Evaluating validity and test-retest reliability in four drive for muscularity questionnaires

The current study assessed relationships among four commonly used drive for muscularity questionnaires, along with their 7 and 14 day test-retest reliability. Sample 1 was comprised of young British adult males (N=272; M(AGE)=20.3) who completed the questionnaires once. Sample 2, a group of young British adult males (N=54, M(AGE)=19.3), completed the questionnaires three times spaced 7 and 14 days apart. Correlations among Sample 1 ranged from .20 to .82 providing evidence for concurrent and discriminant validities. Evidence for test-retest reliability emerged with intraclass correlations ranging from .78 to .95 (p<.001) and generally nonsignificant t-tests (p>.05). Overall, the data support the psychometric properties of the drive for muscularity inventories; however, the shared variance (35-67%) hints that refinement is possible.     

Friends with benefits: the evolved psychology of same- and opposite-sex friendship

During human evolution, men and women faced distinct adaptive problems, including pregnancy, hunting, childcare, and warfare. Due to these sex-linked adaptive problems, natural selection would have favored psychological mechanisms that oriented men and women toward forming friendships with individuals possessing characteristics valuable for solving these problems. The current study explored sex-differentiated friend preferences and the psychological design features of same- and opposite-sex friendship in two tasks. In Task 1, participants (N = 121) categorized their same-sex friends (SSFs) and opposite-sex friends (OSFs) according to the functions these friends serve in their lives. In Task 2, participants designed their ideal SSFs and OSFs using limited budgets that forced them to make trade-offs between the characteristics they desire in their friends. In Task 1, men, more than women, reported maintaining SSFs for functions related to athleticism and status enhancement and OSFs for mating opportunities. In Task 2, both sexes prioritized agreeableness and dependability in their ideal SSFs, but men prioritized physical attractiveness in their OSFs, whereas women prioritized economic resources and physical prowess. These findings suggest that friend preferences may have evolved to solve ancestrally sex-linked adaptive problems, and that opposite-sex friendship may directly or indirectly serve mating functions.     

Human sexual conflict from molecules to culture

Coevolutionary arms races between males and females have equipped both sexes with mutually manipulative and defensive adaptations. These adaptations function to benefit individual reproductive interests at the cost of the reproductive interests of opposite- sex mates, and arise from evolutionary dynamics such as parental investment (unequal reproductive costs between the sexes) and sexual selection (unequal access to opposite-sex mates). Individuals use these adaptations to hijack others' reproductive systems, psychological states, and behaviors-essentially using other individuals as extended phenotypes of themselves. Such extended phenotypic manipulation of sexual rivals and opposite-sex mates is enacted by humans with the aid of hormones, pheromones, neurotransmitters, emotions, language, mind-altering substances, social institutions, technologies, and ideologies. Furthermore, sexual conflict may be experienced at an individual level when maternal genes and paternal genes are in conflict within an organism. Sexual conflict may be physically and emotionally destructive, but may also be exciting and constructive for relationships. By extending the biological concept of sexual conflict into social and cultural domains, scholars may successfully bridge many of the interdisciplinary gaps that separate the sciences from the humanities.     

Psychometric properties of the Revised Male Body Attitudes Scale among Irish men

The psychometric properties of a revised version of the Male Body Attitudes Scale (Tylka, Bergeron, & Schwartz, 2005) were investigated using two independent online samples of Irish men (ns=241 and 253, respectively). Exploratory factor analyses suggested that a 15-item, 3-factor solution representing men's attitudes toward their body fat, muscularity, and height best described the data. The internal consistency and construct validity of scores on the Revised Male Body Attitudes Scale suggest that this measure holds promise as an indicant of men's attitudes toward their physical appearance. Limitations and strengths associated with the current research are discussed and directions for future research are outlined.     

The what–where trade-off in multiple-identity tracking

Observers are poor at reporting the identities of objects that they have successfully tracked (Pylyshyn, Visual Cognition, 11, 801-822, 2004; Scholl & Pylyshyn, Cognitive Psychology, 38, 259-290, 1999). Consequently, it has been claimed that objects are tracked in a manner that does not encode their identities (Pylyshyn, 2004). Here, we present evidence that disputes this claim. In a series of experiments, we show that attempting to track the identities of objects can decrease an observer's ability to track the objects' locations. This indicates that the mechanisms that track, respectively, the locations and identities of objects draw upon a common resource. Furthermore, we show that this common resource can be voluntarily distributed between the two mechanisms. This is clear evidence that the location- and identity-tracking mechanisms are not entirely dissociable.     

Stimulus range and discontinuity effects on information-integration category learning and generalization

Two studies are reported that support the hypothesis that categories that require a multiple-unit, as opposed to a single-unit, representation lead to worse initial acquisition but better generalization. On the basis of the constraints imposed by the procedural-based learning system thought to mediate information-integration categorization, we argue that the need to train multiple units during initial category acquisition slows the procedural-based category learning process and adversely affects learning performance. However, we speculate that better generalization occurs because of the increased likelihood that a novel stimulus will activate at least one of the multiple units needed to represent the category. Relations to other findings in the literature and the implications of this work for training and clinical assessment are discussed.     

Risk factors for disordered eating during early and middle adolescence: prospective evidence from mainland Chinese boys and girls

Despite evidence that sociocultural and psychological factors contribute to disordered eating, researchers have yet to examine the extent to which putative risk factors influence vulnerability for girls versus boys within and across phases of adolescence, particularly in non-Western cultures. In this study, early and middle adolescent samples from China (N = 2,909) completed measures of eating disorder pathology and putative risk factors at baseline and were reassessed 12 months later. Among both younger and older girls, elevations in appearance-focused interactions with friends, negative affect, and body dissatisfaction predicted increases in symptomatology at follow-up. In contrast, there was more discontinuity in risk factors relevant to samples of boys. Although media and friendship influences contributed to later disturbances among early adolescent boys, psychological factors, including body dissatisfaction and negative affect, had stronger effects in the multivariate model for older boys. Implications of finding are discussed in relation to adolescent development and a Chinese cultural context.