Prospective memory and pediatric traumatic brain injury: effects of cognitive demand.

This study investigated the effects of pediatric traumatic brain injury (TBI) on prospective memory. Fourteen children and 14 adolescents with TBI were compared with 25 and 23 noninjured children and adolescents, respectively. Based on a prefrontal model, the cognitive demand on the ongoing component of a prospective-memory task was manipulated. Overall, those with TBI had poorer prospective-memory performance than their noninjured peers. Performance was worse in a high cognitive-demand condition than a low, and younger children performed worse than adolescents. Decreases in performance from the low- to high-demand conditions were not significantly different between the two children's groups but were between the two adolescents' groups. Furthermore, the age and injury effects were reflected in the performances on executive function tests: the Self-ordered Pointing Task (SOPT), and the Stroop Color Word Interference Test. The Tower of London (TOL), which did not produce age or injury effects, was nevertheless found to be an important predictor of performance on the high-demand task in those with TBI. Although previous research has demonstrated impaired prospective memory performance in children with TBI, this study attempted to explain why this might occur, specifically that the prefrontal regions might be implicated.     

Development of Prospective Memory: Tasks Based on the Prefrontal-Lobe Model

This study investigated the development of prospective memory using tasks based on the prefrontal-lobe model. Three groups each of 30 children, adolescents, and young adults were compared on prospective-memory performance using ongoing tasks with two levels of cognitive demand (low and high), and two levels of importance (unstressed and stressed) of remembering prospective cues. The Self-Ordered Pointing Task (SOPT), Stroop Color Word Interference Test, and Tower of London were also used to assess relationships between prospective memory and prefrontal-lobe functions. The children remembered fewer prospective cues than either the adolescents or adults, but the adolescents and adults remembered equally well. This trend increased significantly as the cognitive demand of the ongoing tasks increased. However, stressing or not stressing the importance of remembering made no difference to prospective-memory performance. Performance on the SOPT and Stroop Colour Word Interference predicted performance on the high- but not on the low-demand condition. These findings implicate the maturation of the brain's prefrontal region in the development of prospective memory.     

Development of prospective memory: tasks based on the prefrontal-lobe model.

This study investigated the development of prospective memory using tasks based on the prefrontal-lobe model. Three groups each of 30 children, adolescents, and young adults were compared on prospective-memory performance using ongoing tasks with two levels of cognitive demand (low and high), and two levels of importance (unstressed and stressed) of remembering prospective cues. The Self-Ordered Pointing Task (SOPT), Stroop Color Word Interference Test, and Tower of London were also used to assess relationships between prospective memory and prefrontal-lobe functions. The children remembered fewer prospective cues than either the adolescents or adults, but the adolescents and adults remembered equally well. This trend increased significantly as the cognitive demand of the ongoing tasks increased. However, stressing or not stressing the importance of remembering made no difference to prospective-memory performance. Performance on the SOPT and Stroop Colour Word Interference predicted performance on the high- but not on the low-demand condition. These findings implicate the maturation of the brain's prefrontal region in the development of prospective memory.     

The Importance of On-going Concurrent Activities as a Function of Age in Time- and Event-based Prospective Memory

Time-based prospective memory is assumed to involve more self-initiated activities than event-based prospective memory. As age negatively affects self-initiated activities, older participants will show more prospectivememory deterioration than younger participants in time-based tasks. Einstein, McDaniel, Richardson, Guynn, and Cunfer (1995) indeed observed such a decrement in time-based prospective memory while d'Ydewalle, Utsi, and Brunfaut (1996) obtained a better time-based than event-based prospective memory among elderly. The on-going concurrent activity in Einstein et al. (1995) involved answering general questions, whereas d'Ydewalle et al. (1996) used a face-identification task. In an attempt to explain the discrepant results, the present experiment compares time- and event-based memory with young and older participants using the two types of on-going task. However, the better performance of the older participants in the timebased prospective memory task is obtained in the two on-going tasks. A difference in timing constraints in the procedure may explain why the older participants in Einstein et al. (1995) did perform more poorly in the timebased task, whereas our ageing participants did not show such a deterioration, suggesting that the slowing down of mental activities may provide a better explanation than the increasing lack of self-initiated activities by the elderly. All age effects in prospective-memory performance disappear when performance on the target items (i.e. items where a prospective-memory response is required) in the on-going task is taken into account. We emphasise the need to study trade-offs in prospective-memory research as a prospective-memory task is always embedded in another (on-going) activity.     

The role of metacognition in prospective memory: Anticipated task demands influence attention allocation strategies

The present study investigates how individuals distribute their attentional resources between a prospective memory task and an ongoing task. Therefore, metacognitive expectations about the attentional demands of the prospective-memory task were manipulated while the factual demands were held constant. In Experiments 1a and 1b, we found attentional costs from a prospective-memory task with low factual demands to be significantly reduced when information about the low to-be-expected demands were provided, while prospective-memory performance remained largely unaffected. In Experiment 2, attentional monitoring in a more demanding prospective-memory task also varied with information about the to-be-expected demands (high vs. low) and again there were no equivalent changes in prospective-memory performance. These findings suggest that attention–allocation strategies of prospective memory rely on metacognitive expectations about prospective-memory task demands. Furthermore, the results suggest that attentional monitoring is only functional for prospective memory to the extent to which anticipated task demands reflect objective task demands.     

Age-related changes in event-related prospective memory performance: a comparison of four prospective memory tasks

The primary purpose of the study was to identify event-based prospective-memory tasks that provide sensitive and reliable tools for assessing effects of normal aging in prospective-memory performance. Four prospective-memory tasks were selected from the literature or were newly developed, with the tasks differing on various dimensions that, for theoretical reasons or based on previous evidence, might determine task sensitivity to age effects on prospective-memory performance: perceptual saliency of prospective target events, frequency of occurrence of prospective target events, complexity of prospective-memory instructions, and provision of feedback after prospective-memory errors. Two of the four tasks yielded large and robust age effects on prospective-memory performance. Correlational analyses suggested that these age effects on prospective-memory performance were mediated, at least in part, by a reduced ability of older adults to maintain prospective intentions in a highly activated state and not by age effects on basic mental speed alone.     

Selective Learning in Children after Traumatic Brain Injury: A Preliminary Study

Selective learning (SL) is the ability to select items to learn from among other items. It requires the use of the executive processes of metacognitive control and working memory, which are considered to be mediated by the frontal cortex and its circuitry. We studied the efficiency with which verbal items of greater value are selectively learned from among items varying in value in 14 children ages 8-15 years who had sustained severe traumatic brain injury (TBI) and in 39 typically developing age-matched children. We hypothesized that children with TBI would be disproportionately compromised in selective learning efficiency in contrast to memory span when compared to normally developing children. The results supported our hypothesis, as children with TBI performed significantly worse than controls on a measure of selective learning efficiency, but the two groups performed similarly on a measure of word recall within the same task. Furthermore, the effect of TBI on performance was demonstrated to take place at the time of encoding, rather than at retrieval.     

Selective learning in children after traumatic brain injury: a preliminary study.

Selective learning (SL) is the ability to select items to learn from among other items. It requires the use of the executive processes of metacognitive control and working memory, which are considered to be mediated by the frontal cortex and its circuitry. We studied the efficiency with which verbal items of greater value are selectively learned from among items varying in value in 14 children ages 8-15 years who had sustained severe traumatic brain injury (TBI) and in 39 typically developing age-matched children. We hypothesized that children with TBI would be disproportionately compromised in selective learning efficiency in contrast to memory span when compared to normally developing children. The results supported our hypothesis, as children with TBI performed significantly worse than controls on a measure of selective learning efficiency, but the two groups performed similarly on a measure of word recall within the same task. Furthermore, the effect of TBI on performance was demonstrated to take place at the time of encoding, rather than at retrieval.     

Attention After Pediatric Traumatic Brain Injury: A Multidimensional Assessment

Attentional disturbance is a common complaint after TBI in children and adolescents, however, few studies have assessed post-traumatic attentional functions. The attentional constructs proposed by Mirsky, Anthony, Duncan, Ahearn, and Kellam (1991) provided a multidimensional framework for prospective assessment of late attentional disturbance after mild-moderate (n = 34) and severe (n = 57) traumatic brain injury (TBI). Attention was evaluated from 5 to 8 years after TBI in children ages 0 to 15 years at the time of injury. Children with severe TBI performed more poorly than children with mild-moderate TBI on tests comprising the focus/execute and shift constructs. Younger children scored below older children irrespective of injury severity on the Digit Span subtest and interstimulus interval scores from an adaptive rate continuous performance test reflecting the encode and sustain constructs of Mirsky et al. (1991). Age × Severity interaction effects were found for speeded perceptual-motor tests; scores were reduced following mild-moderate and severe TBI in younger children and following severe TBI in older patients. Results are discussed in terms of the vulnerability of skills in a rapid stage of development to disruption by acquired brain injury.     

Prospective memory in young and older adults: the effects of ongoing-task load

Prospective memory involves remembering to perform intended actions in the future. Previous work with the multinomial model of event-based prospective memory indicated that adult age-related differences in prospective-memory performance were due to the prospective (not the retrospective) component of the task (Smith & Bayen, 2006 , Journal of Experimental Psychology: Learning, Memory, and Cognition, 32, 623). However, ongoing-task performance was also lower in older adults in that study. In the current study with young and older adults, the difficulty of the ongoing task was manipulated by varying the number of colors per trial to create easier and harder versions of the ongoing task for each age group. The easier version included 2 colors per trial for older adults and 4 colors for young adults. The harder version included 4 colors for older adults and 6 colors for young adults. By adjusting the ongoing-task difficulty, older adults were able to perform the ongoing task as well or better than the young adults. Analyses with the multinomial model revealed that making the ongoing task easier for older adults (or more difficult for young adults) did not eliminate age-related differences in prospective-memory performance and the underlying prospective component.     

Emerging narrative discourse skills 18 months after traumatic brain injury in early childhood

This study examined the longer term effect of traumatic brain injury (TBI), approximately 18 months post-injury, on emerging narrative discourse skills of 85 children with orthopaedic injury (OI), 43 children with moderate TBI, and 19 children with severe TBI who were between 3 years and 6 years 11 months at injury. Children with TBI performed worse than children with OI on most discourse indices. Children with severe TBI were less proficient than children with moderate TBI at identifying unimportant story information. Age and pragmatic skills were predictors of discourse performance.     

Impaired discourse gist and working memory in children after brain injury

Emerging evidence suggests that a traumatic brain injury (TBI) in childhood may disrupt the ability to abstract the central meaning or gist-based memory from connected language (discourse). The current study adopts a novel approach to elucidate the role of immediate and working memory processes in producing a cohesive and coherent gist-based text in the form of a summary in children with mild and severe TBI as compared to typically developing children, ages 8-14 years at test. Both TBI groups showed decreased performance on a summary production task as well as retrieval of specific content from a long narrative. Working memory on n-back tasks was also impaired in children with severe TBI, whereas immediate memory performance for recall of a simple word list in both TBI groups was comparable to controls. Interestingly, working memory, but not simple immediate memory for a word list, was significantly correlated with summarization ability and ability to recall discourse content.     

The rise and decline of prospective memory performance across the lifespan

In the present study, the trajectory of prospective memory across the lifespan was investigated in a total of 200 participants from five age groups (4- to 6-year-old children, 13- to 14-year-old adolescents, 19- to 26-year-old adults, 55- to 65-year-old adults, and 65- to 75-year-old adults). In an event-based prospective memory task the prospective and the retrospective components were assessed separately. For the prospective component, the results showed better performance for adolescents and young adults than for children and 65- to 75-year-old adults. In addition, participants belonging to the latter group were more likely to forget the retrospective component after having noticed the prospective memory targets. Overall, these results indicate that across the lifespan prospective memory performance follows a similar inverted u-shape function as is well known for retrospective episodic memory.     

The rise and decline of prospective memory performance across the lifespan

In the present study, the trajectory of prospective memory across the lifespan was investigated in a total of 200 participants from five age groups (4- to 6-year-old children, 13- to 14-year-old adolescents, 19- to 26-year-old adults, 55- to 65-year-old adults, and 65- to 75-year-old adults). In an event-based prospective memory task the prospective and the retrospective components were assessed separately. For the prospective component, the results showed better performance for adolescents and young adults than for children and 65- to 75-year-old adults. In addition, participants belonging to the latter group were more likely to forget the retrospective component after having noticed the prospective memory targets. Overall, these results indicate that across the lifespan prospective memory performance follows a similar inverted u-shape function as is well known for retrospective episodic memory.     

Prevalence and Correlates of Depressive Symptoms Following Traumatic Brain Injuries in Children

The prevalence and correlates of depressive symptoms following childhood traumatic brain injuries (TBI) were examined using data drawn from a prospective longitudinal study. Participants included 38 children with severe TBI, 51 with moderate TBI, and 55 with orthopedic injuries (OI). Assessments occurred shortly after injury (baseline) and at 6- and 12-month follow-ups. Children completed the Child Depression Inventory (CDI). Parents rated depressive symptoms using the Child Behavior Checklist (CBC), with baseline ratings reflecting premorbid status. Assessments also included measures of children's neurocognitive functioning and the family environment. The three groups did not differ overall in self-reported symptoms on the CDI, but did display different trends over time. The three groups did not differ on parent ratings of premorbid depressive symptoms on the CBC, but parents reported more depressive symptoms in the TBI groups than in the OI group at 6- and 12-month follow-ups. Child and parent reports were correlated for children in the TBI groups, but not for those in the OI group. Depressive symptoms were related to socioeconomic status in all groups. Socioeconomic status also was a significant moderator of group differences, such that the effects of TBI were exacerbated in children from more disadvantaged homes. Although self-reports of depressive symptoms were related inconsistently to children's verbal memory, parent reports of depressive symptoms were unrelated to IQ or verbal memory. The findings suggest that TBI increases the risk of depressive symptoms, especially among more socially disadvantaged children, and that depressive symptoms are not strongly related to post-injury neurocognitive deficits.     

The development of prospective memory in young schoolchildren: The impact of ongoing task absorption,cue salience,and cue centrality

This study presents evidence that 9- and 10-year-old children outperform 6- and 7-year-old children on a measure of event-based prospective memory and that retrieval-based factors systematically influence performance and age differences. All experiments revealed significant age effects in prospective memory even after controlling for ongoing task performance. In addition, the provision of a less absorbing ongoing task (Experiment 1), higher cue salience (Experiment 2), and cues appearing in the center of attention (Experiment 3) were each associated with better performance. Of particular developmental importance was an age by cue centrality (in or outside of the center of attention) interaction that emerged in Experiment 3. Thus, age effects were restricted to prospective memory cues appearing outside of the center of attention, suggesting that the development of prospective memory across early school years may be modulated by whether a cue requires overt monitoring beyond the immediate attentional context. Because whether a cue is in or outside of the center of attention might determine the amount of executive control needed in a prospective memory task, findings suggest that developing executive control resources may drive prospective memory development across primary school age.     

轻度阿尔茨海默症患者的前瞻记忆

轻度阿尔茨海默症往往伴随着不同程度的前瞻记忆衰退。已有研究以轻度阿尔茨海默症与前瞻记忆衰退的关联程度为主线, 对比了这一关联与“其他认知缺陷疾病-前瞻记忆衰退”、“轻度阿尔茨海默症-回溯记忆衰退”以及“轻度阿尔茨海默症-遗传表达”这三种关联的类似程度。此外, 也有研究涉及到了如何促进轻度阿尔茨海默症患者的前瞻记忆。将来的研究应引入病情程度、前瞻记忆任务类型等变量, 深入探讨轻度阿尔茨海默症与前瞻记忆衰退的关联, 并使用ERP、fMRI等神经生理技术确定轻度阿尔茨海默症患者前瞻记忆衰退的机制。     

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.     

The effects of ongoing task absorption on event-based prospective memory in preschoolers

The current study applied a 2 × 2 experimental design to investigate the effects of ongoing task absorption on event-based prospective memory performance of children aged 3 and 5 years. Children were required to label pictures as ongoing task but to remember to refrain from picture naming and to respond to the target cues in a different way as the prospective memory task. Two differently absorbing ongoing tasks (high absorbing scenario game task vs. low absorbing computer-based task) were administered. Results indicated that prospective memory performance of 5-year-old children was significantly better than that of 3-year-old children. Ongoing task absorption affected the ongoing task performance of preschoolers, but not overall prospective memory performance. Only the 3-year-olds were negatively affected by high ongoing task absorption, which was not the case for the 5-year-olds. The findings are discussed within the light of the multiprocess theory.     

Prospective memory performance in preschoolers: Inhibitory control matters

The present study focuses on prospective memory in preschoolers. We specifically investigated the effects of age, retrospective memory, and task interruption on prospective memory performance. In the first experiment, testing 60 children aged 3, 4 and 5 years with a prospective memory task that required active ongoing task interruption we obtained an age effect indicating better prospective memory performance for the two older cohorts. Varying retrospective memory load did influence prospective memory response time but did not affect prospective memory accuracy. However, retrospective memory performance showed an age effect and individual differences in retrospective memory ability were related to individual differences in prospective memory performance, even after partialling age. In the second study, we applied a prospective memory task that did not require active ongoing task interruption. Here, testing 62 children aged 3, 4 and 5 years we still found an age effect in retrospective memory but neither an effect of age nor retrospective memory on prospective memory performance. It is concluded that preschoolers even at the age of 3 years can perform prospective memory tasks to a certain extent. Moreover, while retrospective memory still seems to be somewhat related to prospective memory in preschoolers, inhibitory control required for ongoing task interruption seems to be an especially important factor influencing task performance in preschoolers.