Mental time travel: Effects of trial duration on episodic and semantic content

Studies exploring mental time travel commonly use cue-word paradigms to elicit past and future autobiographical events. However, the effect of trial duration (how long participants are allowed to describe events) on the relationship between episodic and nonepisodic detail and episodic specificity (i.e., whether longer durations increase event specificity) has not been examined. To resolve these issues, a cue-word study was devised whereby participants described past and future events under three randomly administered time constraints: short (1-min), standard (3-min), and long (5-min) durations. Findings indicated that an individual's capacity for episodic and nonepisodic thought for the past and future were unrelated. This lends supports to the idea that independent mechanisms are responsible for episodic and semantic information. This study also offers clarity concerning the effect of different trial durations on episodic specificity, which may aid the design of future studies of mental time travel.     

Cognitive approaches to the study of episodic future thinking

The concept of episodic future thinking—the ability to simulate events that may take place in the personal future—has given rise to an exponentially growing field of research that spans a variety of sub-disciplines within psychology and neuroscience. In this introduction to the special issue, we provide a brief historical overview of factors that have shaped research on the topic and highlight the need for additional behavioural work to uncover cognitive mechanisms that support episodic future thinking and differentiate it from other related modes of future-oriented cognition. We conclude by discussing the manner in which the various contributions to the special issue fill the gaps in our knowledge and make some of our own suggestions for future work.     

Procrastination,consideration of future consequences,and episodic future thinking

Despite the intrinsic temporal nature of procrastination, little research has examined the link between this form of self-regulatory failure and the consideration of future consequences, and no study has addressed the link between procrastination and episodic future thinking. The aim of the present study was to explore these relationships. Participants were asked to project themselves into possible future events and to rate the amount of sensory-perceptual details and autonoetic consciousness associated with their representations. They were also asked to complete questionnaires that assessed procrastination, the consideration of future consequences, and negative affect. Results showed that both the consideration of future consequences and episodic future thinking were associated with procrastination, and in particular with procrastination-related decision making abilities and procrastination-related motivational dispositions, respectively.     

The organization of prospective thinking: Evidence of event clusters in freely generated future thoughts

Recent research suggests that many imagined future events are not represented in isolation, but instead are embedded in broader event sequences—referred to as event clusters. It remains unclear, however, whether the production of event clusters reflects the underlying organizational structure of prospective thinking or whether it is an artifact of the event-cuing task in which participants are explicitly required to provide chains of associated future events. To address this issue, the present study examined whether the occurrence of event clusters in prospective thought is apparent when people are left to think freely about events that might happen in their personal future. The results showed that the succession of events participants spontaneously produced when envisioning their future frequently included event clusters. This finding provides more compelling evidence that prospective thinking involves higher-order autobiographical knowledge structures that organize imagined events in coherent themes and sequences.     

Autonoetic consciousness: Reconsidering the role of episodic memory in future-oriented self-projection

Following the seminal work of Ingvar (1985. “Memory for the future”: An essay on the temporal organization of conscious awareness. Human Neurobiology, 4, 127–136), Suddendorf (1994. The discovery of the fourth dimension: Mental time travel and human evolution. Master's thesis. University of Waikato, Hamilton, New Zealand), and Tulving (1985. Memory and consciousness. Canadian Psychology/PsychologieCanadienne, 26, 1–12), exploration of the ability to anticipate and prepare for future contingencies that cannot be known with certainty has grown into a thriving research enterprise. A fundamental tenet of this line of inquiry is that future-oriented mental time travel, in most of its presentations, is underwritten by a property or an extension of episodic recollection. However, a careful conceptual analysis of exactly how episodic memory functions in this capacity has yet to be undertaken. In this paper I conduct such an analysis. Based on conceptual, phenomenological, and empirical considerations, I conclude that the autonoetic component of episodic memory, not episodic memory per se, is the causally determinative factor enabling an individual to project him or herself into a personal future.     

Back to the future: autobiographical planning and the functionality of mind-wandering

Given that as much as half of human thought arises in a stimulus independent fashion, it would seem unlikely that such thoughts would play no functional role in our lives. However, evidence linking the mind-wandering state to performance decrement has led to the notion that mind-wandering primarily represents a form of cognitive failure. Based on previous work showing a prospective bias to mind-wandering, the current study explores the hypothesis that one potential function of spontaneous thought is to plan and anticipate personally relevant future goals, a process referred to as autobiographical planning. The results confirm that the content of mind-wandering is predominantly future-focused, demonstrate that individuals with high working memory capacity are more likely to engage in prospective mind-wandering, and show that prospective mind-wandering frequently involves autobiographical planning. Together this evidence suggests that mind-wandering can enable prospective cognitive operations that are likely to be useful to the individual as they navigate through their daily lives.     

Visual perspective in remembering and episodic future thought

According to the constructive episodic simulation hypothesis, remembering and episodic future thinking are supported by a common set of constructive processes. In the present study, we directly addressed this assertion in the context of third-person perspectives that arise during remembering and episodic future thought. Specifically, we examined the frequency with which participants remembered past events or imagined future events from third-person perspectives. We also examined the different viewpoints from which third-person perspective events were remembered or imagined. Although future events were somewhat more likely to be imagined from a third-person perspective, the spatial viewpoint distributions of third-person perspectives characterizing remembered and imagined events were highly similar. These results suggest that a similar constructive mechanism may be at work when people remember events from a perspective that could not have been experienced in the past and when they imagine events from a perspective that could not be experienced in the future. The findings are discussed in terms of their consistency with—and as extensions of—the constructive episodic simulation hypothesis.     

Patients with bipolar disorder show a selective deficit in the episodic simulation of future events

A substantial body of evidence suggests that autobiographical recollection and simulation of future happenings activate a shared neural network. Many of the neural regions implicated in this network are affected in patients with bipolar disorder (BD), showing altered metabolic functioning and/or structural volume abnormalities. Studies of autobiographical recall in BD reveal overgeneralization, where autobiographical memory comprises primarily factual or repeated information as opposed to details specific in time and in place and definitive of re-experiencing. To date, no study has examined whether these deficits extend to future event simulation. We examined the ability of patients with BD and controls to imagine positive, negative and neutral future events using a modified version of the Autobiographical Interview (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002) that allowed for separation of episodic and non-episodic details. Patients were selectively impaired in imagining future positive, negative, and neutral episodic details; simulation of non-episodic details was equivalent across groups.     

Making the future memorable: The phenomenology of remembered future events

Although our ability to remember future simulations conveys an adaptive advantage, enabling us to better prepare for upcoming events, the factors influencing the memorability of future simulations are not clear. In this study, participants generated future simulations that combined specific people, places and objects from memory, and for each trial, made a series of phenomenological ratings about the event components and the simulation as a whole. Memory for simulations was later assessed using a cued-recall test. We used multilevel modelling to determine whether the phenomenological qualities of event components (familiarity, emotionality and significance) and simulations (detail, plausibility) were predictive of whether the simulation was successfully encoded and later accessible. Our results demonstrate that person familiarity, detail and plausibility were significant predictors of whether a given future simulation was encoded into memory and later accessible. These findings suggest that scaffolding future simulations with pre-existing episodic memories is the path to a memorable future.     

Characterizing the subjective experience of episodic past,future, and counterfactual thinking in healthy younger and older adults

Recent evidence demonstrates remarkable overlap in the neural and cognitive mechanisms underlying episodic memory, episodic future thinking, and episodic counterfactual thinking. However, the extent to which the phenomenological characteristics associated with these mental simulations change as a result of ageing remains largely unexplored. The current study employs adapted versions of the Memory Characteristics Questionnaire and the Autobiographical Interview to compare the phenomenological characteristics associated with both positive and negative episodic past, future, and counterfactual simulations in younger and older adults. Additionally, it explores the influence of perceived likelihood in the experience of such simulations. The results indicate that, across all simulations, older adults generate more external details and report higher ratings of vividness, composition, and intensity than young adults. Conversely, younger adults generate more internal details across all conditions and rated positive and negative likely future events as more likely than did older adults. Additionally, both younger and older adults reported higher ratings for sensory, composition, and intensity factors during episodic memories relative to future and counterfactual thoughts. Finally, for both groups, ratings of spatial coherence and composition were higher for likely counterfactuals than for both unlikely counterfactuals and future simulations. Implications for the psychology of mental simulation and ageing are discussed.     

Exploring the experience of episodic past,future, and counterfactual thinking in younger and older adults: A study of a Colombian sample

Although extant evidence suggests that many neural and cognitive mechanisms underlying episodic past, future, and counterfactual thinking overlap, recent results have uncovered differences among these three processes. However, the extent to which there may be age-related differences in the phenomenological characteristics associated with episodic past, future and counterfactual thinking remains unclear. This study used adapted versions of the Memory Characteristics Questionnaire and the Autobiographical Interview in younger and older adults to investigate the subjective experience of episodic past, future and counterfactual thinking. The results suggest that, across all conditions, younger adults generated more internal details than older adults. However, older adults generated more external details for episodic future and counterfactual thinking than younger adults. Additionally, younger and older adults generated more internal details, and gave higher sensory and contextual ratings, for memories rather than future and counterfactual thoughts. Methodological and theoretical consequences for extant theories of mental simulation are discussed.     

The relationship between prospective memory and episodic future thinking in younger and older adulthood

Episodic future thinking (EFT), the ability to project into the future to “preexperience” an event, and prospective memory (PM), remembering to perform an intended action, are both examples of future-oriented cognition. Recently it has been suggested that EFT might contribute to PM performance but to date few studies have examined the relationship between these two capacities. The aim of the present study was to investigate the nature and specificity of this relationship, as well as whether it varies with age. Participants were 125 younger and 125 older adults who completed measures of EFT and PM. Significant, positive correlations between EFT and PM were identified in both age groups. Furthermore, EFT ability accounted for significant unique variance in the young adults, suggesting that it may make a specific contribution to PM function. Within the older adult group, EFT did not uniquely contribute to PM, possibly indicating a reduced capacity to utilize EFT, or the use of compensatory strategies. This study is the first to provide systematic evidence for an association between variation in EFT and PM abilities in both younger and older adulthood and shows that the nature of this association varies as a function of age.     

Episodic future thinking: Linking neuropsychological performance with episodic detail in young and old adults

Episodic future thinking (EFT) has been linked with our ability to remember past events. However, its specific neurocognitive subprocesses have remained elusive. In Experiment 1, a study of healthy older adults was conducted to investigate the candidate subprocesses of EFT. Participants completed a standard EFT cue word task, two memory measures (Verbal Paired Associates I, Source Memory), and two measures of executive function (Trail Making Test, Tower Test). In Experiment 2, healthy young adults also completed an EFT task and neuropsychological measures. The link between neurocognitive measures and five characteristics of EFT was investigated. Specifically, it was found that Source Memory and Trail Making Test performance predicted the episodic specificity of future events in older but not younger adults. Replicating previous findings, older adults produced future events with greater semantic but fewer episodic details than did young adults. These results extend the data and emphasize the importance of the multiple subprocesses underlying EFT.     

Frequency,characteristics, and perceived functions of emotional future thinking in daily life

While many thoughts and mental images that people form about their personal future refer to emotionally significant events, there is still little empirical data on the frequency and nature of emotional future-oriented thoughts (EmoFTs) that occur in natural settings. In the present study, participants recorded EmoFTs occurring in daily life and rated their characteristics, emotional properties, and perceived functions. The results showed that EmoFTs are frequent, occur in various contexts, and are perceived to fulfil important functions, mostly related to goal pursuit and emotion regulation. When distinguishing between anticipatory and anticipated emotions (i.e., emotions experienced in the present versus emotions expected to occur in the future), a positivity bias in the frequency of EmoFTs was found to be restricted to anticipated emotions. The representational format and perceived function of EmoFTs varied according to their affective valence, and the intensity of anticipatory and anticipated emotions were influenced by the personal importance and amount of visual imagery of EmoFTs. Mood states preceding EmoFTs influenced their emotional components, which, in turn, impacted ensuing mood states. Overall, these findings shed further light on the emotional properties of future-oriented thoughts that are experienced in daily life.     

The influence of action on episodic memory: A virtual reality study

A range of empirical findings suggest that active learning is important for memory. However, few studies have focused on the mechanisms underlying this enactment effect in episodic memory using complex environments. Research using virtual reality has yielded inconsistent results. We postulated that the effect of action depends on the degree of interaction with the environment and freedom in the planning of an itinerary. To test these hypotheses, we disentangled the interaction and planning components of action to investigate whether each enhances factual and spatial memory. Seventy-two participants (36 male and 36 female) explored a virtual town in one of three experimental conditions: (a) a passive condition where participants were immersed as passenger of the car (no interaction, no planning); (b) a planning-only condition (the subject chose the itinerary but did not drive the car); (c) an interaction-only condition (the subject drove the car but the itinerary was fixed). We found that itinerary choice and motor control both enhanced spatial memory, while factual memory was impaired by online motor control. The role of action in memory is discussed.     

Working memory deficits in boys with attention deficit/hyperactivity disorder (ADHD): An examination of orthographic coding and episodic buffer processes

The episodic buffer component of working memory was examined in children with attention deficit/hyperactivity disorder (ADHD) and typically developing peers (TD). Thirty-two children (ADHD = 16, TD = 16) completed three versions of a phonological working memory task that varied with regard to stimulus presentation modality (auditory, visual, or dual auditory and visual), as well as a visuospatial task. Children with ADHD experienced the largest magnitude working memory deficits when phonological stimuli were presented via a unimodal, auditory format. Their performance improved during visual and dual modality conditions but remained significantly below the performance of children in the TD group. In contrast, the TD group did not exhibit performance differences between the auditory- and visual-phonological conditions but recalled significantly more stimuli during the dual-phonological condition. Furthermore, relative to TD children, children with ADHD recalled disproportionately fewer phonological stimuli as set sizes increased, regardless of presentation modality. Finally, an examination of working memory components indicated that the largest magnitude between-group difference was associated with the central executive. Collectively, these findings suggest that ADHD-related working memory deficits reflect a combination of impaired central executive and phonological storage/rehearsal processes, as well as an impaired ability to benefit from bound multimodal information processed by the episodic buffer.     

The effects of gender on the retrieval of episodic and semantic components of autobiographical memory

Despite consistent evidence that women exhibit greater episodic memory specificity than men, little attention has been paid to gender differences in the production of episodic details during autobiographical recall under conditions of high and low retrieval support. Similarly the role of gender on the production of semantic details used to support autobiographical memory recollections of specific events has been largely unexplored. In the present study an undergraduate sample of 50 men and 50 women were assessed using the Autobiographical Interview (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002). Women recalled more episodic information compared to men in the high retrieval support condition, whereas no gender differences were found in the low retrieval support condition. In addition, women produced more repetitions compared to men in the high retrieval support condition. No gender differences were found in the production of semantic details. These results are interpreted in terms of gender differences in encoding and reminiscence practices. This research adds to the literature on gender differences in memory recall and suggests that gender is an important variable in explaining individual differences in AM recall.