The role of occlusion in the perception of depth, lightness, and opacity

A theory is presented that explains how the visual system infers the lightness, opacity, and depth of surfaces from stereoscopic images. It is shown that the polarity and magnitude of image contrast play distinct roles in surface perception, which can be captured by 2 principles of perceptual inference. First, a contrast depth asymmetry principle articulates how the visual system computes the ordinal depth and lightness relationships from the polarity of local, binocularly matched image contrast. Second, a global transmittance anchoring principle expresses how variations in contrast magnitudes are used to infer the presence of transparent surfaces. It is argued that these principles provide a unified explanation of how the visual system computes the 3-D surface structure of opaque and transparent surfaces.     

Amygdala size and hypothalamus size predict social play frequency in nonhuman primates: a comparative analysis using independent contrasts

The amygdala and hypothalamus become sexually differentiated by gonadal hormones giving rise to sexually differentiated behaviors, which include play behavior. Phylogenetic comparative analyses test for relationships between social play and brain structure volumes. Relative volume of the amygdala and hypothalamus correlated with social play, but not nonsocial play, even after controlling for the size of other brain structures. The authors propose that behaviors such as social assessment, recognizing and responding to facial expression, and social response appropriateness, which are mediated by the amygdala, are developed through social play. Additionally, the hypothalamus may regulate the motivation to engage in play through positive reinforcement of pleasurable activity. Thus, the instinctive socio-emotive aspects of play in primates appear to be those regulated by the amygdala and hypothalamus.     

Toward a perceptual theory of transparency

Theories of perceptual transparency have typically been developed within the context of a physical model that generates the percept of transparency (F. Metelli's episcotister model, 1974b). Here 2 fundamental questions are investigated: (a) When does the visual system initiate the percept of one surface seen through another? (b) How does it assign surface properties to a transparent layer? Results reveal systematic deviations from the predictions of Metelli's model, both for initiating image decomposition into multiple surfaces and for assigning surface attributes. Specifically, results demonstrate that the visual system uses Michelson contrast as a critical image variable to initiate percepts of transparency and to assign transmittance to transparent surfaces. Findings are discussed in relation to previous theories of transparency, lightness, brightness, and contrast-contrast.     

Exploring the Structure of Adolescent Problem Behaviors and the Associated Adult Outcomes

This study expands on previous research on adolescent problem behaviors by examining whether different constellations of problem behavior in adolescence differentially impact outcomes during emerging adulthood. Data from the in-home interviews of waves 2 and 3 of the National Longitudinal Study of Adolescent Health (Add Health) were used to examine these relationships. Latent class analysis, using nineteen problem behaviors measured at wave 2, identified three classes of adolescents representing “low risk, abstainers,” “sexually-active, experimenters,” and a “high risk, diverse behavior” group. Multivariate logistic regression analyses were then used to identify class differences (measured at wave 3) in social stability, general health and service utilization, and criminal justice system involvement during emerging adulthood. Important class differences in the likelihood of negative outcomes during early adulthood were identified. The implications of these findings and suggestions for future research are discussed.     

Television exposure predicts body size ideals in rural Nicaragua

Internalization of a thin ideal has been posited as a key risk factor in the development of pathological eating attitudes. Cross‐culturally, studies have found a preference for heavier bodies in populations with reduced access to visual media compared to Western populations. As yet, however, there has been little attempt to control for confounding variables in order to isolate the effects of media exposure from other cultural and ecological factors. Here, we examined preferences for female body size in relation to television consumption in Nicaraguan men and women, while controlling for the potential confounding effects of other aspects of Westernization and hunger. We included an urban sample, a sample from a village with established television access, and a sample from a nearby village with very limited television access. The highest BMI preferences were found in the village with least media access, while the lowest BMI preferences were found in the urban sample. Data from the rural sample with established television access were intermediate between the two. Amongst rural women in particular, greater television consumption was a stronger predictor of body weight preferences than acculturation, education, hunger, or income. We also found some evidence for television consumption increasing the likelihood of women seeking to lose weight, possibly via body shape preferences. Overall, these results strongly implicate television access in establishing risk factors for body image disturbances in populations newly gaining access to Western media.     

Adolescent Religiosity as a Mediator of the Relationship Between Parental Religiosity and Adolescent Health Outcomes

Studies have demonstrated the positive impacts of both parent and adolescent religiosity on adolescent outcomes; however, the relationships among these variable have not been studied. Our study was conducted to assess whether adolescent religiosity mediates the relationship between parent religiosity and adolescent emotional and behavioral health outcomes. A sample of 491 late adolescents ages 18–22 completed surveys that assessed their parents’ religious practices, their own religious practices, deviant behaviors, and internalizing behaviors. Findings suggest that adolescent religiosity mediates the relationship between parents’ religiosity and adolescent health outcomes such as drug and alcohol use and depression.     

On Representations of Intended Structures in Foundational Theories

Journal of Philosophical Logic - Often philosophers, logicians, and mathematicians employ a notion of intended structure when talking about a branch of mathematics. In addition, we know that there...     

More Than Attendance: The Importance of After-School Program Quality

A central theme of the articles featured in this issue is the need to improve the quality of after-school programs. In this commentary, we discuss why student engagement, program characteristics and implementation, staff training, and citywide policy are key considerations in the effort to define and achieve high quality programs for youth.