. Conclusions: The findings of this study highlight the vulnerability of non-focal event-based PM to the disruption of regional functional connectivity in bilateral superior and middle frontal gyri in patients with SIVD.