The dimensions of episodic simulation

Eliminating episodic memory?

In Tulving's initial characterization, episodic memory was one of multiple memory systems. It was postulated, in pursuit of explanatory depth, as displaying proprietary operations, representations and substrates such as to explain a range of cognitive, behavioural and experiential phenomena. Yet the subsequent development of this research programme has, paradoxically, introduced surprising doubts about the nature, and indeed existence, of episodic memory. On dominant versions of the 'common system' view, on which a single simulation system underlies both remembering and imagining, there are no processes unique to memory to support robust generalizations with inductive potential. Eliminativism about episodic memory seems to follow from the claim that it has no dedicated neurocognitive system of its own. After identifying this under-noticed threat, we push back against modern eliminativists by surveying recent evidence that still indicates specialized mechanisms, computations and representations that are distinctly mnemic in character. We argue that contemporary realists about episodic memory can retain lessons of the common system approach while resisting the further move to eliminativism. This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

Episodic recombination and the role of time in mental travel

Mental time travel is often presented as a singular mechanism, but theoretical and empirical considerations suggest that it is composed of component processes. What are these components? Three hypotheses about the major components of mental time travel are commonly considered: (i) remembering and imagining might, respectively, rely on different processes, (ii) past- and future-directed forms of mental time travel might, respectively, rely on different processes, and (iii) the creation of episodic representations and the determination of their temporal orientation might, respectively, rely on different processes. Here, we flesh out the last of these proposals. First, we argue for 'representational continuism': the view that different forms of mental travel are continuous with regard to their core representational contents. Next, we propose an updated account of episodic recombination (the mechanism generating these episodic contents) and review evidence in its support. On this view, episodic recombination is a natural kind best viewed as a form of compositional computation. Finally, we argue that episodic recombination should be distinguished from mechanisms determining the temporal orientation of episodic representations. Thus, we suggest that mental travel is a singular capacity, while mental time travel has at least two major components: episodic representations and their temporal orientation. This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

Beyond the episodic-semantic continuum: the multidimensional model of mental representations

Tulving's concept of mental time travel (MTT), and the related distinction of episodic and semantic memory, have been highly influential contributions to memory research, resulting in a wealth of findings and a deeper understanding of the neurocognitive correlates of memory and future thinking. Many models have conceptualized episodic and semantic representations as existing on a continuum that can help to account for various hybrid forms. Nevertheless, in most theories, MTT remains distinctly associated with episodic representations. In this article, we review existing models of memory and future thinking, and critically evaluate whether episodic representations are distinct from other types of explicit representations, including whether MTT as a neurocognitive capacity is uniquely episodic. We conclude by proposing a new framework, the Multidimensional Model of Mental Representations (MMMR), which can parsimoniously account for the range of past, present and future representations the human mind is capable of creating. This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

Autonomous communication with normative information facilitates positive spillover: promoting pro-environmental behaviors in a local setting

A pro-environmental behavior (PEB) intervention may increase the adoption of other PEBs that were not targeted by the intervention, leading to a positive spillover effect. Communication that both support autonomy, as defined by self-determination theory, and compliance with descriptive norms may promote the targeted PEBs and positive spillover effect. Such communication may enhance autonomous motivation to adopt PEBs. A pilot study (N = 350) about waste management in a university campus found that autonomous communication supplemented by normative information influenced both targeted and non-targeted behavioral intentions, compared to autonomous-only and controlling communication. Findings were replicated in a main study (N = 629). An intervention combining autonomy support and descriptive norms increased the likelihood of a positive spillover effect in contrast to an intervention combining controlling communication and descriptive norms. In both studies, autonomous motivation mediated the positive spillover effect. Results suggest that communication that promotes autonomous motivation by fulfilling basic self-determination needs may have a broader effect on a wider range of PEBs.

How to Become a Memory: The Individual and Collective Aspects of Mnemicity

Human adults distinguish their mental event simulations along various dimensions-most prominently according to their "mnemicity": we track whether these simulations are outcomes of past personal experiences or not (i.e., whether we are "remembering" or "imagining"). This distinction between memory and imagination is commonly thought to reflect a deep architectural distinction in the mind. Against this idea, I argue that mnemicity is not based on a fundamentalstructural difference between memories and imaginations but is instead the result of metacognitive attribution and social construction. On this attributional view, mnemicity is likely a uniquely human capacity that both serves collective functions and has been shaped by collective norms. First, on the individual level, mnemicity attribution is an outcome of metacognitive learning: it relies on acquired interpretations of the phenomenal features of mental event simulations. Such interpretations are in part acquired through interactive reminiscing with other community members. Further, how the distinction between memory and imagination is drawn is likely sensitive to cultural norms about what remembering is, when it is appropriate to claim to remember, what can be remembered, and what remembering entails. As a result, how individuals determine whether they remember or imagine is bound to be deeply enculturated. Second, mnemicity attribution solves an important collective challenge: who to grant epistemic authority about the past. Solving this challenge is important because-for humans-the past represents not just an opportunity to learn about the future but to coordinate present social realities. How a community determines such social realities both draws on individuals' remembering and in turn shapes when, what, and how individuals remember.

Isolating the effects of visual imagery on prospective memory

Two experiments investigated the role of visual imagery in prospective memory (PM). In experiment 1, 140 participants completed a general knowledge quiz which included a PM task of writing a letter "X" next to any questions that referred to space. Participants either visualised themselves performing this task, verbalised an implementation intention about the task, did both, or did neither. Performance on the PM task was enhanced in both conditions involving visual imagery but not by implementation intentions alone. In experiment 2, 120 participants imagined themselves writing a letter "X" next to questions about space, or in a bizarre imagery condition imagined themselves drawing an alien next to those questions. Relative to the control condition, PM was significantly enhanced when participants imagined writing a letter "X" next to the target questions, but not by the bizarre imagery task. The findings indicate that the robust effects of imagery observed in retrospective memory also extend to PM.

Long-term memory for movie details: selective decay for verbal information at one week

Mnemonic representations of complex events are multidimensional, incorporating information about objects and characters, their interactions and their spatial-temporal context. The present study investigated the degree to which detailed verbal information (i.e., dialogues), as well as semantic and spatiotemporal (i.e., "what", "where", and "when") elements of episodic memories for movies, are forgotten over the course of a week. Moreover, we tested whether the amount of dimension-specific forgetting differed as a function of the participant's age. In a mixed design, younger and middle-aged participants were asked to watch a ∼90 min movie and provide yes/no answers to detailed questions about different dimensions of the presented material after 1, 3 days, and 1 week. The results indicate that memory decay mainly affects the verbal dimension, both in terms of response accuracy and confidence. Instead, detailed information about objects/characters' features and spatiotemporal context seems to be relatively preserved, despite a general decrease in response confidence. Furthermore, younger adults were in general more accurate and confident than middle-aged participants, although, again, the verbal dimension exhibited a significant age-related difference. We propose that this selective forgetting depends on the progressive advantage of visual compared to auditory/verbal information in memory for complex events.

Repeated simulation increases belief in the future occurrence of uncertain events

The feeling that an imagined event will or will not occur in the future - referred to as belief in future occurrence - plays a key role in guiding our decisions and actions. Recent research suggests that this belief may increase with repeated simulation of future events, but the boundary conditions for this effect remain unclear. Considering the key role of autobiographical knowledge in shaping belief in occurrence, we suggest that the effect of repeated simulation only occurs when prior autobiographical knowledge does not clearly support or contradict the occurrence of the imagined event. To test this hypothesis, we investigated the repetition effect for events that were either plausible or implausible due to their coherence or incoherence with autobiographical knowledge (Experiment 1), and for events that initially appeared uncertain because they were not clearly supported or contradicted by autobiographical knowledge (Experiment 2). We found that all types of events became more detailed and took less time to construct after repeated simulation, but belief in their future occurrence increased only for uncertain events; repetition did not influence belief for events already believed or considered implausible. These findings show that the effect of repeated simulation on belief in future occurrence depends on the consistency of imagined events with autobiographical knowledge.

A language of episodic thought?

We propose that episodic thought (i.e., episodic memory and imagination) is a domain where the language-of-thought hypothesis (LoTH) could be fruitfully applied. On the one hand, LoTH could explain the structure of what is encoded into and retrieved from long-term memory. On the other, LoTH can help make sense of how episodic contents come to play such a large variety of different cognitive roles after they have been retrieved.

Mnemicity: A Cognitive Gadget?

Episodic representations can be entertained either as "remembered" or "imagined"-as outcomes of experience or as simulations of such experience. Here, we argue that this feature is the product of a dedicated cognitive function: the metacognitive capacity to determine the mnemicity of mental event simulations. We argue that mnemicity attribution should be distinguished from other metacognitive operations (such as reality monitoring) and propose that this attribution is a "cognitive gadget"-a distinctively human ability made possible by cultural learning. Cultural learning is a type of social learning in which traits are inherited through social interaction. In the case of mnemicity, one culturally learns to discriminate metacognitive "feelings of remembering" from other perceptual, emotional, action-related, and metacognitive feelings; to interpret feelings of remembering as indicators of memory rather than imagination; and to broadcast the interpreted feelings in culture- and context-specific ways, such as "I was there" or "I witnessed it myself." We review evidence from the literature on memory development and scaffolding, metacognitive learning and teaching, as well as cross-cultural psychology in support of this view before pointing out various open questions about the nature and development of mnemicity highlighted by our account.

Episodic representation: A mental models account

This paper offers a modeling account of episodic representation. I argue that the episodic system constructs mental models: representations that preserve the spatiotemporal structure of represented domains. In prototypical cases, these domains are events: occurrences taken by subjects to have characteristic structures, dynamics and relatively determinate beginnings and ends. Due to their simplicity and manipulability, mental event models can be used in a variety of cognitive contexts: in remembering the personal past, but also in future-oriented and counterfactual imagination. As structural representations, they allow surrogative reasoning, supporting inferences about their constituents which can be used in reasoning about the represented events.

Self-projection in early childhood: No evidence for a common underpinning of episodic memory, episodic future thinking, theory of mind, and spatial navigation

Buckner and Carroll [Trends in Cognitive Sciences (2007), Vol. 11, pp. 49-57] argued that episodic memory (EM), episodic future thinking (EFT), theory of mind (ToM), and spatial navigation all build on the same mental mechanism-self-projection, that is, the ability to disengage from the immediate present and shift perspective to alternative temporal, mental, or spatial situations. Developmental studies indeed show that all four abilities undergo profound developmental changes around 4 years of age, and there are first indications of developmental interrelations between some of the abilities. However, strong evidence for the self-projection account, namely that all four abilities are interrelated in their emergence during early childhood, is still lacking. To thoroughly investigate the self-projection hypothesis, we tested 151 4-year-old children on 12 different tasks assessing their EM, EFT, ToM, and spatial navigation skills (3 tasks per ability). Structural equation modeling under maximum likelihood estimation was conducted on a final sample of 144 children to evaluate a model with the 12 tasks as indicators and self-projection as the latent factor. The model showed a very good fit to the data. However, the factor loadings, indicating the strength of association between the latent factor and the indicators, were very low-which speaks against the validity of the measurement model. In summary, the results do not support the assumption of a common latent factor underlying the various abilities EM, EFT, ToM, and spatial navigation. Implications of our results for the self-projection account and possible related theoretical and methodological challenges are discussed.

Visual mental imagery: Inside the mind's eyes

What are mental images needed for? A variety of everyday situations calls for us to plan ahead; one of the clever ways our mind prepares and strategizes our next move is through mental simulation. A powerful tool in running these simulations is visual mental imagery, which can be conceived as a way to activate and maintain an internal representation of the to-be-imagined object, giving rise to predictions. Therefore, under normal conditions imagination is primarily an endogenous process, and only more rarely can mental images be activated exogenously, for example, by means of intracerebral stimulation. A large debate is still ongoing regarding the neural substrates supporting mental imagery, with the neuropsychological and neuroimaging literature agreeing in some cases, but not others. This chapter reviews the neuroscientific literature on mental imagery, and attempts to reappraise the neuropsychological and neuroimaging evidence by drawing a model of mental imagery informed by both structural and functional brain data. Overall, the role of regions in the ventral temporal cortex, especially of the left hemisphere, stands out unequivocally as a key substrate in mental imagery.

A long time ago in a galaxy far, far away: How temporal are episodic contents?

A prominent feature of mental event (i.e. 'episodic') simulations is their temporal orientation: human adults can generate episodic representations directed towards the past or the future. Here, we investigated how the temporal orientation of imagined events relates to the contents of these events. Is there something intrinsically temporal about episodic contents? Or does their temporality rely on a distinct set of representations? In three experiments (N = 360), we asked participants to generate and later recall a series of imagined events differing in (1) location, (2) time of day, (3) temporal orientation, and (4) weekday. We then tested to what extent successful recall of episodic content (i.e. (1) and (2)) would predict recall of temporality and/or weekday information. Results showed that recall of temporal orientation was only weakly predicted by recall of episodic contents. Nonetheless, temporal orientation was more strongly predicted by content recall than weekday recall. This finding suggests that episodic simulations are unlikely to be intrinsically temporal in nature. Instead, similar to other forms of temporal information, temporal orientation might be determined from such contents by reconstructive post-retrieval processes. These results have implications for how the human ability to 'mentally travel' in time is cognitively implemented.

The trajectory of counterfactual simulation in development

Young children often struggle to answer the question "what would have happened?" particularly in cases where the adult-like "correct" answer has the same outcome as the event that actually occurred. Previous work has assumed that children fail because they cannot engage in accurate counterfactual simulations. Children have trouble considering what to change and what to keep fixed when comparing counterfactual alternatives to reality. However, most developmental studies on counterfactual reasoning have relied on binary yes/no responses to counterfactual questions about complex narratives and so have only been able to document when these failures occur but not why and how. Here, we investigate counterfactual reasoning in a domain in which specific counterfactual possibilities are very concrete: simple collision interactions. In Experiment 1, we show that 5- to 10-year-old children (recruited from schools and museums in Connecticut) succeed in making predictions but struggle to answer binary counterfactual questions. In Experiment 2, we use a multiple-choice method to allow children to select a specific counterfactual possibility. We find evidence that 4- to 6-year-old children (recruited online from across the United States) do conduct counterfactual simulations, but the counterfactual possibilities younger children consider differ from adult-like reasoning in systematic ways. Experiment 3 provides further evidence that young children engage in simulation rather than using a simpler visual matching strategy. Together, these experiments show that the developmental changes in counterfactual reasoning are not simply a matter of whether children engage in counterfactual simulation but also how they do so. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Visual mental imagery engages the left fusiform gyrus, but not the early visual cortex: A meta-analysis of neuroimaging evidence

The dominant neural model of visual mental imagery (VMI) stipulates that memories from the medial temporal lobe acquire sensory features in early visual areas. However, neurological patients with damage restricted to the occipital cortex typically show perfectly vivid VMI, while more anterior damages extending into the temporal lobe, especially in the left hemisphere, often cause VMI impairments. Here we present two major results reconciling neuroimaging findings in neurotypical subjects with the performance of brain-damaged patients: (1) A large-scale meta-analysis of 46 fMRI studies, of which 27 investigated specifically visual mental imagery, revealed that VMI engages fronto-parietal networks and a well-delimited region in the left fusiform gyrus. (2) A Bayesian analysis showed no evidence for imagery-related activity in early visual cortices. We propose a revised neural model of VMI that draws inspiration from recent cytoarchitectonic and lesion studies, whereby fronto-parietal networks initiate, modulate, and maintain activity in a core temporal network centered on the fusiform imagery node, a high-level visual region in the left fusiform gyrus.

The Phenomenology of Remembering Is an Epistemic Feeling

This article aims to provide a psychologically informed philosophical account of the phenomenology of episodic remembering. The literature on epistemic or metacognitive feelings has grown considerably in recent years, and there are persuasive reasons, both conceptual and empirical, in favor of the view that the phenomenology of remembering-autonoetic consciousness, as Tulving influentially referred to it, or the feeling of pastness, as we will refer to it here-is an epistemic feeling, but few philosophical treatments of this phenomenology as an epistemic feeling have so far been proposed. Building on insights from the psychological literature, we argue that a form of feeling-based metacognition is involved in episodic remembering and develop an integrated metacognitive feeling-based view that addresses several key aspects of the feeling of pastness, namely, its status as a feeling, its content, and its relationship to the first-order memories the phenomenology of which it provides.

Witnessing, Remembering, and Testifying: Why the Past Is Special for Human Beings

The past is undeniably special for human beings. To a large extent, both individuals and collectives define themselves through history. Moreover, humans seem to have a special way of cognitively representing the past: episodic memory. As opposed to other ways of representing knowledge, remembering the past in episodic memory brings with it the ability to become a witness. Episodic memory allows us to determine what of our knowledge about the past comes from our own experience and thereby what parts of the past we can give testimony about. In this article, we aim to give an account of the special status of the past by asking why humans have developed the ability to give testimony about it. We argue that the past is special for human beings because it is regularly, and often principally, the only thing that can determine present social realities such as commitments, entitlements, and obligations. Because the social effects of the past often do not leave physical traces behind, remembering the past and the ability to bear testimony it brings is necessary for coordinating social realities with other individuals.