Theses and dissertations

This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students. 

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The Impact of Blocked vs. Distributed Category Learning on Subsequent Generalization

Description
It is a well-established finding in memory research that spacing or distributing information, as opposed to blocking all the information together, results in an enhanced memory of the learned material. Recently, researchers have decided to investigate if this spacing effect is also beneficial in category learning. In a set of…

It is a well-established finding in memory research that spacing or distributing information, as opposed to blocking all the information together, results in an enhanced memory of the learned material. Recently, researchers have decided to investigate if this spacing effect is also beneficial in category learning. In a set of experiments, Carvalho & Goldstone (2013), demonstrated that a blocked presentation showed an advantage during learning, but that ultimately, the distributed presentation yielded better performance during a post-learning transfer test. However, we have identified a major methodological issue in this study that we believe contaminates the results in a way that leads to an inflation and misrepresentation of learning levels. The present study aimed to correct this issue and re-examine whether a blocked or distributed presentation enhances the learning and subsequent generalization of categories. We also introduced two shaping variables, category size and distortion level at transfer, in addition to the mode of presentation (blocked versus distributed). Results showed no significant differences of mode of presentation at either the learning or transfer phases, thus supporting our concern about the previous study. Additional findings showed benefits in learning categories with a greater category size, as well as higher classification accuracy of novel stimuli at lower-distortion levels.
ContributorsJacoby, Victoria Leigh (Author) / Homa, Donald (Thesis director) / Brewer, Gene (Committee member) / Davis, Mary (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
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The Comparison of Frontostriatal Tracts Between Adolescents with ADHD and a Typically Developing Adolescent Control Group

Description
The frontostriatal reward circuit serves an underlying role in reward processing, cognitive planning, and motor control in the context of achieving a goal. Furthermore, research suggests a relationship between the reward circuits and behavior expressed in Attention Deficit Hyperactivity Disorder (ADHD); however, the specific structural differences of the reward circuits…

The frontostriatal reward circuit serves an underlying role in reward processing, cognitive planning, and motor control in the context of achieving a goal. Furthermore, research suggests a relationship between the reward circuits and behavior expressed in Attention Deficit Hyperactivity Disorder (ADHD); however, the specific structural differences of the reward circuits in those with ADHD remain ambiguous. Diffusion tensor imaging (DTI) techniques were used to analyze diffusion weighted magnetic resonance imaging (DWI) data in order to examine the structural connectivity of frontostriatal reward pathways in ADHD adolescents compared to typically developing (TD) adolescents. It was hypothesized that measures of impulsivity would be predicted by white matter tract integrity measures in frontostriatal tracts related to affective processing (ventromedial prefrontal cortex to ventral striatum, vmPFC) in adolescents with ADHD, and that there would be reduced tract integrity in tracts related to executive control (dorsolateral prefrontal and anterior cingulate cortex—dlPFC and ACC, respectively). Frontostriatal tracts as well as the hippocampus and amygdala were examined in relation to age and impulsivity using both correlation and regression models. Results indicated that impulsivity declined with age in the TD group while no significant trend was identified for the ADHD group. The hypotheses were not supported and results for both predictions on the affective and executive circuits showed opposite trends from what was expected.
ContributorsHarrison, Sydney Rae (Author) / McClure, Samuel (Thesis director) / Brewer, Gene (Committee member) / Davis, Mary (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12