CHull: A generic convex-hull-based model selection method

When analyzing data, researchers are often confronted with a model selection problem (e.g., determining the number of components/factors in principal components analysis [PCA]/factor analysis or identifying the most important predictors in a regression analysis). To tackle such a problem, researchers may apply some objective procedure, like parallel analysis in PCA/factor analysis or stepwise selection methods in regression analysis. A drawback of these procedures is that they can only be applied to the model selection problem at hand. An interesting alternative is the CHull model selection procedure, which was originally developed for multiway analysis (e.g., multimode partitioning). However, the key idea behind the CHull procedure—identifying a model that optimally balances model goodness of fit/misfit and model complexity—is quite generic. Therefore, the procedure may also be used when applying many other analysis techniques. The aim of this article is twofold. First, we demonstrate the wide applicability of the CHull method by showing how it can be used to solve various model selection problems in the context of PCA, reduced K-means, best-subset regression, and partial least squares regression. Moreover, a comparison of CHull with standard model selection methods for these problems is performed. Second, we present the CHULL software, which may be downloaded from http://ppw.kuleuven.be/okp/software/CHULL/, to assist the user in applying the CHull procedure.     

Broadening the individual differences lens on party support and voting behavior: Cynicism and prejudice as relevant attitudes referring to modern-day political alignments

Social-cultural and economic-hierarchical ideological attitudes have long been used to explain variation in political partisanship. We propose two additional, stable attitudes (political cynicism and ethnic prejudice) that may help in explaining contemporary political alignments. In a Belgian (N = 509) and Dutch sample (N = 628), we showed that party support can be segmented into four broad families: left, libertarian, traditionalist, and far-right parties. Both studies revealed that social-cultural and economic-hierarchical right-wing attitudes were negatively related to left party support and positively to libertarian, traditionalist and far-right support. Importantly, additional variance was consistently explained by political cynicism (lower libertarian and traditionalist support), ethnic prejudice (lower left support), or both (higher far-right support). Study 2 additionally demonstrated these patterns for self-reported voting.     

Longitudinal effects of human supremacy beliefs and vegetarianism threat on moral exclusion (vs. inclusion) of animals

Stronger beliefs in human supremacy over animals, and stronger perceived threat posed by vegetarianism to traditional practices, are associated with stronger speciesism and more meat consumption. Both variables might also be implicated in the moral exclusion of animals. We tested this potential in a 16-month longitudinal study in the USA (N = 219). Human supremacy showed longitudinal effects on the moral exclusion of all animals. Vegetarianism threat only predicted moral exclusion of food animals (e.g., cows and pigs), and, unexpectedly, appealing wild animals (e.g., chimps and dolphins). These findings demonstrate the importance of both human supremacy and perceived threat in explaining moral exclusion of animals and highlight potential paradoxical negative consequences of the rise of vegetarianism.     

Appraisal-emotion relationships in daily life

Using a daily process design, the present study examined relationships between momentary appraisals and emotional experience based on Smith and Lazarus' (1993) theory of emotions (1993). Nine times a day for 2 weeks, participants (N = 33, 23 women) recorded their momentary experience of 2 positive emotions (joy, love) and 4 negative emotions (anger, guilt, fear, sadness) and the core relational theme appraisal contents Smith and Lazarus hypothesized as corresponding to these emotions. A series of multilevel modeling analyses found that the hypothesized relationships between appraisal contents and these emotions were stronger than relationships between contents and other emotions, although appraisals were related to other emotions in many cases. Moreover, there were some individual differences in the strength of these relationships. These results suggest that there are no one-to-one relationships between appraisal contents and specific emotional experiences, and that specific emotions are associated with different appraisal contents, and that specific appraisals are associated with different emotions.     

Prognosis in epilepsy and tactics to be applied in terminating anti-epilepsy therapy

This paper compares basic concepts published by eminent epileptologists, supplementing them by a specific analysis of 350 case records. The author, on the basis of data reported in the literature and the results of his own investigations, makes concrete recommendations for the discontinuation of anticonvulsives in the treatment of epilepsy.     

Versuche mit der waagrechten strecke-punkt-figur

The straight line-dot-illusion with horizontally extending figure was ascertained experimentally and explored under several conditions. In the case of binocular perception two “external” and one “internal” factors were found influencing the intensity of the illusion. Observations with right eye and left eye respectively proved themselves to be unequal. The previous interpretations of optical illusions failed to provide a satisfactory explanation of the straight line-dot-illusion. A new explaining assumption was considered.     

Statistical inferences about the error variance

This paper is a presentation of an essential part of the sampling theory of the error variance and the standard error of measurement. An experimental assumption is that several equivalent tests with equal variances are available. These may be either final forms of the same test or obtained by dividing one test into several parts. The simple model of independent and normally distributed errors of measurement with zero mean is employed. No assumption is made about the form of the distributions of true and observed scores. This implies unrestricted freedom in defining the population. First, maximum-likelihood estimators of the error variance and the standard error of measurement are obtained, their sampling distributions given, and their properties investigated. Then unbiased estimators are defined and their distributions derived. The accuracy of estimation is given special consideration from various points of view. Next, rigorous statistical tests are developed to test hypotheses about error variances on the basis of one and two samples. Also the construction of confidence intervals is treated. Finally, Bartlett's test of homogeneity of variances is used to provide a multi-sample test of equality of error variances.     

Intergroup contact buffers against the intergenerational transmission of authoritarianism and racial prejudice

The present study focused on the buffering role of positive intergroup contact in the intergenerational transmission of authoritarianism and racial prejudice in a sample of adolescents and one of their parents. In accordance with our expectations, adolescents’ intergroup contact experiences moderated the mediated relationships between parental authoritarianism and adolescents’ prejudice, both via adolescents’ authoritarianism and via parental prejudice. These relationships were stronger among adolescents with lower, rather than higher, levels of intergroup contact. We conclude that intergroup contact buffers the indirect relationship between parents’ authoritarianism and adolescents’ racial prejudice and therefore constitutes a promising means of reducing the intergenerational transmission of prejudice.     

Longitudinal intergroup contact effects on prejudice using self- and observer-reports

Longitudinal effects of intergroup contact on prejudice were investigated in a sample of 65 young adults (Sample 1) and a sample of their close friends (Sample 2, N= 172), adopting a full cross-lagged panel design. We first validated the self-report measure of intergroup contact from Sample 1 with observer ratings from Sample 2 by demonstrating that self-reports and observer ratings of contact were highly correlated. Moreover, we obtained significant cross-lagged effects of intergroup contact on prejudice with both contact measures, thereby providing a second validation for the use of self-reports of intergroup contact. Finally, by the use of latent change modelling, we demonstrated that, although no overall significant change in contact and prejudice over time was found, there was meaningful variation in absolute change in the individual levels of intergroup contact and prejudice. In particular, some individuals showed increases while others showed decreases in contact or prejudice across time. Moreover, higher levels of intergroup contact at Time 1 were followed by larger subsequent decreases in prejudice between Time 1 and Time 2, and changes in contact were significantly and negatively related to changes in prejudice. Methodological implications of the findings are discussed.     

Is Sexism a Gender Issue? A Motivated Social Cognition Perspective on Men's and Women's Sexist Attitudes Toward Own and Other Gender

The present research investigated the antecedents of ambivalent sexism (i.e., hostile and benevolent forms) in both men and women toward own and other gender. In two heterogeneous adult samples (Study 1: N = 179 and Study 2: N = 222), it was revealed that gender itself was only a minor predictor of sexist attitudes compared with the substantial impact of individual differences in general motivated cognition (i.e., need for closure). Analyses further showed that the relationship between need for closure and sexism was mediated by social attitudes (i.e., right‐wing authoritarianism and social dominance orientation), which were differently related to benevolent and hostile forms of sexism. In the discussion, it is argued that sexism primarily stems from individual differences in motivated cognitive style, which relates to peoples' perspective on the social world, rather than from group differences between men and women. Copyright © 2011 John Wiley & Sons, Ltd.