Mental time travel into the past and the future in healthy aged adults: an fMRI study

Remembering the past and envisioning the future rely on episodic memory which enables mental time travel. Studies in young adults indicate that past and future thinking share common cognitive and neural underpinnings. No imaging data is yet available in healthy aged subjects. Using fMRI, we scanned older subjects while they remembered personal events (PP: last 12 months) or envisioned future plans (FP: next 12 months). Behaviorally, both time-periods were comparable in terms of visual search strategy, emotion, frequency of rehearsal and recency of the last evocation. However, PP were more episodic, engaged a higher state of autonoetic consciousness and mental visual images were clearer and more numerous than FP. Neuroimaging results revealed a common network of activation (posterior cingulate cortex, precuneus, prefrontal cortex, hippocampus) reflecting the use of similar cognitive processes. Furthermore, the episodic nature of PP depended on hippocampal and visuo-spatial activations (occipital and angular gyri), while, for FP, it depended on the inferior frontal and lateral temporal gyri, involved in semantic memory retrieval. The common neural network and behavior suggests that healthy aged subjects thought about their future prospects in the past. The contribution of retrospective thinking into the future that engages the same network as the one recruited when remembering the past is discussed. Within this network, differential recruitment of specific areas highlights the episodic distinction between past and future mental time travel.     

Individual differences in the phenomenology of mental time travel: The effect of vivid visual imagery and emotion regulation strategies

It has been claimed that the ability to remember the past and the ability to project oneself into the future are intimately related. We sought support for this proposition by examining whether individual differences in dimensions that have been shown to affect memory for past events similarly influence the experience of projecting oneself into the future. We found that individuals with a higher capacity for visual imagery experienced more visual and other sensory details both when remembering past events and when imagining future events. In addition, individuals who habitually use suppression to regulate their emotions experienced fewer sensory, contextual, and emotional details when representing both past and future events, while the use of reappraisal had no effect on either kind of events. These findings are consistent with the view that mental time travel into the past and into the future relies on similar mechanisms.     

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.     

"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.     

How did I do it then? How will I do it later? A theoretical review of the impact of mental time travel on decision-making processes

Mentally traveling to one's personal past and future connects the current self with self at different points in time. When making decisions in the present, individuals benefit from their past and potential future decisions with the help of mental time travel. This review documents the theoretical and empirical studies concerning mental time travel to past and future decisions and their influence on current decision-making processes. Particularly, certain characteristics of past and future decisions directly or indirectly influence present life decisions. Synthesizing the existing literature, we developed a theoretical model suggests that temporally close decisions tend to include different type of details and diverge from distant decisions in terms of personal meaningfulness. Further, past and future decisions that are elaborated and meaningful, have a great impact on present decisions. Future empirical work testing this model has the potential to generate findings that will inform intervention strategies towards improved decision-making.     

The evolution of foresight: What is mental time travel, and is it unique to humans?

In a dynamic world, mechanisms allowing prediction of future situations can provide a selective advantage. We suggest that memory systems differ in the degree of flexibility they offer for anticipatory behavior and put forward a corresponding taxonomy of prospection. The adaptive advantage of any memory system can only lie in what it contributes for future survival. The most flexible is episodic memory, which we suggest is part of a more general faculty of mental time travel that allows us not only to go back in time, but also to foresee, plan, and shape virtually any specific future event. We review comparative studies and find that, in spite of increased research in the area, there is as yet no convincing evidence for mental time travel in nonhuman animals. We submit that mental time travel is not an encapsulated cognitive system, but instead comprises several subsidiary mechanisms. A theater metaphor serves as an analogy for the kind of mechanisms required for effective mental time travel. We propose that future research should consider these mechanisms in addition to direct evidence of future-directed action. We maintain that the emergence of mental time travel in evolution was a crucial step towards our current success.     

Animals may not be stuck in time

Humans have the ability to mentally travel forward and back in time. They can retrieve vivid memories of past events (episodic memories) and can imagine the future (planning). Although it has been suggested that this is a uniquely human ability, the evidence for subjective time travel in humans is typically based on verbal report and elaboration. Such evidence cannot be obtained from animals. However, we may have indirect evidence for episodic memory and planning. For example, we can show that animals can ‘report’ about their recent past experience when they are unexpectedly asked to do so—performance that is analogous to episodic memory. We can also show that animals use the anticipation of a future event as the basis for a present action—analogous to planning. Thus, we have suggestive evidence that animals may not be stuck in time.     

The impact of perceived self-efficacy on mental time travel and social problem solving

Current models of autobiographical memory suggest that self-identity guides autobiographical memory retrieval. Further, the capacity to recall the past and imagine one's self in the future (mental time travel) can influence social problem solving. We examined whether manipulating self-identity, through an induction task in which students were led to believe they possessed high or low self-efficacy, impacted episodic specificity and content of retrieved and imagined events, as well as social problem solving. Compared to individuals in the low self efficacy group, individuals in the high self efficacy group generated past and future events with greater (a) specificity, (b) positive words, and (c) self-efficacious statements, and also performed better on social problem solving indices. A lack of episodic detail for future events predicted poorer performance on social problem solving tasks. Strategies that increase perceived self-efficacy may help individuals to selectively construct a past and future that aids in negotiating social problems.     

As we fall asleep we forget about the future: A quantitative linguistic analysis of mentation reports from hypnagogia

We present a quantitative study of mental time travel to the past and future in sleep onset hypnagogia. Three independent, blind judges analysed a total of 150 mentation reports from different intervals prior to and after sleep onset. The linguistic tool for the mentation report analysis grounds on established grammatical and cognitive-semantic theories, and proof of concept has been provided in previous studies. The current results indicate that memory for the future, but not for the past, decreases in sleep onset – thereby supporting preliminary physiological evidence at the level of brain function. While recent memory research emphasizes similarities in the cognitive and physiological processes of mental time travel to the past and future, the current study explores a state of consciousness which may serve to dissociate between the two.     

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.     

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。     

Memory and planning processes in solutions to well-structured problems

Although many studies in the problem-solving literature have considered the factors that might determine the strategies that are employed to solve well-structured problems, these have typically focused upon variants of means-end analysis. In general, such models imply that strategies unfold in a temporally forward direction, that problem solvers typically restrict forward-planning activities to just one or two moves ahead of the current problem state, and that one important heuristic is the avoidance of previous moves. Although studies have demonstrated the importance of such anti-looping heuristics, few have systematically explored the possibility that problem solvers may also plan retrospectively in order to try and assess whether a move might take them back to a state that they have previously visited. Those models of problem solving that promote the role of an anti-looping heuristic have assumed that the ability to use such a heuristic is based upon memory for previous states, but other interpretations are possible. In this paper several studies are reported that attempt systematically to explore participants' attempts to recognize previously visited problem solving states. The findings suggest that there is a systematic relationship between the success of this process, the time taken to make this judgement, and distance from the current state. It is also demonstrated that estimations about where future positions are likely to occur are symmetrical to estimations about past positions. It is suggested that this provides evidence that problem solvers engage in retrospective planning processes in order to try and avoid previous moves, and that this strategy may not be based straightforwardly upon their ability to remember previous problem states.     

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.     

Whichever way you choose to categorize, working memory helps you learn

There has been growing interest in the relationship between the capacity of a person's working memory and their ability to learn to categorize stimuli. While there is evidence that working memory capacity (WMC) is related to the speed of category learning, it is unknown whether WMC predicts which strategies people use when there are multiple possible solutions to a categorization problem. To explore the relationship between WMC, category learning, and categorization strategy use, 173 participants completed two categorization tasks and a battery of WMC tasks. WMC predicted the speed of category learning, but it did not predict which strategies participants chose to perform categorization. Thus, WMC does not predict which categorization strategies people use but it predicts how well they will use the strategy they select.     

Study time allocation deficit of older adults: The role of environmental support at encoding?

The present research evaluated both metacognitive and environmental support accounts of age-related changes in the way study time is adapted to task difficulty. The original aim was to examine whether providing environmental support at encoding would allow older adults to adjust their study time to the task difficulty by using effective encoding strategies. The difficulty of the learning task was manipulated by varying the strength of association of cue-target pairs (i.e., weak vs. strong associates). This allowed us to measure metacognitive control in aging and, specifically, the ability to adjust study time according to task difficulty. The level of environmental support at encoding was manipulated to examine whether it could be used by older adults to adjust their study time according to the task difficulty. In contrast to the classical literature on the effect of aging on metacognitive control, we found that older adults were able to adjust their study time to task difficulty when environmental support was provided. Furthermore, providing encoding strategies with information about their effectiveness helped older adults adjust their study time to task difficulty optimally by improving their strategy use and compensating for their associative memory deficit. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Whichever way you choose to categorize,working memory helps you learn

There has been growing interest in the relationship between the capacity of a person's working memory and their ability to learn to categorize stimuli. While there is evidence that working memory capacity (WMC) is related to the speed of category learning, it is unknown whether WMC predicts which strategies people use when there are multiple possible solutions to a categorization problem. To explore the relationship between WMC, category learning, and categorization strategy use, 173 participants completed two categorization tasks and a battery of WMC tasks. WMC predicted the speed of category learning, but it did not predict which strategies participants chose to perform categorization. Thus, WMC does not predict which categorization strategies people use but it predicts how well they will use the strategy they select.     

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.     

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.