Event-based prospective memory in depression: The impact of cue focality

This study is the first to compare event-based prospective memory performance in individuals with depression and healthy controls. The degree to which self-initiated processing is required to perform the prospective memory task was varied. Twenty-eight individuals with depression and 32 healthy controls worked on a computerised prospective memory task. Prospective cues were either presented focally or non-focally to the ongoing activity. Collapsing data across both conditions, controls outperformed individuals with depression in the prospective memory task. Overall, participants showed a poorer prospective memory performance in the non-focal condition that required self-initiated processing to a higher degree than the focal condition. Importantly, as revealed by a group by task condition interaction, groups did not differ in the focal condition, whereas, controls outperformed individuals with depression in the non-focal condition. The results are in line with the multiprocess framework of event-based prospective remembering and the cognitive-initiative account of depression-related cognitive deficits.     

Deficits in prospective memory following damage to the medial subdivision of the mediodorsal thalamic nucleus

Identifying the neurocognitive mechanisms that lead individuals remembering to execute an intention at the right moment (prospective memory, PM) and how such mechanisms are influenced by the features of that intention is a fundamental theoretical challenge. In particular, the functional contribution of subcortical regions to PM is still unknown. This study was aimed at investigating the role of the medial subdivision of the mediodorsal thalamic nucleus (mMDT) in PM, with particular focus on the processes that are mediated by the projections from/to this structure. We analysed the performance of a patient (OG) with a right-sided lesion involving the mMDT in a series of PM tasks that varied for focality (i.e., overlapping of processes for the PM and ongoing tasks) and emotional valence of the stimuli, comparing the patient's performance with that of a control group. We found that the mMDT damage led to deficits in PM that were modulated by focality and emotional valence. OG indeed showed: a greater cost in the ongoing performance when a non-focal PM task was added; a slowing down in retrieving the intentions, in particular when these were associated with focal PM cues; an abnormal performance in the task with positive PM cues. Our findings provide evidence of a contribution of mMDT to PM and suggest a modulation of prefrontal-dependent strategic monitoring and a possible interaction with the limbic structures in the integration of emotion and PM processes. They also give support to the still controversial idea that connections with the perirhinal cortex mediate familiarity-based recognition.     

Fitting an ex-Gaussian function to examine costs in event-based prospective memory: Evidence for a continuous monitoring profile

Event-based prospective memory (PM) tasks require individuals to remember to perform a deferred action when a target event occurs. PM task requirements can slow ongoing task responses on non-target trials (‘costs’) under conditions where the defining features of targets are non-focal to the ongoing task, which is indicative that individuals have allocated some form of cognitive control process to the PM task. Recent fits of the ex-Gaussian mathematical function to non-target trial response distributions by prior studies have indicated that these control processes are transiently allocated. In the current paper, fits of the ex-Gaussian function to data reported by Loft and Humphreys (2012) demonstrate a shift in the entire response time distribution (μ) and an increase in skew (τ) for a non-focal PM condition required to remember to make a PM response if presented with category exemplars, compared to a control condition. This change in μ is indicative of a more continuous PM monitoring profile than that reported by prior studies. In addition, within–subject variability in μ was reliably correlated with PM accuracy, suggesting that these control processes allocated on a regular basis were functional to PM accuracy. In contrast, when the ongoing task directed attention to the defining features of targets (focal PM) there was a trend level increase in μ, but the within–subject variability in μ was not correlated with PM accuracy, consistent with the theoretical premise that focal PM tasks are not as dependent on cognitive control as non-focal PM tasks.     

Acute pain disrupts prospective memory cue detection processes

Prospective memory refers to the planning, retention, retrieval, and execution of intentions for future behaviours and it is integral to the enterprise of daily living. Although prospective memory relies upon retrospective memory and executive processes often disrupted by pain, limited research has explored the influence of acute or chronic pain on the ability to complete prospective memory tasks. In the present study we investigated the influence of acute pain on prospective memory tasks that varied in their demands on executive processes (i.e., non-focal versus focal prospective memory cues). Complex-span working memory tasks were also administered to examine whether individual differences in working memory capacity moderated any negative impact of pain on prospective memory. Acute pain significantly impaired prospective memory performance in conditions that encouraged non-focal strategic processing of prospective memory cues, but not in conditions that encouraged more spontaneous focal processing. Individual differences in working memory capacity did not moderate the effect of acute pain on non-focal prospective memory. These findings provide new insights into prospective memory dysfunction created by painful experiences.     

Does episodic future thinking improve prospective remembering?

Extant findings suggest interesting avenues for the investigation of the potential relationship between EFT and PM. However, as they stand, they are inconclusive as to the causal role that EFT may play in aiding prospective remembering. In one Experiment, we showed that accuracy in a prospective memory (PM) task performed on the second day was significantly higher when participants, on the first day, had mentally simulated the sequence of events expected to occur on the second day, including the PM task, than when they had performed control tasks. These data extend previous findings on the functional benefit of future simulations in different domains by revealing a substantial facilitation effect of future-oriented thoughts on PM performance when the mentally simulated future task matched the actually executed task.     

线索聚焦性影响前瞻记忆意向维持与提取：来自眼动追踪的证据

研究以眼动追踪的方法探讨线索聚焦性对前瞻记忆(prospective memory, PM）加工过程的影响。实验1中,28名被试完成了线索聚焦和非聚焦两类PM眼动追踪任务。结果发现,个体在聚焦和非聚焦两类PM任务意向维持、意向提取阶段上均表现出不同的眼动加工特征。实验2中,研究进一步对线索聚焦和非聚焦两个PM任务中PM线索词重复次数进行平衡,并重复了实验1的研究结果,说明实验1所观测到的效应不是PM线索词重复造成的混淆,线索聚焦性影响PM的意向维持、意向提取过程,研究结果支持多重加工理论。     

Assessing absentmindedness: Prospective memory complaint and impairment in middle-aged adults

In two experiments, metamemorial differences between prospective and retrospective memory performance were examined. Participants in Experiment 1 were recruited through newspaper advertisements and comprised middle-aged women who experienced exceptional problems in prospective remembering. Experiment 2 involved self-reporters and nonreporters of retrospective memory problems, who were selected from a large population-based sample of middle-aged adults. In both experiments, memory performance was assessed by using a variety of tasks, including five retrospective memory tasks and three prospective memory tasks that varied in level of realism and retrieval support. In both experiments, there were selective differences in memory performance, so that participants who experienced (retrospective or prospective) memory problems showed impaired performance in prospective, but not in retrospective, memory tasks. These findings suggest that memory for future intentions provides a more sensitive task criterion than does memory for past events for assessing individual differences in self-reports of episodic memory problems. Task-specific differences in reliance on frontally mediated executive processes might underlie these differences.     

前瞻记忆后效的加工机制：对自发提取观点和抑制观点的检验

摘 要 实验1探究前瞻记忆后效的产生是否消耗认知资源,实验2进一步探究前瞻记忆后效产生过程中消耗的认知资源的去向。实验1结果显示在完成阶段,相比于基线条件,其它四种实验条件的进行中任务反应速度均较慢,实验2结果显示无论线索是否显著,前瞻记忆后效均会随着认知负荷的提高而提高。结果表明前瞻记忆后效产生过程中会消耗认知资源对原意向进行抑制。本研究支持了抑制的观点。     

背景任务刺激间的时距对前瞻干扰效应的影响

前瞻记忆是指形成和保持一个意向直到合适的情境或时间再执行的一种记忆任务。由于在执行背景任务的过程中保持和提取前瞻意向, 使成功执行前瞻记忆任务与加工背景任务之间存在着相互影响。保持前瞻记忆意向对背景任务的反应时和正确率有影响的现象称之为前瞻干扰效应。本研究通过操纵背景任务刺激间时距的两个实验, 考察了背景任务刺激间时距长度对时间性前瞻记忆和事件性前瞻记忆干扰效应量的对比关系的影响。结果发现随着背景任务刺激间时距缩短, 两类前瞻记忆干扰效应量的对比关系发生了变化, 且在背景任务刺激间时距长度不同的情况下执行时间性前瞻记忆任务时, 被试查看时钟的策略也有差异。提示了时间性前瞻记忆任务与事件性前瞻记忆任务认知加工机制上的不同。     

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

The current study compared monitoring in time- and event-based prospective memory (PM). Time- and event-based non-focal task instructions were given after a baseline block of a lexical decision ongoing task. Delay between instruction and presentation of PM cue/time was manipulated between-subjects to examine monitoring across short delays (1–6?min). Longer delays decreased performance in the event-based task, but not in the time-based task. This accuracy decline was accompanied by a decline in monitoring (as measured by PM cost to the ongoing task in the trials immediately before the PM cue was presented) between the 1 and 3?min delays. Monitoring was only evident for the time-based task at the 6?min delay as measured by PM cost to the ongoing task. Clock checks were also not affected by delay, but did increase in frequency as the response time neared. These results suggest that delay from the time of intention formation decreases both accuracy and monitoring in event-based tasks, but does not decrease accuracy or monitoring in time-based tasks.     

Prospective memory in children: the effects of age and task interruption

Prospective memory (PM), remembering to carry out a task in the future, is highly relevant to children's everyday functioning, yet relatively little is known about it. For these reasons the effects of age and task interruption on PM were studied in 3 experiments. Children aged 4, 5, and 7 years were asked to name pictures in stacks of cards (the ongoing task) and to remember to do something when they saw a target picture (the PM task). Significant age differences were identified, but age explained only a small amount of variance. As predicted, children in the no-interruption condition performed significantly better than those who had to interrupt the ongoing activity in order to carry out the PM task. An additional finding was that no relation was detected between performance on prospective and retrospective memory tasks. Taken together, these findings provide support for current models of PM and identify ways to assist children's PM.     

Effects of delay of prospective memory cues in an ongoing task on prospective memory task performance

To address the mixed results reported in previous studies, the present experiments examined forgetting in prospective memory (PM) by manipulating the delay between the PM instructions and cue presentation in event-based PM tasks. PM performance was measured for delays of 2–20 min in Experiment 1 and for delays of approximately 1–10 min in Experiment 2. Experiment 2 included both focal and nonfocal PM tasks, and speed on the ongoing task was measured to examine evidence for monitoring processes across the delays tested. The results suggest that nonfocal PM performance follows a nonlinear forgetting function (i.e., rapid decline for shorter delays and slower decline for longer delays) when tested over delays from 1 to 20 min. No effect of delay was seen for the focal task tested in Experiment 2 from 1 to 10 min. In Experiment 2, ongoing-task costs were also found for the first delay but not for longer delays, suggesting that monitoring was significantly reduced between 1 and 2.5 min of the ongoing-task trials.     

Dismantling the “age–prospective memory paradox”: The classic laboratory paradigm simulated in a naturalistic setting

Previous research has identified “the age–prospective memory paradox”—that adult ageing results in reliably poorer performance on laboratory-based tasks of prospective memory (PM), but improved performance on such tasks carried out in real-life settings. We hypothesized that even in their everyday environment, older adults might be worse at PM tasks that are triggered during an experimenter-generated ongoing activity. The present study used a task that captured the key features of the classic laboratory paradigm, but which was completed in a setting that met key criteria to be considered naturalistic. In their everyday setting, participants' PM was assessed, with the cue to remember occurring either (a) during their day-to-day activities, or (b) during an experimenter-generated ongoing task. The results confirmed previous naturalistic findings, in showing that older adults (n = 28) exhibited better PM than their younger counterparts (n = 65) when prompted during their everyday activities. However, older adults were also then subsequently less likely to show effective PM during experimenter-generated ongoing activity. Reproducing the paradox within a single dataset, these data indicate that older adults can effectively act on intentions during everyday activities, but have difficulty in prospective remembering during experimenter-generated ongoing tasks.     

Number of cues influences the cost of remembering to remember

A current focus in the prospective memory literature is the extent to which a prospective memory task (remembering to perform a future action) interferes with ongoing activities (defined in this study as lexical decision latencies). In the present study, participants had to detect one, two, three, four, five, or six prospective memory cues. Results showed no significant increase in lexical decision latencies with one or two targets; however, significant costs emerged with three or more targets. Furthermore, task interference showed a linear increase in task costs for word trial performance but not for nonword trial performance. Practical and theoretical implications of these findings are discussed.     

Prior task experience and comparable stimulus exposure nullify focal and nonfocal prospective memory retrieval differences

We explored the nature of focal versus nonfocal event-based prospective memory retrieval. In the context of a lexical decision task, people received an intention to respond to a single word (focal) in one condition and to a category label (nonfocal) for the other condition. Participants experienced both conditions, and their order was manipulated. The focal instruction condition was a single word presented multiple times. In Experiment 1, the stimuli in the nonfocal condition were different exemplars from a category, each presented once. In the nonfocal condition retrieval was poorer and reaction times were slower during the ongoing task as compared to the focal condition, replicating prior findings. In Experiment 2, the stimulus in the nonfocal condition was a single category exemplar repeated multiple times. When this single-exemplar nonfocal condition followed in time the single-item focal condition, focal versus nonfocal performance was virtually indistinguishable. These results demonstrate that people can modify their stimulus processing and expectations in event-based prospective memory tasks based on experience with the nature of prospective cues and with the ongoing task.     

The effect of semantic context on prospective memory performance

The current study provides evidence for spontaneous processing in prospective memory (PM) or memory for intentions. Discrepancy-plus-search is the spontaneous processing of PM cues via disruptions in processing fluency of ongoing task items. We tested whether this mechanism can be demonstrated in an ongoing rating task with a dominant semantic context. Ongoing task items were manipulated such that the PM cues were members of a semantic category (i.e., Body Parts) that was congruent or discrepant with the dominant semantic category in the ongoing task. Results showed that participants correctly responded to more PM cues when there was a category discrepancy between the PM cues and ongoing task items. Moreover, participants' identification of PM cues was accompanied by faster ongoing task reaction times when PM cues were discrepant with ongoing task items than when they were congruent. These results suggest that a discrepancy-plus-search process supports PM retrieval in certain contexts, and that some discrepancy-plus-search mechanisms may result from the violation of processing expectations within a semantic context.     

任务规律性对前瞻记忆的影响

采用混合实验设计,结合行为和眼动数据,探讨任务规律性对前瞻记忆的影响。行为结果显示规律已知条件下前瞻记忆成绩显著高于规律未知和无规律条件,规律未知条件下的前瞻记忆成绩在靶线索之后刺激上有高于无规律条件的趋势;眼动结果显示规律已知条件下的注视点最多,首次注视时间最长。结果说明:(1)任务规律性对前瞻记忆成绩具有促进作用;(2)任务规律性促进了对前瞻记忆任务的自动化加工;(3)在规律已知条件下前瞻记忆的加工过程呈现出动态交替的特点。     

MPT模型在事件性前瞻记忆研究中的应用

前瞻性记忆是指对将要进行的活动或事件的记忆。前瞻记忆中,包含了前瞻成分和回溯成分。前人研究中,缺乏对前瞻成分和回溯成分有效的分离手段,使得对前瞻记忆机制的探讨缺乏深入挖掘。本文将MPT模型与Cohen等人的研究范式对比,分析了该模型在事件性前瞻记忆研究中的优势。文章对模型的理论基础,模型的主要内容,模型的数据计算方法,模型的效度以及模型的应用等几个方面进行了介绍,同时对模型使用中需要注意的问题进行了讨论。     

The effect of different distractions on remembering delayed intentions

In safety-critical domains, frequently intentions need to be delayed until an ongoing task is completed. Research using the delay-execute paradigm showed that interruptions during the delay cause forgetting. However, staff members often handle an initial distraction not by interrupting the ongoing task but by acknowledging the distraction or multitasking. In Experiments 1a and 1b, we observed that, compared to a no distraction condition, multitasking significantly decreased remembering of intentions and interrupting decreased remembering even further. In Experiment 2, interruptions with context change reduced remembering of intentions compared to uninterrupted delays, and at the same time, interruptions without context change improved memory performance compared to uninterrupted delays. However, improved memory performance resulted in decreased interrupting task performance. Theoretically, the results support the contextual cueing mechanism of delay-execute tasks. Considering safety-critical domains, multitasking, interruptions and context changes can contribute to forgetting of tasks.