Remembering the past and thinking about the future: Is it really about time?

In this paper we discuss some literature relating to episodic memory, future episodic thinking and mental time travel in humans and non-human animals. We discuss the concept of mental time travel and argue that the concept relies on subjective phenomena such as consciousness and on this basis is not useful when studying episodic memory and future episodic thinking, particularly in non-human animals. We discuss recent work which emphasizes views of both episodic memory and future thinking which do not rely on such mental time travel and, more importantly, give less prominence to the concept of time. The implications of such a view for research into future thinking in non-human animals are considered.     

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 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.     

Personality and mental time travel: a differential approach to autonoetic consciousness

Recent research on autonoetic consciousness indicates that the ability to remember the past and the ability to project oneself into the future are closely related. The purpose of the present study was to confirm this proposition by examining whether the relationship observed between personality and episodic memory could be extended to episodic future thinking and, more generally, to investigate the influence of personality traits on self-information processing in the past and in the future. Results show that Neuroticism and Harm Avoidance predict more negative past memories and future projections. Other personality dimensions exhibit a more limited influence on mental time travel (MTT). Therefore, our study provide an additional evidence to the idea that MTT into the past and into the future rely on a common set of processes by which past experiences are used to envision the 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。     

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.     

Experiencing past and future personal events: functional neuroimaging evidence on the neural bases of mental time travel

Functional MRI was used in healthy subjects to investigate the existence of common neural structures supporting re-experiencing the past and pre-experiencing the future. Past and future events evocation appears to involve highly similar patterns of brain activation including, in particular, the medial prefrontal cortex, posterior regions and the medial temporal lobes. This result seems to support the view of a common neurocognitive system, which would allow humans to mentally travel through time. Past events recollection was associated with greater amplitude of hippocampal and anterior medial prefrontal hemodynamic responses. This result is discussed in terms of the involvement of the self in the conscious experience of past and future events representations. More generally, our data provide new evidence in favour of the idea that re- and pre-experiencing past and future events may rely on similar cognitive capacities.     

The time machine in our mind

This article provides the first comprehensive conceptual account for the imagistic mental machinery that allows us to travel through time--for the time machine in our mind. It is argued that language reveals this imagistic machine and how we use it. Findings from a range of cognitive fields are theoretically unified and a recent proposal about spatialized mental time travel is elaborated on. The following novel distinctions are offered: external versus internal viewing of time; 'watching" time versus projective 'travel" through time; optional versus obligatory mental time travel; mental time travel into anteriority or posteriority versus mental time travel into the past or future; single mental time travel versus nested dual mental time travel; mental time travel in episodic memory versus mental time travel in semantic memory; and 'seeing" versus 'sensing" mental imagery. Theoretical, empirical, and applied implications are discussed.     

Schizotypy and mental time travel

Mental time travel is the capacity to imagine the autobiographical past and future. Schizotypy is a dimensional measure of psychosis-like traits found to be associated with creativity and imagination. Here, we examine the phenomenological qualities of mental time travel in highly schizotypal individuals. After recollecting past episodes (autobiographical memory) and imagining future events (episodic future thinking), those scoring highly on positive schizotypy reported a greater sense of ‘autonoetic awareness,’ defined as a greater feeling of mental time travel and re-living/‘pre-living’ imagined events. Furthermore, in contrast to other sensory domains, imagery of the past and future episodes contained more olfactory detail in these high scorers. The results are discussed in relation to previous reports of anomalous olfactory experiences in schizotypy and heightened vividness of olfactory imagery in post-traumatic stress disorder, for which schizotypy is a risk factor.     

心理时间旅行与自我:发展中关系模式的转换

该研究分别考察了儿童中晚期(9~12岁)、少年期(13~15岁)和青年早期(17岁、19岁、21岁)个体心理时间旅行的发展模式,并进一步探讨了不同年龄阶段,情景记忆和自我对情景预见作用模式的转换。研究采用访谈法评估心理时间旅行,以自我描述(儿童期和少年期)或自我连续性(青年早期)作为评估自我的指标。研究发现:(1)儿童中晚期,想象未来情景细节的数量随年龄增长而增加,少年期和青年早期的情景预见能力则趋于平稳,与情景记忆的发展趋势一致;(2)无论在哪个年龄段,情景记忆对情景预见都是有效的预测源;(3)自我描述在少年期才开始对情景预见产生预测作用;(4)青年早期,情景记忆以自我连续性为中介变量作用于情景预见。     

Make it real: Belief in occurrence within episodic future thought

While the cognitive and neural bases of episodic future thinking are well documented, questions remain as to what gives the sense that an imagined event belongs to one’s personal future. Capitalizing on previous research on metacognitive appraisals in autobiographical remembering, we propose that episodic future thinking involves, in varying degrees, a subjective belief in the potential occurrence of imagined future events and we explore the nature and determinants of such belief. To this aim, participants provided justifications for belief in occurrence for a series of past and future events. For each event, they also assessed their subjective feelings (belief in occurrence, autonoetic experience, and belief in accuracy) and rated various characteristics of mental representations that might contribute to these feelings. Results showed that belief in the occurrence of future events mostly related to their integration in a broader autobiographical context, especially their relevance to personal goals and their personal plausibility. We also found that belief in occurrence, autonoetic experience, and belief in accuracy represented distinct subjective appraisals of future events, which depended in part on different determinants. Based on these findings, we propose a new theoretical model of subjective feelings associated with episodic future thinking that conceives of belief in occurrence as arising from metacognitive appraisals that shape the sense that imagined events belong to one’s personal future.     

Self-projection and the brain

When thinking about the future or the upcoming actions of another person, we mentally project ourselves into that alternative situation. Accumulating data suggest that envisioning the future (prospection), remembering the past, conceiving the viewpoint of others (theory of mind) and possibly some forms of navigation reflect the workings of the same core brain network. These abilities emerge at a similar age and share a common functional anatomy that includes frontal and medial temporal systems that are traditionally associated with planning, episodic memory and default (passive) cognitive states. We speculate that these abilities, most often studied as distinct, rely on a common set of processes by which past experiences are used adaptively to imagine perspectives and events beyond those that emerge from the immediate environment.     

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.     

Visual perspective as a two-dimensional construct in episodic future thought

Visual perspective (first-person vs. third-person) is a salient characteristic of memory and mental imagery with important cognitive and behavioural consequences. Most work on visual perspective treats it as a unidimensional construct. However, third-person perspective can have opposite effects on emotion and motivation, sometimes intensifying these and other times acting as a distancing mechanism, as in PTSD. For this reason among others, we propose that visual perspective in memory and mental imagery is best understood as varying along two dimensions: first, the degree to which first-person perspective predominates in the episodic imagery, and second, the degree to which the self is visually salient from a third-person perspective. We show that, in episodic future thinking, these are anticorrelated but non-redundant. These results further our basic understanding of the potent but divergent effects visual perspective has on emotion and motivation, both in everyday life and in psychiatric conditions.     

Self-projection in younger and older adults: a study of episodic memory,prospection, and theory of mind

Self-projection is the ability to orient the self in different places in time and space. Episodic memory, prospection, and theory of mind (ToM) are all cognitive abilities that share an element of self-projection. Previous research has posited that each of these abilities stems from the same neural network. The current study compared performance of cognitively healthy older adults and younger adults on several self-projection tasks to examine the relatedness of these constructs behaviorally. Episodic memory and prospection were measured using an episodic interview task where the participants were asked to remember or imagine events that either had happened in the past or could happen in the future and then gave ratings describing the extent to which they were mentally experiencing the event and from what perspective they viewed it. ToM was measured by asking participants to make judgments regarding the intentions of characters described in stories that involved cognitive, affective, or ironic components. Our results demonstrate that aging influences episodic memory, prospection, and ToM similarly: older adult participants showed declines on each of these measures compared to younger adults. Further, we observed correlations between performance on the measures of episodic memory and prospection as well as between episodic memory and ToM, although no correlation between prospection and ToM was observed after controlling for chronological age. We discuss these results in the light of theories suggesting that each of these abilities is governed by a common brain system.     

"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.     

Episodic future thinking in children compared to adolescents

Episodic thinking involves the ability to re-create past and to construct future personal events, which contain event-specific (episodic) and general (semantic) details. The richness of episodic thought for past events improves as children move into adolescence. The current study aims to examine changes in episodic future thinking and to establish the cognitive underpinning of these changes. Typically developing children (n = 14) and adolescents (n = 15) were tested using an adapted version of the Child Autobiographical Interview (CAI) that required generation of past and future personally relevant events. Relational memory and executive skills were also examined. Significant developmental gains were found in richness of events recall across temporal directions (past and future) and across different types of details (episodic and semantic). Developmental gains in richness of past events were also shown to correspond to developmental gains in generation of future events. Moreover, developmental changes in relational memory and (to a lesser extent) executive functions were found to relate to increases in the amount of episodic (but not semantic) details provided. Our study highlighted the similarities between past and future episodic thinking in typically developing children and adolescents. It also raises a possibility that children with developmental and neurological disorders with impaired relational memory and/or executive skills may be at risk of difficulties with episodic thinking.     

Evolutionary economics of mental time travel?

What is the function of our capacity for 'mental time travel'? Evolutionary considerations suggest that vivid memory and imaginative foresight may be crucial cognitive devices for human decision making. Our emotional engagement with past or future events gives them great motivational force, which may counter a natural tendency towards time discounting and impulsive, opportunistic behavior. In this view, whereas simple episodic memory provides us with a store of relevant, case-based information to guide decisions, mental time travel nudges us towards more restrained choices, which in the long term are advantageous, especially so given human dependence on cooperation and coordination.     

The temporal distribution of past and future autobiographical events across the lifespan

Knowledge and awareness of past and future autobiographical events may be mediated by a common system that supports intentional, goal-directed behavior. The purpose of this study was to assess the correspondence of past and future autobiographical thought. In Experiment 1, 300 undergraduates aged 19 years generated and assigned dates to past and f utu re autobiographical events. Thetemporal distribution of past events replicated a power function for retention as has been described in past research. The intention function of future autobiographical events fit the inverse of this same power function, reflecting a temporality of past and future mental time travel centered around the present moment. In Experiment 2, these findings were extended to young, middle-aged, and older groups. These data provide empirical support for the notion that thinking outside of "now" is mediated by a common system, regardless of whether one is thinking about the past or the future.