Evolutionary Psychology of Spatial Representations in the Hominidae

How can I find what I want? Can children, chimpanzees and capuchin monkeys form abstract representations to guide their behavior in a sampling task?

concepts are a powerful tool for making wide-ranging predictions in new situations based on little experience. Whereas looking-time studies suggest an early emergence of this ability in human infancy, other paradigms like the relational match to sample task often fail to detect abstract concepts until late preschool years. Similarly, non-human animals show difficulties and often succeed only after long training regimes. Given the considerable influence of slight task modifications, the conclusiveness of these findings for the development and phylogenetic distribution of abstract reasoning is debated. Here, we tested the abilities of 3 to 5-year-old children, chimpanzees, and capuchin monkeys in a unified and more ecologically valid task design based on the concept of "overhypotheses" (Goodman, 1955). Participants sampled high- and low-valued items from containers that either each offered items of uniform value or a mix of high- and low-valued items. In a test situation, participants should switch away earlier from a container offering low-valued items when they learned that, in general, items within a container are of the same type, but should stay longer if they formed the overhypothesis that containers bear a mix of types. We compared each species' performance to the predictions of a probabilistic hierarchical Bayesian model forming overhypotheses at a first and second level of abstraction, adapted to each species' reward preferences. Children and, to a more limited extent, chimpanzees demonstrated their sensitivity to abstract patterns in the evidence. In contrast, capuchin monkeys did not exhibit conclusive evidence for the ability of abstract knowledge formation.

Cognitive and sensory capacity each contribute to the canine spatial bias

Dogs interpret cues as being about location, which human infants would relate to objects. This spatial bias could shed light on the evolution of object-centered thought, however, research needs to rule out that this is not a by-product of dogs' weaker (compared to humans) visual capacities. In this study, we used a data set in which dogs were tested in two types of learning tasks (discrimination and reversal learning) with two types of rewarded cues (location and object features). In both tasks, dogs displayed spatial bias, that is, faster learning when the rewarded cue was a location. We investigated how sensory and cognitive capacity each contributes to this spatial bias. To this end, an estimate for general cognitive ability (g) was obtained from a battery of tests for some of the dogs. Cephalic index, a feature targeted in breeding and linked to differences in visual capacity, correlated negatively with the expression of spatial bias only in the easier discrimination learning task, while a negative correlation between g factor and spatial bias scores emerged in the more difficult reversal learning task. We conclude that dogs' spatial bias cannot be reduced to a sensory limitation and is easier to overcome with greater cognitive capacity.

Relational reasoning in wild bumblebees revisited: the role of distance

In reasoning tasks, non-human animals attend more to relational than to object similarity. It is precisely this focus on relational similarity that has been argued to explain the reasoning gap between humans and other animals. Work with humans has revealed that objects placed near each other are represented to be more similar than objects placed farther apart. Will distance between objects also affect non-human animals' abilities to represent and reason about objects? To test this, wild bumblebees were presented with a spatial reasoning task (with competing object matches) in which the objects or features alone (colour, shape) were placed close together or far apart. Bumblebees spontaneously attended to objects over relations, but only when the objects were far apart. Features alone were not strong enough to drive object matching-suggesting that bumblebees bound colour and shape into their object representations. These findings question whether the ability to focus on and compare objects is what makes human abstract reasoning unique.

Great ape cognition is structured by stable cognitive abilities and predicted by developmental conditions

Great ape cognition is used as a reference point to specify the evolutionary origins of complex cognitive abilities, including in humans. This research often assumes that great ape cognition consists of cognitive abilities (traits) that account for stable differences between individuals, which change and develop in response to experience. Here, we test the validity of these assumptions by assessing repeatability of cognitive performance among captive great apes (Gorilla gorilla, Pongo abelii, Pan paniscus, Pan troglodytes) in five tasks covering a range of cognitive domains. We examine whether individual characteristics (age, group, test experience) or transient situational factors (life events, testing arrangements or sociality) influence cognitive performance. Our results show that task-level performance is generally stable over time; four of the five tasks were reliable measurement tools. Performance in the tasks was best explained by stable differences in cognitive abilities (traits) between individuals. Cognitive abilities were further correlated, suggesting shared cognitive processes. Finally, when predicting cognitive performance, we found stable individual characteristics to be more important than variables capturing transient experience. Taken together, this study shows that great ape cognition is structured by stable cognitive abilities that respond to different developmental conditions.

The origins of cognitive flexibility in chimpanzees

Cognitive flexibility is a core component of executive function, a suite of cognitive capacities that enables individuals to update their behavior in dynamic environments. Human executive functions are proposed to be enhanced compared to other species, but this inference is based primarily on neuroanatomical studies. To address this, we examined the nature and origins of cognitive flexibility in chimpanzees, our closest living relatives. Across three studies, we examined different components of cognitive flexibility using reversal learning tasks where individuals first learned one contingency and then had to shift responses when contingencies flipped. In Study 1, we tested n = 82 chimpanzees ranging from juvenility to adulthood on a spatial reversal task, to characterize the development of basic shifting skills. In Study 2, we tested how n = 24 chimpanzees use spatial versus arbitrary perceptual information to shift, a proposed difference between human and nonhuman cognition. In Study 3, we tested n = 40 chimpanzees on a probabilistic reversal task. We found an extended developmental trajectory for basic shifting and shifting in response to probabilistic feedback-chimpanzees did not reach mature performance until late in ontogeny. Additionally, females were faster to shift than males were. We also found that chimpanzees were much more successful when using spatial versus perceptual cues, and highly perseverative when faced with probabilistic versus consistent outcomes. These results identify both core features of chimpanzee cognitive flexibility that are shared with humans, as well as constraints on chimpanzee cognitive flexibility that may represent evolutionary changes in human cognitive development.

Specialization in the vicarious learning of novel arbitrary sequences in humans but not orangutans

Sequence learning underlies many uniquely human behaviours, from complex tool use to language and ritual. To understand whether this fundamental cognitive feature is uniquely derived in humans requires a comparative approach. We propose that the vicarious (but not individual) learning of novel arbitrary sequences represents a human cognitive specialization. To test this hypothesis, we compared the abilities of human children aged 3-5 years and orangutans to learn different types of arbitrary sequences (item-based and spatial-based). Sequences could be learned individually (by trial and error) or vicariously from a human (social) demonstrator or a computer (ghost control). We found that both children and orangutans recalled both types of sequence following trial-and-error learning; older children also learned both types of sequence following social and ghost demonstrations. Orangutans' success individually learning arbitrary sequences shows that their failure to do so in some vicarious learning conditions is not owing to general representational problems. These results provide new insights into some of the most persistent discontinuities observed between humans and other great apes in terms of complex tool use, language and ritual, all of which involve the cultural learning of novel arbitrary sequences. This article is part of the theme issue 'Ritual renaissance: new insights into the most human of behaviours'.

Travel linearity and speed of human foragers and chimpanzees during their daily search for food in tropical rainforests

To understand the evolutionary roots of human spatial cognition, researchers have compared spatial abilities of humans and one of our closest living relatives, the chimpanzee (Pan troglodytes). However, how humans and chimpanzees compare in solving spatial tasks during real-world foraging is unclear to date, as measuring such spatial abilities in natural habitats is challenging. Here we compared spatial movement patterns of the Mbendjele BaYaka people and the Taï chimpanzees during their daily search for food in rainforests. We measured linearity and speed during off-trail travels toward out-of-sight locations as proxies for spatial knowledge. We found similarly high levels of linearity in individuals of Mbendjele foragers and Taï chimpanzees. However, human foragers and chimpanzees clearly differed in their reactions to group size and familiarity with the foraging areas. Mbendjele foragers increased travel linearity with increasing familiarity and group size, without obvious changes in speed. This pattern was reversed in Taï chimpanzees. We suggest that these differences between Mbendjele foragers and Taï chimpanzees reflect their different ranging styles, such as life-time range size and trail use. This result highlights the impact of socio-ecological settings on comparing spatial movement patterns. Our study provides a first step toward comparing long-range spatial movement patterns of two closely-related species in their natural environments.

Chimpanzees flexibly update working memory contents and show susceptibility to distraction in the self-ordered search task

Working memory (WM) is a core executive function that allows individuals to hold, process and manipulate information. WM capacity has been repeatedly nominated as a key factor in human cognitive evolution; nevertheless, little is known about the WM abilities of our closest primate relatives. In this study, we examined signatures of WM ability in chimpanzees (Pan troglodytes). Standard WM tasks for humans (Homo sapiens) often require participants to continuously update their WM. In Experiment 1, we implemented this updating requirement in a foraging situation: zoo-housed chimpanzees (n = 13) searched for food in an array of containers. To avoid redundant searches, they needed to continuously update which containers they had already visited (similar to WM paradigms for human children) with 15 s retention intervals in between each choice. We examined chimpanzees' WM capacity and to what extent they used spatial cues and object features to memorize their previous choices. In Experiment 2, we investigated how susceptible their WM was to attentional interference, an important signature, setting WM in humans apart from long-term memory. We found large individual differences with some individuals remembering at least their last four choices. Chimpanzees used a combination of spatial cues and object features to remember which boxes they had chosen already. Moreover, their performance decreased specifically when competing memory information was introduced. Finally, we found that individual differences in task performance were highly reliable over time. Together, these findings show remarkable similarities between human and chimpanzee WM abilities despite evolutionary and life-history differences.

Heterochrony in chimpanzee and bonobo spatial memory development

OBJECTIVES

The emergence of human-unique cognitive abilities has been linked to our species' extended juvenile period. Comparisons of cognitive development across species can provide new insights into the evolutionary mechanisms shaping cognition. This study examined the development of different components of spatial memory, cognitive mechanisms that support complex foraging, by comparing two species with similar life history that vary in wild ecology: bonobos (Pan paniscus) and chimpanzees (Pan troglodytes).

MATERIALS AND METHODS

Spatial memory development was assessed using a cross-sectional experimental design comparing apes ranging from infancy to adulthood. Study 1 tested 73 sanctuary-living apes on a task examining recall of a single location after a 1-week delay, compared to an earlier session. Study 2 tested their ability to recall multiple locations within a complex environment. Study 3 examined a subset of individuals from Study 2 on a motivational control task.

RESULTS

In Study 1, younger bonobos and chimpanzees of all ages exhibited improved performance in the test session compared to their initial learning experience. Older bonobos, in contrast, did not exhibit a memory boost in performance after the delay. In Study 2, older chimpanzees exhibited an improved ability to recall multiple locations, whereas bonobos did not exhibit any age-related differences. In Study 3, both species were similarly motivated to search for food in the absence of memory demands.

DISCUSSION

These results indicate that closely related species with similar life history characteristics can exhibit divergent patterns of cognitive development, and suggests a role of socioecological niche in shaping patterns of cognition in Pan.

Why Cross-Cultural Psychology Is Incomplete Without Comparative and Developmental Perspectives

We argue that comparing adult behavior and cognition across cultures is insufficient to capture the multifaceted complexity of cultural variation. We champion a multidisciplinary perspective that draws on biological and psychological theory and methods. We provide examples for ways in which cross-cultural, developmental, and comparative studies might be combined to unravel the interplay between universal species-typical behaviors and behavioral variation across groups and, at the same time, to explain uniquely human cultural diversity by identifying the unique and universal patterns of human behavior and cognition in early childhood that create, structure, and maintain variation across groups. Such a perspective adds depth to explanations of cultural variation and universality and firmly roots accounts of human culture in a broader, biological framework. We believe that, therefore, the field of cross-cultural psychology may benefit from combining efforts with comparative and developmental psychologists.

The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds' Search Performance in Spatial Rotation Tasks

Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N = 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children.

Eye Contact Affects Object Representation in 9-Month-Old Infants

Social cues in interaction with others enable infants to extract useful information from their environment. Although previous research has shown that infants process and retain different information about an object depending on the presence of social cues, the effect of eye contact as an isolated independent variable has not been investigated. The present study investigated how eye contact affects infants' object processing. Nine-month-olds engaged in two types of social interactions with an experimenter. When the experimenter showed an object without eye contact, the infants processed and remembered both the object's location and its identity. In contrast, when the experimenter showed the object while making eye contact with the infant, the infant preferentially processed object's identity but not its location. Such effects might assist infants to selectively attend to useful information. Our findings revealed that 9-month-olds' object representations are modulated in accordance with the context, thus elucidating the function of eye contact for infants' object representation.

Reading the landscape: Legible environments and hominin dispersals

Wayfinding, or the ability to plan and navigate a course over the landscape, is a subject of investigation in geography, neurophysiology, psychology, urban planning, and landscape design. With the prevalence of GPS-assisted navigation systems, or "wayfinders," computer scientists are also increasingly interested in understanding how people plan their movements and guide others. However, the importance of wayfinding as a process that regulates human mobility has only recently been incorporated into archeological research design. Hominin groups were able to disperse widely during the course of prehistory. The scope of these dispersals speaks to the innate navigation abilities of hominins. Their long-term success must have depended on an ability to communicate spatial information effectively. Here, we consider the extent to which some landscapes may have been more conducive to wayfinding than others. We also describe a tool we have created for quantifying landscape legibility (sensu Gollege), a complex and under-explored concept in archeology, with a view to investigating the impact of landscape structure on human wayfinding and thus, patterns of dispersal during prehistory. To this end, we have developed a method for quantifying legibility using a Geographic Information System (GIS) and apply it to a test case in prehistoric Iberia.

[The evolution of human cultural behavior: notes on Darwinism and complexity]

The article analyzes three schools that can be understood as central in studies of the evolution of human behavior within the paradigm of evolution by natural selection: human behavioral ecology (HBE), evolutionary psychology, and dual inheritance. These three streams of thought are used to depict the Darwinist landscape and pinpoint its strong suits and limitations. Theoretical gaps were identified that seem to reduce these schools' ability to account for the diversity of human evolutionary behavior. Their weak points include issues related to the concept of reproductive success, types of adaptation, and targets of selection. An interdisciplinary approach is proposed as the solution to this dilemma, where complex adaptive systems would serve as a source.

Feature or location? Infants and adults adopt different strategies to search for a hidden toy in an ambiguous task

Evidence suggests that infants and adults attribute different importance to certain object properties when performing object-directed actions. Namely, infants tend to rely on information about an object's location, whereas adults are more likely to base their actions on its features. In this study, we tested whether the strategic choices of infants (aged 13 months) and adults would be modified by the context of the demonstration. Participants watched as an experimenter hid a ball under one of two different coloured containers, using either a communicative or a non-communicative manner. Then, the locations of the two containers were changed out of sight of the participant. During the test, participants were encouraged to look for the ball under one of the containers. We found that adults were more likely to follow a feature-based strategy than infants. However, there was no effect of the context of the demonstration, suggesting that communication may play different roles in encoding object properties and directing overt behaviour.

Chimpanzees and bonobos exhibit divergent spatial memory development

Spatial cognition and memory are critical cognitive skills underlying foraging behaviors for all primates. While the emergence of these skills has been the focus of much research on human children, little is known about ontogenetic patterns shaping spatial cognition in other species. Comparative developmental studies of nonhuman apes can illuminate which aspects of human spatial development are shared with other primates, versus which aspects are unique to our lineage. Here we present three studies examining spatial memory development in our closest living relatives, chimpanzees (Pan troglodytes) and bonobos (P. paniscus). We first compared memory in a naturalistic foraging task where apes had to recall the location of resources hidden in a large outdoor enclosure with a variety of landmarks (Studies 1 and 2). We then compared older apes using a matched memory choice paradigm (Study 3). We found that chimpanzees exhibited more accurate spatial memory than bonobos across contexts, supporting predictions from these species' different feeding ecologies. Furthermore, chimpanzees - but not bonobos - showed developmental improvements in spatial memory, indicating that bonobos exhibit cognitive paedomorphism (delays in developmental timing) in their spatial abilities relative to chimpanzees. Together, these results indicate that the development of spatial memory may differ even between closely related species. Moreover, changes in the spatial domain can emerge during nonhuman ape ontogeny, much like some changes seen in human children.

Rotational displacement skills in rhesus macaques (Macaca mulatta)

Rotational displacement tasks, in which participants must track an object at a hiding location within an array while the array rotates, exhibit a puzzling developmental pattern in humans. Human children take an unusually long time to master this task and tend to solve rotational problems through the use of nongeometric features or landmarks as opposed to other kinds of spatial cues. We investigated whether these developmental characteristics are unique to humans by testing rotational displacement skills in a monkey species, the rhesus macaque (Macaca mulatta), using a looking-time method. Monkeys first saw food hidden in two differently colored boxes within an array. The array was then rotated 180° and the boxes reopened to reveal the food in an expected or unexpected location. Our first two experiments explored the developmental time-course of performance on this rotational displacement task. We found that adult macaques looked longer at the unexpected event, but such performance was not mirrored in younger-aged macaques. In a third study, we systematically varied featural information and visible access to the array to investigate which strategies adult macaques used in solving rotational displacements. Our results show that adult macaques need both sets of information to solve the task. Taken together, these results suggest both similarities and differences in mechanisms by which human and nonhuman primates develop this spatial skill.

Children's reasoning about spatial relational similarity: the effect of alignment and relational complexity

We investigated 4- and 5-year-old children's mapping strategies in a spatial task. Children were required to find a picture in an array of three identical cups after observing another picture being hidden in another array of three cups. The arrays were either aligned one behind the other in two rows or placed side by side forming one line. Moreover, children were rewarded for two different mapping strategies. Half of the children needed to choose a cup that held the same relative position as the rewarded cup in the other array; they needed to map left-left, middle-middle, and right-right cups together (aligned mapping), which required encoding and mapping of two relations (e.g., the cup left of the middle cup and left of the right cup). The other half needed to map together the cups that held the same relation to the table's spatial features-the cups at the edges, the middle cups, and the cups in the middle of the table (landmark mapping)-which required encoding and mapping of one relation (e.g., the cup at the table's edge). Results showed that children's success was constellation dependent; performance was higher when the arrays were aligned one behind the other in two rows than when they were placed side by side. Furthermore, children showed a preference for landmark mapping over aligned mapping.

Great apes use landmark cues over spatial relations to find hidden food

We investigated whether chimpanzees, bonobos, and orangutans encoded the location of a reward hidden underneath one of three identical cups in relation to (1) the other cups in the array-i.e., the relative position of the baited cup within the array; or (2) the landmarks surrounding the cups-e.g., the edge of the table. Apes witnessed the hiding of a food reward under one of three cups forming a straight line on a platform. After 30 s, they were allowed to search for the reward. In three different experiments, we varied the distance of the cups to the edge of the platform and the distance between the cups. Results showed that both manipulated variables affected apes' retrieval accuracy. Subjects' retrieval accuracy was higher for the outer cups compared with the Middle cup, especially if the outer cups were located next to the platform's edge. Additionally, the larger the distance between the cups, the better performance became.

Origins of spatial, temporal and numerical cognition: Insights from comparative psychology

Contemporary comparative cognition has a large repertoire of animal models and methods, with concurrent theoretical advances that are providing initial answers to crucial questions about human cognition. What cognitive traits are uniquely human? What are the species-typical inherited predispositions of the human mind? What is the human mind capable of without certain types of specific experiences with the surrounding environment? Here, we review recent findings from the domains of space, time and number cognition. These findings are produced using different comparative methodologies relying on different animal species, namely birds and non-human great apes. The study of these species not only reveals the range of cognitive abilities across vertebrates, but also increases our understanding of human cognition in crucial ways.

The weirdest people in the world?

Behavioral scientists routinely publish broad claims about human psychology and behavior in the world's top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies. Researchers – often implicitly – assume that either there is little variation across human populations, or that these “standard subjects” are as representative of the species as any other population. Are these assumptions justified? Here, our review of the comparative database from across the behavioral sciences suggests both that there is substantial variability in experimental results across populations and that WEIRD subjects are particularly unusual compared with the rest of the species – frequent outliers. The domains reviewed include visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ. The findings suggest that members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans. Many of these findings involve domains that are associated with fundamental aspects of psychology, motivation, and behavior – hence, there are no obviousa priorigrounds for claiming that a particular behavioral phenomenon is universal based on sampling from a single subpopulation. Overall, these empirical patterns suggests that we need to be less cavalier in addressing questions ofhumannature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity. We close by proposing ways to structurally re-organize the behavioral sciences to best tackle these challenges.

Video Games and Spatial Cognition

Video game enthusiasts spend many hours at play, and this intense activity has the potential to alter both brain and behavior. We review studies that investigate the ability of video games to modify processes in spatial cognition. We outline the initial stages of research into the underlying mechanisms of learning, and we also consider possible applications of this new knowledge. Several experiments have shown that playing action games induces changes in a number of sensory, perceptual, and attentional abilities that are important for many tasks in spatial cognition. These basic capacities include contrast sensitivity, spatial resolution, the attentional visual field, enumeration, multiple object tracking, and visuomotor coordination and speed. In addition to altering performance on basic tasks, playing action video games has a beneficial effect on more complex spatial tasks such as mental rotation, thus demonstrating that learning generalizes far beyond the training activities in the game. Far transfer of this sort is generally elusive in learning, and we discuss some early attempts to elucidate the brain functions that are responsible. Finally, we suggest that studying video games may contribute not only to an improved understanding of the mechanisms of learning but may also offer new approaches to teaching spatial skills.

Bonobos, chimpanzees, gorillas, and orang utans use feature and spatial cues in two spatial memory tasks

Animals commonly use feature and spatial strategies when remembering places of interest such as food sources or hiding places. We conducted three experiments with great apes to investigate strategy preferences and factors that may shape them. In the first experiment, we trained 17 apes to remember 12 different food locations on the floor of their sleeping room. The 12 food locations were associated with one feature cue, so that feature and spatial cues were confounded. In a single test session, we brought the cues into conflict and found that apes, irrespective of species, showed a preference for a feature strategy. In the second experiment, we used a similar procedure and trained 25 apes to remember one food location on a platform in front of them. On average, apes preferred to use a feature strategy but some individuals relied on a spatial strategy. In the final experiment, we investigated whether training might influence strategy preferences. We tested 21 apes in the platform set-up and found that apes used both, feature and spatial strategies irrespective of training. We conclude that apes can use feature and spatial strategies to remember the location of hidden food items, but that task demands (e.g. different numbers of search locations) can influence strategy preferences. We found no evidence, however, for the role of training in shaping these preferences.

Random Walker Test: a computerized alternative to the Road-Map Test

The Road-Map Test (RMT) is a popular neurological assessment of left-right orientation, using a simplified road map. Inspired by the RMT, we developed a new computerized navigation test, the Random Walker Test (RWT), for further quantitative assessment of left-right orientation ability. RWT provides verbal or nonverbal instructions for the direction (left, right, or front) in which to proceed, and participants must judge the spatially correct direction. Perspectives rotate by 90 degrees during navigation. Verbal judgments demand verbal-to-spatial mapping of left/right/front and, if necessary, egocentric perspective rotation. Using the RWT, we evaluated the left-right orientation of normal male participants. The RWT reliably recorded the response times and error rates for participant performance and also revealed egocentric perspective rotation as an unreliable mental process with large intra- and interpersonal variability. These results indicate that the RWT may be useful in investigating left-right orientation and/or egocentric perspective rotation in both normal participants and neuropathological patients.

Regional Differences in Spatial Frame of Reference Systems for People in Different Areas of China

Levinson defined spatial frame of reference systems into three types and found that people who spoke different languages all over the world had different habits in the use of these systems. Some quasi-experimental designed research in China suggested that Chinese people in various areas had different preferences for frame of reference systems in nonlinguistic spatial tasks. In this study, a newly designed and strictly controlled laboratory experiment was conducted to measure performance on linguistic spatial tasks. Response times of two groups of participants, respectively selected from the north (10 men and 12 women; M age = 24 yr., SD = 4) and south (11 men and 12 women; M age = 24 yr., SD = 3) of China, were compared on processing of spatial terms used in different systems: absolute (e.g., east) versus relative (e.g., right). To reduce the effect of living experience, the Northern participants with less than 4 yr. living experience in the south of China were included, and vice versa. Analysis showed that Southerners, but not Northerners, differed in response times to terms between absolute and relative systems. This finding suggests that speed of processing spatial terms differs among people who speak the uniform language Mandarin but live in geographically distinct home areas in China and use different frame of reference systems.

Great apes' capacities to recognize relational similarity

Recognizing relational similarity relies on the ability to understand that defining object properties might not lie in the objects individually, but in the relations of the properties of various object to each other. This aptitude is highly relevant for many important human skills such as language, reasoning, categorization and understanding analogy and metaphor. In the current study, we investigated the ability to recognize relational similarities by testing five species of great apes, including human children in a spatial task. We found that all species performed better if related elements are connected by logico-causal as opposed to non-causal relations. Further, we find that only children above 4 years of age, bonobos and chimpanzees, unlike younger children, gorillas and orangutans display some mastery of reasoning by non-causal relational similarity. We conclude that recognizing relational similarity is not in its entirety unique to the human species. The lack of a capability for language does not prohibit recognition of simple relational similarities. The data are discussed in the light of the phylogenetic tree of relatedness of the great apes.

Communication-induced memory biases in preverbal infants

Human teaching, a highly specialized form of cooperative information transmission, depends not only on the presence of benevolent communicators in the environment, but also on the preparedness of the students to learn from communication when it is addressed to them. We tested whether 9-month-old human infants can distinguish between communicative and noncommunicative social contexts and whether they retain qualitatively different information about novel objects in these contexts. We found that in a communicative context, infants devoted their limited memory resources to encoding the identity of novel objects at the expense of encoding their location, which is preferentially retained in noncommunicative contexts. We propose that infants' sensitivity to, and interpretation of, the social cues distinguishing infant-directed communication events represent important mechanisms of social learning by which others can help determine what information even preverbal human observers retain in memory.

Past and present challenges in theory of mind research in nonhuman primates

This paper presents the trajectory of theory of mind research in nonhuman primates, with a special focus on chimpanzees as they have been the most intensely studied species. It analyzes the main developments in the field, the critiques that they raised, the responses that they have generated and the current challenges faced by the field. Currently, the most plausible working hypothesis is that at least chimpanzees know what others can and cannot see. Using tasks with a high ecological validity and mapping out key concepts such association and inference are postulated as fundamental steps to further advance our knowledge in this area.

Spatial cognition in apes and humans

The debate on whether language influences cognition is sometimes seen as a simple dichotomy: cognitive development is governed either by innate predispositions or by influences of language and culture. In two recent papers on spatial cognition, Haun and colleagues break new ground in bringing together a comparative cognition approach with a cross-linguistic framework to arrive at a third position: that humans begin with the same spatial reference frames as our near relatives, the great apes, and diverge later owing to the influence of language and culture.

Cognitive cladistics and cultural override in Hominid spatial cognition

Current approaches to human cognition often take a strong nativist stance based on Western adult performance, backed up where possible by neonate and infant research and almost never by comparative research across the Hominidae. Recent research suggests considerable cross-cultural differences in cognitive strategies, including relational thinking, a domain where infant research is impossible because of lack of cognitive maturation. Here, we apply the same paradigm across children and adults of different cultures and across all nonhuman great ape genera. We find that both child and adult spatial cognition systematically varies with language and culture but that, nevertheless, there is a clear inherited bias for one spatial strategy in the great apes. It is reasonable to conclude, we argue, that language and culture mask the native tendencies in our species. This cladistic approach suggests that the correct perspective on human cognition is neither nativist uniformitarian nor "blank slate" but recognizes the powerful impact that language and culture can have on our shared primate cognitive biases.

Apes know that hidden objects can affect the orientation of other objects

Four bonobos, seven gorillas, and six orangutans were presented with two small rectangular boards on a platform. One of the boards had a piece of food under it so that it acquired an inclined orientation whereas the other remained flat on the platform. Subjects preferentially selected the inclined board. In another experiment, subjects were initially presented with two inclined boards and a transformation took place in which one of the boards fell flat to the platform while the other remained inclined. Subjects also preferred the board that remained inclined. Two additional experiments highlighted some of the possible limitations of their reasoning in this task. Presented with two inclined boards, one of which was visibly supported by a piece of wood, they failed to systematically select the unsupported one whose only reason for being inclined was the presence of the reward. Another experiment presented two rewards in each trial (instead of the customary one) in one of the following two combinations: large banana vs. small carrot or small banana vs. large carrot. Prior to the test, E presented both rewards to the subject and then hid each of them under one of the boards so that both boards were differentially inclined due to the different sizes of the rewards involved. Although subjects selected the board that showed a greater inclination (thus securing the larger reward), they disregarded the type of food that was involved. This often meant that they chose the large carrot over the small banana even though they reversed such a choice when the rewards were not occluded by the boards. Providing subjects with a 'reminder' of the type of reward hidden under the boards did not alter the original results. There was no evidence of learning throughout the various experiments and control tests ruled out the possibility of inadvertent cuing by the experimenter, poor performance due to a lack of motivation, or good performance due to a predisposition to select objects with sloped surfaces. It is concluded that subjects made some inferences about the reason for the inclined orientation of the boards, and not simply associated an inclined orientation with the presence of the reward.