Left-handedness in twin families: support of an environmental hypothesis

Information on handedness, assessed as writing-hand, was collected from 197 MZ twin pairs and 203 DZ twin pairs and from their parents, spouses, and children. Associations for pairs of relatives were studied by 2 X 2 tables, computing chi squared-values and tetrachoric correlations. Correlations of about .3 were obtained for mother-offspring and sibling pairs, while for cousins the correlation was .25 (in a small sample). No other significant associations were found, not even for twins. These results suggest only a small, if any, genetic effect, and only a small environmental between family effect, most of which seems to be a maternal effect. The lack of cotwin correlations and correlations for one of the twins with her/his ordinary brothers/sisters suggest the existence of an effect specific to twins, since the correlation for pairs of ordinary siblings is significant. Conclusions drawn from twin studies alone may be biased. The frequency of left-hand writers has increased from 1% to 10% in the different age groups born during the last century in Norway. This age effect is present mainly in hand writing and not so much in handedness generally, suggesting a decrease in cultural repression against left-hand writing.     

References for motor tasks--gender differences across age in motor performance: a meta-analysis

In 1985 we published a meta-analysis of gender differences across age in motor performance in Psychological Bulletin, but it did not include an indexing of each motor task to the references from which it was obtained. This paper provides a table listing the 20 motor tasks and the references from which data for each task were taken. The range of tasks was from fundamental movements (e.g., catching, jumping, running, throwing) to motor fitness (e.g., agility, arm hang, balance, grip strength) to perceptual-motor abilities (e.g., anticipation timing, fine eye-motor coordination, pursuit-rotor tracking, reaction time). The arm hang was represented in the fewest papers (n = 2) while the dash and long jump were most frequently referenced (n = 21).     

In search of the false-uniqueness phenomenon: fear and estimates of social consensus

An examination of the social perception literature yields little evidence for the false-uniqueness phenomenon (Valins & Nisbett, 1972), the perception that one's attributes are more unique than is the case. In contrast, the tendency for individuals to project their own characteristics onto other people and assume that more people are like themselves is a robust phenomenon. One reason researchers may not have found false uniqueness is that they have not looked at the accuracy of consensus estimates. A close look at the results of Tabachnik, Crocker, and Alloy (1983) and Sanders and Mullen (1983), who did assess accuracy, suggests that people possessing undesirable attributes over-estimate consensus, whereas people holding desirable attributes underestimate consensus. The latter pattern is a form of false uniqueness. In this study we looked at the accuracy of social consensus estimates in the context of psychological fears. A sample of subjects filled out an abbreviated version of a fear survey and made estimates of consensus. The results showed that both high- and low-fear respondents overestimated the incidence of high fear among their peers, but high-fear subjects were more inaccurate in their estimates. A false-uniqueness effect was found on the part of low-fear subjects, as they tended to underestimate the incidence of low fear among their peers. These findings are consistent with a motivational interpretation that emphasizes the individual's need to justify or normalize stigmatized behavior and to bolster perceived self-competence.     

On comprehension of active/passive sentences and language processing in a Polish agrammatic aphasic

This paper presents the results of a study of active/passive sentence comprehension by a Polish-speaking agrammatic aphasic. The patient showed good performance on canonically ordered active and passive structures, but performed poorly on inverted variants. The systematically normal and deviant comprehension patterns observed are accounted for by normal interpretative strategies applied to syntactic structures built around verbs with reduced inflectional morphology. The differences between our Polish data and the English data discussed in the literature are explained by the fact that Polish possesses a richer derivational verb morphology. The interpretation of inverted sentences demonstrates the importance of S-V-O word order preference. Our analysis draws upon the notion of grammatical functions to explain the data.     

Negative implications of fragmented public perspectives toward local alcohol programs

Strengthening local alcohol programs so as to emphasize primary prevention is an active concern among mental health professionals; yet interventions intended to achieve this aim have produced only modest shifts in program orientation in most communities. An analysis of data obtained from those active in local affairs in a small community, using Q-sort techniques, suggested that contrasting perspectives toward alcohol abuse as a social problem may stand as an unseen barrier to relevant change.     

Predicting child behavior problems in maritally violent families

Previous research indicates that children from violent marriages are more likely to suffer from conduct problems and/or anxiety disorders than children from nonviolent, satisfactory marriages. However, knowledge regarding specific factors present in violent marriages relating to child problems is limited. The present study examined the relationships involving interspousal aggression, parent-child aggression, and child behavior problems in a sample of 45 children from maritally violent families. Mothers indicated how often their children witnessed interspousal aggression and were victims of parent-child aggression. Mothers also rated their children's problem behaviors while children reported on their own depressive symptoms. The witnessing of interspousal aggression was highly associated with parental aggression directed toward children. Parent-child aggression related to attention problems, anxiety-withdrawl, motor excess, and conduct problems in children. However, the witnessing of interspousal aggression was not significantly related to child behavior problems. These results are consistent with theoretical predictions linking marital problems to child behavior by virtue of their association with parenting.This research was supported in part by a Grant-in-Aid of Research awarded to the first author by Sigma Xi, the Scientific Research Society, and NIMH Grant No. MH35340 awarded to the third author. The authors wish to thank Martha Wray and her staff at VIBS for their help throughout this project.     

Mechanisms underlying satiation of feeding behavior of the mollusc Aplysia

Animals filled almost to satiation by nonnutritive bulk do not satiate when they ingest a small amount of seaweed. This suggests that satiation is not triggered by chemostimulation of an anteriorly located "hot spot." Inflation of a balloon placed in the gut of the animal results in satiation as reflected in a number of different parameters of feeding behavior. The suppressive effect of a relatively brief inflation is rapidly and fully reversible, although repeated inflation and deflation appeared to produce slowly reversible or irreversible effects. The parameters of the changes in feeding during gut inflation are comparable to those of normal animals that are slowly fed individual pieces of food. The inflation volume needed to satiate the animal is a function of the rate of inflation--more rapid inflations requiring larger volumes. Cutting of the esophageal nerves results in a significant increase in the volume needed to satiate the animals, but nevertheless they eventually cease feeding and generally do not show a burst gut. The evidence indicates that the satiation that eventually occurs in nerve-sectioned animals, at least in part, is due to depression of feeding following very prolonged sensory stimulation. The data suggest that for a rapidly consumed meal, satiation results primarily due to distension-related gut signals conveyed by the esophageal nerves, whereas for very slowly consumed meals, the former factor interacts with a process associated with sensory stimulation, such as receptor adaptation. The current results indicate that balloon distension can serve as a reasonable stimulus in experiments in simplified preparations in which the nervous system can be studied.