Comparing latent distributions

We consider the problem of comparingm latent population distributions when the observed values are scores on a test battery with binary items. The latent densities are assumed to be normal densities, and we consider a test for equality of the means as well as a test equality of the variances. In addition, we consider a longitudinal model, where the test battery has been applied to the same individuals at different points in time. This model allows for correlations between the latent variable at different time points, and methods are discussed for estimating the correlation coefficient.This work was supported in part by a grant from the Danish Social Science Research Council.     

Beyond artificial, sex-linked distinctions to conceptualize female sexuality: comment on Baumeister (2000)

The authors comment on three aspects of R. F. Baumeister's (2000) theoretical article on female sexuality. Questioning the predominance of nature versus cultural factors in accounting for sexual outcomes for men and women, the authors draw attention to the similarities (as opposed to differences) in the sexual attitudes, behaviors, and responses of men and women, and directly question the suggestion of "controlling" women's sexual attitudes, behaviors, responses, etc. to meet social needs for change.     

Assessing stress in cancer patients: a second-order factor analysis model for the Perceived Stress Scale

Using the Perceived Stress Scale (PSS), perceptions of global stress were assessed in 111 women following breast cancer surgery and at 12 and 24 months later This is the first study to factor analyze the PSS. The PSS data were factor analyzed each time using exploratory factor analysis with oblique direct quartimin rotation. Goodness-of-fit indices (root mean square error of approximation [RMSEA]), magnitude and pattern of factor loadings, and confidence interval data revealed a two-factor solution of positive versus negative stress items. The findings, replicated across time, also indicate factor stability. Hierarchical factor analyses supported a second-order factor of "perceived stress." This alternative factor model of the PSS is presented along with observations regarding the measure's use in cancer research.     

IQ stability: the relation between child and young adult intelligence test scores in low-birthweight samples

The stability of IQ from childhood to adulthood in low-birthweight subjects was measured in two independent samples with follow-up intervals of approximately 14 and 9.5 years. In both samples, intelligence was assessed with the WISC at a mean age of 9.5. Twenty-six subjects were retested with the WAIS at a mean age of 23.5, and 78 subjects with the BPP (the Danish Military Draft Board Intelligence Test) at the age of 19.1. Both samples obtained childhood and adult test scores below the expected means. For the Wechsler Verbal, Performance and Full-Scale IQs, the stability quotients were 0.86, 0.86, and 0.89 in the WAIS sample, and the retest correlations for the three IQs with the BPP score were 0.66, 0.65, and 0.74. Thus, the majority of children showed stable patterns of intellectual development from middle childhood to young adulthood.     

The discrimination of heading from optic flow is not retinally invariant

Three experiments were conducted to determine whether the discrimination of heading from optic flow is retinally invariant and to determine the importance of acuity in accounting for heading eccentricity effects. In the first experiment, observers were presented with radial flow fields simulating forward translation through a three-dimensional volume of dots. The flow fields subtended 10° of visual angle and were presented at 0°, 10°, 20°, and 40° of retinal eccentricity. The observers were asked to indicate whether the simulated movement was to the right or the left of a target that appeared at the end of the display sequence. Eye movements were monitored with an electrooculogram apparatus. In a second experiment, static acuity thresholds were derived for each of the observers at the same retinal eccentricities. There was a significant increase in heading detection thresholds with retinal eccentricity (from 0.92° at 0° retinal eccentricity to 3.47° at 40°). An analysis of covariance indicated that the variation in sensitivity to radial flow, as a function of retinal eccentricity, is independent of acuity. Similar results were obtained when the Vernier acuity of observers was measured. These results suggest that the discrimination of heading from radial flow is not retinally invariant.     

Exposure to Media Images of Female Attractiveness and Concern with Body Weight Among Young Women1

Despite the popular belief that the thinstandard of female attractiveness currently presented inthe media is a primary contributor to the high level ofconcern with body weight among women, experimental studies have not shown that exposure to mediaimages increases women's weight concern. Threeexperiments are reported demonstrating that exposure tomedia images does often result in increased weightconcern among women, but that body dissatisfaction, astable personality characteristic, is a moderator ofvulnerability to this effect. Although most womenreported higher weight concern when exposed to media vs. neutral images, women with low initial bodydissatisfaction did not. In addition, this researchsuggests that negative effects on weight concern mayresult from even passive exposure to media images, but that exposure to realistic attractivenessis less likely to cause increased weight concern. Theethnicity of the participants in these studies reflectedthat of the local population, with over 90% white. The nonwhite participants primarily belonged toone of the following groups; Asian, Pacific Islander,Latino.     

Sex-role typing as related to acceptance of self, acceptance of others, and discriminatory attitudes toward women

This study examines four hypotheses relating sex-role typing to self-acceptance, acceptance of others, and sexist attitudes toward women. University students completed the Bem Sex-Role Inventory, the Berger Self-Acceptance Scale, and the Macho Scale. Findings showed more self-acceptance than acceptance of others among masculine-typed subjects and more acceptance of others than self-acceptance among feminine-typed subjects. Feminine-typed males and masculine-type females showed least self-acceptance among the six groups, while androgynous subjects showed highest self-acceptance. Masculine-typed males were least accepting of others and scored highest in discriminatory attitudes toward women. Male subjects showed greater variability than did female subjects on all scales, and Bem's measure of sex-role typing proved a more efficient moderator of scores of males than of those of females. Additional personality and behavioral research with sex-role typing variables is proposed.     

Estimating the parameters of the latent population distribution

Under consideration is a test battery of binary items. The responses ofn individuals are assumed to follow a Rasch model. It is further assumed that the latent individual parameters are distributed within a given population in accordance with a normal distribution. Methods are then considered for estimating the mean and variance of this latent population distribution. Also considered are methods for checking whether a normal population distribution fits the data. The developed methods are applied to data from an achievement test and from an attitude test.