The computerized version of the Wisconsin Card Sorting Test (WCST) was administered to a sample of 96 subjects (Ss), constituted in equal parts by monozygotic twins (MZ), dizygotic twins (DZ), unique children and couples of “almost contemporary” brothers. The statistic tests (Analysis of principal components, ANOVA) underline, as far as the rapidity to define a category is concerned, a statistically significant difference between DZ and singletons, independently from the fact that the latter may be unique children. A significant difference emerged neither between MZ and singletons, nor between MZ and DZ.

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Abstract.A major problem that researchers attempting to elaborate mathematical models of neurophysiological and/or psychophysiological processes are confronted with is the identification of the mechanisms that give rise, in a neural network, to oscillatory behavior, either spontaneous or induced by external stimuli. The present work starts by considering a network model of a central pattern generator (CPG), introduced by Sompolinsky and co-authors. The present authors try to generalize this model to a wider range of biological situations, by introducing into it dynamic adjustments of connections among the processing units. Although the study performed so far is quite preliminary, some analytical considerations can be presented, supported by the results of numerical simulations, which show always a relaxation of the network toward specific stable states.

Abstract. It is hypothesized that marginal behavioral deviations, through their aggregation, may generate impressions of discomfort and disturbance, leading in their turn to progressive social seclusion, lower self-esteem, and maladjustment. The article describes an attempt to assess the development of a stable aggressive behavior, by means of a neuro-fuzzy model of the relationships between sociometric predictors (popularity/refusal rates among peers, hyperactivity, prosocial behavior) and yearly variations in physical and verbal aggressive conduct in children. A hardly noticeable initial difference (classification into marginally aggressive and marginally nonaggressive) is sufficient to lead to relevant differences, such as a resilience to change the judged aggressive level in the presence of changes of sociometric predictors for marginally aggressive children only.

This study considers the replies to a 14-item questionnaire, by 27 monozytogic (MZ) and 38 dizygotic (DZ) pairs. Another sample consisting of 48 sets of parents of twins (24 of whom were MZ and 24 DZ, not necessarily corresponding to the couples of twins actually studied) was used, to answer a questionnaire directly related the one put to the twin pairs. The results of statistical tests performed (canonical correlation and Fisher's discriminant) indicate that only in MZ twins does self-awareness outweigh pair-awareness. This does not seem to be related to any difference between MZ and DZ twins in the education/upbringing received from their parents.