Cognition and Perception Commons^™

Hiv And Early Life Stress On Neuroimaging And Risky Behavior, Paola Garcia Egan

Dissertations

This study examined the interactive effects of early life stress (ELS) and HIV on brain morphometry, diffusion-basis-spectrum-imaging (DBSI), risky decision-making, and sex-risk behavior. 122 people with HIV (PWH) and 113 people without HIV (PWoH), free of major psychiatric illness and neurological confounds, were stratified into high (≥ 3 events) vs. low (< 3 events) ELS [PWoH/low ELS (n = 57), PWoH/high ELS (n =56), PWH/low ELS (n = 43), PWH/high ELS (n = 79)] and underwent structural magnetic resonance imaging, DBSI, neuropsychological, and risky-behavior assessment; all PWH were virologically controlled. Compared to PWoH, PWH had smaller orbitofrontal cortex (OFC), parietal lobes, insula, caudate and anterior cingulate. No ELS effects were detected in volumetric measures. Significant interactions were found between HIV serostatus and ELS on the OFC and on cellularity of the inferior fronto-occipital fasciculus after multiple comparisons adjustment. Specifically, PWH/high ELS exhibited significantly smaller OFC and PWoH/high ELS show significantly larger OFC than the other groups. PWoH/high ELS exhibited higher DBSI cellularity (neuroinflammation proxy) of the inferior-occipital-fasciculus compared to PWoH/high ELS. Regardless of HIV status, executive function moderated the relationship between the OFC and sex-risk behavior such that individuals within the sample who performed above average on a measure of executive function and had a larger OFC reported fewer sex partners in past six months than individuals with smaller volumes. No interaction was found between HIV serostatus and ELS on risky behavior measures. Clustering analyses defined ELS subgroups in PWH that were determined by demographic characteristics, duration of infection, recent CD4+ T-cell count, nadir CD4+ T-cell count and high/low ELS.Even in PWH that are virologically controlled, without major current psychiatric comorbidities, there is evidence of a synergistic impact of ELS and HIV on OFC volumes. Higher volumes in the OFC were detrimental when associated with lower executive function scores or advantageous when associated with higher executive function. Findings suggest that ELS is associated with different brain signatures among PWoH and virally suppressed PWH. However, ELS was not directly associated with risky behaviors, and subgroups in PWH were characterized by demographic variables, past substance use and HIV clinical variables.

Does Optic Flow Provide Information About Actions?, Hannah Masoner

Dissertations

Optic flow, the pattern of light generated in the visual field by motion of objects and the observer’s body, serves as information that underwrites perception of events, actions and affordances. This visual pattern informs the observer about their own actions in relation to their surroundings, as well as those of others. This study explored the limits of action detection for others as well as the role of optic flow. First-person videos were created using camera recordings of the actor’s perspective as they performed various movements (jumping jacks, jumping, squatting, sitting, etc.). In three experiments participants attempted to detect the action …

Bottlenose Dolphin (Tursiops Truncatus) Vocal Responses To Sonar And Spectrally Pink Background Noise, Maria Zapetis

Dissertations

As human populations rise, the level of man-made noise increases globally. Naval sonar and boat traffic are underwater sound sources of particular concern to marine mammal welfare. To better understand the impact of these noise increases on cetaceans, studies can explore animals’ behavioral changes in response to noise. Studies have investigated the ‘dose-response’ relationship between the received sound pressure level of sonar signals and the behavior of cetaceans in the wild, but exposure studies in controlled environments are limited. The studies in this dissertation examined bottlenose dolphin vocal modifications during various experimental noise treatments. Acoustic recordings previously obtained for bottlenose …

The Predictors Of Juvenile Recidivism: Testimonies Of Adult Students 18 Years And Older Exiting From Alternative Education, La Toshia Palmer

Dissertations

Purpose: The purpose of this descriptive, qualitative study was to identify and describe the importance of the predictors of juvenile recidivism and the effectiveness of efforts to prevent/avoid juvenile recidivism as perceived by previously detained, arrested, convicted, and/or incarcerated adult students 18 years of age and older exiting from alternative education in Northern California. A second purpose was to explore the types of support provided by alternative schools and the perceived importance of the support to avoid recidivism according to adult students 18 years of age and older exiting from alternative education.

Methodology: This qualitative, descriptive research design identified …

Increasing Vocal Behavior And Establishing Echoic Stimulus Control In Children With Autism, Joseph Shane

Dissertations

Many children with autism fail to demonstrate vocal-verbal behavior, including echoic behavior, as early as their typically developing peers. Some also make very limited vocal sounds in general, remaining mostly mute aside from crying or engaging in stereotypy. Echoic behavior involves auditory discrimination and matching, and functions as a beneficial, if not necessary, prerequisite for many other vocal-verbal skills. The purpose of this study was to develop and implement an echoic training procedure for primarily non-vocal children who did not demonstrate auditory discrimination in baseline. The intervention consisted initially of sessions in which any vocal sounds were reinforced. Then differential …

Olfactory Enrichment In California Sea Lions (Zalophus Californianus), Mystera M. Samuelson

Dissertations

In the wild, California sea lions (Zalophus californianus) are exposed to a wide array of sensory information at all times. However, it is impossible for captive environments to provide this level of complexity. Therefore unique procedures and practices are necessary for the maintenance of physiological and psychological health in captive animals (Wells, 2009). This project aims to explore the behavioral effect of scent added to the environment, with the goal of improving the welfare of captive sea lions by introducing two scent types: 1.) Natural scents, found in their native environment, and 2.) Non-natural scents, not found in …

Dynamics Of Perceptual Organization In Complex Visual Search: The Identification Of Self Organized Criticality With Respect To Visual Grouping Principles, Attila Jozsef Farkas

Dissertations

The current project applies modern quantitative theories of visual perception to examine the effect of the Gestalt Law of proximity on visual cognition. Gestalt Laws are spontaneous dynamic processes (Brunswik & Kamiya, 1953; Wertheimer, 1938) that underlie the principles of perceptual organization. These principles serve as mental short-cuts, heuristic rule-of-thumb strategies that shorten decision-making time and allow continuous, efficient processing and flow of information (Hertwig & Todd, 2002). The proximity heuristic refers to the observation that objects near each other in the visual field tend to be grouped together by the perceptual system (Smith-Gratto & Fisher, 1999). Proximity can be …

Assessing The Effects Of A Rectangular Rapid-Flashing Beacon On Vehicle Speeds Along A Four-Lane Divided Highway, Michelle Van Wagner

Dissertations

In 2008, nearly 31% of vehicle fatalities were related to failure to adhere to safe vehicle speeds (National Highway Traffic Safety Administration (NHTSA), 2009). Two studies were conducted to evaluate the effects of a Rectangular Rapid-Flashing Beacon (RRFB) triggered by excessive speed on vehicle speed using a combined alternating treatments and reversal design. Experiment 1 assessed the RRFB's impact on speeds as compared to baseline conditions only. Experiment 2 compared the RRFB to two standard beacon configurations. Both experiments were conducted at the same site during approximately the same time period and both employed the same data collection methodology. The …

Disruptive Effects Of Aβ Oligomers To The Radial-Arm Maze Performance Of Rats, Kineta Lynn Morgan-Paisley

Dissertations

Converging lines of research have implicated a causal relationship between oligomers of amyloid-β and the cognitive impairments associated with Alzheimer's disease (AD); however, very few studies have provided direct experimental evidence of this relationship and none of those studies have used an established model of working memory. The present study used an established model of working memory, the radial-arm maze, to examine the effects of amyloid-β oligomers on the memory of two groups of rats. The experimental group received ICV injections of the culture media (CM) of Chinese Hamster Ovary (CHO) cells transfected with a human mutation of APP containing …

Social Anxiety: Attentional Bias In Reaction To Emotional Faces Before And After Participation In A College Level Public Speaking Course, Scott Walter Maieritsch

Dissertations

This study was designed to examine the effectiveness of a semester-long public speaking course in reducing the self-reported levels of communication anxiety and social anxiety among college students enrolled in such a course. The current study also sought to replicate and extend a recent line of research that has demonstrated that highly socially anxious individuals show an attentional bias away from emotional faces under conditions of social-evaluative threat. The current study extended this line of research by conducting the same reaction time procedure with participants in a pretest/post-test design. The project was designed to determine if groups (rating high vs. …