Comparing time-based and event-based prospective memory over short delays

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.

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.

Influence of the physical effort of reminder-setting on strategic offloading of delayed intentions

Intention offloading involves using external reminders such as diaries, to-do lists, and digital alerts to help us remember delayed intentions. Recent studies have provided evidence for various cognitive and metacognitive factors that guide intention offloading, but little research has investigated the physical cost of reminder-setting itself. Here, we present two pre-registered experiments investigating how the cost of physical effort associated with reminder-setting influences strategic intention offloading under different levels of memory load. At all memory loads, reminder-setting was reduced when it was more effortful. The ability to set reminders allowed participants to compensate for the influence of memory load on accuracy in the low-effort condition; this effect was attenuated in the high-effort condition. In addition, there was evidence that participants with less confidence in their memory abilities were more likely to set reminders. Contrary to prediction, physical effort had the greatest effect on reminder-setting at intermediate memory loads. We speculate that the physical costs of reminder-setting might have the greatest impact when participants are uncertain about their strategy choice. These results demonstrate the importance of physical effort as one of the factors relevant to cost-benefit decision-making about cognitive offloading strategies.

The effect of verbal praise on prospective memory

Verbal praise is often used to improve prospective memory performance in daily life. According to the motivation cognitive model, the promotional effect of verbal praise on prospective memory may depend largely on redeploying attentional resources, so its promotional effect is likely to be influenced by attention. Two groups of college students (n = 128, n = 117) participated in two experimental studies that examined this hypothesis. Experiment 1 manipulated attention load by changing the difficulty of the ongoing tasks to focus on the effect of verbal praise on prospective memory under different attention load conditions. The results showed that verbal praise promoted prospective memory performance under both attentional load conditions (low, high), but verbal praise mainly promoted the prospective component when the attentional load was low, meanwhile, verbal praise mainly promoted the retrospective component when the attention load was high. Experiment 2 altered the dependence of prospective memory tasks on attentional resources by manipulating the cue focality, further exploring the promotional effect of verbal praise on prospective memory with different types of cues under the low attention load condition. The results showed that verbal praise only promoted prospective memory when non-focal cues were used. The results of this study partially verified the motivation cognitive model.

Effects of bilateral repetitive transcranial magnetic stimulation on prospective memory in patients with schizophrenia: A double-blind randomized controlled clinical trial

AIMS

To investigate effects of repetitive transcranial magnetic stimulation (rTMS) on the prospective memory (PM) in patients with schizophrenia (SCZ).

METHODS

Fifty of 71 patients completed this double-blind placebo-controlled randomized trial and compared with 18 healthy controls' (HCs) PM outcomes. Bilateral 20 Hz rTMS to the dorsolateral prefrontal cortex at 90% RMT administered 5 weekdays for 4 weeks for a total of 20 treatments. The Positive and Negative Symptom Scale (PANSS), the Scale for the Assessment of Negative Symptoms (SANS), and PM test were assessed before and after treatment.

RESULTS

Both Event-based PM (EBPM) and Time-based PM (TBPM) scores at baseline were significantly lower in patients with SCZ than that in HCs. After rTMS treatments, the scores of EBPM in patients with SCZ was significantly improved and had no differences from that in HCs, while the scores of TBPM did not improved. The negative symptom scores on PANSS and the scores of almost all subscales and total scores of SANS were significantly improved in both groups.

CONCLUSIONS

Our findings indicated that bilateral high-frequency rTMS treatment can alleviate EBPM but not TBPM in patients with SCZ, as well as improve the negative symptoms.

SIGNIFICANCE

Our results provide one therapeutic option for PM in patients with SCZ.

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.

Aging and time-based prospective memory in the laboratory: a meta-analysis on age-related differences and possible explanatory factors

In older adults' everyday life, time-based prospective memory (TBPM) is relevant as health-related intentions are often part of daily activities. Nonetheless, it is still unclear which task-related factors can potentially moderate the magnitude of age-related differences, such as duration of the PM target time (the time-window within which an individual must complete a given TBPM task), the frequency of the TBPM tasks, and the criterion chosen to compute PM accuracy. The present meta-analysis aimed to quantify age-related differences in laboratory TBPM tasks, and to investigate how specific task-related factors potentially moderate the magnitude of age effects. The results showed that age effects consistently emerged among the studies, with older adults showing lower TBPM performance and checking the clock less often than younger adults, especially for shorter intervals (e.g., ≤ 4 min). Furthermore, the results indicated that the duration of the PM target time interacted with the frequency of the PM task, suggesting that learning effects may attenuate the magnitude of age differences in TBPM performance. The results are discussed in terms of potential implications about the possible cognitive processes involved in TBPM and aging, as well as in terms of robustness of the TBPM laboratory paradigm in aging research.

Prior experience with target encounter affects attention allocation and prospective memory performance

We examined how prior experience encountering targets affected attention allocation and event-based prospective memory. Participants performed four color match task blocks with a difficult, but specified prospective memory task (Experiment 1) or an easier, but unspecified prospective memory task (Experiment 2). Participants were instructed to search for targets on each block. Participants in the prior experience condition saw targets on each block, participants in the no prior experience condition only saw targets on the fourth block, and, in Experiment 2, participants in the mixed prior experience condition encountered some of the targets on the first three blocks, and saw all the targets on the fourth block. In Experiment 1, participants in the no prior experience condition were less accurate at recognizing targets and quicker to respond on ongoing task trials than participants in the prior experience condition. In Experiment 2, we replicated the effect of prior experience on target accuracy, but there was no effect on ongoing trial response time. The mixed experience condition did not vary from the other conditions on either dependent variable, but their target accuracy varied in accordance with their experience. These findings demonstrate that prospective memory performance is influenced by experience with related tasks, thus extending our understanding of the dynamic nature of search efforts across related prospective memory tasks. This research has implications for understanding prospective memory in applied settings where targets do not reliably occur such as baggage screenings and missing person searches.

An ecologically valid examination of event-based and time-based prospective memory using immersive virtual reality: the effects of delay and task type on everyday prospective memory

Recent research has focused on assessing either event- or time-based prospective memory (PM) using laboratory tasks. Yet, the findings pertaining to PM performance on laboratory tasks are often inconsistent with the findings on corresponding naturalistic experiments. Ecologically valid neuropsychological tasks resemble the complexity and cognitive demands of everyday tasks, offer an adequate level of experimental control, and allow a generalisation of the findings to everyday performance. The Virtual Reality Everyday Assessment Lab (VR-EAL), an immersive virtual reality neuropsychological battery with enhanced ecological validity, was implemented to comprehensively assess everyday PM (i.e., focal and non-focal event-based, and time-based). The effects of the length of delay between encoding and initiating the PM intention and the type of PM task on everyday PM performance were examined. The results revealed that everyday PM performance was affected by the length of delay rather than the type of PM task. The effect of the length of delay differentially affected performance on the focal, non-focal, and time-based tasks and was proportional to the PM cue focality (i.e., semantic relationship with the intended action). This study also highlighted methodological considerations such as the differentiation between functioning and ability, distinction of cue attributes, and the necessity of ecological validity.

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

Although much recent research has focused on event-based prospective memory (PM), fewer studies have compared event- and time-based PM. In the current study, two experiments were conducted to directly compare ongoing task costs of focal and non-focal event-based tasks with a time-based task. In the second experiment, an external reminder of the task was present to test whether this reduced the cost of the time-based task. PM accuracy was significantly greater for the focal conditions, as predicted. Response times (RT) were highest in the non-focal tasks, with similar RTs in the focal and time-based tasks. Clock check frequency was significantly related to making a PM response in the time-based task, with clock checks increasing as the 7 min target time approached. While time-based tasks may be more difficult to complete, they do not seem to result in the speed cost to an ongoing task that non-focal PM tasks do.

Event-, Time- and Activity-Based Prospective Memory in Children with ADHD

We examined prospective memory (PM) function in children with attention deficit hyperactivity disorder (ADHD). A group of 28 children with ADHD and 28 typically developing children completed event-, time- and activity-based PM tasks and attention tests. ADHD children had impaired attention but intact PM performance. Both groups performed best in activity-based PM tasks, followed by event-based PM tasks, and performed worst in time-based PM tasks. ADHD children had lower ongoing task performance in the event-based PM task. The findings indicate that children with ADHD may have an intact PM, but this may be at the cost of ongoing task performance.