Time-based prospective memory in young children—Exploring executive functions as a developmental mechanism

The overall aim of the current thesis was to explore three key components of future-oriented thinking, namely episodic future thinking (EFT), episodic foresight, and prospective memory (PM), in middle childhood. The developmental literature examining each of these future-oriented abilities has generally focused on their emergence in the preschool years, with less known about how these abilities present in middle childhood. In addition, research investigating what cognitive mechanisms may drive these abilities in this age band is limited and findings of those studies that have been conducted are inconsistent. Lastly, the literature has predominantly examined EFT, episodic foresight, and PM in isolation, and research has only just begun to explore interrelations between these future-oriented constructs. The first empirical study therefore aimed to investigate whether EFT ability was associated with age and to examine what cognitive mechanisms may contribute to this skill. The second empirical study aimed to examine, for the first time, whether episodic foresight was associated with age across middle childhood. A second aim of this study was to provide the first investigation of the cognitive mechanisms that may contribute to episodic foresight in this age group, with the particular interest in whether EFT contributed to episodic foresight. The final empirical study aimed to explore whether age was associated with children’s PM performance across event-based and time-based PM tasks. An additional aim of this study was to explore the cognitive abilities that contribute to children’s performance on both event-based and time-based PM tasks, with a particular interest in the contribution of EFT. A single sample of 80 children aged 8 to 12 years were recruited for this research project. Study 1 indicated greater EFT ability was associated with age, consistent with some of the limited studies previously conducted with this age group. Study 1 also demonstrated strong evidence regarding the contribution from episodic memory to children’s EFT and a lack of contribution from executive functions. Study 2 was the first study to examine episodic foresight beyond the preschool years. Results of this study provided the first evidence of an association between age and better episodic foresight performance across the ages of 8 to 12 years. In addition, Study 2 identified age and IQ as significant contributors to successful episodic foresight performance, while retrospective memory, executive functions, and EFT were not found to contribute. The lack of contribution from EFT may have been due to the specific form of episodic foresight task used in this study, which did not require a specific scenario to be envisaged. Further research is now required to investigate whether EFT contributes to other types of episodic foresight task that involve clear scenarios that can be envisaged. The results of Study 3 indicated age was significantly correlated with performance on both event-based and time-based PM tasks. The findings also clearly revealed age, retrospective memory, and EFT were significant contributors to event-based PM performance, while retrospective memory was the only significant contributor to time-based PM performance. Furthermore, the results clearly demonstrated a lack of contribution from executive functions to performance on both task types. Importantly, Study 3 demonstrated that EFT selectively contributed to children’s event-based PM performance. This finding is consistent with the only other study in this age band and used a more comprehensive set of predictors than this previous study. The current research provided novel insights into the profile of children’s future-oriented thinking across the middle childhood period. The findings regarding age-related improvements in EFT, episodic foresight, and PM help to bridge the gap in understanding of the development of these abilities between their emergence in the preschool years and their presentation later in development. Longitudinal research that extends from early childhood to adulthood is now needed to provide a thorough understanding of the developmental trajectory of these abilities across the lifespan. In addition, the current research revealed a clear pattern of results regarding the cognitive mechanisms that contribute to each of these abilities, providing some clarity to the previously mixed findings in the children’s future oriented-thinking literature. Results regarding the inter-relationships between the future-oriented constructs also provided an important extension to current understanding of future-oriented thinking as a broader taxonomy. Furthermore, the current findings bring attention to the need for further theoretical distinction between different forms of episodic foresight and the cognitive processes that contribute to this skill. Overall, the findings from the current thesis have important implications for children’s daily living. In particular, greater understanding of future-oriented thinking in the middle childhood period gained from this thesis may assist in fostering the development of these abilities early in life. This in turn will enable parents and teachers to create reasonable expectations regarding children’s capacity to use these skills in their everyday functioning, thereby maximising success and minimising failure.

Frontal lobe involvement in a task of time-based prospective memory

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.

ABSTRACTTime-based prospective memory (PM) is the ability to remember to perform an intended action at a given time in the future. It is a competence that is crucial for effective performance in everyday life and may be one of the main causes of problems for individuals who have difficulty in planning and organizing their life, such as children with attention deficit/hyperactivity disorder (ADHD). This study systematically examines different aspects of time-based PM performance in a task that involves taking an action at a given future time in a group of 23 children with ADHD who were compared with a matched group of typically-developing (TD) children. The children were asked to watch a cartoon and then answer a questionnaire about its content (ongoing task). They were also asked to press a key every 2 minutes while watching the cartoon (PM task). The relationships of time perception and verbal working memory with PM performance were examined by administering appropriate tasks. The results showed that the children with ADHD were less accurate than the TD children in the PM task and exhibited less strategic time-monitoring behavior. Time perception was found to predict PM accuracy, whereas working memory was mainly involved in time-monitoring behavior, but this applied more to the TD group than to the ADHD group, suggesting that children with ADHD are less able to use their cognitive resources when meeting a PM request.

Prospective Memory (PM) refers to remembering an intention to be acted upon in the future. Such a memory may be triggered by an event (i.e., Event-based PM) where a specific cue reminds one of the previously encoded intention. PM can be assessed in a lab-setting by having subjects learn a baseline task, subsequently receiving a PM instruction, completing a distractor task, and then going through a test phase where the PM task (i.e., responding to PM cues) is embedded within the ongoing task. The multiprocess view (McDaniel & Einstein, 2000) posits that PM can be retrieved primarily using two different strategies: one can strategically monitor for the PM cue to keep the intention in mind or spontaneously retrieve the intention by coming across the cue. The multiprocess view suggests that monitoring or spontaneous retrieval strategies are chosen based on whether one’s current task is focal or non-focal to the nature of the PM task. When processing of the ongoing task stimuli and PM stimuli overlap (i.e., focal), spontaneous retrieval of the encoded intention is thought to occur more often. On the other hand, when processing of the PM stimuli is peripheral (i.e., non-focal) to the ongoing task, one may have to consistently monitor for the PM cue for successful task performance. Manipulation of PM task focality has shown a PM performance advantage in focal conditions (Einstein & McDaniel, 2005), confirming the focality effect posited by the Multiprocess view. Past studies (e.g., Schnitzspahn, Stahl, Zeintl, Kaller, & Kliegel, 2013) have suggested that some aspects of executive function (EF) are involved in non-focal PM performance. However, according to the multiprocess view, spontaneous retrieval of the PM cue can occur when the ongoing task is focal to the PM task. Because subjects may not need to appropriate as many cognitive resources toward the PM task, EF might be unrelated to PM performance in focal tasks. The current study tested this idea by examining a sample of college-aged subjects on two event-based PM (category and syllable judgments) and two EF (inhibition and task-switching) tasks. Subjects were assigned to focal or non-focal conditions for the PM tasks. The prediction of a focal condition advantage was found for PM performance measures, particularly in the syllables task. No relationships were found between PM performance and EF measures for the focal condition, as predicted. However, most of the predicted relationships between PM performance and EF measures for the

Whilst the deleterious effects of alcohol on retrospective remembering have been widely documented, no study has yet objectively determined alcohol's effects on prospective memory (PM)--remembering to do something in the future. With this aim, the present study determined the acute effects of alcohol upon PM using a laboratory measure that simulates the PM tasks in everyday life--'Virtual Week'--both (a) in its standard form with regular, irregular, event-based and time-based PM tasks; and (b) an adapted version which enabled exploration of how future event simulation at encoding impacted upon subsequent PM. Forty healthy volunteers were administered 0.6 g/kg ethanol or a matched placebo in a double-blind fashion and completed the two versions of Virtual Week along with prose recall (to tap retrospective memory) and an executive function task. Alcohol acutely produced global impairments across all (regular, irregular, event-based and time-based) PM tasks. It also produced impairments of episodic memory which positively correlated with PM performance of irregular tasks. Future-event simulation tended to enhance PM in the placebo but not in the alcohol group. These findings on an objective measure of PM suggest that 4-5 units of alcohol will compromise PM abilities in everyday life.

The aim of the present study was to deepen knowledge about the effect of a lowered vigilance state on time-based prospective memory (TBPM) performance. For this purpose 2 TBPM tasks (primary and interpolated), which shared a portion of the retention interval, and 3 reasoning tasks, as ongoing activities, were administered after total sleep deprivation and in a regular sleep condition. The results showed a detrimental effect of sleep deprivation on prospective memory performance and a partial dissociation between clock-checking behavior and time estimation for prospective compliance. This study clearly indicates that total sleep deprivation im- pairs the ability to complete multiple prospective task assignments in a timely fashion. Results are discussed suggesting the existence of different mechanisms involved in time monitoring and other cognitive functions underlying TBPM performance.

Cognitive correlates of prospective memory in dystonia

ObjectiveTime-based prospective memory (PM), remembering to do something at a particular moment in the future, is considered to depend upon self-initiated strategic monitoring, involving a retrieval mode (sustained maintenance of the intention) plus target checking (intermittent time checks). The present experiment was designed to explore what brain regions and brain activity are associated with these components of strategic monitoring in time-based PM tasks.Method24 participants were asked to reset a clock every four minutes, while performing a foreground ongoing word categorisation task. EEG activity was recorded and data were decomposed into source-resolved activity using Independent Component Analysis. Common brain regions across participants, associated with retrieval mode and target checking, were found using Measure Projection Analysis.ResultsParticipants decreased their performance on the ongoing task when concurrently performed with the time-based PM task, reflecting an active retrieval mode that relied on withdrawal of limited resources from the ongoing task. Brain activity, with its source in or near the anterior cingulate cortex (ACC), showed changes associated with an active retrieval mode including greater negative ERP deflections, decreased theta synchronization, and increased alpha suppression for events locked to the ongoing task while maintaining a time-based intention. Activity in the ACC was also associated with time-checks and found consistently across participants; however, we did not find an association with time perception processing per se.ConclusionThe involvement of the ACC in both aspects of time-based PM monitoring may be related to different functions that have been attributed to it: strategic control of attention during the retrieval mode (distributing attentional resources between the ongoing task and the time-based task) and anticipatory/decision making processing associated with clock-checks.

Enhancing cue salience improves aspects of naturalistic time-based prospective memory in older adults with HIV disease.

Prospective memory (PM) impairment in recreational drug users has been documented in recent years. However, most studies on the effects of drugs on PM contain several methodological challenges, such as small sample size (< 100 participants), unrepresentative sample type (e.g., student or patient), short abstinence period (< 7days), and lack of control of potential confounds (e.g., sleep and IQ). The present study investigated the possible consequences of recreational drug use on prospective memory, using self-report and lab-based prospective memory measures while overcoming the methodological challenges. The sample was composed of 47 non-users (27 females, age range from 18 to 50 +) and 53 drug users (21 females, age range from 18 to 50 +). Recreational drug users reported significantly more deficits in the long-term episodic, short-term habitual, and internally cued PM failures subscales of the Prospective Memory Questionnaire. However, these deficits were eliminated after controlling for covariates (e.g., age, sleep quality, general health, alcohol usage). Recreational drug users also performed worse than non-users in the short-term, long-term, event-based, and time-based PM subscales of the Royal Prince Alfred Prospective Memory Test. These results remained significant after controlling for the covariates. Drug users demonstrated greater impairments on time-based and long-term PM tasks thought to be linked with executive functioning. Taken together, the present study provides further support for recreational drug-related deficits in PM and highlights a dissociation between self-report and lab-based PM measures.

Objective: Prospective memory (PM) is the ability to remember to carry out an intended action. Working memory is the ability to store information in mind while processing potentially distracting information. The few previous studies of PM in autism spectrum disorder (ASD) have yielded inconsistent findings. Studies of working memory ability in ASD have suggested a selective impairment of “visual working memory.” However, it remains unclear whether any such impairment is the result of diminished (domain-specific; visual/verbal) storage capacity or diminished (domain-general) processing capacity. We aim to clarify these issues and explore the relation between PM and working memory in ASD. Method: Seventeen adults with ASD and 17 age- and IQ-matched comparison participants completed experimental measures of both event-based (perform action x when event y occurs) and time-based (perform action a at time b) PM, plus a self-report measure of PM skills. Participants also completed a working memory test battery. Results: Participants with ASD self-reported diminished PM skill, and showed diminished performance on the time-based, but not event-based, PM task. On the working memory test battery, visual but not verbal storage capacity was diminished among participants with ASD, as was processing ability. Whereas visual storage was associated with event-based PM task performance among comparison participants, verbal storage was associated among ASD participants. Conclusions: ASD appears to involve a selective deficit in time-based PM and a selective difficulty with aspects of working memory that depend on the storage of visual information. However, event-based PM may be achieved through compensatory strategies in ASD.

ABSTRACTWe 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.

Time-based prospective memory in children and adolescents with traumatic brain injury: Impact of working memory demands.

This study investigated the effects of emotional valence on prospective memory (PM) performance in individuals with traumatic brain injury (TBI) compared to healthy controls. Using an emotional version of the Virtual Week paradigm, we examined how positive, negative, and neutral emotional content influenced both event-based and time-based PM tasks. Thirty-one participants with TBI and 31 matched healthy controls completed the computerised PM measure over three simulated days, and a recognition task to assess the retrospective component of PM. Participants with TBI performed less accurately than controls across all conditions. For event-based tasks, positive emotional content enhanced PM performance in both groups. Time-based tasks showed a different pattern, with neutral content leading to better performance. Analysis of the retrospective component revealed a significant group by valence interaction: participants with TBI showed enhanced recognition of negative stimuli in time-based tasks, while healthy controls maintained high recognition accuracy across all valence conditions. These findings suggest a complex interaction between emotional valence, task type, and PM components in TBI, with implications for cognitive rehabilitation strategies.