Longitudinal associations between adolescent alcohol use and parents' sources of knowledge

The aim of this study was to test the direction of effect in the relationship between parents' sources of knowledge (parental monitoring and child disclosure) and adolescent alcohol use. The participants were 215 adolescents and their mothers, randomly selected from urban and rural areas in Cyprus. A 3‐month, two‐timepoint longitudinal design was used in which adolescents completed the alcohol use disorders identification test while mothers completed a parental knowledge questionnaire. The results of this study showed that parental monitoring did not predict subsequent adolescent alcohol use. However, child disclosure at Time 1 negatively predicted adolescent alcohol use at Time 2. Moreover, adolescents' alcohol dependence symptoms at Time 1 negatively predicted both sources of parental knowledge at Time 2.     

The nature of adaptation in distance perception based on oculomotor cues

In previous work by the senior authors, brief adaptation to glasses that changed the accommodation and convergence with which objects were seen resulted in large alterations in size perception. Here, two further effects of such adaptation are reported: alterations in stereoscopic depth perception and a change when distance is represented by a response of S’s arm. We believe that the three effects are manifestations of one primary effect, an alteration of the relation between accommodation and convergence on the one hand and the distance they represent in the nervous system (registered distance) on the other. This view was supported by the results of two experiments, each of which demonstrated that the alterations in stereoscopic depth perception could be obtained after adaptation periods which had provided no opportunity to use stereoscopic vision, and that the adaptation effect was larger for depth perception than for size perception when it was obtained under the same conditions; the latter finding was expected if both effects resulted from the same change in registered distance. In three of the five experiments here reported, the variety of cues that could represent veridical distance during the adaptation period was limited. In one condition of adaptation, only the pattern of growth of the retinal images of objects that S approached and the kinesthetic cues for S’s locomotion served as cues to veridical distance. In two other conditions S remained immobile. In one of these, only the perspective distortion in the projection of the scene that S viewed mediated veridical distance, and in the other one familiar objects of normal size were successively illuminated in an otherwise totally dark field, conditions from which opportunities to use stereoscopic vision were again absent. After exposure to each of these adaptation conditions, adaptive changes in perceived size and larger ones in perceived stereoscopic depth were obtained. Because we found that familiar size may serve as the sole indicator of veridical distance in an adaptation process, we concluded that it can function as a perceptual as distinguished from an inferential cue to distance.     

Adaptation in distance perception based on oculomotor cues

Accommodation and convergence primarily serve to adjust the eyes to the distance of the object viewed, but, once made, these oculomotor adjustments serve as cues for the object’s distance. Experiments are reported that show that the relation between oculomotor adjustments and the distances they signify can be changed by adaptation to glasses that cause alteration in the oculomotor adjustments with which objects are viewed. This changed relation manifested itself in marked alterations of size perception. Wearing, for 30 min, glasses that caused a change in accommodation and convergence corresponding to a smaller object distance and equivalent to 1.5 lens diopters caused subsequent mean size increases that ranged from 50% to 65%. Adaptation to glasses that changed oculomotor adjustments in the same amount but in the opposite direction resulted in decreases in perceived sizes that varied from 18% to 40%, dependent on the distance of the test object. These were the results of size estimates obtained before and after the adaptation period under conditions where only accommodation and convergence served as cues for distance. A newly developed test of size perception was also used, in which S adjusted the size of the projected image of an array of familiar objects on a screen until the size of the objects appeared normal. Again, such adjustments were made before and after the adaptation period, and size differences were obtained that were in the direction to be expected of adaptation and varied in amount between 12% and 33%, dependent on the distance of the screen. The reason for the different amounts of size change measured by the two kinds of tests was investigated.     

Adaptation in the constancy of visual direction measured by a one-trial method

Adaptation to field displacement during head movements in the direction with the head rotation and in the direction against it was produced under otherwise identical conditions and compared; the field displacement rate was also varied. A rapid training procedure was used, and a novel one-trial test was employed that could measure the adaptation well enough to compare the effects of various training conditions. The one-trial test measured the magnitude of one of the manifestations of adaptation, the apparent displacement of a stationary target during head movements. This apparent horizontal target displacement was transformed into an oblique one by having the head movements that brought forth the apparent target displacement simultaneously cause an objective vertical target displacement. The slant of the resultant apparent motion path varied with the magnitude of the apparent horizontal target displacement. It was measured by having S reproduce its slant angle. It was found that adaptation to field displacement in the direction with the head rotation was consistently greater than adaptation to the opposite displacement conditions. An explanation for this result is offered.     

Serious and playful aggression in Brazilian girls and boys

We report on an observational study on sex differences in serious and playful aggression in early childhood. The sample included 14 girls and 14 boys, aged 2 to 4. The study was carried out in Porto Alegre, Brazil. Half of the subjects attended a nursery school for children from a favela (slum district); the others attended a nursery school that was run by a local university and represented the life conditions of the middle class of the Brazilian society. Each of the children was observed at school for 3 hours (divided into 12–15 minutes episodes) through a focal sampling technique. Significant sex differences are found for the frequency of playful aggression for both the actor's and the victim's part of the aggressive act, but for the actor's role the effect holds only for the middle class setting. There are also tremendous differences between the frequencies of serious aggression in girls and some of the boys, although the effect is not statistically significant. When several types of aggression are compared, it becomes evident that sex differences are restricted to bullying (dominant aggression). The rates of instrumental and reactive aggression are similar in both sexes. Girls and boys from the favela setting do not differ in the relative importance of the different types of serious aggression, but in middle class children the proportion of acts of bullying is much higher in boys than in girls.Revised and elaborated version of the contribution to the Paper Session onFemale Aggression at the90th Annual Meeting of the American Anthropological Association in Chicago, 1991. We thank Claúdio Simon Hutz and Tânia Sperb who helped us to carry out the observations and Simone Schenk and Iris Seltenreich for help in data analysis. We are also grateful to the children and the staff of two nursery schools in Porto Alegre, Brazil, who participated in the study.