Planning and realization of complex intentions in traumatic brain injury and normal aging

The realization of delayed intentions (i.e., prospective memory) is a highly complex process composed of four phases: intention formation, retention, re-instantiation, and execution. The aim of this study was to investigate if executive functioning impairments are related to problems in the formation, re-instantiation, and execution of a delayed complex intention. In this context, it was another aim of the study to investigate the executive functioning hypothesis of cognitive aging in prospective memory performance. It was, therefore, explored if age-related prospective memory decline leads to similar decrements in the process of prospective remembering as executive functioning-related decline in young patients with traumatic brain injury. A group of patients with traumatic brain injury with retrospective memory within normal limits but impaired executive functions, a group of healthy older and a group of healthy younger adults completed a complex prospective memory task that allows for the separate assessment of the four phases of the prospective memory process. All groups showed a similarly high performance in the intention retention phase, whereas the patients with deficits in executive functioning and the older participants performed worse than the healthy young participants in the intention formation, re-instantiation and execution phases. The importance of executive functioning for prospective remembering in traumatic brain injury and normal aging is discussed.     

前瞻记忆的理论模型综述

前瞻记忆是相对于回溯记忆提出的一种特殊的长时记忆,是指记住在将来某个恰当的时间执行先前意向的行为。本文介绍了近年来研究者提出的前瞻记忆认知和提取机制的理论模型,并对其做了评述。最后,本文针对目前研究中的薄弱环节尝试性地提出了今后前瞻记忆研究进一步发展的方向。     

认知负荷与编码方式影响小学数学学业不良生的前瞻记忆及其成分

通过两个实验探讨认知负荷对小学数学学业不良生前瞻记忆及其成分的影响, 以及是否可以通过执行意向编码提高其前瞻记忆及其成分的成绩。实验1结果显示数学学业不良生前瞻记忆、前瞻成分及回溯成分正确率显著低于数学学优生, 高认知负荷条件前瞻记忆、前瞻成分及回溯成分的正确率显著低于低认知负荷条件; 实验2结果显示执行意向编码条件下, 数学学业不良生前瞻记忆成绩显著好于标准编码条件, 前瞻成分和回溯成分的正确率高于标准编码条件。结果表明数学学业不良生前瞻记忆及其成分表现差于数学学优生; 无论认知负荷高低, 执行意向编码均可通过提升前瞻成分和回溯成分改善数学学业不良生前瞻记忆表现。     

The involvement of executive functions in prospective memory performance of adults

The present study examines the relationship between prospective memory performance and executive functioning. The four phases of the prospective memory process—intention formation, intention retention, reinstantiation of the intention, and intention execution—are assumed to require different amounts of executive processing, most of which is demanded in the phases of intention formation and intention execution. At present, though, it is still unclear whether, and to what extent, prefrontal executive systems are involved in different kinds of prospective memory tasks, as some findings suggest that prospective memory might rather rely on nonstrategic processes that are unlikely to depend on prefrontal executive systems. Therefore, this study focuses on the following questions: (1) to what degree does executive functioning predict prospective memory performance in different standard prospective memory tasks and, furthermore, are certain executive measures better predictors than others; (2) are age‐related effects in different prospective memory measures due to individual differences in executive functioning; and (3) do age‐related differences in prospective memory exist that are not explained by individual differences in executive functioning. In a sample of 80 adults (20‐80 years), we applied four instruments to measure prospective memory: a traditional single‐task paradigm, two more complex tasks—one time‐based and one event‐based—and a highly complex multi‐task paradigm. We further assessed a broadly defined construct of executive functioning using several standard neuropsychological tests. Results showed that executive functioning did not predict performance in the simple single‐task paradigm. However, executive functioning, but not age, predicted performance in the two more complex standard tests of prospective remembering, and both executive functioning and age predicted performance in the most complex paradigm. In sum, the obtained data underline the assumption that frontal/ executive functions are related to prospective memory performance across a range of prospective paradigms. It also seems clear that age differences in prospective memory performance partially depend on age‐related individual differences in frontal/executive functions.     

Prospective Memory Impairment in Mild Cognitive Impairment: An Analytical Review

Mild cognitive impairment (MCI) is a heterogeneous condition characterized by the presence in an otherwise healthy elderly individual of cognitive deficits involving specific domains in the absence of significant functional impairments. Reports indicate that prospective memory (PM), that is, the ability to remember to execute delayed intentions, is impaired in individuals with MCI. The present review discusses the current debate in the literature on PM functioning in MCI by focusing on the relationship between prospective retrieval and retrospective memory functioning. Analysis of the reported evidence revealed that both the prospective component and the retrospective component of PM can be impaired in MCI. Declarative memory dysfunction may account for the retrospective memory impairment, while either reduced executive abilities or a deficit of reflexive mechanisms could explain the prospective component impairment.     

Implementation intention encoding does not automatize prospective memory responding

An implementation intention encoding, one that specifies the concrete situation that is appropriate for initiating an intended action and links that situational cue to the intended action, has been shown to improve prospective memory. One proposed mechanism is that implementation intentions create automatized prospective remembering. This view anticipates that implementation intentions should prevent prospective memory decline in highly cognitively demanding situations. Contrary to this expectation, although implementation intention encoding enhanced prospective memory (Experiments 1 and 2), implementation-intention encoding did not buffer against significant prospective memory decline in high-cognitive-demand conditions (Experiments 1–3), and in Experiment 3, implementation intention encoding produced lower levels of prospective memory performance than did behavioral practice in the high-cognitive-demand situation. We suggest that although implementation intentions may stimulate a strong associative encoding (between an anticipated environmental cue and an intended action), that encoding does not support a completely automatized prospective memory response.     

The intention‐superiority effect for naturally occurring activities: The role of intention accessibility in everyday prospective remembering in young and older adults

This study examined age differences in the accessibility of a single pool of naturally occurring intentions both before and after completion. Following Maylor, Darby, and Della Sala (2000), accessibility was measured in terms of the number of activities generated in a 4‐minute activity fluency task. Each participant undertook two such tasks. A prospective task in which they generated activities intended for completion during the following week and a retrospective task, 1 week later, in which they generated activities carried out over the previous week. In a partial replication of Maylor et al.'s findings, young, but not healthy older, adults generated more to‐be‐completed intentions than completed ones, demonstrating an intention‐superiority effect (ISE) for everyday activities. The absence of an ISE for older adults appeared to reflect the reduced accessibility of intentions prior to completion, rather than the impaired inhibition of fulfilled intentions. Moreover, both groups showed greater inaccessibility of completed than intended activities, thus demonstrating an intention‐completion effect for naturally occurring intentions that is preserved in healthy ageing (cf. Marsh, Hicks, & Bink, 1998). Despite showing a reduced accessibility of intended activities, older adults reported having completed a greater proportion of their intentions during the week than young adults. Moreover, there was a correlation between the ability to access intentions and the proportion of intentions completed only for young adults. These observations suggest that older adults' everyday prospective memory performance may be relatively less dependent on intention accessibility and more dependent on other factors. While there was no age difference in the reported use and effectiveness of external retrieval aids, older adults demonstrated a greater level of temporal organization in the production of their intentions in the fluency task. This is consistent with the possibility that older adults may have more structured daily lives and may be able to use information about the sequence of ongoing events to support superior everyday prospective remembering.     

The source of adult age differences in event-based prospective memory: a multinomial modeling approach

Event-based prospective memory involves remembering to perform an action in response to a particular future event. Normal younger and older adults performed event-based prospective memory tasks in 2 experiments. The authors applied a formal multinomial processing tree model of prospective memory (Smith & Bayen, 2004) to disentangle age differences in the prospective component (remembering that you have to do something) and the retrospective component (remembering when to perform the action) of prospective memory performance. The modeling results, as well as more traditional analyses, indicate age differences in the resource-demanding prospective component.     

The Compensatory Role of Implementation Intentions for Young Adults with Low Working Memory Capacity

Many factors improve prospective memory performance both inside and outside of the laboratory, including the detailed planning of the situational cue and intended action (i.e., implementation intentions). In the current study, we obtained measures of working memory capacity and laboratory event‐based prospective memory performance in college‐aged adults. Half of our participants formed an implementation intention in the prospective memory task. Because of evidence that implementation intentions increase the encoding/retrieval efficiency of the prospective memory, it was predicted that forming an implementation intention would serve as a compensatory strategy for those with low working memory ability. Our results supported this hypothesis in that working memory capacity no longer correlated with prospective memory performance when participants employed an implementation intention encoding strategy. These findings suggest that implementation intentions may be an effective way for individuals with low working memory capacity to improve their performance in an attentionally demanding prospective memory task. Copyright © 2015 John Wiley & Sons, Ltd.     

Event‐based prospective memory and obsessive–compulsive disorder intrusive obsessional thoughts

Recent studies have found poorer prospective remembering among students selected for elevated obsessive–compulsive disorder (OCD) checking and washing. However, as prospective memory performance also requires retrospective remembering, it is not clear from earlier work whether deficits in prospective memory in samples with OCD symptomatology are due to problems with prospective remembering, or to retrospective memory failures that result in poorer performance on prospective memory tasks. The present study examines performance on matched prospective and retrospective memory tasks among students selected for high (n = 48) and low (n = 44) scores on the Obsessive–Compulsive Inventory‐Revised Obsession subscale. Significant differences between the groups were found in prospective memory (regardless of whether the word was neutral or harm/danger‐related), but not retrospective memory. The findings are consistent with the prediction that obsessional thoughts that occupy working memory capacity would have a deleterious effect on a resource‐demanding prospective memory task. An additional finding was that there were no group differences in self‐reported complaints of problems with prospective memory.     

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.     

Prospective memory and aging: preserved spontaneous retrieval,but impaired deactivation,in older adults

Prospective remembering is partially supported by cue-driven spontaneous retrieval processes. We investigated spontaneous retrieval processes in younger and older adults by presenting prospective memory target cues during a lexical decision task following instructions that the prospective memory task was finished. Spontaneous retrieval was inferred from slowed lexical decision responses to target cues (i.e., intention interference). When the intention was finished, younger adults efficiently deactivated their intention, but the older adults continued to retrieve their intentions. Levels of inhibitory functioning were negatively associated with intention interference in the older adult group, but not in the younger adult group. These results indicate that normal aging might not compromise spontaneous retrieval processes but that the ability to deactivate completed intentions is impaired.     

Implementation intentions facilitate prospective memory under high attention demands

An implementation intention is a planning technique that involves specifying a situation for initiating an intended action and linking these specific cues to the intention. In two experiments with young adults, we found significant increases in prospective memory with implementation intentions. With an implementation intention, but not with standard instructions, prospective memory performance was maintained under demanding attentional conditions (Experiment 2). Ongoing task performance did not decline, however, in relation with a no prospective memory control. Positive effects were not observed when the imagery component of the implementation intention was isolated from the verbal component. We suggest that implementation intention planning (relative to standard instructions) increases the likelihood that people will encode a robust associative link between the target cue and the intended action, thereby promoting reflexive triggering of the intended action on presentation of the target cue.     

Evidence for a detrimental relationship between hypertension history, prospective memory, and prefrontal cortex white matter in cognitively normal older adults

Hypertension affects many older adults and is associated with impaired neural and cognitive functioning. We investigated whether a history of hypertension was associated with impairments to prospective memory, which refers to the ability to remember to perform delayed intentions, such as remembering to take medication. Thirty-two cognitively normal older adult participants with or without a history of hypertension (self-reported) performed two laboratory prospective memory tasks, one that relied more strongly on executive control (nonfocal prospective memory) and one that relied more strongly on spontaneous memory retrieval processes (focal prospective memory). We observed hypertension-related impairments for nonfocal, but not focal, prospective memory. To complement our behavioral approach, we conducted a retrospective analysis of available structural magnetic resonance imaging data. Lower white matter volume estimates in the anterior prefrontal cortex were associated with lower nonfocal prospective memory and with a history of hypertension. A history of hypertension may be associated with worsened executive control and lower prefrontal white matter volume. The translational implication is that individuals who must remember to take antihypertensive medications and to monitor their blood pressure at home may be impaired in the executive control process that helps to support these prospective memory behaviors.     

Investigating the encoding and retrieval of intentions with event-related potentials

Strong evidence exists in the literature that remembering to complete intentions involves executive processing subserved by the frontal lobes. Event-related potentials were measured during the encoding of actions with the intention to perform versus more neutral material about which there was no such intentionality. Event-related potentials were also measured in a two-alternative discrimination task requiring identification of the to-be-performed actions and to-be-memorized actions. The results suggest that formation and retrieval of intentions differs from encoding and retrieval of similar material committed to memory. Additionally, the results suggest that right frontal areas may play an important role in the formation of prospective actions and that intentions are kept active in memory by processing mediated by the left frontal pole.     

前瞻记忆的年老化效应:前瞻成分和回溯成分的调节作用

关注事件性前瞻记忆的年老化,采用基于双重任务的实验室研究范式,实验一控制线索与意向的关联性和线索的显著性操纵概念驱动加工和数据驱动加工过程,比较前瞻记忆的前瞻成分和回溯成分的年老化影响;实验二检验前瞻成分在前瞻记忆年老化中的作用。结果显示,线索与意向的关联性和线索与背景的区别性作为概念驱动加工和数据驱动加工的重要表现形式可以显著地促进老年人的前瞻记忆水平,前瞻记忆年老化主要存在于前瞻记忆的前瞻成分;前瞻成分较高的注意资源需求导致前瞻记忆的年龄差异主要受任务的认知需求水平所影响,当前瞻记忆是相对自动加工时,年龄差异小;当任务需要较多的控制加工时,年龄差异相对较大。本研究进一步揭示了导致前瞻记忆年龄差异的原因。     

Prospective memory and ageing: Is task importance relevant?

Memory for activities to be performed in the future, i.e., prospective memory, such as remembering to take medication or remembering to give a colleague a message, is a pervasive real‐world memory task that has recently begun to attract the attention of numerous researchers. Age effects in prospective memory have been found particularly in complex paradigms requiring participants to remember to switch between several subtasks in a limited time period (e.g., Kliegel, McDaniel, & Einstein, 2000). Here, most of the older adults try to complete one or two subtasks and to forget the prospective instruction to work on all subtasks. Since recent findings in this context show that one profits from tips regarding the relevant task in complex double tasks, it seems likely that age effects in prospective memory tasks might also be due to the lack of information about the importance of the prospective task. To test this hypothesis, the importance of the prospective task was varied in the present study with 104 young and old participants by providing motivational incentives to interrupt and switch during the introduction phase (plan formation) as well as during the execution phase. Also, interindividual differences regarding nonexecutive as well as executive cognitive resources were analysed, thus allowing estimation of the relationship between these factors and (age‐related) performance in complex prospective remembering. The results show age effects in favour of the younger group in all task components of the complex prospective multitask. In contrast, there was no effect of the present experimental manipulation of motivational incentives. Finally, in regression analyses, intention formation, in particular, was found to be a significant predictor of intention execution, explaining most of the age‐related variance. In sum, our results specifically highlight the fundamental importance of adequately planning the complex intention and do not support the hypothesis that age‐related decrements in performance are reflecting a lack of motivation in the present complex prospective memory paradigm.     

No effects of executive control depletion on prospective memory retrieval processes

Research has suggested that prospective memory retrieval is reliant on executive control processes, and the degree to which these processes are necessary for intention fulfillment is dependent on a host of variables related to the prospective memory task. Based on results suggesting that aspects of the prospective memory task vary in their need for executive control, the current study examined the possibility that executive control depletion from the Stroop task would negatively transfer to prospective memory performance. Depletion of executive control, measured objectively in a Stroop task, did not impair prospective memory performance in either low or high cue-target association conditions. However, participants’ subjective assessments of their own cognitive fatigue correlated significantly with their prospective memory performance, regardless of the association between cues and target responses.     

Evidence for spontaneous retrieval of suspended but not finished prospective memories

McDaniel and Einstein (2007) argued that prospective memories can be retrieved through spontaneous retrieval processes stimulated by the presence of a target cue. To test this claim, we investigated whether presenting a prospective memory cue during a task that did not require an intention to be performed spontaneously triggered remembering of that intention. In two experiments, participants performed an image-rating task in which a prospective memory task (to press the “Q” key when a target word appeared) was embedded. Then, participants were told that their intention was finished or suspended. Finally, participants performed a lexical decision task in which each target (and a matched control) word appeared. RTs were slower to target words than to control words when the intention was suspended but not when it was finished. These results suggest that target cues associated with suspended intentions can spontaneously trigger remembering but that finished intentions are quickly deactivated.     

Recognition,recollection, familiarity and executive function in medicated patients with moderate Parkinson's disease

There is conflicting evidence about whether Parkinson's disease (PD) is associated with deficiencies in recognition memory (RM) and the processes which underlie it, namely recollection (a form of recall) and familiarity (a feeling of memory in the absence of recall). The aims of the current study were to examine forced‐choice verbal RM (assessed with the Warrington Recognition memory Test), yes‐no RM, recollection, familiarity and executive functioning in 17 patients with moderate PD and 17 healthy volunteers matched for age and premorbid intelligence. We predicted that patients with moderate PD would display a significant recollection deficit on the yes‐no RM test, because their strategic memory processing that depends on executive functioning and is necessary for efficient encoding and/or retrieval, was disrupted. In contrast, familiarity memory, which is not dependent on these processes, and forced‐choice RM (which is largely dependent on familiarity) should show higher levels of preservation. We also predicted that recollection should be correlated with severity of executive dysfunction. Our findings revealed that the PD patients were as likely to accurately discriminate between targets and distractors as the healthy volunteers on both RM tests. However, the PD patients were significantly less reliant on recollection‐driven recognition decisions on the yes‐no RM test when compared with the healthy control group. The patients also displayed executive function deficits, but these were not correlated with recollection. The extent to which the PD patients' reliance on familiarity at the expense of recollection is explained by impairments in strategic memory processes/executive function and/or medial temporal lobe retrieval processes needs further exploration.