We consider three possible reasons why humans might accord a privileged status to emotional information when mentally traveling backward or forward in time. First, mental simulation of emotional situations helps one to make adaptive decisions. Second, it can serve an emotion regulation function. Third, it helps people to construct and maintain a positive view of the self.

Episodic memory is certainly a unique endowment, but its primary purpose is something other than to provide raw material for creative synthesis of future scenarios. Remembered episodes are exactly those that are worth telling. The function of episodic memory, in my view, is to accumulate stories that are relevant to recount in conversation.

We examine and reject the claim that the past-directed aspect of mental time travel (episodic memory) is unique to humans. Recent work in our laboratory with rats has demonstrated behaviours that resemble “remember, know” judgements about past occasions. Similar to human episodic memory, we can also demonstrate a dissociation in the neural basis of recollection and familiarity in nonhumans.

The role of time in episodic memory and mental time travel is considered in light of findings on humans' temporal memory and anticipation. Time is not integral or uniform in memory for the past or anticipation of the future. The commonalities of episodic memory and anticipation require further study.

Mental time travel is a principled, but a narrow and computationally limiting, implementation of foresight. Future events can be predicted with sufficient specificity without having to have episodic memory of specific past events. Bayesian estimation theory provides a framework by which one can make predictions about specific future events by combining information about various generic patterns in the past experience.

The overlap of representations of past and future is not a completely new idea. Suddendorf & Corballis (S&C) usefully discuss the problems of testing the existence of such representations. Our taxonomy of memory differs from theirs, emphasizing the late evolutionary emergence of notions of time in memory.

A number of difficulties encumber the Suddendorf & Corballis (S&C) proposal regarding mental time travel into the future. Among these are conceptual issues turning on the inherent asymmetry of time and causality with regard to past and future, and the bearing of such asymmetry on the uses and utility of retrospective versus prospective mental time travel, on which I comment.

Suddendorf & Corballis (S&C) claim that mental time travel has significantly affected human cultural change. This echoes a common criticism of theories of Darwinian cultural evolution: that, whereas evolution is blind, culture is directed by people who can foresee and plan for future events. Here I argue that such a claim is premature, and more rigorous tests of S&C's claim are needed.

Mental time travel requires the sense of a past and future self, which is lacking in the early years of life. Research on the development of autobiographical memory and development of self sheds light on the difference between memory in other animals and its cultural narrative basis in humans.

The number of studies concerning the neurobiology of human prospection is now rapidly exploding. Recent works suggest that prospection can be better understood in a broader context of self-projection into other times, places, or agents that can share the same cerebral basis involving medial aspects of prefrontal, parietal, and temporal cortices. Mental time travel may be extended more generally to “mental traveling,” accomplished by stimulus-independent mental processes typical of human thought.

We are not entirely satisfied with the evolutionary explanation provided by Suddendorf & Corballis (S&C) for why only humans should be capable of advanced mental time travel. General social factors do not suffice, given that other primates are also highly social. We discuss the evolutionary mechanisms that have generated mental time travel typical to humans, focusing on ecological factors.

Although the mental time travel (MTT) hypothesis provides a rich, conceptual framework, the absence of clear, empirically tractable, behavioural criteria for determining the capacity for MTT restricts its usefulness in comparative research. Examples of empirical criteria for evaluating MTT in animals are given. We also question the authors' evaluation of semantic foresight and their even-handedness in assessing human and nonhuman behaviour.

We consider the relation between past and future events from the perspective of the constructive episodic simulation hypothesis, which holds that episodic simulation of future events requires a memory system that allows the flexible recombination of details from past events into novel scenarios. We discuss recent neuroimaging and behavioral evidence that support this hypothesis in relation to the theater production metaphor.

The title of the target article suggests an agenda for research on cognitive evolution that is doubly flawed. It implies that we can learn directly about animals' mental states, and its focus on human uniqueness impels a search for an existence proof rather than for understanding what components of given cognitive processes are shared among species and why.

Suddendorf & Corballis (S&C) argue that animals are not capable of mental time travel (MTT) or its components. However, new results on chimpanzees suggest that they plan for the future and possess some MTT components. Moreover, future-oriented behaviour and episodic-like memory in other animals suggest that not all animals are limited to the present. Animals' capacities should not be dismissed without testing them.

We add one point to Suddendorf & Corballis's (S&C's) story of mental time travel: For the future success of this hot, new area of research, it is imperative to pay attention to the fundamental distinction between the general brain/mind capacity that makes possible conscious awareness of the past and the future (the “medium”), on the one hand, and specific expressions of this capacity in a large variety of future-related mental activities (the “message”), on the other.

There is a growing interest in mental time travel in cognitive psychology, neuroscience, developmental psychology, comparative psychology, and evolutionary psychology. Here we review current issues in each of these disciplines. To help move the debates forward we name and distinguish 15 key hypotheses about mental time travel. We argue that foresight has for too long lived in the shadows of research on memory and call for further research efforts.