Tool use by chimpanzees (Pan troglodytes) of the Arnhem Zoo community

Abstract: Chimpanzees have a large repertoire of tool-use behaviors. This study reports on the variety and the extent of tool use exhibited by the chimpanzees of the Arnhem Zoo community in The Netherlands, living in an enriched captive setting since 1971. The use of tools by 29 chimpanzees aged from 0 to 37 years was observed. We identified 13 types of tool use comparable to those found in the wild. Some of these types of tool use seem to be specific to this community, and can be explained by the ecological characteristics of this captive setting. Chimpanzees started to use tools from the age of 2 years. Young chimpanzees, from 5 to 9 years old, showed a greater repertoire of tool use than infants and adults. All types of tool use in the community have appeared by the age of 10, the age of puberty for chimpanzees. Multivariate analysis was applied for the 29 individuals by 13 types of tool use in a one-zero matrix. The results show two major categories of tool use, one in a practical or substantial context and the other in a nonpractical or play context. The subjects clustered into groups reflecting developmental stages, although there are great individual differences. In conclusion, this captive community provides a unique opportunity to clarify the details of tool use by chimpanzees.     

Changes in Behaviour and Body Weight Following a Single or Double Social Defeat in Rats

In a series of experiments, the consequences of a single and double social conflict on various behaviours and body weight in rats were studied. Animals were subjected to social defeat by placing them into the territory of an aggressive male conspecific for one hour, either once, or twice at the same time on two consecutive days. To assess the consequences of social defeat, three experiments were performed with independent groups of rats. In the first experiment, an open field test was performed two days after the last conflict. Locomotor activity was strongly reduced after social defeat. There were no differences between the single and double defeat group. To assess the effects of social defeat on subsequent social behaviour, a second experiment was performed in which experimental animals were confronted with an unfamiliar non-aggressive rat two days after a single or double conflict. Social defeat resulted in a reduction of social contact with the unfamiliar conspecific. There was no difference between the single and double conflict group. In the third experiment, the effects of social conflict on food intake, body weight and saccharine preference were measured. Food intake was not affected after a single conflict, but in the double conflict group food intake was decreased for several days. Body weight gain was decreased after both single and double social defeat. The decrease was stronger in the double conflict group. Water intake and saccharine preference were not significantly affected. This study revealed that social defeat in rats causes pronounced changes in various behaviours and body weight. Different aspects of behaviour are differentially affected by defeat with respect to the magnitude and time course of the changes induced. Moreover, different behavioural parameters are differentially sensitive to repetition of the stressor.     

The Relationship Between Creativity and Conformity Among Preschool Children

The current study investigated the relationship between creativity and conformity based on the work of Starkweather (1964). The subjects were 45 preschool children. Creativity was assessed using the Multidimensional Stimulus Fluency Measure (Moran, Sawyers, Fu, & Milgram, 1983), an original thinking task. Two forms of conformity were assessed: social conformity and impersonal conformity using the Starkweather Social Conformity Test and the Starkweather Form Boards Test respectively (Starkweather, 1964). Starkweather's hypothesis of a curvilinear relationship between conformity and creativity was found for the social conformity task (X² = 11.69, p < .01). The findings support the hypothesis that highly conforming and highly nonconforming children do not score as high on creativity measurements as their freedom of expression (i.e., not following a rigid pattern of conforming/nonconforming) counterparts. Chi‐square analyses revealed significantly more children in the high creativity and freedom of expression group as compared to the low creativity and conforming/nonconforming children. That is, significantly fewer children were found in the low conformity/low creativity cell and more in the low conformity/high creativity cell than were expected by chance. No differences were found for impersonal conformity, perhaps due to the insensitivity of the instrumentation to assess conformity. It is concluded that freedom of expression may be seen as an important personality trait in the identification and nurturance of creative potential and problem solving in young children.     

TEST OF A MULTISTAGE MODEL OF DISTAL AND PROXIMAL ANTECEDENTS OF LEADER PERFORMANCE

The authors developed and tested a multistage model of distal and proximal predictors of leader performance in an effort to shed greater light on the intermediate linkages between broad leader traits and performance. Predictor and criterion data were obtained from 471 noncommissioned officers in the U.S. Army. A model with cognitive ability and 3 of the Big 5 personality factors as distal antecedents, leadership experiences and motivation to lead as semidistal antecedents, and the knowledge, skills, and ability (KSAs) to lead as proximal antecedents of leader performance provided a good fit to the data. More specifically, the effects of the distal and semidistal antecedents on leader performance were partially mediated by more proximal variables, whereas leader KSAs demonstrated a relatively strong, direct influence on performance. The 1 exception was that Conscientiousness—a hypothesized distal antecedent—had a notable direct effect on leader performance. The implications of these findings for leadership research and practice are discussed.     

Situational precursors of revenge: Social exclusion,relationship type,and opportunity

Little is known about the situational factors that turn feelings of revenge into actual acts of revenge. Addressing this gap in the literature, this study selected a representative sample of people who acted on their feelings of revenge (avengers) and of people who did not (nonavengers), obtaining a reflection of typical antecedents of revenge. Results revealed that avengers did not report more severe offenses. Neither did avengers report less closeness to offenders nor a larger number of audience members toward whom they might want to prove something. Results did reveal that revenge was more prevalent (a) among young, male friends and acquaintances; (b) in contexts involving social exclusion; and (c) if there was a possibility to take revenge.