Browsing by Author "Munson, Brandin A."
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Item An Exploration of Variability Due to Low Power in Structural MRI Studies of Bilingualism(2018-12) Munson, Brandin A.; Hernandez, Arturo E.; Francis, David J.; Tamber-Rosenau, Benjamin J.; Chiarello, ChristineThe adequacy of replicability among psychological findings has previously been questioned, especially for neuroscientific fields of research. Researchers increasingly point towards the negative effects of low power on replicability of findings. Though decreased sensitivity in smaller samples is a well-known consequence of inadequate power, many overlook the increased likelihood of inflated observed effects and weakened positive predictive values. The aim of this study is to reveal the expected degrees of uncertainty among neuroimaging findings by conducting tests in different sample sizes from a larger-than-average sample, in an area of research with wide-ranging findings that have been proposed by some to be due in part to inadequate sample sizes: bilingual-monolingual structural brain differences. Bilinguals (n = 216) were compared with monolinguals (n = 146) using grey matter density in whole-brain analyses and grey matter volume measures across region-of-interest tests. Variability among findings were compared with the true full-sample findings, and taken in the context of expected differences within the larger bilingualism neuroimaging literature. Results demonstrate excessive variability across the lowest sample sizes (e.g. samples totaling 20 – 80 participants), and this is explored through the trends of subsample outcomes and effect sizes across sample sizes. The extent to which infrequently utilized methods such as multivariate analyses of covariance (MANCOVAs) and Bayes Factors can improve the accuracy of results at lower sample sizes were also explored. It is our hope that this study helps to demonstrate the influences of power on expected variability among sample findings, especially for bilingual researchers and any researchers interested in exploring group differences using neuroimaging.Item DIFFERENCES IN FOREIGN VOCABULARY LEARNING OUTCOMES BETWEEN VIRTUAL ENVIRONMENT IMMERSION-BASED, TEXT-BASED, AND PICTURE-BASED LEARNING(2016-12) Munson, Brandin A.; Hernandez, Arturo E.; Cirino, Paul T.; Foss, Donald J.The main focus of the present study was to compare foreign vocabulary learning outcomes between immersion-based, text-based, and picture-based training within a virtual environment. Researchers have yet to quantitatively compare outcomes of foreign vocabulary learning between students who use virtual environments as immersive tools and more traditional text-based and picture-based training methods. The present study explored differences across time between groups assigned to one of these training methods on quizzes testing generalization of foreign vocabulary to real-world pictures. A 3D virtual foreign vocabulary learning environment created by ESLI, a language learning company, was utilized. All three groups learned material within the game in order to minimize computer-based group differences, but only the immersion group was able to explore the world and see the physical objects, while the other two were limited to learning Spanish phonology from either 1) English text translations or 2) picture presentations, both within a classroom area. Each group completed all 3 sections of material on 4 separate occasions, and took quizzes on vocabulary knowledge and generalization after every section. Analyses were conducted on a final sample of 32 participants. T-tests revealed no differences between individual times, and immersion-based learning to have lower overall accuracy than either text-based or picture-based learning, with no significant differences between text-based or picture based learning. A 3x4 mixed-measures ANCOVA was conducted, comparing participants of different foreign vocabulary learning methods (either immersion, text, or picture) on quiz accuracy over a time period of 4 learning and testing sessions, while controlling for prior foreign (Spanish) vocabulary knowledge. While Spanish vocabulary and time each significantly predicted accuracy (p’s < 0.05), neither the main effect of condition nor the interaction of condition and time significantly predicted accuracy (p’s > 0.1). Implications and potential future directions are explored.