Aggressive behavior in a confined troop of Japanese macaques: Effects of density,season, and gender

A troop of Japanese macaques (Macaca fuscata) confined in a 2-acre outdoor corral increased from 107 to 192 individuals during the 5-year tenure of a project that assessed the effects of density, season, and gender on the expression of adult aggressive behavior. Two statistical subgroups of 16 males and 28 females that were adults at the start of the project and that survived until its completion were studied intensively. There were significant season and sex differences in all groups: males were much more aggressive than females, and males were most aggressive during the fall and and winter mating season; females were most aggressive during the spring and summer birth season. Only the 16 adult males increased their frequency of aggressive behavior as the population density increased. This increase was due to the greater number of potential antagonists available each year.     

Do common ravens (<Emphasis Type="Italic">Corvus corax</Emphasis>) rely on human or conspecific gaze cues to detect hidden food?

The ability of non-human animals to use experimenter-given cues in object-choice tasks has recently gained interest. In such experiments, the location of hidden food is indicated by an experimenter, e.g. by gazing, pointing or touching. Whereas dogs apparently outperform all other species so far tested, apes and monkeys have problems in using such cues. Since only mammalian species have been tested, information is lacking about the evolutionary origin of these abilities. We here present the first data on object-choice tasks conducted with an avian species, the common raven. Ravens are highly competitive scavengers, possessing sophisticated cognitive skills in protecting their food caches and pilfering others’ caches. We conducted three experiments, exploring (i) which kind of cues ravens use for choosing a certain object, (ii) whether ravens use humans’ gaze for detecting hidden food and (iii) whether ravens would find hidden food in the presence of an informed conspecific who potentially provides gaze cues. Our results indicate that ravens reliably respond to humans’ touching of an object, but they hardly use point and gaze cues for their choices. Likewise, they do not perform above chance level in the presence of an informed conspecific. These findings mirror those obtained for primates and suggest that, although ravens may be aware of the gaze direction of humans and conspecifics, they apparently do not rely on this information to detect hidden food.     

Social Categorization and Stereotyping: How Social Categorization Biases Person Perception and Face Memory

The current article offers a brief history of research and theory related to social categorization and stereotyping. We begin by outlining research focusing on category selection, category activation, and category application. We then discuss the consequences of social categorization, noting that one of the most important and ubiquitous effects of social categorization is homogenization or assimilation. We then extend this research related to the assimilative consequences of social categorization to the realm of face memory. Specifically, we introduce the Categorization‐Individuation Model (see also Hugenberg et al., forthcoming) as a new model of the Cross‐Race Effect, or the difficulty many perceivers have in recognizing members of other racial groups. The Categorization‐Individuation Model argues that the Cross‐Race Effect is due to the tendency to categorize out‐group members but individuate in‐group members. Finally, we summarize the extant research in support of this new model of person memory and close by discussing the current state of, and potential future directions for, social categorization research.     

Contaminated Generativity: Holocaust Survivors and Their Children in Germany

This paper addresses the trauma transfer from survivors of the Shoah to the Second Generation in Germany. What does it mean for both generations to beget children after Auschwitz? This necessarily entails perceiving non-Jewish Germans and their way of dealing with history. Survivors cannot live without their memory, nor is it possible for them to conceive of a life unencumbered by this constant “contaminant”. It is not possible to integrate the persecution experiences. On the contrary, decades after liberation, dissociated elements of traumatic memories penetrate everyday experiences, thought, affect and imagination as contaminants. Occasionally, these fragments of persecution experiences, like “encapsulated memories” hidden in crypts suddenly break open and frighten the survivors themselves and even more so the people around them.     

The rule of three: How the third event signals the emergence of a streak

It is well established that people perceive streaks where they do not exist. However, little is known about what constitutes a streak in the mind of an observer. This paper proposes that the third repeat event in a sequence is pivotal to the subjective belief that a streak is occurring. In five studies, we find direct and indirect evidence that perceived streakiness plateaus with the third repeat outcome in a sequence. The evidence to support this rule of three comes from various domains, including: observation of randomly determined probabilistic outcomes, investment decisions in response to performance histories, and basketball shooting percentages.     

5-HT2A: its role in frontally mediated executive function and related psychopathology

Serotonin (5-HT)2A receptors are widely distributed, with high levels in the frontal cortex, where postsynaptic activation may increase activity in pyramidal glutamatergic neurons and mediate various executive functions. More specifically, reciprocal cortical-raphe pathways may allow the ventral prefrontal cortex to inhibit stress-induced neural activity in the brainstem when stressors are perceived as controllable. However, early adversity and negative attitudes may be associated with higher frontal 5-HT2A receptor levels and greater risk for stress-induced psychopathology, and certain 5-HT2A gene variants have been associated with increased risk for impulsive behavior. Conversely, many antidepressants result in decreased levels of 5-HT2A receptor levels, and blockade of 5-HT2A receptors has proven useful in the treatment of a number of psychiatric disorders.     

Strengthening parent well‐being at the work—family interface: A German trial on workplace Triple P

This study examines the efficacy of a parenting training (Workplace Triple P (WPTP)) especially designed for the needs of employed parents. The program aims to reduce stress at the work–parenting interface by targeting family risk and protective factors and assisting parents to manage competing work and family demands. Ninety‐seven part‐ and full‐time working parents (74 mothers and 23 fathers; intervention group: n = 42 parents; waitlist‐control group n = 55 parents) from multiple organizations and multiple occupations with children between 2 and 10 years were randomly assigned to an intervention and a waitlist‐control condition. After the training, parents from the intervention condition, compared to those from the waitlist‐control condition, reported a significant reduction in individual and work‐related stress. Additionally, they reported a significant reduction in dysfunctional parenting and significant higher levels of parental and occupational self‐efficacy. Within the intervention condition all effects were maintained at the 3‐ and 6‐month follow‐up examinations. The findings support the notion that WPTP promotes parental well‐being and reduces stress at the work–parenting interface. Given that strengthening parenting skills has the potential to strengthen work, strategies to implement WPTP in organizational resources and community‐based services are discussed. Copyright © 2010 John Wiley & Sons, Ltd.