Leaf swallowing behavior in chimpanzees (Pan troglodytes): biased learning and the emergence of group level cultural differences

Demonstrating the ability to ‘copy’ the behavior of others is an important aspect in determining whether social learning occurs and whether group level differences in a given behavior represent cultural differences or not. Understanding the occurrence of this process in its natural context is essential, but can be a daunting task in the wild. In order to test the social learning hypothesis for the acquisition of leaf swallowing (LS), a self-medicative behavior associated with the expulsion of parasites, we conducted semi-naturalistic experiments on two captive groups of parasite-free, naïve chimpanzees (Pan troglodytes). Individuals in the group were systematically provided appropriate stimuli (rough hispid leaves) identical to those used by chimpanzees in the wild. Individuals initially responded in a variety of ways, ranging from total aversion to normal chewing and swallowing. Over time, however, the two groups adopted different variants for inserting and folding the leaves in the mouth prior to swallowing them (complete and partial LS), following the specific method spontaneously displayed by the first and primary LS models in their respective groups. These variants were similar to LS displayed by chimpanzees in the wild. Using the option-bias method, we found evidence for social learning leading to group-level biased transmission and group-level stabilization of these two variants. This is the first report on two distinct cultural variants innovated in response to the introduction of natural stimuli that emerged and spread spontaneously and concurrently within two adjacent groups of socially housed primates. These observations support the assertion that LS may reflect a generalized propensity for ingesting rough hispid leaves, which can be socially induced and transmitted within a group. Ingesting an adequate number of these leaves induces increased gut motility, which is responsible for the subsequent expulsion of particular parasite species in the wild. Cultural transmission and maintenance of LS within a group and associative learning by the individual of the positive consequences of this otherwise non-nutritive mode of ingestion is proposed to be the pivotal link between this feeding propensity and its maintenance as a self-medicative behavior by great apes in the wild.     

Knowledge space theory, formal concept analysis, and computerized psychological assessment

In the present study, the use of knowledge space theory (KST), jointly with formal concept analysis (FCA), is proposed for developing a formal representation of the relations between the items of a questionnaire and a set of psychodiagnostic criteria. This formal representation can be used to develop an efficient adaptive tool for psychological assessment. Rusch and Wille (1996) have shown some interesting connections between KST and FCA; these connections are applied in the construction of knowledge structures, starting from a formal context representing the relations between items and criteria. The proposed general methodology was applied, as an example, to the Maudsley Obsessional-Compulsive Questionnaire. We used a data set provided by a sample of patients with a diagnosis of obsessive-compulsive disorder to validate the obtained structures. The parameters of the basic local independence model (BLIM) were estimated for the obtained knowledge structures. The fit of each model was tested by parametric bootstrap because of the sparseness of the derived data matrix. The results are discussed in light of both psychological and methodological relapses. In particular, we propose a reinterpretation of the BLIM parameters that seems suitable for testing reliability and construct validity; furthermore, it is pointed out how the obtained structures could represent the starting point for the development of a computerized assessment tool.     

The influence of sexual harassment frequency and perceptions of organizational justice on victim responses to sexual harassment

Organizational justice theory was used to understand the conditions that influence how women respond when sexually harassed. Specifically, this study examined whether sexual harassment frequency interacts with perceptions of four types of organizational justice (procedural, distributive, interpersonal, and informational) to predict two types of victim responses (confrontation and reporting). With data collected from 257 female employees, it was found that the interaction between sexual harassment frequency and perceptions of distributive justice and the interaction between sexual harassment frequency and perceptions of procedural justice predicted reporting, whereas the interaction between sexual frequency and perceptions of distributive justice predicted confrontation. The interaction between sexual harassment frequency and perceptions of informational justice predicted both confrontation and reporting. Implications for organizations are discussed.     

Coping with bullying in the workplace

The purpose of the study was to investigate the 1-year prevalence of bullying in the form of repeated exposure to slander and/or nasty teasing in Danish workplaces, and to analyse whether respondents subjected to bullying use the same coping strategies as respondents who are not subjected to bullying. The results show that approximately 2% of the Danish employees are subjected to bullying at work. We compared the use of coping strategies in three groups: a non-exposed group, a somewhat exposed group, and a very exposed group (i.e., bullied). The results showed no linear association between the three groups, but a difference between being exposed and not exposed. The results seem to indicate that it is not necessarily the quantity of the negative acts that cause the change in behaviour but more the fact of being exposed to such acts.     

Infants' mu suppression during the observation of real and mimicked goal‐directed actions

Since their discovery in the early 1990s, mirror neurons have been proposed to be related to many social‐communicative abilities, such as imitation. However, research into the early manifestations of the putative neural mirroring system and its role in early social development is still inconclusive. In the current EEG study, mu suppression, generally thought to reflect activity in neural mirroring systems was investigated in 18‐ to 30‐month‐olds during the observation of object manipulations as well as mimicked actions. EEG power data recorded from frontal, central, and parietal electrodes were analysed. As predicted, based on previous research, mu wave suppression was found over central electrodes during action observation and execution. In addition, a similar suppression was found during the observation of intransitive, mimicked hand movements. To a lesser extent, the results also showed mu suppression at parietal electrode sites, over all three conditions. Mu wave suppression during the observation of hand movements and during the execution of actions was significantly correlated with quality of imitation, but not with age or language level.     

Implicit chaining in cotton-top tamarins (Saguinus oedipus) with elements equated for probability of reinforcement

Three experiments examined the implicit learning of sequences under conditions in which the elements comprising a sequence were equated in terms of reinforcement probability. In Experiment 1 cotton-top tamarins (Saguinus oedipus) experienced a five-element sequence displayed serially on a touch screen in which reinforcement probability was equated across elements at .16 per element. Tamarins demonstrated learning of this sequence with higher latencies during a random test as compared to baseline sequence training. In Experiments 2 and 3, manipulations of the procedure used in the first experiment were undertaken to rule out a confound owing to the fact that the elements in Experiment 1 bore different temporal relations to the intertrial interval (ITI), an inhibitory period. The results of Experiments 2 and 3 indicated that the implicit learning observed in Experiment 1 was not due to temporal proximity between some elements and the inhibitory ITI. The results taken together support two conclusion: First that tamarins engaged in sequence learning whether or not there was contingent reinforcement for learning the sequence, and second that this learning was not due to subtle differences in associative strength between the elements of the sequence.     

Secondary Data Analysis: An Important Tool for Addressing Developmental Questions

Existing data sets can be an efficient, powerful, and readily available resource for addressing questions about developmental science. Many of the available databases contain hundreds of variables of interest to developmental psychologists, track participants longitudinally, and have representative samples. In this article, the authors discuss the benefits and limitations of secondary data analysis so that researchers can make informed decisions about when it makes sense to use existing data and when it does not. They then provide an overview of best practices for handling the most common conceptual, methodological, and practical issues that arise when adopting this approach.     

State-dependent changes of prefrontal–posterior coupling in the context of affective processing: Susceptibility to humor

The aim of the present study was to examine whether interindividual differences in the coupling or decoupling of prefrontal and posterior cortices during the exposure to social–emotional information may predict an individual’s positive emotional responsiveness. Susceptibility to humor was assessed in a behavioral paradigm several weeks after the EEG recordings. State-dependent changes of prefrontal–posterior EEG beta coherence were recorded during stimulation with other people’s auditory expressions of cheerfulness and sadness. Greater decreases of coherence during the stimulation with positive affect expressions prospectively predicted greater positive emotional responsiveness, indicated by higher amusement ratings in response to cartoons and higher scores in a questionnaire measure of exhilarability. Greater increases of coherence during the stimulation with negative affect expressions did not predict perceived funniness but were related to shorter response latencies to the amusement ratings. The results further support the notion that a more loose prefrontal–posterior coupling may be related to loosening of control of the prefrontal cortex over incoming emotional information and, thus, to a propensity to deeper emotional involvement and a greater impact of perceptual input, whereas increased prefrontal–posterior coupling may be related to strong control and the propensity to protect oneself from becoming emotionally affected.     

Problematic eating behaviors and nutritional status in 7 to 12 year-old Chilean children

Overweight and obesity are medical conditions that require a multidisciplinary analysis of their causes and treatment. In Chile a sustained increase in the presence of obesity and excess weight has been observed in children. However, the amount and the dynamics of the aforementioned problematic eating behaviours in Chilean children are unknown. The aim of this study was to assess the relationship between restrained, external, and emotional eating, and variations in body mass index (BMI) in Chilean children. Consequently, 453 children from 7 to 12 years of age responded to the Children's Dutch Eating Behaviour Questionnaire, Spanish version. In addition, their anthropometric data were obtained. A positive association was found between restrained eating and BMI, and a negative correlation between external eating and BMI. Emotional eating demonstrated a modest inverse relationship with BMI. A significant interaction between problematic behaviour and nutritional status (normal-weight, overweight, obese) was revealed. Restrained eating was characteristic of obese children whereas external eating of normal-weight children. These results suggest that problematic eating behaviours and their relationship with body weight are similar to those described in studies in Europe.     

Local Dialogue Heard Around the World

The authors of this article examine deliberative democracy and the value of dialogue in promoting the engagement of communities in deliberation and involvement in public issues. Focusing on the Texas Forum (TF), a member of the National Issues Forum (NIF), the authors discuss how diverse individuals are brought together with the purpose of cultivating public dialogue and discourse about significant policy issues, with a focus on the public's participation in the democratic process. The article addresses changes in civic engagement, dialogue, and the use of technology to mediate civic discourse and create virtual civic communities. The TF and NIF provide practical examples of the work needed in promoting deliberative democracy and civic engagement.