Primates do not spontaneously use shape properties for object individuation: a competence or a performance problem?

Several recent studies have documented that non-human primates can individuate objects according to property and/or kind information in much the same way as human infants do from around one year of age when they begin to acquire language. Some studies suggest, however, that only some properties are used for the individuation of food items: color, but not shape. The present study investigated whether these findings reveal a true competence problem with shape properties in the food domain or whether they merely reveal a performance problem (e.g., lack of attention to shapes). We tested 25 great apes (chimpanzees, bonobos and gorillas) in two food individuation tasks. We manipulated subjects’ experience with differences in color and shape properties of food items. Results indicated (i) that all subjects, regardless of their prior experience, solved the color-based object individuation task and (ii) that only the group with previous experience with different shape properties succeeded in the shape-based individuation task. Great apes can thus be primed to take shape into account for individuating food objects, and this results clearly speaks in favor of a performance (rather than a competence) problem in using shape for object individuation of food items.     

Chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) quantify split solid objects

Recent research suggests that gorillas’ and orangutans’ object representations survive cohesion violations (e.g., a split of a solid object into two halves), but that their processing of quantities may be affected by them. We assessed chimpanzees’ (Pan troglodytes) and bonobos’ (Pan paniscus) reactions to various fission events in the same series of action tasks modelled after infant studies previously run on gorillas and orangutans (Cacchione and Call in Cognition 116:193–203, 2010b). Results showed that all four non-human great ape species managed to quantify split objects but that their performance varied as a function of the non-cohesiveness produced in the splitting event. Spatial ambiguity and shape invariance had the greatest impact on apes’ ability to represent and quantify objects. Further, we observed species differences with gorillas performing lower than other species. Finally, we detected a substantial age effect, with ape infants below 6 years of age being outperformed by both juvenile/adolescent and adult apes.     

Do gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus) fail to represent objects in the context of cohesion violations?

Recent research suggests that witnessing events of fission (e.g., the splitting of a solid object) impairs human infants’, human adults’, and non-human primates’ object representations. The present studies investigated the reactions of gorillas and orangutans to cohesion violation across different types of fission events implementing a behavioral paradigm previously used with human infants. Results suggest that fission events vary in their impact on representational abilities but do not destroy apes’ representations of continuously existing objects.     

Object permanence in adult common marmosets (Callithrix jacchus): not everything is an “A-not-B” error that seems to be one

In this paper, we describe a behaviour pattern similar to the “A-not-B” error found in human infants and young apes in a monkey species, the common marmosets (Callithrix jacchus). In contrast to the classical explanation, recently it has been suggested that the “A-not-B” error committed by human infants is at least partially due to misinterpretation of the hider’s ostensively communicated object hiding actions as potential ‘teaching’ demonstrations during the A trials. We tested whether this so-called Natural Pedagogy hypothesis would account for the A-not-B error that marmosets commit in a standard object permanence task, but found no support for the hypothesis in this species. Alternatively, we present evidence that lower level mechanisms, such as attention and motivation, play an important role in committing the “A-not-B” error in marmosets. We argue that these simple mechanisms might contribute to the effect of undeveloped object representational skills in other species including young non-human primates that commit the A-not-B error.     

Differences in gorilla nettle-feeding between captivity and the wild: local traditions,species typical behaviors or merely the result of nutritional deficiencies?

Behavioral and cognitive studies on captive apes often pay little attention to the specific environmental conditions of their study subjects. A recent report form Byrne et al. (Anim Cogn doi:, 2011), comparing nettle-feeding techniques between captive and wild gorillas, claimed to document “the strongest evidence yet to come from any great ape that observational learning of a skilled conspecific” can allow social learning and culture in gorillas. An earlier study with similar findings placed emphasis instead on the many similarities and claims for species typical behavior, thus a genetic hypothesis instead of a cultural hypothesis. This commentary aims at formulating a third environmental hypothesis based on path-dependent behavioral differences owing to different diet and availability of nutritional resources of wild and captive gorillas. Captive diet provides gorillas with a much lower concentration of fibers. Gorillas are hindgut fermenters, and this deficit of natural fermentation of fibers may impact their health and their behavior in zoos. Results of Byrne et al.’s study will be discussed comparing feeding choice and availability of nutritional resources of wild and captive gorillas, showing that in captivity gorilla, motivation to consume certain food or certain plant parts may differ drastically from that of wild gorillas. This view does not intend to deny that social learning and culture may exist in gorillas, but to guide and encourage future works investigating social learning in great apes to take more accurately into account the living conditions and, when comparing populations, the possible environmental differences.     

Joint Attention and Attachment in Toddlers with Autism

Joint attention is often referred to as a triadic relation between self, other and object. Young children with autism show deficiencies in the use of joint attention behaviors. Individual differences may be expected, and they may be determined by the children’s cognitive development or the characteristics of the relationship of the child with the caregiver. Although most joint attention skills develop under the age of three, most studies of joint attention in children with autism involved children older than 3 years of age, due to difficulties in diagnosing autism under this age. In this study we investigated joint attention behaviors of 78 young children (mean age 25.7 months, SD 6.1) with autism spectrum disorders (n = 20), other developmental delays (n = 18), and typically developing children (n = 40). Following the pertinent literature and confirmed by factor analysis, two types of joint attention behaviors were distinguished, Basic Joint Attention (BJA) and Associated Joint Attention (AJA). We found that cognitive delays and autistic symptoms—but not attachment insecurity or disorganization—were related to less joint attention. Already at the age of 2 years, children with more autistic symptoms show less joint attention, even after controlling for developmental level.     

Agents of Reform?: Children’s Literature and Philosophy

Children’s literature was first published in the eighteenth century at a time when the philosophical ideas of Jean-Jacques Rousseau on education and childhood were being discussed. Ironically, however, the first generation of children’s literature (by Maria Edgeworth et al) was incongruous with Rousseau’s ideas since the works were didactic, constraining and demanded passive acceptance from their readers. This instigated a deficit or reductionist model to represent childhood and children’s literature as simple and uncomplicated and led to children’s literature being overlooked and its contribution to philosophical discussions being undermined. Although Rousseau advocates freeing the child to develop, he does not feel that reading fiction promotes child development, which is a weakness in an otherwise strong argument for educational reform. Yet, rather ironically, the second generation of children’s writers, from Lewis Carroll onwards, more truly embraced Rousseau’s broader philosophical ideas on education and childhood than their predecessors, encouraging and freeing readers to imagine, reflect and actively engage in ontological enquiry. The emphasis had changed with the child being embraced in education and society as active participant rather than passive or disengaged recipient. Works deemed to be seminal to the canon of children’s literature such as Alice’s Adventures in Wonderland, Peter Pan and The Chronicles of Narnia challenge readers to work through conflicts many of which can be identified retrospectively as exhibiting postmodern characteristics. By exploring moral and spiritual dilemmas in their writing, Carroll, Barrie and Lewis’s works can be regarded as contributing to discussions on theodical postmodernism. The successes of The Lord of the Rings and Narnia films suggest that there is an interest in exploring moral dilemmas, fulfilling a need (perhaps for tolerance and understanding) in society at large. Children’s literature has an almost divine power to restore, to repair and to heal, all characteristics of theodical postmodernism but differing from the more widely held conception of postmodernism which pulls apart, exacerbates and exposes. Children’s literature therefore offers a healthy and constructive approach to working through moral dilemmas. In their deconstruction of childhood, these authors have brought children’s literature closer to aspects of enquiry traditionally found in the domain of adult mainstream literature. As the boundaries between childhood and adulthood become more fluid, less certain, debate is centring around whether the canon of children’s literature itself has become redundant or meaningless since there are no longer any restrictions on which subjects can be treated in children’s literature. Despite the fact that children’s literature clearly engages with difficult issues, it continues to be left out of the critical equation, not given serious attention, disregarded as simplistic and ignored in contemporary philosophical discussions concerning morality, postmodernism and the future of childhood. With children’s literature coming closer to mainstream literature, and exhibiting prominent features of postmodernism, however, it is only a matter of time before philosophical discussions actively engage with children’s literature and recognise its contribution to the resolution and reconciliation of ontological dilemmas. When this occurs, philosophy and children’s literature will re-engage, enriching contemporary investigations of existence, ethics and knowledge and fruitfully developing thought in these areas. This paper aims to contribute to this process.

Are apes essentialists? Scope and limits of psychological essentialism in great apes

Human reasoning is characterized by psychological essentialism (Gelman in The essential child: origins of essentialism in everyday thought. Oxford University Press, New York, 2003): when reasoning about objects, we distinguish between deep essential properties defining the object’s kind and identity, and merely superficial features that can be changed without altering the object’s identity. To date, it is unclear whether psychological essentialism is based on the acquisition of linguistic means (such as kind terms) and therefore uniquely human, or whether it is a more fundamental cognitive capacity which might be present also in the absence of language. In the present study, we addressed this question by testing whether, and if so, under which circumstances non-human apes also rely on psychological essentialism to identify objects. For this purpose, we adapted classical verbal transformation scenarios used in research on psychological essentialism (Keil in Concepts, kinds, and cognitive development. MIT Press, Cambridge, 1989) and implemented them in two nonverbal tasks: first, a box task, typically used to test object individuation (Experiment 1), and second, an object choice task, typically used to test object discrimination, object preferences and logical inferences (Experiments 2–4). Taken together, the results of the four experiments suggest that under suitable circumstances (when memory and other task demands are minimized), great apes engage in basic forms of essentialist reasoning. Psychological essentialism is thus possible also in the absence of language.     

Gorillas’ (Gorilla gorilla) use of experimenter-given manual and facial cues in an object-choice task

Several experiments have been performed to examine the great apes’ use of experimenter-given manual and visual cues in object-choice tasks. Considering their use of referential gestures in gaze-following paradigms, great apes perform surprisingly unsuccessfully in object-choice tasks. However, the large majority of object-choice experiments have been conducted with chimpanzees (Pan troglodytes) with very few experiments including other great ape species, making it difficult to generalize about the great apes. Interestingly, the only object-choice task conducted with gorillas (Gorilla gorilla) has indicated successful use of both manual and visual cues. It was the aim of the present study to gather more data on gorillas’ use of human manual and facial cues on the object-choice task. Gorilla subjects in this study did not show consistent use of three types of referential cues.     

Maternal Perceptions of Competence and Children’s Academic Adjustment: Longitudinal Relations across Early Elementary School

Children’s perceptions of their academic ability play an important role in their academic adjustment, but relatively little research has examined the factors affecting academic self perceptions of young children, especially the role of parents. Seventy-seven children and their mothers were followed longitudinally from kindergarten to fourth grade to assess the association between mothers’ early perceptions of children’s academic abilities in reading and math and children’s later academic adjustment. Mothers’ perceptions of children’s reading ability in kindergarten were associated with children’s later self-perceptions of academic competence and later achievement, above and beyond kindergarten achievement. However, mothers’ perceptions of math ability in kindergarten were not significantly associated with later outcomes. In reading, mothers’ perceptions of children’s natural talent were positively associated with later self-perceptions and mothers’ perceptions of children’s difficulty in school were negatively associated with later self-perceptions. Additionally, mothers’ perceptions of children’s reading competence were positively associated with later reading achievement. This was the youngest sample in which these relations have been examined to date. Longer-term implications for early parental perceptions are discussed.     

Tracking and inferring spatial rotation by children and great apes

Finding hidden objects in space is a fundamental ability that has received considerable research attention from both a developmental and a comparative perspective. Tracking the rotational displacements of containers and hidden objects is a particularly challenging task. This study investigated the ability of 3-, 5-, 7-, and 9-year-old children and great apes (chimpanzees, bonobos, gorillas, and orangutans) to (a) visually track rotational displacements of a baited container on a platform and (b) infer its displacements by using the changes of position or orientation of 3 landmarks: an object on a container, the color of the containers, and the color of the platform on which the containers rested. Great apes and 5-year-old and older children successfully tracked visible rotations, but only children were able to infer the location of a correct cup (with the help of landmarks) after invisible rotations. The ability to use landmarks changed with age so that younger children solved this task only with the most explicit marker on the baited container, whereas older children, particularly 9-year-olds, were able to use landmark orientation to infer correct locations.     

Features enhance the encoding of geometry

Successful navigation within an environment requires that the traveler establish the correct heading—a process referred to as orienting. Many studies have now shown that humans and non-human animals can use the geometric properties of an enclosure to orient. In the present study, two groups of Clark’s nutcrackers (Nucifraga columbiana) were trained, in a reference memory task, to find food hidden in one of four containers arranged to form a rectangular array. One group had unique objects placed next to each of the containers, whereas the second group had identical objects placed next to each of the containers. Here, I show for the first time that for the Clark’s nutcracker, the distinctive properties of these objects enhanced the encoding of the array’s geometry compared to the learning of geometric properties from an array of identical objects, which remained at chance after substantial amounts of training. Subsequent transformation tests showed that an object not associated with reward, but sharing the same geometric properties as the correct object, may have had inhibitory qualities. Furthermore, by systematically removing objects from the array, I show that although nutcrackers encoded the geometry of the array, they did not encode a complete featural representation of the objects within the array.     

Multimodal communication by captive chimpanzees (Pan troglodytes)

Many studies have shown that apes and monkeys are adept at cross-modal matching tasks requiring the subject to identify objects in one modality when information regarding those objects has been presented in a different modality. However, much less is known about non-human primates’ production of multimodal signaling in communicative contexts. Here, we present evidence from a study of 110 chimpanzees demonstrating that they select the modality of communication in accordance with variations in the attentional focus of a human interactant, which is consistent with previous research. In each trial, we presented desirable food to one of two chimpanzees, turning mid-way through the trial from facing one chimpanzee to facing the other chimpanzee, and documented their communicative displays, as the experimenter turned towards or away from the subjects. These chimpanzees varied their signals within a context-appropriate modality, displaying a range of different visual signals when a human experimenter was facing them and a range of different auditory or tactile (attention-getting) signals when the human was facing away from them; this finding extends previous research on multimodal signaling in this species. Thus, in the impoverished circumstances characteristic of captivity, complex signaling tactics are nevertheless exhibited by chimpanzees, suggesting continuity in intersubjective psychological processes in humans and apes.     

Gorillas’ use of the escape response in object choice memory tests

The ability to monitor and control one’s own cognitive states, metacognition, is crucial for effective learning and problem solving. Although the literature on animal metacognition has grown considerably during last 15 years, there have been few studies examining whether great apes share such introspective abilities with humans. Here, we tested whether four gorillas could meet two criteria of animal metacognition, the increase in escape responses as a function of task difficulty and the chosen-forced performance advantage. During testing, the subjects participated in a series of object choice memory tests in which a preferable reward (two grapes) was placed under one of two or three blue cups. The apes were required to correctly select the baited blue cup in this primary test. Importantly, the subjects also had an escape response (a yellow cup), where they could obtain a secure but smaller reward (one grape) without taking the memory test. Although the gorillas received a relatively small number of trials and thus experienced little training, three gorillas significantly declined the memory tests more often in difficult trials (e.g., when the location of the preferred reward conflicted with side bias) than in easy trials (e.g., when there was no such conflict). Moreover, even when objective cues were eliminated that corresponded to task difficulty, one of the successful gorillas showed evidence suggestive of improved memory performance with the help of escape response by selectively avoiding trials in which he would be likely to err before the memory test actually proceeded. Together, these findings demonstrate that at least some gorillas may be able to make optimal choices on the basis of their own memory trace strength about the location of the preferred reward.     

Local traditions in gorilla manual skill: evidence for observational learning of behavioral organization

Elaborate manual skills of food processing are known in several species of great ape; but their manner of acquisition is controversial. Local, “cultural” traditions show the influence of social learning, but it is uncertain whether this includes the ability to imitate the organization of behavior. Dispute has centered on whether program-level imitation contributes to the acquisition of feeding techniques in gorillas. Here, we show that captive western gorillas at Port Lympne, Kent, have developed a group-wide habit of feeding on nettles, using two techniques. We compare their nettle processing behavior with that of wild mountain gorillas in Rwanda. Both populations are similar in their repertoires of action elements, and in developing multi-step techniques for food processing, with coordinated asymmetric actions of the hands and iteration of parts of a process as “subroutines”. Crucially, however, the two populations deal in different ways with the special challenges presented by nettle stings, with consistently different organizations of action elements. We conclude that, while an elaborate repertoire of manual actions and the ability to develop complex manual skills are natural characteristics of gorillas, the inter-site differences in nettle-eating technique are best explained as a consequence of social transmission. According to this explanation, gorillas can copy aspects of program organization from the behavior of others and they use this ability when learning how to eat nettles, resulting in consistent styles of processing by most individuals at each different site; like other great apes, gorillas have the precursor abilities for developing culture.     

Variations in 10-month-old infant imitation of people and things

To explore 10-month-old infants' abilities to engage in intentional imitation, they were shown a human agent, a non-human agent (stuffed animal), and a surrogate object (mechanical pincers) model actions on objects. The tendency of infants to perform the target act was compared in several situations: (a) after test items were manipulated but the target action was not shown, (b) after the target act was demonstrated successfully, and (c) after the target act was demonstrated unsuccessfully. Although infants imitated the successful actions of human and non-human agents, they completed the unsuccessful actions of humans only. Toward the surrogate object infants did not respond differentially. These findings suggest that although infant may mimic the actions of human and non-human agents, they only engage in intentional imitation with people.     

Early activation of object names in visual search

In a visual search experiment, participants had to decide whether or not a target object was present in a fourobject search array. One of these objects could be a semantically related competitor (e.g.,shirt for the targettrousers) or a conceptually unrelated object with the same name as the target—for example,bat (baseball) for the targetbat (animal). In the control condition, the related competitor was replaced by an unrelated object. The participants’ response latencies and eye movements demonstrated that the two types of related competitors had similar effects: Competitors attracted the participants’ visual attention and thereby delayed positive and negative decisions. The results imply that semantic and name information associated with the objects becomes rapidly available and affects the allocation of visual attention.     

Gaze alternation during “pointing” by squirrel monkeys (<Emphasis Type="Italic">Saimiri sciureus</Emphasis>)?

Gaze alternation (GA) is considered a hallmark of pointing in human infants, a sign of intentionality underlying the gesture. GA has occasionally been observed in great apes, and reported only anecdotally in a few monkeys. Three squirrel monkeys that had previously learned to reach toward out-of-reach food in the presence of a human partner were videotaped while the latter visually attended to the food, a distractor object, or the ceiling. Frame-by-frame video analysis revealed that, especially when reaching toward the food, the monkeys rapidly and repeatedly switched between looking at the partner’s face and the food. This type of GA suggests that the monkeys were communicating with the partner. However, the monkeys’ behavior was not influenced by changes in the partner’s focus of attention.     

Do apes know that they could be wrong?

When confronted with uncertain or incomplete information in decision-making situations, monkeys and apes opt for either escaping the situation or seeking additional information. These responses have been interpreted as evidence of metacognitive abilities. However, this interpretation has been challenged. On the one hand, studies using the information-seeking paradigm have been criticized because subjects may simply engage in a search for information routine (e.g., search until spot the reward) without any metacognitive involvement. On the other hand, studies using the escape response paradigm have been criticized because subjects may not recognize their own state of uncertainty but have learned to use the escape response in the presence of certain stimuli configurations that create uncertainty. The current study attempted to address these two criticisms by presenting great apes (seven gorillas, eight chimpanzees, four bonobos, seven orangutans) with a seeking information task whose basic procedure consisted of presenting two hollow tubes, baiting one of them and letting subjects choose. Conditions varied depending on whether subjects had visual access to the baiting, the cost associated with seeking information, the time interval between baiting and choosing, the food quality and the additional information offered regarding the food’s location. Although subjects showed a high retrieval accuracy when they had witnessed the baiting, they were more likely to check inside the tube before choosing when high stakes were involved (Experiment 3) or after a longer period of time had elapsed between the baiting and the retrieval of the reward (Experiment 2). In contrast, providing subjects with indirect auditory information about the food’s location or increasing the cost of checking reduced checking before choosing (Experiment 1). Taken together, these findings suggest that subjects knew that they could be wrong when choosing.     

Association Between Independent Reports of Maternal Parenting Stress and Children’s Internalizing Symptomatology

Although considerable research has investigated parenting stress and children’s externalizing behavior problems, comparatively less has considered parenting stress in relation to children’s internalizing difficulties. Even less research on parenting stress has incorporated children’s report of their internalizing symptoms or the potential mediating role of children’s attributional style. The current study hypothesized that children’s independent reports of internalizing symptoms would be associated with mothers’ reports of parenting stress through children’s attributional style. A community sample of 92 mother–child dyads participated. Results suggest maternal parenting stress from both child and parent sources were significantly associated with children’s anxious and depressive symptoms. Parenting stress was associated with children’s internalizing symptoms partially mediated by children’s maladaptive attributional style, primarily negative attributions for positive outcomes. Findings are discussed in terms of future directions to tease apart specific areas of parenting stress that may be most pertinent as well as to explore other cognitive mechanisms in children that may relate to parenting stress and children’s adjustment.