Although involuntary past and future mental time travel (MTT) has been examined outside the laboratory in diary studies, MTT has primarily been studied in the context of laboratory studies using voluntary construction tasks. In this study, we adapted and extended a paradigm previously used to elicit involuntary and voluntary memories (Schlagman & Kvavilashvili in Memory & Cognition, 36, 920-932, 2008). Our aim was -for the first time -to examine involuntary and voluntary future MTT under controlled laboratory conditions. The involuntary task involved a monotonous task that included potential cues for involuntary MTT. Temporal direction was manipulated between participants whereas retrieval mode was manipulated within participants. We replicated robust past-future differences, such as the future positivity bias. Additionally, we replicated key voluntary-involuntary differences: Involuntary future representations had similar characteristics as involuntary memories in that they were elicited faster, were more specific, and garnered more emotional impact than their voluntary counterparts. We also found that the future and past involuntary MTT led to both positive and negative mood impact, and that the valence of the impact was associated with the emotional valence of the event. This study advances scientific understanding of involuntary future representations in healthy populations and validates a laboratory paradigm that can be flexibly and systematically utilized to explore different characteristics of voluntary and involuntary MTT, which has not been possible within naturalistic paradigms.

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.

In this article, we address an apparent paradox in the literature on mental time travel and mind-wandering: How is it possible that future thinking is both constructive, yet often experienced as occurring spontaneously? We identify and describe two 'routes' whereby episodic future thoughts are brought to consciousness, with each of the 'routes' being associated with separable cognitive processes and functions. Voluntary future thinking relies on controlled, deliberate and slow cognitive processing. The other, termed involuntary or spontaneous future thinking, relies on automatic processes that allows 'fullyfledged' episodic future thoughts to freely come to mind, often triggered by internal or external cues. To unravel the paradox, we propose that the majority of spontaneous future thoughts are 'pre-made' (i.e., each spontaneous future thought is a reiteration of a previously constructed future event), and therefore based on simple, well-understood, memory processes. We also propose that the pre-made hypothesis explains why spontaneous future thoughts occur rapidly, are similar to involuntary memories, and predominantly about upcoming tasks and goals. We also raise the possibility that spontaneous future thinking is the default mode of imagining the future. This dual process approach complements and extends standard theoretical approaches that emphasise constructive simulation, and outlines novel opportunities for researchers examining voluntary and spontaneous forms of future thinking.

This is the accepted version of the paper.This version of the publication may differ from the final published version. concluded, based on their own review of cognitive and neuroimaging studies of true versus false memories, that "it might be virtually impossible to tell reliably if a particular memory is true or false without independent corroboration (p.373)". On the basis of this evidence it was suggested (Conway, 2009) that perhaps we should be using the term remembering-imaging system (RIS) rather than simply memory system. Permanent repository link:The RIS is considered further below but first I will consider some aspects of the future. The Problem Of the FutureIn classical physics/mechanics a system, a collection of objects e.g. particles, fields, waves, etc. is deterministic and reversible (Susskind & Hrabovshy, 2013). This 4 means that given the laws that govern the system and its changes are known, a future state can be predicted exactly. Similarly knowing the state of a system at any given time means that the state of the system at an earlier or later time can be precisely established. Supposing we knew the laws that governed the cognitive, mind/brain, system, could we then, for any given individual, predict the exact state of the system at a future point? I suggest that we could not, (see Dudai & Edelson, submitted for publication, for related arguments). Just as in certain areas of physics, e.g. quantum mechanics, it is not possible to precisely predict a future state of a system, so with people the future is only probable. However, once a future state has come into being it may be possible to work back to previous states. Thus, the cognitive system may be retrospectively reversible (a point interestingly made by Freud, 1920, in the case of psychological states, which given the initial conditions cannot be predicted but working back to initial conditions is at least partly possible). Nevertheless, retrospectively reversible or not, given that there are an infinite number of indeterminate possible futures, this poses a major adaptive problem for goal-driven organisms. This is particularly so as the end point of all unrealized goals lies somewhere in the future. Indeed, in order to have a goal a future state has to be anticipated and often consciously imagined (Cole & Berntsen, 2015). To what extent does the idealized representation of the RIS shown in Figure 1 accurately reflect our memory for the recent past and imaginations of the near future?In a recent study we (Loveday & Conway, 2015) had people list all the personal events they could remember for each of the past 5 days and all the personal events that they the imagined could plausibly occur on each of the next 5 days. The numbers of remembered and imagined future events for each are shown in Figure 2. Figure 2 about hereIt can be seen in Figure 2 that the number of recent memories that can be accessed decreases rapidly over the first 3 days but then seems to stabilize and even increase slightly at a retention interval of 5 days. Also, intere...