The functions of freezing in the social interactions of juvenile high‐ and low‐aggressive mice

Selectively bred low‐aggressive mice are frequently observed to freeze on social contact, despite the fact that this behavior was never a direct target of selection. To elucidate this finding, the present research aimed to identify the possible functions freezing may serve in social interactions. It was hypothesized that freezing may modify social interactions through self‐regulatory mechanisms and/or via its modulating effects on the actions of social partners. These hypotheses were evaluated with respect to the sequential changes observed over the course of a 10‐min dyadic test in freezing, social reactivity, and approaches among juvenile (24–30‐day‐old) mice from the NC900 and NC100 high‐ and low‐aggressive lines. Analyses of the patterns of social interactions between subjects and partners revealed two primary results. First, freezing was more than an expression of fear; it also functioned as a regulator of emotional arousal, as suggested by the substantial reduction of reactive behaviors seen in animals that showed high levels of freezing. Second, freezing functioned to facilitate high levels of affiliative social interaction with social partners. The implications of these results for understanding how the differentiation of the NC900 and NC100 occurred within microevolution and development are discussed. Aggr. Behav. 27:463–475, 2001. © 2001 Wiley‐Liss, Inc.     

Mediating factors in chick social pecking: II. effects of exposure to movement

Unfamiliarity with movement may lead isolated chicks to respond aggressively when tested with live, moving conspecifics. This hypothesis was tested by comparing the number and locus of pecks by isolated chicks to a stationary or moving model of a chick, and to a live chick. In a second test of the hypothesis chicks that viewed a moving object during isolation and chicks isolated without movement were tested with a live con-specific and their number and locus of pecks were compared. Neither experiment supported the hypothesis. Movement alone failed to excite aggressive pecks and prior experience with movement failed to suppress aggressive pecks. In the first experiment imlated chicks treated the live testmate more aggressively than the moving or stationary model. In the second experiment aggressive pecking of chicks was unaffected by prior experience with movement, These fmdmgs do not support the hypothesis that movement excites aggression in isolated chicks. Nonetheless the results focus attention on the generally neglected problem of emotional and motivational states produced by isolation.     

A note on modulation of gait in man: Effects of constraining stride length and frequency

In this study, our aim was to investigate the effect of an imposed stride-length on walking speed and stride-frequency, and the effect of an imposed stride-frequency on walking speed and stride-length. These variations were determined in relation to the values obtained by analysing the subject's preferred pace. In the first case, the subject had to step on transversal stripes on the floor; in the second case, he had to synchronize his stride with a regular auditory signal. The results obtained with 8 subjects show that speed was the most variable factor. Variations in speed were correlated with variations in the imposed parameter: whenever the subject lengthened his stride or increased his stride-frequency, his walking speed increased proportionally. These results point to a relative independence between stride-length and stride-frequency, and a strong correlation between each of these parameters and speed.     

Evaluating a dual‐process model of risk: affect and cognition as determinants of risky choice

In three studies we addressed the impact of perceived risk and negative affect on risky choice. In Study 1, we tested a model that included both perceived risk and negative affect as predictors of risky choice. Study 2 and Study 3 replicated these findings and examined the impact of affective versus cognitive processing modes. In all the three studies, both perceived risk and negative affect were shown to be significant predictors of risky choice. Furthermore, Study 2 and Study 3 showed that an affective processing mode strengthened the relation between negative affect and risky choice and that a cognitive processing mode strengthened the relation between perceived risk and risky choice. Together, these findings show support for the idea of a dual‐process model of risky choice. Copyright © 2008 John Wiley & Sons, Ltd.     

Characteristics of a French African Caribbean Epidemiological Psychiatric Sample with a History of Suicide Attempt

Research on vulnerability factors among ethnic groups, independent of primary psychiatric diagnosis, may help to identify groups at risk of suicidal behavior. French African Caribbean general psychiatric patients (N = 362) were recruited consecutively and independently of the primary psychiatric diagnosis. Demographic and clinical characteristics and lifetime history of suicide attempts were recorded. Sixty‐five patients (18%) had a history of at least one suicide attempt. Presence of professional qualifications, children, poor social contacts, treatment with benzodiazepine at inclusion, and poor treatment compliance were all associated with a lifetime history of suicide attempts.     

Harmonic analysis of a complex motor behavior

This study deals with the learning of a complex motor task. The example used is rock climbing, where the subject's motricity is highly constrained by the natural environment. The working hypothesis is that the sensorimotor system searches for behavioral solutions characterized by minimal energy expenditure in the dissipation of forces. Harmonic systems — which satisfy this requirement — are used as models for testing the source signal defined by the acceleration curve at the learner's center of gravity. It is shown that only the dynamics of an expert's motor behavior are harmonic, while those of a beginner are stochastic (or chaotic). It is also shown that for experts, the process of adaptation to environmental constraints involves the relaxation of the dynamics and the ensuing emergence of a stable state which corresponds to a quasi-periodic attractor. A harmonic analysis is used to distinguish the environmental and intrinsic components of the behavioral dynamics, shown to result from the coupling of these two components via resonance.     

Agricultural research networks in sub-Saharan Africa: An analysis of the situation and its consequences

The purpose of this article is to compare the theory and reality of agricultural research networks in sub-Saharan Africa. Networking is a mode of organization that generally suits the new environmental conditions. The analysis of the agricultural research network environment in sub-Saharan Africa shows that when institutional networks started to proliferate, human and institutional conditions were not yet ripe. This explained some of the problems. Nowadays, conditions have improved. Despite all difficulties, networks have contributed to creating a scientific community, have participated in apportioning and even harmonizing research activities, and have made it possible to maintain research activities in countries going through a crisis. Marie de Lattre-Gasquet is a researcher from the Centre de coopération internationale en recherche agronomique pour le développement (CIRAD), in France. Within the external relations directorate of CIRAD, she has been responsible for the relationships between CIRAD and international organizations. She has also actively participated in the preparation of CIRAD’s long-term strategy. She worked for the International Service for National Agricultural Research (ISNAR) in The Netherlands from 1983 to 1985. She holds a Master in International Management (AGSIM, Thunderbird Campus) and a Doctorate in Economy (Université de Paris X). He is mostly working on the agricultural research networks in sub-Saharan Africa. He holds a diploma from the Institut National d’Agronomie—Paris Grignon.