A LORETA study of mental time travel: Similar and distinct electrophysiological correlates of re-experiencing past events and pre-experiencing future events

Previous studies exploring mental time travel paradigms with functional neuroimaging techniques have uncovered both common and distinct neural correlates of re-experiencing past events or pre-experiencing future events. A gap in the mental time travel literature exists, as paradigms have not explored the affective component of re-experiencing past episodic events; this study explored this sparsely researched area. The present study employed standardized low resolution electromagnetic tomography (sLORETA) to identify electrophysiological correlates of re-experience affect-laden and non-affective past events, as well as pre-experiencing a future anticipated event. Our results confirm previous research and are also novel in that we illustrate common and distinct electrophysiological correlates of re-experiencing affective episodic events. Furthermore, research from this experiment yields results outlining a pattern of activation in the frontal and temporal regions is correlated with the time frame of past or future events subjects imagined.     

Mental time travel for self and other in three- and four-year-old children

Humans possess the unique ability to mentally travel backward in time to re-experience past events (i.e., episodic memory) and forward in time to pre-experience future events (i.e., episodic foresight). Although originally viewed as different cognitive skills, they are now both viewed as components of the episodic memory system. Recently, it has been suggested that the episodic system may allow us to not only pre-experience and predict our own future but also that of another person. In the current study, we investigate this possibility by examining the ability of three- and four-year-old children to plan for their own future and for that of another person. We found that both three- and four-year-old children performed equally, when planning for their own future or when planning for the experimenter's future. These data are consistent with the finding that planning for someone else's future recruits the same neural structures that are used when planning for one's own future.     

心理时间旅行的动力机制：自我的作用

选取120名大学生,通过两个研究考察了自我在心理时间旅行中的动力机制。研究1以核心自我评价为评估自我概念的指标,发现自尊和一般自我效能对指向未来的心理时间旅行具有一定的预测效力。研究2通过启动使不同类型的自我概念在意识中占优,发现互倚组比独立组报告出更多具体的事件,且更关注他人和关系。研究表明,自我概念能够引导个体对过去和未来事件的建构。     

Episodic memory and episodic foresight in 3- and 5-year-old children

In the present study, we examined the development of episodic memory and episodic foresight. Three- and 5-year-olds were interviewed individually using a personalised timeline that included photographs of them at different points in their life. After constructing the timeline with the experimenter, each child was asked to discuss a number of different events: an event that happened yesterday, an event that happened earlier today, an event that would happen later today, and an event that would happen tomorrow. As judged by their parents, children's accounts were highly accurate. After controlling for age and language scores, there was a strong relation between amount of information reported about past and future events. Overall, 5-year-olds reported more total information than 3-year-olds; however, reports by 3-year-olds included a similar proportion of first-person reference as did reports by 5-year-olds. No age difference appeared in proportion of future-oriented talk. We conclude that the present task provides a promising method of exploring the emergence of mental time travel during early childhood.     

Constructing autobiographical events within a spatial or temporal context: a comparison of two targeted episodic induction techniques

ABSTRACT

Recalling and imagining autobiographical experiences involves constructing event representations within spatiotemporal contexts. We tested whether generating autobiographical events within a primarily spatial (where the event occurred) or temporal (the sequence of actions that occurred) context affected how the associated mental representation was constructed. We leveraged the well-validated episodic specificity induction (ESI) technique, known to influence the use of episodic processes on subsequent tasks, to develop variants that selectively enhance spatial or temporal processing. We tested the effects of these inductions on the details used to describe past and future autobiographical events. We first replicated the standard ESI effect, showing that ESI enhances generating episodic details, particularly those that are perception-based, when describing autobiographical events (Experiment 1). We then directly compared the effects of the spatial and temporal inductions (Experiment 2 and 3). When describing autobiographical events, spatial induction enhanced generating episodic details, specifically perception-based details, compared to the control or temporal inductions. A greater proportion of the episodic details generated after the temporal induction were gist-based than after the spatial induction, but this proportion did not differ from a control induction. Thus, using a spatial or temporal framework for autobiographical event generation alters the associated details that are accessed.     

Coding of stimuli by animals: Retrospection, prospection, episodic memory and future planning

When animals code stimuli for later retrieval they can either code them in terms of the stimulus presented (as a retrospective memory) or in terms of the response or outcome anticipated (as a prospective memory). Although retrospective memory is typically assumed (as in the form of a memory trace), evidence of prospective coding has been found when response intentions and outcomes are particularly salient. At a more abstract level is the question of whether animals are able figuratively to travel back in time to recover memories of past events (episodic memory) and forward in time to predict future events (future planning). Although what would constitute adequate evidence of episodic memory and future planning is controversial, preliminary evidence suggests that animals may be capable of both forms of subjective time travel.     

Emotion matters: The influence of valence on episodic future thinking in young and older adults

In young adults, valence not only alters the degree to which future events are imagined in rich episodic detail, but also how memorable these events are later on. For older adults, how valence influences episodic detail generation while imagining future events, or recalling these details at another time, remains unclear. We investigated the effect of valence on the specificity and memorability of episodic future thinking (EFT) in young and older adults. Among young and older adults, negative EFT was accompanied by less episodic detail generation relative to positive and neutral EFT. A similar reduction in episodic specificity for negative EFT was found two days later when participants recalled their previously imagined events. Notably, while older adults generated less episodically specific future thoughts relative to young adults, age did not influence the effect of valence on episodic detail generation at imagination or recollection.     

"When did I learn and when shall I act?": The developmental relationship between episodic future thinking and memory

This study investigated the development of the ability to reflect on one’s personal past and future. A total of 64 4- to 6-year-olds received tasks of delayed self-recognition, source memory, delay of gratification, and a newly developed task of future-oriented action timing. Although children’s performance on delayed self-recognition, source memory, and action timing improved with age, their performance on delay of gratification did not. Children’s errors in source memory and action timing were solely and strongly associated with each other in older children (5–6 years) even after controlling for age and verbal ability. Results are discussed in terms of mental time travel underlying episodic memory and future thinking that includes both the projection of oneself into the past and future and the appreciation of events’ temporal relations.     

Exploring the Use of Experience Sampling to Assess Episodic Thought

Mental time travel is the ability to mentally relive events in one's own past (episodic recall) and pre‐live potential personal future events (episodic foresight). Recent research has used experience sampling to reveal when and how often we think about the past and future in everyday life; however, it remains unclear how much of thought is episodic, involving the sense of self that underpins mental time travel. In this study, we investigate the use of experience sampling to assess the frequency of episodic past and future thought in everyday life. Participants (n = 214) were exposed to 20 short message service prompts over 1 or 2 days. Half of thoughts were sited in the present; of the remainder, future‐oriented thoughts were more frequent than past‐oriented thoughts. Participants reported 20% of thoughts as episodic. This study suggests that experience sampling methodology can provide a means of assessing episodic thought during everyday activities.Copyright © 2016 John Wiley & Sons, Ltd.     

Episodic future thought: Contributions from working memory

The ability to imagine hypothetical events in one’s personal future is thought to involve a number of constituent cognitive processes. We investigated the extent to which individual differences in working memory capacity contribute to facets of episodic future thought. College students completed simple and complex measures of working memory and were cued to recall autobiographical memories and imagine future autobiographical events consisting of varying levels of specificity (i.e., ranging from generic to increasingly specific and detailed events). Consistent with previous findings, future thought was related to analogous measures of autobiographical memory, likely reflecting overlapping cognitive factors supporting both past and future thought. Additionally, after controlling for autobiographical memory, residual working memory variance independently predicted future episodic specificity. We suggest that when imagining future events, working memory contributes to the construction of a single, coherent, future event depiction, but not to the retrieval or elaboration of event details.     

Priming,not inhibition,of related concepts during future imagining

Remembering the past and imagining the future both involve the retrieval of details stored in episodic memory and rely on the same core network of brain regions. Given these parallels, one might expect similar component processes to be involved in remembering and imagining. While a strong case can be made for the role of inhibition in memory retrieval, few studies have examined whether inhibition is also necessary for future imagining and results to-date have been mixed. In the current study, we test whether related concepts are inhibited during future imagining using a modified priming approach. Participants first generated a list of familiar places and for each place, the people they most strongly associate with it. A week later, participants imagined future events involving recombinations of people and places, immediately followed by a speeded response task in which participants made familiarity decisions about people’s names. Across two experiments, our results suggest that related concepts are not inhibited during future imagining, but rather are automatically primed. These results fit with recent work showing that autobiographically significant concepts (e.g., friends’ names) are more episodic than semantic in nature, automatically activating related details in memory and potentially fuelling the flexible simulation of future events.     

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.     

Evidence that an episodic mode of thinking facilitates encoding of perceptually rich memories for naturalistic events relative to a gist-based mode of thinking

ABSTRACT

Several studies have demonstrated that an episodic specificity induction (ESI) can influence cognitive abilities that involve episodic processes at retrieval. To better understand the downstream implications of an “episodic mode of thinking,” we investigate whether an ESI influences encoding of new events. In a between-subjects design, participants were given an ESI or gist (control) induction. In an ostensibly unrelated task, participants then were shown film clips of naturalistic events. After a filled delay, participants were given a surprise memory test, which required narrative recollection of the film clips. Participants who received the ESI generated narratives that contained more perceptual details specifically. Relative to gist thinking, an episodic mode of thinking appears to facilitate encoding of perceptually rich memories for naturalistic events.     

The role of personal goals in autonoetic experience when imagining future events

Although autonoetic experience—a sense of mental time travel—has been considered as the hallmark of episodic future thinking, what determines this subjective feeling is not yet fully understood. Here, we investigated the role of autobiographical knowledge by manipulating the relevance of imagined events for personal goals. Participants were asked to imagine three types of events (goal-related future events, experimenter-provided future events, and atemporal events) and to assess various characteristics of their mental representations. The results showed that the three types of events were represented with similar levels of detail and vividness. Importantly, however, goal-related future events were associated with a stronger autonoetic experience. Furthermore, autonoetic experience was significantly predicted by the importance of imagined events for personal goals. These findings suggest that the subjective feeling of pre-experiencing one’s personal future in part depends on the extent to which imagined events can be placed in an autobiographical context.     

Imagining novel futures: The roles of event plausibility and familiarity

The constructive episodic simulation hypothesis suggests that episodic memory supports the simulation of future events through extraction and recombination of stored information. The current study explicitly investigated the use of past episodic thought in the simulation of future scenarios. Participants simulated one of three possible scenarios, differing in plausibility and participants’ prior experience of similar events. Participants recorded related memories and whether they were explicitly used during future event simulation. Memories were rated for source (self-experienced, other-experienced, or media). Findings suggest prior experience and event plausibility did not impact upon ease of future event simulation or the extent of memory usage during simulations. Differences emerged in the source of information used to assist future event simulation. These findings provide support for the hypothesis that episodic memories from a variety of sources are recombined when generating future simulations of novel events.     

Mental time travel into the episodic future,episodic past,and episodic counterfactual past in everyday life

To date, studies exploring the relationship of counterfactual thoughts with episodic memories and episodic future thoughts have focused mainly on voluntary mental time travel. We explore mental time travel in everyday life and find that episodic counterfactual thinking occurs to a much lesser extent than thinking about the past or the future (12%, 22%, and 54%, respectively), is used mainly for mood regulation purposes, and the temporal distribution decreases as a function of time. We observe similarities in phenomenological detail: memories and counterfactual thoughts sharing similar ratings of sensory detail, memories and future thoughts sharing similar ratings of positivity, and counterfactual and future thoughts sharing similar ratings of mental time travel. We discuss the implications of episodic counterfactual thinking in everyday life.     

Prevalence and determinants of direct and generative modes of production of episodic future thoughts in the word cueing paradigm

Recent research suggests that episodic future thoughts can be formed through the same dual mechanisms, direct and generative, as autobiographical memories. However, the prevalence and determinants of the direct production of future event representations remain unclear. Here, we addressed this issue by collecting self-reports of production modes, response times (RTs), and verbal protocols for the production past and future events in the word cueing paradigm. Across three experiments, we found that both past and future events were frequently reported to come directly to mind in response to the cue, and RTs confirmed that events were produced faster for direct than for generative responses. When looking at the determinants of direct responses, we found that most past and future events that were directly produced had already been thought of on a previous occasion, and the frequency of previous thoughts predicted the occurrence of direct access. The direct production of autobiographical thoughts was also more frequent for past and future events that were judged important and emotionally intense. Collectively, these findings provide novel evidence that the direct production of episodic future thoughts is frequent in the word cueing paradigm and often involves the activation of personally significant “memories of the future.”