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Experimental psychologist Jonathan Crystal and evolutionary psychologist Thomas Suddendorf debate with nonhuman animals experience human-like episodic memory.

The quality and frequency of human technical innovation differentiates us from all other species, and has played a primary role in creating the cognitive niche that we occupy. Yet, despite the centrality of technical innovation to human culture and our daily lives, most people rarely if ever innovate new products. To address this discrepancy we consider our evolutionary history, and how it might have created a species whose members are both highly innovative and highly unlikely to invent new products. We propose the social innovation hypothesis, which suggests that our minds evolved to innovate, but with a social rather than a technical orientation. Because people find social relations rewarding, they gravitate toward social rather than technical solutions to their problems. Thus, it may primarily be people who are less socially oriented who innovate technically. Consistent with this possibility, 1) engineers and physical scientists are less socially oriented and more likely to innovate new products than people in the humanities and social sciences, and 2) men are less socially oriented and more likely to innovate new products than women.

Prospection refers to thinking about the future, a capacity that has become the subject of increasing research in recent years. Here we first distinguish basic prospection, such as associative learning, from more complex prospection commonly observed in humans, such as episodic foresight, the ability to imagine diverse future situations and organize current actions accordingly. We review recent studies on complex prospection in various contexts, such as decision-making, planning, deliberate practice, information gathering, and social coordination. Prospection appears to play many important roles in human survival and reproduction. Foreseeing threats and opportunities before they arise, for instance, drives attempts at avoiding future harm and obtaining future benefits, and recognizing the future utility of a solution turns it into an innovation, motivating refinement and dissemination. Although we do not know about the original contexts in which complex prospection evolved, it is increasingly clear through research on the emergence of these capacities in childhood and on related disorders in various clinical conditions, that limitations in prospection can have profound functional consequences.

Humans have evolved mechanisms for the detection and management of possible threats in order to abate their negative consequences for fitness. Internally generated ('detached') cognition may have evolved in part because of its contributions to this broad function, but important questions remain about its role in threat management. In this article, we therefore present a taxonomy of threat-related internally generated cognition comprising episodic and semantic formats of memory and prospection. We address the proximate mechanisms of each of the capacities in this taxonomy, and discuss their respective contributions to adaptive threat management in humans. For instance, mental time travel empowers people to contemplate and learn from threats experienced long ago, as well as to plan for dangers that might arise in the distant future. However, despite their functional benefits, these thought processes are also central to contemporary anxiety disorders and may be a potent source of distress.

Despite the wealth of research examining children’s future-oriented cognition, little is known about the development of spontaneous information seeking behavior aimed at achieving future goals. Here we present a first experiment directly investigating the emergence of such behavior in 4- to 7-year-old children. We presented children with two sets of cards: one with target information that they were told they would be tested on in the future, and a second set with distractor information that they were told had no future purpose. Without being provided instructions on which information to memorize, children were then given time to study the cards in preparation for the future event. The 6- and 7-year-olds, but not the 4- and 5-year-olds, spent significantly more time attending to target cards than distractor cards. While only a minority of children used overt learning strategies (e.g., verbal rehearsal, self-testing), the number of children who did so increased with age.

Mody and Carey (2016) investigated children's capacity to reason by the disjunctive syllogism by hiding stickers within two pairs of cups (i.e., there is one sticker in cup A or B, and one in cup C or D) and then showing one cup to be empty. They found that children as young as 3 years of age chose the most likely cup (i.e., not A, therefore choose B; and disregard C and D) and suggested that these children were representing the dependent relationship between A and B by applying the logical operator “or”. However, it is possible that children succeeded using simpler strategies, such as avoiding the empty cup and choosing within the manipulated pair. We devised a new version of the task in which a sticker was visibly removed from one of the four cups so that 2.5- to 5-year-old children (N = 100) would fail if they relied on such strategies. We also included a conceptual replication of Mody and Carey's (2016) original condition. Our results replicated their findings and showed that even younger children, 2.5 years of age, could pass above chance levels. Yet, 2.5-, 3- and 4-year-olds failed the new condition. Only 5-year-old children performed above chance in both conditions and so provided compelling evidence of deductive reasoning from the premise “A or B", where “or” is exclusive. We propose that younger children may instead conceive of the relationship between A and B as inclusive “or” across both versions of the task.

Animal brains have evolved to predict outcomes of events in the immediate environment [1, 2, 3, 4 and 5]. Adult humans are particularly adept at dealing with environmental uncertainty, being able to mentally represent multiple, even mutually exclusive versions of the future and prepare accordingly. This capacity is fundamental to many complex future-oriented behaviors [6 and 7], yet little is known about when it develops in children [8] and whether it is shared with non-human animals [9]. Here we show that children become able to insightfully prepare for two mutually exclusive versions of an undetermined future event during the middle preschool years, whereas we find no evidence for such a capacity in a sample of chimpanzees and orangutans. We gave 90 preschool children and 8 great apes the opportunity to catch an item dropped into a forked tube with two bottom openings. Children’s performance improved linearly across age groups (2, 2.5, 3, 3.5, and 4 years), with none of the youngest group but most of the oldest group spontaneously covering both openings the first time they prepared to catch the item. The apes performed like 2-year-olds on the first trial, with none of them covering both openings. Some apes and 2-year-olds eventually passed the task, but only in a manner consistent with trial-and-error learning. Our results reveal the developmental trajectory of a critical cognitive ability that allows humans to prepare for future uncertainty, and they also raise the possibility that this ability is not shared with other hominids.

Human children copy others' actions with high fidelity, supporting early cultural learning and assisting in the development and maintenance of behavioral traditions [1]. Imitation has long been assumed to occur from birth [2-4], with influential theories (e.g., [5-7]) placing an innate imitation module at the foundation of social cognition (potentially underpinned by a mirror neuron system [8, 9]). Yet, the very phenomenon of neonatal imitation has remained controversial. Empirical support is mixed and interpretations are varied [10-16], potentially because previous investigations have relied heavily on cross-sectional designs with relatively small samples and with limited controls [17, 18]. Here, we report surprising results from the most comprehensive longitudinal study of neonatal imitation to date. We presented infants (n = 106) with nine social and two non-social models and scored their responses at 1, 3, 6, and 9 weeks of age. Longitudinal analyses indicated that the infants did not imitate any of the models, as they were just as likely to produce the gestures in response to control models as they were to matching models. Previous positive findings were replicated in limited cross-sections of the data, but the overall analyses confirmed these findings to be mere artifacts of restricted comparison conditions. Our results undermine the idea of an innate imitation module and suggest that earlier studies reporting neonatal imitation were methodologically limited.

There has been a persistent debate about how to define episodic memory and whether it is a uniquely human capacity. On the one hand, many animal cognition studies employ content-based criteria, such as the what-where-when criterion, and argue that nonhuman animals possess episodic memory. On the other hand, many human cognition studies emphasize the subjective experience during retrieval as an essential property of episodic memory and the distinctly human foresight it purportedly enables. We propose that both perspectives may examine distinct but complementary aspects of episodic memory by drawing a conceptual distinction between episodic memory traces and mental time travel. Episodic memory traces are sequential mnemonic representations of particular, personally experienced episodes. Mental time travel draws on these traces, but requires other components to construct scenarios and embed them into larger narratives. Various nonhuman animals may store episodic memory traces, and yet it is possible that only humans are able to construct and reflect on narratives of their lives - and flexibly compare alternative scenarios of the remote future.

Visual self-recognition is often controversially cited as an indicator of self-awareness and assessed with the mirror-mark test. Great apes and humans, unlike small apes and monkeys, have repeatedly passed mirror tests, suggesting that the underlying brain processes are homologous and evolved 14-18 million years ago. However, neuroscientific, developmental, and clinical dissociations show that the medium used for self-recognition (mirror vs photograph vs video) significantly alters behavioral and brain responses, likely due to perceptual differences among the different media and prior experience. On the basis of this evidence and evolutionary considerations, we argue that the visual self-recognition skills evident in humans and great apes are a byproduct of a general capacity to collate representations, and need not index other aspects of self-awareness.

Across two different contexts, Kabadayi and Osvath found that ravens preferentially selected items that could be used to obtain future rewards. Do these results demand a rethink of the evolution of flexible planning, or are there leaner alternative explanations for the performance of ravens?

This study investigated changes in the production of temporal terms over the preschool years. Ninety-three parents of 3-, 4- and 5-year-old children completed a questionnaire in which they indicated their child's production, and accurate use, of a list of temporal words. The results suggest that use and command emerge at different ages for different terms. Correlation and difference analyses were conducted to document the pattern of development. Words representing the present (e.g., now) and very general temporal terms (e.g., ‘later’) were produced and used accurately by the majority of even the youngest children. Some terms describing specific timeframes (e.g., ‘yesterday’) were also produced from a young age but demonstrated more gradual acquisition of appropriate use across the preschool years. Other terms appeared in children's vocabularies only later in the preschool years, and were inaccurately used even by the oldest children (e.g., ‘hours’). These findings provide an initial survey of reported child competence with temporal words that has implications for research, education, and judicial contexts.

If episodic memory is an adaptation, it must have evolved to benefit present or future survival and reproduction, rather than to provide an accurate record of the past per se. Recent research has documented various links between the ability to construct episodes of the past and imagine potential future episodes, and it has been argued that the former may be a design feature of the latter. Thus, claims about the existence of episodic memory in non-verbal organisms may be evaluated by examining behavioural evidence for foresight. Here we review recent data on foresight in animals and conclude that the evidence to suggest episodic memory so far is equivocal. We suggest specific experimental criteria that could provide stronger evidence. We maintain that there must be uniquely human traits for which there are no animal models and it remains possible that mental time travel depends on several such traits. Identification of what precisely is unique about the human capacity and what is not, can inform us about the nature and evolution of the human capacities.

Three experiments (N = 123) investigated the development of live-video self-recognition using the traditional mark test. In Experiment 1, 24-, 30- and 36-month-old children saw a live video image of equal size and orientation as a control group saw in a mirror. The video version of the test was more difficult than the mirror version with only the oldest children's performance approaching ceiling. In Experiment 2, most 24-month-olds showed self-recognition when presented with a TV-set that featured a mirror in place of a screen. This finding does not substantiate the possibility that expectations about what appears on TV are responsible for the asynchrony. In Experiment 3, children were given a mark-test involving only their legs. Again, a video version was more difficult than previously reported performance with mirrors, suggesting that the impossibility of eye-contact in video cannot explain this developmental asynchrony. The findings suggest that self-recognition can be added to the growing list of contexts in which 2-year-olds display what has been called a "video deficit" [Anderson, D. R., & Pempek, T. A. (2005). Television and very young children. American Behavioral Scientist, 48, 505-532].

Three-, 4- and 5-year-old children were asked to report something that they did do yesterday and something that they were going to do tomorrow. They were also asked to recall events that had not occurred yesterday, and predict events that would not occur tomorrow. In two studies these simple questions revealed striking age differences in the ability to report personal events from the past and the future. Only a minority of 3-year-olds but a majority of the older children were able to appropriately answer these questions. These findings substantiate the proposal that the ability to recall past events and the ability to predict future events (i.e., mental time travel), emerge in tandem between the ages of 3 and 5 years. (c) 2005 Elsevier Inc. All rights reserved.

Mechanisms that produce behavior which increase future survival chances provide an adaptive advantage. The flexibility of human behavior is at least partly the result of one such mechanism, our ability to travel mentally in time and entertain potential future scenarios. We can study mental time travel in children using language. Current results suggest that key developments occur between the ages of three to five. However, linguistic performance can be misleading as language itself is developing. We therefore advocate the use of methodologies that focus on future-oriented action. Mental time travel required profound changes in humans' motivational system, so that current behavior could be directed to secure not just present, but individually anticipated future needs. Such behavior should be distinguishable from behavior based on current drives, or on other mechanisms. We propose an experimental paradigm that provides subjects with an opportunity to act now to satisfy a need not currently experienced. This approach may be used to assess mental time travel in nonhuman animals. We conclude by describing a preliminary study employing an adaptation of this paradigm for children. (c) 2005 Elsevier Inc. All rights reserved.

Children with autistic spectrum disorder (ASD) may have poor audio-visual integration, possibly reflecting dysfunctional 'mirror neuron' systems which have been hypothesised to be at the core of the condition. In the present study, a computer program, utilizing speech synthesizer software and a 'virtual' head (Baldi), delivered speech stimuli for identification in auditory, visual or bimodal conditions. Children with ASD were poorer than controls at recognizing stimuli in the unimodal conditions, but once performance on this measure was controlled for, no group difference was found in the bimodal condition. A group of participants with ASD were also trained to develop their speech-reading ability. Training improved visual accuracy and this also improved the children's ability to utilize visual information in their processing of speech. Overall results were compared to predictions from mathematical models based on integration and non-integration, and were most consistent with the integration model. We conclude that, whilst they are less accurate in recognizing stimuli in the unimodal condition, children with ASD show normal integration of visual and auditory speech stimuli. Given that training in recognition of visual speech was effective, children with ASD may benefit from multi-modal approaches in imitative therapy and language training.

This study investigated whether children's ability to recognize themselves in delayed video feedback indicates changes in self-awareness (Povinelli, Landau, & Perilloux, 1996,Child Development,67, 1540–1554). Children were presented with 3-min-old videos of themselves to test whether they would investigate the current state of affairs upon seeing a surprising element in the video. In one condition, a sticker had been covertly placed into the child's hair, and in another an object had been hidden in a box. Both conditions proved equally difficult and performance correlated. Four-year-olds performed better than 3-year-olds, and children who failed the tasks retrieved the “surprise” item when presented with a mirror. There was no evidence to suggest that children's difficulties were due to immature metarepresentational thinking, lack of experience, problems with the questions, or problems appreciating the correspondence between image and referent. Yet, the parallel results in both conditions and the likelihood of false positives and false negatives indicate that the video test in its present form may not be a valid measure of differences in self-awareness.

A Q & A interview with Thomas Suddendorf, Professor of Psychology at the University of Queensland, Australia, whose research on the development of mental capacities in young children and in nonhuman animals seeks to answer fundamental questions about the nature and evolution of the human mind.

Over 15 years ago, Michael Corballis and I first discussed the evolution of the human capacity to travel mentally in time [1]. Extensive research has since aimed to demonstrate similar nonhuman animal capacities [2], but Corballis and I have repeatedly found the evidence wanting [3,4]. It is hence noteworthy that, in light of new neuroscientific data [5,6], Corballis is now questioning whether mental time travel is uniquely human [7]. Here, I outline reasons why I think the evidence fails to show that animals travel mentally in time as humans do.

In response to our recent paper on mental time travel (MTT) in animals [1], Clayton et al. [2] defend their own case for episodic-like memory in scrub jays. Other than suggesting an alternative label, ‘www-memory’, that we thought less likely to conjure up unwanted notions of human phenomenology, we did not actually argue with their case. Contrary to their reading, we did not question the evidence for episodic-like memory, nor did we list new necessary criteria for it. Scrub jays demonstrate episodic-like memory.

Elsewhere in this issue (p. 388) Josep Call summarizes an elegant series of studies in support of the conclusion that chimpanzees use a form of ‘knowledge abstraction’ to solve novel social problems, including those requiring recognition of what competitors may be informed about through having ‘seen’ objects or events. Call rightly notes that this is consistent with the ‘intervening variables’ mental model previously developed by one of us 1xWhen does smart behaviour reading become mindreading?. Whiten, A. : 277–292CrossrefSee all References1, the significance of which he recognizes and outlines accurately. However, two issues require refinement if confusion is to be avoided in future discussion of the alternative explanations Call goes on to discuss.First, Call describes the intervening variables model as ‘a kind of meta-representational account’. This is correct when ‘meta-representational’ is used as a synonym for ‘second-order’ representations of the kind ‘X thinks that Y knows where the banana is’. This was what Leslie did in considering the origins of theory of mind in children 2xPretense and representation in infancy: the origins of ‘theory of mind’. Leslie, A.M. Psychol Rev. 1987; 94: 84–106Crossref | PubMedSee all References2, and Whiten and Byrne followed this usage in analysing ape cognition 3xThe emergence of metarepresentation in human ontogeny and primate phylogeny. Whiten, A. and Byrne, R.W. : 267–281See all References3. Perner, however, argued that ‘meta-representation’ should be a term reserved for representation of the concept of representation itself 4xPerner, J. See all References4. Children are assumed to have achieved this only when they become able to attribute false beliefs, implying a capacity to represent the possibility of mis-representation 4xPerner, J. See all References4. This sense of ‘meta-representation’ has become common in developmental psychology.Perner distinguished three steps in children's cognitive development, culminating in a capacity for meta-representation (i.e. the third step) 4xPerner, J. See all References4. Step 1 is characterized by ‘primary representations’ only, that function essentially to represent the world as it is. In the second year, however, Perner postulated the achievement of ‘secondary representation’, which makes use of, yet goes beyond, primary representation. Secondary representation adds the ability to model hypothetical situations, making possible the entertainment of multiple, simultaneous, mental models. This development is proposed to explain the emergence of a suite of capacities including pretence, means-ends reasoning and the beginnings of mental attribution. In mental attribution, the operation of multiple models means that the child is able to recognize that although she sees or knows about a specific thing, another individual may not. This is the task set in the ape experiments Call describes. Whiten 5xImitation, pretence and mindreading: secondary representation in comparative primatology and developmental psychology?. Whiten, A. : 300–324See all References5 and Suddendorf 6xThe rise of the metamind. Suddendorf, T. : 218–260See all References6 independently suggested that the concept of secondary representation fits not only the level of mental attribution achieved by apes, but is also consistent with other aspects of ape cognition that map to the correlations observed in children's cognitive development. In a paper published this month 7xMental evolution and development: evidence for secondary representation in children, great apes and other animals. Suddendorf, T. and Whiten, A. Psychol Bull. 2001; 127: 629–650Crossref | PubMedSee all References7, we examine the evidence for this hypothesis more thoroughly. Although we interpret the data as supporting secondary representation in apes, thus far it suggests that meta-representation in the sense advocated by Perner 4xPerner, J. See all References4 is not achieved. One of the most compelling demonstrations of this is an experiment on false-belief attribution performed by Call et al.8xA non-verbal false belief task: the performance of children and great apes. Call, J. and Tomasello, M. Child Dev. 1999; 70: 381–395Crossref | PubMedSee all References8 (not cited in Call's present paper). By contrast, the case portrayed in Call's Box 2 Figure (last part) does imply meta-representation of the ‘Perner kind’, for it involves the intentional creation of a false belief. However, an intervening variable that signified only ‘seeing’ or ‘knowing’ (versus ignorance) need not operate at this complex level. It is consistent with secondary representation. There is thus no disagreement between what we and Call have written: his Figure is indeed not consistent with the mentality of apes as demonstrated by current research.The second major issue is Call's assertion that ‘insight into other's subjective experience is a key component of the (‘meta-representational’) account’ attributed to one of us 1xWhen does smart behaviour reading become mindreading?. Whiten, A. : 277–292CrossrefSee all References1. This is not necessarily the case. The jury still appears to be out on the extent to which intervening variables, as mental states attributed to others, should be thought to contain ‘subjective experiences’ of the person doing the mindreading, even in humans. Some states, of which seeing and knowing are likely examples, might be represented only in the austere terms of their epistemic or information-processing significance. Perhaps if the mindreading process were to operate by mental simulation of others, as some suggest 9xRadical’ simulationism. Gordon, R.M. : 11–21CrossrefSee all References9, the notion of attributing ‘subjective experiences’ would seem to become more appropriate. Gordon, indeed, has described simulation models as ‘hot’, in contrast to models that postulate that children use a ‘cold’ theory-building appoach to mindreading 9xRadical’ simulationism. Gordon, R.M. : 11–21CrossrefSee all References9. However, Gordon is also at pains to point out that his own simulation model does not rest upon introspection. In any case, the extent to which either simulation or theory models are correct remains to be empirically established.The work Call describes is amongst the most fruitful in the area. Our efforts to clarify some residual but important potential confusions should be read in the context of our broad and emphatic approval for the approaches now being taken.