A Comparison of Multilevel Mediation Modeling Methods: Recommendations for Applied Researchers

Multilevel structural equation modeling (MSEM) has been proposed as a valuable tool for estimating mediation in multilevel data and has known advantages over traditional multilevel modeling, including conflated and unconflated techniques (CMM & UMM). Recent methodological research has focused on comparing the three methods for 2-1-1 designs, but in regards to 1-1-1 mediation designs, there are significant gaps in the published literature that prevent applied researchers from making educated decisions regarding which model to employ in their own specific research design. A Monte Carlo study was performed to compare MSEM, UMM, and CMM on relative bias, confidence interval coverage, Type I Error, and power in a 1-1-1 model with random slopes under varying data conditions. Recommendations for applied researchers are discussed and an empirical example provides context for the three methods.     

Integrating covariates into circumplex structures: an extension procedure for Browne’s circular stochastic process model

Circumplex structures are elements of various psychological domains. Most work focuses on assessing the circular ordering of circumplex indicators and their relationships with covariates. In this article, an extension procedure for Browne’s circumplex model is presented. Our approach models the relationships among circumplex indicators and the relationships of covariates with a latent circumplex simultaneously without affecting the circumplex indicators’ positions on the circumplex. The approach builds upon Browne’s Fourier series parameterization of a correlation function, which is used to model the latent circumplex correlation structure. It extends the shape of the correlation function to the profile of each covariate’s correlations with the circumplex. The model is specified in the framework of structural equation modeling, thereby making it possible to test various hypotheses. Procedures are presented for deriving interval estimates for the parameters that relate the covariates to the circumplex. The model is compared to other approaches for assessing the relationships of a circumplex with covariates. The results of the exemplary applications and a simulation study were in favor of the suggested model. The approach is furthermore illustrated with a real-data example, focusing on the relationships between the interpersonal circumplex and the rivalry and admiration aspects of narcissism.     

Philosophy for Computers: Some Explorations in Philosophical Modeling

Philosophical modeling has a long and distinguished history, but the computer offers new and powerful prospects for the creation and manipulation of models. It seems inevitable that the computer will become a major tool in future philosophical research. Here I offer an overview of explorations in philosophical computer modeling that we in the Group for Logic and Formal Semantics at SUNY Stony Brook have undertaken: explorations regarding (1) the potential emergence of cooperation in a society of egoists, (2) self-reference and paradox in fuzzy logic, (3) a fractal approach to formal systems, and (4) on-going explorations with models for the emergence of communication. The attempt is not to give a detailed report on any of these but to give a bird s-eye view of them all, emphasizing the general form that the models take, the philosophical motivations behind them, and the kinds of philosophical results that they may have to offer.     

Learning representations in a gated prefrontal cortex model of dynamic task switching

The prefrontal cortex is widely believed to play an important role in facilitating people's ability to switch performance between different tasks. We present a biologically‐based computational model of prefrontal cortex (PFC) that explains its role in task switching in terms of the greater flexibility conferred by activation‐based working memory representations in PFC, as compared with more slowly adapting weight‐based memory mechanisms. Specifically we show that PFC representations can be rapidly updated when a task switches via a dynamic gating mechanism based on a temporal‐differences reward‐prediction learning mechanism. Unlike prior models of this type, the present model develops all of its internal representations via learning mechanisms as shaped by the demands of continuous periodic task switching. This advance opens up a new domain of research into the interactions between working memory task demands and the representations that develop to meet them. Results on a version of the Wisconsin card sorting task are presented for the full model and a number of comparison networks that test the importance of various model features. Furthermore, we show that a lesioned model produces perseverative errors like those seen in frontal patients.     

The influence of ADHD-hyperactivity/impulsivity symptoms on the development of oppositional defiant disorder symptoms in a 2-year longitudinal study

The structural relations among ADHD–inattention (IN), ADHD–hyperactivity/impulsivity (H/I), and oppositional defiant disorder (ODD) factors were examined in a 2-year longitudinal study with 752 children. Structural equation procedures showed that higher scores on the H/I factor in Year 1 were associated with higher scores on ODD factor in Years 2 and 3. Higher scores on the H/I factor in Year 2 were also associated with higher scores on ODD factor in Year 3. The ODD factor did not predict the H/I and IN factors in subsequent years. The IN factor did not predict the ODD and H/I factors in subsequent years and the H/I factor did not predict the IN factor. The ability of the H/I factor to predict the subsequent ODD factor occurred even after taking into account the ability of the ODD, H/I, and IN factors to predict themselves across time. These results suggest that the H/I aspect of ADHD influences the development of ODD behavior.     

The Children of Mothers with Eating Disorders

There is good evidence that children of parents with psychological disorders are themselves at increased risk of disturbances in their development. Although there has been considerable research on a variety of disorders such as depression and alcohol, research on the children of parents with eating disorders has been relatively recent. This paper aims to review the evidence and covers a number of areas, including genetic factors, pregnancy, the perinatal and postpartum period, infancy, and the early years of life, focusing on feeding and mealtimes, general parenting functions, and growth. This is followed by a consideration of psychopathology in the children, parental attitudes to children's weight and shape, and adolescence. What is clear is that although there are numerous case reports and case series, the number of systematic controlled studies is relatively small, and almost nothing has been written about the children of fathers with eating disorders. What is evident from the available evidence is that children of mothers with eating disorders are at increased risk of disturbance, but that the risk depends on a variety of factors, and that difficulties in the children are far from invariable. The paper concludes by summarizing five broad categories of putative mechanisms, based on the evidence to date, by which eating disturbance in parents can influence child development.     

Subcellular interactions between parallel fibre and climbing fibre signals in purkinje cells predict sensitivity of classical conditioning to interstimulus interval

Classical conditioning of the nictitating membrane response requires a specific temporal interval between conditioned stimulus and unconditioned stimulus, and produces an incrase in Protein Kinase C (PKC) activation in Purkinje cells. To evaluate whether biochemical interactions within the Purkinje cell may explain the temporal sensitivity, a model of PKC activation byCa ²⁺, diacylglycerol (DAG), and arachidonic acid (AA) is developed.Ca ²⁺ elevation is due to CF stimulation and IP3 inducedCa ²⁺ release (IICR). DAG andIP ₃ result from PF stimulation, while AA results from phospholipase A2 (PLA ₂). Simulations predict increased PKC activation when PF stimulation precedes CF stimulation by 0.1 to 3 s. The sensitivity of IICR to the temporal relation between PF and CF stimulation, together with the buffering system of Purkinje cells, significantly contribute to the temporal sensitivity.     

The interplay between parental behaviors and adolescents' sports-related values in understanding adolescents' dropout of organized sports activities

Using short-term longitudinal data, the primary goal of the present study was to examine the interplay between adolescents’ sports-related intrapersonal (e.g., sports values) and interpersonal factors (e.g., perceived parental involvement) in relation to sports dropout. A secondary goal was to explore the direction of effects in the association between intra- and interpersonal factors. A total of 420 adolescents (39% girls, M_age = 14.06; SD_age = 0.33) responded to a set of survey questions over two consecutive years. Results from structural equation modeling suggested that parental involvement predicted adolescents’ dropout one year later, via sports values. Further, the results suggested that the direction of influence is mainly from parents to adolescents. Overall, the findings indicate that adolescents whose parents attend their practices and games perceive sports activities as fun, important and useful; as a result, adolescents are less likely to dropout. The findings offer an improved understanding of how parents’ behaviors may influence adolescents’ dropout of organized sports.