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).     

Interhemispheric integration of compound nouns: effects of stimulus arrangement and mode of presentation

Normal subjects had to name German compound nouns which were presented tachistoscopically. The compound nouns were displayed either unilaterally to the left or right visual field or bilaterally with one element to each visual field. In the bilateral condition a distinction was made as to whether familiar or unfamiliar arrangement of the elements was used. Representation in print was compared with pictorial representation of the compound nouns. A right visual-field superiority was observed with printed representation, but no laterality effects with pictorial representation. Bilateral processing was superior to unilateral processing. Within the bilateral conditions, the familiar arrangement of the elements yielded a significantly better performance than unfamiliar arrangement. This difference can be explained by reading habits and/or by different styles of interhemispheric integration.     

Differential visual field-interhemispheric transfer: can it explain sex and handedness differences in lateralization?

104 men and women were tested for visual field-hemispheric transfer of spatial information on a dot-localization task. Right-handed subjects showed significant improvement when stimuli were presented to the left visual field of the right hemisphere (LVF-RH) after practice on the same task presented to the right visual field of the left hemisphere (RVF-LH) first. No improvement was found when the task was presented in the reverse order (LVF-RH first followed by RVF-LH). It was concluded that, for right-handers, transfer of spatial information to the right hemisphere is facilitated while transfer to the left hemisphere is inhibited. Left-handed subjects demonstrated no significant improvement in either condition, suggesting inhibition or lack of transfer of spatial information in either direction. No sex differences were found in either right-handed or left-handed subjects. The findings suggest that there may be different mechanisms underlying the similarities in functional lateralization of women and left-handers.     

The varieties of fear

Conclusion I shall conclude with a methodological moral. I have tried to show that there are several fundamentally different kinds of fear. One is a pure propositional attitude, one is partially a bodily state, and one is a relation between a person and a nonpropositional object. Other emotions come in similar varieties, such as hope and happiness, but with significant differences. The state of happiness, for example, does not entail any particular bodily state or feeling. So one lesson is this: it is hard to generalize about the emotions. Further detailed, analytical studies of particular emotions are needed before a general theory of the emotions can be fruitfully attempted.     

SELF-ASSESSED TRAINING NEEDS: THE EFFECTS OF ATTITUDES TOWARD TRAINING, MANAGERIAL LEVEL, AND FUNCTION

Self-assessment research has concentrated on validity and psychometric issues in selection and appraisal contexts. Little is known about factors that affect self-assessment of training needs. The present study examines the influence of managerial position (level, function) and managerial attitudes toward training utility on self-reported training needs. A training-needs survey consisting of items related to basic managerial, interpersonal, administrative, and quality control skills was completed by 506 lower and middle level managers across four functional areas. Correlational and regression analyses indicated that managerial level and function had some effect on reported administrative training needs, while function and attitudes towards training utility had some impact on self-reported training needs for quality control. Level, function, and attitude were not related to reported basic managerial and interpersonal training needs. The implications and limitations of the results are discussed, and future research directions are presented.     

Specific temporal-lobe signs and enhanced delayed cross-modal matching performance

Structural damage to the amygdala severely retards delayed cross-modal (tactile-to-sight) matching in primates. Conversely, we hypothesized that people who display signs suggestive of specific temporal lobe lability should show enhanced delayed cross-modal matching performance. The hypothesis was supported. In a single experiment involving 25 subjects, significant negative correlations obtained between the numbers of errors on the cross-modal matching task and numbers of affirmative responses within clusters of items that contained themes of meaningfulness, religious beliefs or ictal, complex partial epileptic (limbic) states. On the other hand, the numbers of errors were not significantly correlated with either clusters of control items or items that are presumed to reflect the function of other temporal-lobe structures. Both matching and questionnaire data were collected under double-blind conditions.     

Stress as a state of anticipatory vigilance

The pituitary-adrenocortical system is activated in stressful situations, and the adrenocortical hormones have been implicated by Selye in the diseases of stress. Evidence indicates that the adrenocortical hormones peak during the period of anticipation of stressful events, not during actual confrontation with them. The circadian cortisol rhythm shows peaks before waking, not during active periods of the day, and cortisol does not appear to be required during physical activity. The role of these hormones appears to be to suppress ongoing physiological activity in order to increase vigilance and to get the organism ready to take action before the impact of dangers.     

Book Reviews

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