Sex differences in genetic and environmental influences on DSM-III-R attention-deficit/hyperactivity disorder

Approximately 5% of children are affected by attention-deficit/hyperactivity disorder (ADHD), and more boys are affected than girls. This study examined the magnitude of genetic and environmental influences on ADHD and several questions regarding sex differences in its prevalence and liability. The participants were 2,391 twin and sibling pairs from Australia, ages 3-18. ADHD symptoms in the general population were highly heritable (h2 = .85-.90), as were deviant ADHD scores in the selected population. The magnitude of familial influences was similar for boys and girls, although there were shared environmental influences on ADHD in girls but not boys and dominance genetic influences on ADHD in boys but not girls. Specific genetic and environmental influences were highly similar for boys and girls. Evidence supported the polygenic multiple threshold model rather than the constitutional variability model of sex differences in ADHD.     

Individual differences in the effects of spontaneous mimicry on emotional contagion

Two experiments explored the role of mimicry and self-perception processes in emotional contagion. In Study 1, 46 subjects watched two brief film clips depicting an episode of startled fear. In a separate procedure, subjects adopted facial expressions of emotion, and reported whether the expressions had caused them to feel corresponding emotions. Those who reported feeling the emotions were identified as more responsive to self-produced cues for feeling. Subjects who visibly moved to mimic the behavior of the actor were significantly more likely to be those who were more responsive to self-produced cues. In Study 2, 57 subjects watched three film clips depicting happy people. During clips when they inhibited the movements of their faces, subjects reported less happiness than during clips when they moved naturally and were able to mimic, or when they exaggerated their movements. This effect occurred only among subjects who, in a separate procedure, had been identified as more responsive to self-produced cues.The authors would like to thank Paul Ekman, Jerry Ginzburg, and an anonymous reviewer for very helpful suggestions for ways to improve the paper.     

Hyperactivity and the Fragile X Syndrome

Workers who have claimed an association between Fragile X [fra(x)] Syndrome and Hyperactivity and aggressive behavior have done so despite the lack of controlled studies using standard diagnostic criteria. Accordingly, we provided a controlled test of the hypothesis that individuals with the fra(x) Syndrome are more hyperactive and have more symptoms of aggression than other mentally retarded individuals. The test formed part of a study to assess autistic behavior in fra(x) individuals. A sample of fra(x) individuals was obtained from the register of a clinical genetics unit and individually matched for age, sex, and IQ with mentally retarded individuals selected from assessment centres. Fortyfive pairs of fra(x) cases and control individuals were compared on criteria which reflected DSM-III concepts of hyperactivity and on criteria reflecting aggressive behavior. The comparison failed to find a higher prevalence of these symptoms in the fra(x) group. An analysis of the study's statistical power suggested that it is unlikely that the investigation failed to detect a large to medium difference between fra(x) individuals and control individuals in the symptoms investigated.     

Social cognitive predictors of prosocial behavior toward same and alternate race children among white pre-schoolers

Social cognitive predictors of 36 White preschoolers' (18 boys, 18 girls) tendencies to say they would act prosocially toward White and African-American children were examined. White preschoolers completed measures of their tendency to engage in prosocial behaviors directed toward White and African-American children, positive racial beliefs about White and African-American persons, and race schematicity. Consistent with previous research examining prosocial behavior in preschoolers, girls were more likely than boys to say they would act prosocially. White preschoolers' age in months did not correlate significantly with their tendencies to engage in prosocial behaviors toward White children. However, age in months was negatively correlated with White preschoolers' inclinations to direct prosocial behaviors toward African-American children. Consistent with an emerging literature concerning the role of social cognitive factors in young children's race schema development, White preschoolers' race schematicity was significantly predictive of their tendencies to say they would engage in prosocial behaviors toward African-American children. Patterns of results partially replicate previous prosocial behavior research, and demonstrate the importance of social cognitive variables on young children's prosocial behaviors. This research was undertaken as part of a graduate program in psychology at the University of Wyoming by the first author under the direction of the second author. The authors express gratitude to Karen Bartsch, Ph.D., and Bernita Quoss, Ph.D., and Jesse Barber, Sylvia Jones, and Nicole Martin of the University of Wyoming and to Nancy Eisenberg, Ph.D., of Arizona State University.     

Opium of the people? National identification predicts well-being over time

Social group membership and its social-relational corollaries, for example, social contact, trust, and support, are prophylactic for health. Research has tended to focus on how direct social interactions between members of small-scale groups (i.e., a local sports team or community group) are conducive to positive health outcomes. The current study provides evidence from a longitudinal cross-cultural sample (N = 6,748; 18 countries/societies) that the prophylactic effect of group membership is not isolated to small-scale groups, and that members of groups do not have to directly interact, or in fact know of each other to benefit from membership. Our longitudinal analyses suggest that national identification (strength of association with the country/society of which one is a citizen) predicts lower anxiety and improved health; national identification was in fact almost as positively predictive of health status as anxiety was negatively predictive. The findings indicate that identification with large-scale groups, like small-scale groups, is palliative, and are discussed in terms of globalization and banal nationalism.     

Lossy-Context Surprisal: An Information-Theoretic Model of Memory Effects in Sentence Processing

A key component of research on human sentence processing is to characterize the processing difficulty associated with the comprehension of words in context. Models that explain and predict this difficulty can be broadly divided into two kinds, expectation-based and memory-based. In this work, we present a new model of incremental sentence processing difficulty that unifies and extends key features of both kinds of models. Our model, lossy-context surprisal, holds that the processing difficulty at a word in context is proportional to the surprisal of the word given a lossy memory representation of the context—that is, a memory representation that does not contain complete information about previous words. We show that this model provides an intuitive explanation for an outstanding puzzle involving interactions of memory and expectations: language-dependent structural forgetting, where the effects of memory on sentence processing appear to be moderated by language statistics. Furthermore, we demonstrate that dependency locality effects, a signature prediction of memory-based theories, can be derived from lossy-context surprisal as a special case of a novel, more general principle called information locality.     

Placing perceptions of politics in the context of the feedback environment, employee attitudes, and job performance

The authors proposed a model suggesting that organizational environments supporting high levels of informal supervisor and coworker feedback are associated with lower employee perceptions of organizational politics. Furthermore, these lowered perceptions of politics were proposed to result in higher employee morale (as reflected in job satisfaction and affective commitment) and, through morale, to higher levels of task performance and organizational citizenship. The proposed mediational model was supported with empirical results from 150 subordinate-supervisor dyads sampled across a variety of organizations. Higher quality feedback environments were associated with lower perceptions of organizational politics, and morale mediated the relationships between organizational politics and various aspects of work performance. These findings suggest that when employees have greater access to information regarding behaviors that are acceptable and desired at work, perceptions of politics are reduced and work outcomes are enhanced.