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.     

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.     

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.     

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。     

The role of lifetime periods in the organisation of episodic memories

ABSTRACT

Research on the nature of episodic memory associations has suggested that episodic memories are associated by conceptual knowledge, where memories cluster around the same content (e.g. memories about the same people) or general-event knowledge, where memories cluster around extended events (e.g. a holiday in London), repeated events (e.g. Sunday walks in the park), or causally related events (i.e. where one event leads to another). Research has also suggested that episodic memories are associated by lifetime periods (e.g. when I was in high school), where memories cluster within lifetime periods. However, it is unclear whether episodic memories can be associated solely by lifetime periods, or if such associations are subordinate to conceptual or general-event associations. To answer this question, we reanalysed a large sample of involuntary memory chains (Mace, J. H., Clevinger, A. M., & Bernas, R. S. (2013). Involuntary memory chains: What do they tell us about autobiographical memory organisation? Memory, 21, 324–335). The results of this analysis suggested that lifetime periods associations are subordinate to conceptual and general-event associations, as lifetime periods were found to cluster within the latter two associations. The potential functions of this organisation are discussed.     

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.     

自我相关未来思考:两种基本类型及其主要心理成分比较

自我相关未来思考是个体产生自我相关未来想法的心理加工,它包括未来情景思考和未来个人语义思考两种基本类型。两类思考都需记忆、自我和主观时间三种主要心理成分参与,但参与的具体形式可能有所不同:未来情景思考可能主要依赖于情景记忆和语义记忆、情景自我知识和语义自我知识、经验时间;未来个人语义思考可能主要依赖于语义记忆、语义自我知识和知道时间。三种主要心理成分在两种思考类型中的作用可能是相同的,其中,记忆是原材料,自我起引导作用,主观时间是先决条件。将来可以参照思考未来公众抽象问题的研究进一步明确自我和记忆在未来个人语义思考中的作用,还可以通过探究不同心理成分内部及成分间的交互作用进而了解各成分在自我相关未来思考中的作用机制。     

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.     

When does prior knowledge disproportionately benefit older adults’ memory?

Material consistent with knowledge/experience is generally more memorable than material inconsistent with knowledge/experience – an effect that can be more extreme in older adults. Four experiments investigated knowledge effects on memory with young and older adults. Memory for familiar and unfamiliar proverbs (Experiment 1) and for common and uncommon scenes (Experiment 2) showed similar knowledge effects across age groups. Memory for person-consistent and person-neutral actions (Experiment 3) showed a greater benefit of prior knowledge in older adults. For cued recall of related and unrelated word pairs (Experiment 4), older adults benefited more from prior knowledge only when it provided uniquely useful additional information beyond the episodic association itself. The current data and literature suggest that prior knowledge has the age-dissociable mnemonic properties of (1) improving memory for the episodes themselves (age invariant), and (2) providing conceptual information about the tasks/stimuli extrinsically to the actual episodic memory (particularly aiding older adults).     

Assessment of behavioural markers of autonoetic consciousness during episodic autobiographical memory retrieval: a preliminary analysis

There is ongoing theoretical debate regarding episodic memory and how it can be accurately measured, in particular if the focus should be content-based recall of episodic details or something more experiential involving the subjective capacity to mentally travel back in time and "re-live" aspects of the original event. The autonoetic subscale of the Episodic Autobiographical Memory Interview (EAMI) is presented here as a new test instrument that attempts to redress theoretical and methodological shortcomings in autobiographical memory assessment. The EAMI merges a phenomenological detail-based approach with an assessment of autonoetic consciousness, departing considerably from traditional Remember/Know paradigms used within this field. We present findings from an initial pilot study investigating the potential markers of autonoetic consciousness that may accompany episodic retrieval. Key behavioural indices of autonoetic consciousness, notably those of viewer perspective, visual imagery, and emotional re-experiencing, emerged as being inextricably bound with the level of phenomenological detail recalled and the overall re-living judgment. The autonoetic subscale of the EAMI permits conceptually refined assessment of episodic personal memories and the accompanying subjective experience of mental re-living, characteristic of episodic memory.     

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.     

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.     

Language and memory

This paper outlines some of the issues and basic philosophy that have guided my work and that of my students in the last ten years. It describes the progression of conceptual representational theories developed during that time, as well as some of the research models built to implement those theories. The paper concludes with a discussion of my most recent work in the area of modelling memory. It presents a theory of MOPs (Memory Organization Packets), which serve as both processors and organizers of information in memory. This enables effective categorization of experiences in episodic memory, which in turn enables better predictive understanding of new experiences.     

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.     

Are animals stuck in time?

People can time travel cognitively because they can remember events having occurred at particular times in the past (episodic memory) and because they can anticipate new events occurring at particular times in the future. The ability to assign points in time to events arises from human development of a sense of time and its accompanying time-keeping technology. The hypothesis is advanced that animals are cognitively stuck in time: that is, they have no sense of time and thus have no episodic memory or ability to anticipate long-range future events. Research on animals' abilities to detect time of day, track short time intervals, remember the order of a sequence of events, and anticipate future events are considered, and it is concluded that the stuck-in-time hypothesis is largely supported by the current evidence.     

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。     

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.     

未来心理时间的新取向：集体未来思考

集体未来思考是指想象一个尚未发生的群体事件,其与集体记忆之间存在着复杂的相互作用。目前对集体未来思考的研究发现它的记忆基础更多为语义记忆。而有关集体未来思考的脑机制研究则相对较少,但在遗忘症患者中发现个体未来思考和集体未来思考是可分离的,并且非海马依赖的未来场景构建与集体未来思考可能存在重要联系。未来研究应该注重不同文化背景下的集体未来思考,探讨其产生条件及影响因素,并加强在正常人群中神经机制的研究,以更好地揭示集体未来思考的实质。     

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.     

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.