Copyright (c) 2009 University of Nebraska - Lincoln All rights reserved. http://digitalcommons.unl.edu/dcnlfacpub Recent documents in Developmental Cognitive Neuroscience Laboratory - Faculty and Staff Publications en-us Sat, 24 Oct 2009 23:16:35 PDT 3600 http://digitalcommons.unl.edu/dcnlfacpub/45 http://digitalcommons.unl.edu/dcnlfacpub/45 Fri, 23 Oct 2009 12:14:26 PDT Methods for identifying meaningful growth patterns of longitudinal trial data with both nonignorable intermittent and drop-out missingness are rare. In this study, a combined approach with statistical and data mining techniques is utilized to address the nonignorable missing data issue in growth pattern recognition. First, a parallel mixture model is proposed to model the nonignorable missing information from a real-world patient-oriented study and concurrently to estimate the growth trajectories of participants. Then, based on individual growth parameter estimates and their auxiliary feature attributes, a fuzzy clustering method is incorporated to identify the growth patterns. This case study demonstrates that the combined multi-step approach can achieve both statistical generality and computational efficiency for growth pattern recognition in longitudinal studies with nonignorable missing data. Julia Hua Fang http://digitalcommons.unl.edu/dcnlfacpub/44 http://digitalcommons.unl.edu/dcnlfacpub/44 Tue, 13 Oct 2009 09:15:23 PDT Performance of reaction time (RT) tasks was investigated in young children and adults to test the hypothesis that age-related differences in processing speed supersede a "global" mechanism and are a function of specific differences in task demands and processing requirements. The sample consisted of 54 4-year-olds, 53 5-year-olds, 59 6-year-olds, and 35 adults from Russia. Using the regression approach pioneered by Brinley and the transformation method proposed by Madden and colleagues and Ridderinkhoff and van der Molen, age-related differences in processing speed differed among RT tasks with varying demands. In particular, RTs differed between children and adults on tasks that required response suppression, discrimination of color or spatial orientation, reversal of contingencies of previously learned stimulus-response rules, and greater stimulus-response complexity. Relative costs of these RT task differences were larger than predicted by the global difference hypothesis except for response suppression. Among young children, age-related differences larger than predicted by the global difference hypothesis were evident when tasks required color or spatial orientation discrimination and stimulus-response rule complexity, but not for response suppression or reversal of stimulus-response contingencies. Process-specific, age-related differences in processing speed that support heterochronicity of brain development during childhood were revealed. Sergey Kiselev http://digitalcommons.unl.edu/dcnlfacpub/43 http://digitalcommons.unl.edu/dcnlfacpub/43 Wed, 29 Jul 2009 12:01:22 PDT Although DSM-defined DBDs and ADHD manifest during early childhood in meaning¬ful ways, the emphasis of extending the DBD and ADHD nosology, which is based on studies of older youth, to younger children potentially limits the utility of these symptoms. Given that it is clear that DBDs and ADHD often emerge during early childhood and that early intervention is most efficacious, developing a more refined understanding of the clinical phenomenology of behavior disorders in early childhood is a critical next step. We contend that an approach that emphasizes the developmental specification of symptoms has the potential to address several long-standing issues in the literature, including enhancing the specificity, sensitivity, and stability of DBD and ADHD symptoms. Moreover, progress toward developmentally specified symptoms may inform our understanding of which type of treatment works best for whom. Answers to these questions are critical if we are to ultimately intervene to improve the lives of young children affected with DBDs and ADHD. Anil Chacko http://digitalcommons.unl.edu/dcnlfacpub/42 http://digitalcommons.unl.edu/dcnlfacpub/42 Fri, 17 Apr 2009 07:34:39 PDT Abstract Children with very low birth weight (VLBW, < 1500 g) or very pre-term birth (VPTB, < 32 weeks gestational age or GA) have more mathematics disabilities or deficiencies (MD) and higher rates of mathematics learning disabilities (MLD) than normal birth weight term-born children (NBW, > 2500 g and > 36 weeks GA). MD are found even in children without global disorders in cognition or neurosensory status and when IQ is controlled, and they are associated with other learning problems and weaknesses in perceptual motor abilities and executive function. Factors related to poorer mathematics outcomes include lower birth weight and GA, neonatal complications, and possible abnormalities in brain structure. While little is known about the nature of MD in these children, studies of MLD in other neurodevelopmental disorders and in children with learning disabilities provide useful models for further investigation. Further investigation of the neuropsychological and neuropathological correlates of distinct types of mathematics difficulties is also needed. Studies along these lines will yield information about the unique features of MD in children with VLBW/VPTB and about the nature and origins of poor mathematics achievement more generally. H. Gerry Taylor http://digitalcommons.unl.edu/dcnlfacpub/41 http://digitalcommons.unl.edu/dcnlfacpub/41 Thu, 19 Mar 2009 10:27:38 PDT We examined the neural correlates of set-shifting in 5-year-old children and examined whether the ease of switching was affected by varying the number of non-switch trials preceding a switch. Sandra A. Wiebe http://digitalcommons.unl.edu/dcnlfacpub/40 http://digitalcommons.unl.edu/dcnlfacpub/40 Thu, 30 Oct 2008 07:03:09 PDT This study examined whether measures of short-term memory, working memory, and executive functioning in preschool children predict later proficiency in academic achievement at 7 years of age (third year of primary school). Children were tested in preschool (M age = 4 years, 6 months) on a battery of cognitive measures, and mathematics and reading outcomes (from standardized, norm-referenced school-based assessments) were taken on entry to primary school, and at the end of the first adn third year of primary school. Growth curve analyses examined predictors of math and reading achievement across the duration of the study and revealed that better digit span and executive function skills provided children with an immediate head start in math and reading and maintained throughout the first three years of primary school. Visual-spatial short-term memory span was found to be a predictor specifically of math ability. Correlational and regression analyses revealed that visual short-term and working memory were found to specifically predict math achievement at each time point, while executive function skills predicted learning in general rather than learning in one specific domain. The implications of the findings are discussed in relation to further understanding the role of cognitive skills in different mathematical tasks and in relation to the impact of limited cognitive skills in the classroom environment. Rebecca Bull http://digitalcommons.unl.edu/dcnlfacpub/39 http://digitalcommons.unl.edu/dcnlfacpub/39 Mon, 07 Apr 2008 07:04:35 PDT The present study examined the effects of dopamine receptor D2 genotype and PTE status on early infant neurobehavior. Sandra A. Wiebe http://digitalcommons.unl.edu/dcnlfacpub/38 http://digitalcommons.unl.edu/dcnlfacpub/38 Wed, 19 Mar 2008 10:32:17 PDT *This article may not exactly replicate the final version published in the APA journal. It is not the copy of record. http://content.apa.org/journals/0012-1649 Although many tasks have been developed recently to study executive control in the preschool years, the constructs that underlie performance on these tasks are poorly understood. In particular, it is unclear whether executive control is comprised of multiple, separable cognitive abilities (e.g., inhibition and working memory) or whether it is unitary in nature. A sample of 243 normally developing children between 2.25 and 6 years of age completed a battery of ageappropriate executive control tasks. Confirmatory factor analysis (CFA) was used to compare multiple models of executive control empirically. A single-factor, general model was sufficient to account for the data. Furthermore, the fit of the unitary model was invariant across subgroups of children divided by socioeconomic status or sex. Girls displayed a higher level of latent executive control than boys, and children of higher and lower SES did not differ in level. In typically-developing preschool children, tasks conceptualized as indices of working memory and inhibitory control in fact measured a single cognitive ability, despite surface differences between task characteristics. Sandra A. Wiebe http://digitalcommons.unl.edu/dcnlfacpub/37 http://digitalcommons.unl.edu/dcnlfacpub/37 Mon, 19 Nov 2007 14:48:04 PST S. A. Wiebe http://digitalcommons.unl.edu/dcnlfacpub/36 http://digitalcommons.unl.edu/dcnlfacpub/36 Mon, 19 Nov 2007 14:36:01 PST S. A. Wiebe