abstract: The experience of language can, as any other experience, change the way that the human brain is organized and connected. Fluency in more than one language should, in turn, change the brain in the same way. Recent research has focused on the differences in processing between bilinguals and monolinguals, and has even ventured into using different neuroimaging techniques to study why these differences exist. What previous research has failed to identify is the mechanism that is responsible for the difference in processing. In an attempt to gather information about these effects, this study explores the possibility that bilingual individuals utilize lower signal strength (and by comparison less biological energy) to complete the same tasks that monolingual individuals do. Using an electroencephalograph (EEG), signal strength is retrieved during two perceptual tasks, the Landolt C and the critical flicker fusion threshold, as well as one executive task (the Stroop task). Most likely due to small sample size, bilingual participants did not perform better than monolingual participants on any of the tasks they were given, but they did show a lower EEG signal strength during the Landolt C task than monolingual participants. Monolingual participants showed a lower EEG signal strength during the Stroop task, which stands to support the idea that a linguistic processing task adds complexity to the bilingual brain. Likewise, analysis revealed a significantly lower signal strength during the critical flicker fusion task for monolingual participants than for bilingual participants. Monolingual participants also had a significantly different variability during the critical flicker fusion threshold task, suggesting that becoming bilingual creates an entirely separate population of individuals. Future research should perform analysis with the addition of a prefrontal cortex electrode to determine if less collaboration during processing is present for bilinguals, and if signal complexity in the prefrontal cortex is lower than other electrodes. / Dissertation/Thesis / Masters Thesis Psychology 2019

Participants demonstrate the Stroop effect when, in naming the color in which a word appears, reaction times are longer when the color and word are incongruent (e.g., "yellow" printed in blue) compared to when they are congruent (e.g., "yellow" printed in yellow). The literature commonly refers to the difference in reaction times as a measure of the interference of word stimuli upon color stimuli, and is taken as support for the theory of automaticity. This study asks whether the Stroop effect can be analyzed as interactions within and across stimulus classes. Adult participants learned three 3-member classes (color, word, and pattern) in a serialized order of training. In the testing phase, participants were presented with compound stimuli formed from combinations of members within and across classes (e.g., word and color), and reaction times were recorded in similar fashion to the Stroop task. Results show that averaged participants' reaction times are faster to compound stimuli comprised of members within the same class, compared to compound stimuli formed with members from different classes. These group-level data are consistent with the Stroop literature in that congruent compounds produce faster reaction times relative to incongruent compounds. However, individual participant data do not consistently reflect the Stroop effect. Further considerations for future research in this area are discussed.

Media sources, often containing ideal body images, put forth the message of selfimprovement and the need to achieve a thin physique. For some women, striving to achieve an ideal body can lead to increased risk of engaging in disordered eating, anxiety, and an increased fixation toward body or weight stimuli. Previous research examining the relationship between body satisfaction and attention toward body related stimuli has often compared clinical eating disorder and non-clinical samples. However, these findings do not give an accurate picture of how non-clinical samples respond to thin body images. The present study sought to determine if engaging in a downward social comparison would negate the "fixation" or increased attention given to body images. Female participants from a university in northern California were randomly assigned to one of two experimental conditions: downward or upward social comparison. Participants were asked to view an advertisement of a model, and write based on a prompt developed to elicit a downward or upward social comparison. Selective attention toward body related stimuli was then assessed through use of a Stroop task, which randomly displayed thin female silhouettes and abstract images. Error rates and reaction times were recorded, with more errors and slower reactions times reflecting increased attention toward the female silhouette. A hierarchal linear regression found an association for the downward social comparison condition and self-esteem. Longer reaction time toward body images was seen among women who engaged in a downward social comparison and had low levels of self-esteem. Among women with high BMI, less selective attention was observed. Comparisons of the groups on reaction times, error rates, and body image measures are discussed.

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Le but de cette étude est de vérifier si la pression temporelle et le sexe vont avoir un impact sur la performance au test de Stroop. Soixante sujets repartis en quatre groupes égaux effectuent la tâche : femmes sans pression temporelle, hommes sans pression temporelle, femmes avec pression temporelle et hommes avec pression temporelle. Contrairement à certaines études antérieures, les analyses effectuées démontrent peu de résultats significatifs. On n’observe aucune différence sexuelle dans toutes les conditions. Par contre, les seules différences sont obtenues dans le temps de réaction de quelques conditions entre les groupes d’hommes sans pression temporelle et avec pression temporelle. En somme, il est possible de dire que les gens peuvent exécuter une tache simple sans toutefois que la pression temporelle ait un impact sur la performance.

The purpose of this research was two-fold: (1) further validate the Virtual Reality Stroop Task HMMWV [VRST; Stroop stimuli embedded within a virtual high mobility multipurpose wheeled vehicle] via a comparison of the 3-dimensional VRST factor structure to that of a 2-dimensional computerized version of the Stroop task; and (2) model the performance of machine learning [ML] classifiers and hyper-parameters for an adaptive version of the VRST. Both the 3-D VRST and 2-D computerized Stroop tasks produced two-factor solutions: an accuracy factor and a reaction time factor. The factors had low correlations suggesting participants may be focusing on either responding to stimuli accurately or swiftly. In future studies researchers may want to consider throughput, a measure of correct responses per unit of time. The assessment of naive Bayes (NB), k-nearest neighbors (kNN), and support vector machines (SVM) machine learning classifiers found that SVM classifiers tended to have the highest accuracies and greatest areas under the curve when classifying users as high or low performers. NB also performed well but kNN algorithms did not. As such, SVM and NB may be the best candidates for creation of an adaptive version of the VRST.

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