Bayesian Diagnostics of Hidden Markov Structural Equation Models with Missing Data

Cocaine is a type of drug that functions to increase the availability of the neurotransmitter dopamine in the brain. However, cocaine dependence or abuse is highly related to an increased risk of psychiatric disorders and deficits in cognitive performance, attention, and decision-making abilities. Given the chronic and persistent features of drug addiction, the progression of abstaining from cocaine often evolves across several states, such as addiction to, moderate dependence on, and swearing off cocaine. Hidden Markov models (HMMs) are well suited to the characterization of longitudinal data in terms of a set of unobservable states, and have increasingly been used to uncover the dynamic heterogeneity in progressive diseases or activities. However, the existence of outliers or influential points may misidentify the hidden states and distort the associated inference. In this study, we develop a Bayesian local influence procedure for HMMs with latent variables in the presence of missing data. The proposed model enables us to investigate the dynamic heterogeneity of multivariate longitudinal data, reveal how the interrelationships among latent variables change from one state to another, and simultaneously conduct statistical diagnosis for the given data, model assumptions, and prior inputs. We apply the proposed procedure to analyze a dataset collected by the UCLA center for advancing longitudinal drug abuse research. Several outliers or influential points that seriously influence estimation results are identified and removed. The proposed procedure also discovers the effects of treatment and individuals’ psychological problems on cocaine use behavior and delineates their dynamic changes across the cocaine-addiction states.     

Young children discover how to deceive in 10 days: a microgenetic study

We investigated how the ability to deceive emerges in early childhood among a sample of young preschoolers (Mean age = 34.7 months). We did this via a 10‐session microgenetic method that took place over a 10‐day period. In each session, children played a zero‐sum game against an adult to win treats. In the game, children hid the treats and had opportunities (10 trials) to win them by providing deceptive information about their whereabouts to the adult. Although children initially showed little or no ability to deceive, most spontaneously discovered deception and systematically used it to win the game by the tenth day. Both theory of mind and executive function skills were predictive of relatively faster patterns of discovery. These results are the first to provide evidence for the importance of cognitive skills and social experience in the discovery of deception over time in early childhood.     

Semantic size does not matter: "bigger" words are not recognized faster

Sereno, O'Donnell, and Sereno (2009) reported that words are recognized faster in a lexical decision task when their referents are physically large than when they are small, suggesting that "semantic size" might be an important variable that should be considered in visual word recognition research and modelling. We sought to replicate their size effect, but failed to find a significant latency advantage in lexical decision for "big" words (cf. "small" words), even though we used the same word stimuli as Sereno et al. and had almost three times as many subjects. We also examined existing data from visual word recognition megastudies (e.g., English Lexicon Project) and found that semantic size is not a significant predictor of lexical decision performance after controlling for the standard lexical variables. In summary, the null results from our lab experiment--despite a much larger subject sample size than Sereno et al.--converged with our analysis of megastudy lexical decision performance, leading us to conclude that semantic size does not matter for word recognition. Discussion focuses on why semantic size (unlike some other semantic variables) is unlikely to play a role in lexical decision.     

When all signs point to you: lies told in the face of evidence

Young children's ability to tell a strategic lie by making it consistent with the physical evidence of their transgression was investigated along with the sociocognitive correlates of such lie-telling behaviors. In Experiment 1, 247 Chinese children between 3 and 5 years of age (126 boys) were left alone in a room and asked not to lift a cup to see the contents. If children lifted up the cup, the contents would be spilled and evidence of their transgression would be left behind. Upon returning to the room, the experimenter asked children whether they peeked and how the contents of the cup ended up on the table. Experiment 1 revealed that young children are able to tell strategic lies to be consistent with the physical evidence by about 4 or 5 years of age, and this ability increases in sophistication with age. Experiment 2, which included 252 Chinese 4-year-olds (127 boys), identified 2 sociocognitive factors related to children's ability to tell strategic lies. Specifically, both children's theory-of-mind understanding and inhibitory control skills were significantly related to their ability to tell strategic lies in the face of physical evidence. The present investigation reveals that contrary to the prevailing views, even young children are able to tell strategic lies in some contexts.     

Visual working memory contaminates perception

Indirect evidence suggests that the contents of visual working memory may be maintained within sensory areas early in the visual hierarchy. We tested this possibility using a well-studied motion repulsion phenomenon in which perception of one direction of motion is distorted when another direction of motion is viewed simultaneously. We found that observers misperceived the actual direction of motion of a single motion stimulus if, while viewing that stimulus, they were holding a different motion direction in visual working memory. Control experiments showed that none of a variety of alternative explanations could account for this repulsion effect induced by working memory. Our findings provide compelling evidence that visual working memory representations directly interact with the same neural mechanisms as those involved in processing basic sensory events.     

Effects of testing on learning of functions

Is learning of a complex functional relationship enhanced by trying to predict what output will go with a given input, as compared to studying an input–output pair? We examined learning of a bilinear function and transfer to new items outside the trained range. Subjects either saw the input–output pairs (study-only condition) or attempted to guess the output and then saw the pair (test/study condition). The total study times were equated, and motivation was enhanced with a monetary bonus. Performance was markedly better for the test/study condition, both within the trained range and in the transfer test. This benefit of testing during training was observed on a criterial test administered shortly after training. Testing has long been shown to enhance the explicit learning and retention of verbal material; our present findings reveal a novel domain for which testing can also be advantageous—that is, function learning.     

Stigma building blocks: how instruction and experience teach children about rejection by outgroups

Gaining an understanding of intergroup relations and outgroup rejection is an important childhood development. Children learn about rejection by outgroups via their own experiences and external instruction. A comparison of the impact of experience and instruction on first-, third-, and fifth-grade children's evaluations of rejection by outgroups in a minimal-groups paradigm suggests that the relative impact of experience and instruction differs as children age. In Study 1, younger children were more influenced by instruction, and older children were more influenced by what they experienced for themselves. In Study 2, younger children were more influenced by instruction, even when that instruction conflicted with what they experienced; older children were more influenced by their own experiences, even when those experiences contradicted what they were told to expect. These findings suggest that children begin learning about outgroup rejection through instruction but start to rely more on their own experiences as they age.     

Personalized persuasion: tailoring persuasive appeals to recipients' personality traits

Persuasive messages are more effective when they are custom-tailored to reflect the interests and concerns of the intended audience. Much of the message-framing literature has focused on the advantages of using either gain or loss frames, depending on the motivational orientation of the target group. In the current study, we extended this research to examine whether a persuasive appeal's effectiveness can be increased by aligning the message framing with the recipient's personality profile. For a single product, we constructed five advertisements, each designed to target one of the five major trait domains of human personality. In a sample of 324 survey respondents, advertisements were evaluated more positively the more they cohered with participants' dispositional motives. These results suggest that adapting persuasive messages to the personality traits of the target audience can be an effective way of increasing the messages' impact, and highlight the potential value of personality-based communication strategies.     

On Public Aid to Christian Schools in the United States: A Reformed Christian Perspective

This paper seeks to provide a conceptual framework for understanding the topic of public aid to Christian schools in a Reformed Christian perspective. To do so, I need to clarify a Reformed Christian approach in regard to this topic and then review the studies of the issue in legal and educational aspects in the light of the Reformed perspective. Through reviewing legal and educational discussions, I argue that Christian schools are necessary for people to exercise their religious freedom and make a society more moral and spiritual and thus deserve receiving public aid. Nevertheless, public aid to religious schools needs to be carried out in a careful, restricted way.     

Effects of Racial Discrimination,Childhood Trauma,and Trauma Symptoms on Juvenile Delinquency in African American Incarcerated Youth

To understand racial disproportionality in juvenile delinquency, we studied relationships between 2 possible contributors: effects of manifestations of a structural factor (racism) and psychological consequences of trauma. Informed by Carter’s (2007) theory of race-based trauma, we explored the role of experiences of racial discrimination, childhood trauma, and trauma symptoms in juvenile delinquency through self-reported experiences of incarcerated African American youth. We found that childhood trauma, trauma symptoms, and racial discrimination experiences all significantly contributed to juvenile delinquency, but participants who experienced greater racial discrimination had higher posttraumatic stress symptoms and elevated delinquency rates. Considering the well-documented effects of trauma symptoms on juvenile delinquency, race-based trauma experiences might help us understand one aspect of racial disproportionality in juvenile delinquency.