Do chimpanzees anticipate an object’s weight? A field experiment on the kinematics of hammer-lifting movements in the nut-cracking Taï chimpanzees

When humans are about to manipulate an object, our brains use visual cues to recall an internal representation to predict its weight and scale the lifting force accordingly. Such a long-term force profile, formed through repeated experiences with similar objects, has been proposed to improve manipulative performance. Skillful object manipulation is crucial for many animals, particularly those that rely on tools for foraging. However, despite enduring interest in tool use in non-human animals, there has been very little investigation of their ability to form an expectation about an object’s weight. In this study, we tested whether wild chimpanzees use long-term force profiles to anticipate the weight of a nut-cracking hammer from its size. To this end, we conducted a field experiment presenting chimpanzees with natural wooden hammers and artificially hollowed, lighter hammers of the same size and external appearance. We used calibrated videos from camera traps to extract kinematic parameters of lifting movements. We found that, when lacking previous experience, chimpanzees lifted hollowed hammers with a higher acceleration than natural hammers (overshoot effect). After using a hammer to crack open one nut, chimpanzees tuned down the lifting acceleration for the hollowed hammers, but continued lifting natural hammers with the same acceleration. Our results show that chimpanzees anticipate the weight of an object using long-term force profiles and suggest that, similarly to humans, they use internal representations of weight to plan their lifting movements.     

The Moscow Council of 1917–1918

Following a period of decline beginning in the early eighteenth century, the Orthodox Church in Russia held a general council in Moscow from August 1917 to September 1918. More than 500 clergy and laity met, prayed and discussed numerous issues relating to the church’s life and witness. The Moscow Council was prompted by various trends of renewal which were growing ever stronger among the clergy and laity. Political circumstances at the time also made the Council possible: a preparatory preconciliar process was initiated in 1905, in parallel with the first revolution against Emperor Nicholas II, and the Council itself was convened in 1917, in parallel with the establishment of a Provisional Government. However, it was precisely such political events which led to the premature interruption of the Council. The main items on the Council’s agenda were linked to the reformation of church structures and the implementation of conciliar provisions at every level of church life: parish, deanery, diocese and autocephalous church. Special attention was given to the renewal of the pastoral ministries of priests and bishops, and to that of committed laity. In a way, the Moscow Council was a kind of ‘first encounter’ of Orthodoxy with contemporary societies, secularised or on the road to secularisation. Its legacy is therefore of great interest to all Christianity today. This article aims to analyse the Council and the main decisions made, in the light of ecclesiology, and to provide a primary bibliography at the end of the text.     

Neurobehavioral phenotype of Klinefelter syndrome

A defined genetic syndrome with neurobehavioral components offers an unusual paradigm for the correlation of genetic defects with neurodevelopmental abnormalities. The power of the combination of detailed behavioral, neuroanatomical, and genetic studies has been demonstrated in studies of other conditions involving the sex chromosomes, such as Fragile X syndrome (Mazzocco [2000] Ment Retard Develop Disabil Res Rev. 6:96-106) and Turner syndrome (Ross [2000] Ment Retard Develop Disabil Res Rev. 6:135-141). Although the behavioral and neurologic difficulties that have been identified in Klinefelter syndrome (KS) are in most cases milder than the consequences of many other genetic syndromes, the deficits in KS cause significant morbidity, representing a more common, but poorly understood, subtype of those with learning disabilities. Both as children and as adults, KS subjects appear to offer a powerful genetic model for the study of language and language-based learning disabilities. Although it has been proposed that the language-based learning difficulties of KS boys are similar to those of nonaneuploidic dyslexics [Bender et al., 1986; Geschwind et al., 1998], this is not yet well established. The co-morbid frontal-executive dysfunction observed in KS is also a likely contributor to learning difficulties and, perhaps, social cognition, in many KS patients. It is also proposed that altered left-hemisphere functioning, whether causing, or due to, altered functional and anatomical cerebral dominance, is at the core of KS subjects' language problems. Although X chromosomal loci can provide only part of the picture, the study of KS subjects, a population with a relatively homogeneous etiology for dyslexia/dysphasia and frontal-executive dysfunction, offers many advantages over such a study in the general population, in which both dyslexia and attentional disorders are quite genetically heterogeneous [Decker and Bender, 1988; Pennington, 1990; Grigorenko et al., 1997; Geschwind et al., 1998]. Furthermore, the interaction of genetic factors and hormonal influences in the cognitive phenotypes described remains an unexplored area for future investigation. MRDD Research Reviews 2000;6:117-124.     

Perinatal maternal undernutrition programs the offspring hypothalamo-pituitary-adrenal (HPA) axis

There is now compelling evidence, coming both from animal and human studies that an early exposure to undernutrition is frequently associated with low birth weight and programs HPA axis alterations throughout the lifespan. Although animal models have reported conflicting findings arising from differences in experimental paradigms and species, they have clearly demonstrated that such programming not only affects the brain but also the pituitary corticotrophs and the adrenal cortex. In fetuses, maternal undernutrition reduces HPA axis function and implicates a reduction of placental 11beta-HSD2 activity and a greater transplacental transfer of glucocorticoids (GRs). In young adults, usually only fine HPA axis alterations were observed, whereas in older ones, maternal undernutrition was frequently associated with chronic hyperactivity of this neuroendocrine axis. In humans, evidence of HPA axis dysregulation in people who were small at birth has recently emerged. Thus, we suggest that such alterations in adults may be implicated in the aetiology of several disorders related to the metabolic syndrome as well as to immune or inflammatory diseases. To reverse such programming, recent experimental reports have shown that postnatal environmental interventions, dietary modifications and the use of agents modulating the epigenomic state could partly restore physiological functions and thus open new therapeutic strategies.     

Interaction of color and geometric cues in depth perception: When does “red” mean “near”?

Luminance and color are strong and self-sufficient cues to pictorial depth in visual scenes and images. The present study investigates the conditions under which luminance or color either strengthens or overrides geometric depth cues. We investigated how luminance contrast associated with the color red and color contrast interact with relative height in the visual field, partial occlusion, and interposition to determine the probability that a given figure presented in a pair is perceived as nearer than the other. Latencies of near responses were analyzed to test for effects of attentional selection. Figures in a pair were supported by luminance contrast (Experiment 1) or isoluminant color contrast (Experiment 2) and combined with one of the three geometric cues. The results of Experiment 1 show that the luminance contrast of a color (here red), when it does not interact with other colors, produces the same effects as achromatic luminance contrasts. The probability of near increases with the luminance contrast of the color stimulus, the latencies for near responses decrease with increasing luminance contrast. Partial occlusion is found to be a strong enough pictorial cue to support a weaker red luminance contrast. Interposition cues lose out against cues of spatial position and partial occlusion. The results of Experiment 2, with isoluminant displays of varying color contrast, reveal that red color contrast on a light background supported by any of the three geometric cues wins over green or white supported by any of the three geometric cues. On a dark background, red color contrast supported by the interposition cue loses out against green or white color contrast supported by partial occlusion. These findings reveal that color is not an independent depth cue, but is strongly influenced by luminance contrast and stimulus geometry. Systematically shorter response latencies for stronger near percepts demonstrate that selective visual attention reliably detects the most likely depth cue combination in a given configuration.     

Contextual and serial discriminations: a new learning paradigm to assess simultaneously the effects of acute stress on retrieval of flexible or stable information in mice

The present study was aimed at simultaneously determining on the same subject, the effects of stress on retrieval of flexible (contextual or temporal) or stable (spatial) information. Three behavioral paradigms carried out in a four-hole board were designed as follows: (1) Simple Discrimination (SD), in which mice learned a single discrimination; (2) Contextual and Serial Discriminations (CSD), in which mice learned two successive discriminations on two different internal contexts; (3) Spatial Serial Discriminations (SSD), in which mice learned two successive discriminations on an identical internal context. The stressor (three inescapable electric footshocks) was delivered 5 min before retention, occurring 5 min or 24 h after acquisition. Results showed that this stressor increased plasmatic corticosterone levels and fear reactivity in an elevated-plus-maze, as compared with nonstressed mice. The stressor reversed the normal pattern of retrieval observed in nonstressed controls in the CSD task, this effect being context dependent, as it was not observed in the SSD task. Overall, our study shows that stress affected the retrieval of flexible and old information, but spared the retrieval of stable or recent ones. Therefore, these behavioral paradigms allow us to study simultaneously, on the same animal, the effects of stress on distinct forms of memory retrieval.     

Phoneme perception in a neonate with a left sylvian infarct

We report the case of a neonate tested three weeks after a neonatal left sylvian infarct. We studied her perception of speech and non-speech stimuli with high-density event-related potentials. The results show that she was able to discriminate not only a change of timbre in tones but also a vowel change, and even a place of articulation contrast in stop consonants. Moreover, a discrimination response to stop consonants was observed even when syllables were produced by different speakers. Her intact right hemisphere was thus able to extract relevant phonetic information in spite of irrelevant acoustic variation. These results suggest that both hemispheres contribute to phoneme perception during the first months of life and confirm our previous findings concerning bilateral responses in normal infants.     

Is Dutch native English? Linguistic analysis by 2-month-olds

A variant of the non-nutritive habituation/dishabituation sucking method was used to test 2-month-old English infants’ perception of languages. This method tests for the spontaneous interest of the baby to a change in the stimulus. English and Japanese were clearly discriminated. The difference between French and Japanese was equally clearly not of interest to babies using this procedure, the babies behaving as though both languages were classified simply as ‘foreign’. In order to further specify babies’ representation of native and foreign language, we used Dutch, which shares a number of suprasegmental features with English. The results from our last 2 experiments indicate that a portion of our 6–12 week-old babies consider Dutch as native, suggesting that we tapped in a transition period where the babies are still refining the suprasegmental specification of their native language.     

Toward a reconceptualization of the reciprocal imitation phenomenon: Two experiments

This paper reports two experiments which consider the increased imitation exhibited by models who have been imitated. Experiment 1 was concerned with whether the reciprocal imitation effect is really reciprocal or if the subsequent imitation will generalize to someone else. It was found that adult subjects who were previously imitated at the 75% rate on a perceptual judgments task subsequently imitated their partner more, rated their partner more attractive, and felt more confidence when imitated than did subjects imitated at the 25% rate. These results were obtained regardless of which confederate the subjects imitated, thus indicating that reciprocal imitation is not necessarily reciprocal, but is generalizable. Experiment 2 assessed whether the subsequent imitation is the product of the effects of being imitated or is the result of the subject observing the imitator's imitation. The results indicated that after having observed imitation at a 75% rate, adult onlookers are more likely to subsequently imitate and be attracted to the imitator, the imitated person, and a person new to the situation than are onlookers who observed a 25% imitation rate. A theoretical modification is advanced which holds that subsequent imitation effects, whether from observing others imitate or from being the target of the imitation, result from a process of imitation of imitativeness. The results of these two experiments have implications for theory in imitation and social learning.     

Toward a Renewed Theological Culture: Introduction

This article introduces a series of articles analysing the current state of theology and inquiring about the possibilities of a renewed theological culture (not least within secular societies). It places theology, and more precisely, the conditions of a possible renewal thereof, in several fields of tension. Paradigmatic for secular societies is the tension between theology and the natural sciences. It is argued that theology and the natural sciences cultivate different modes of reasoning on different epistemic levels and that no competition between them has to be construed if one is not caught up in the premises of secularism. A brief summary of each of the contributions follows these initial remarks.