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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Exploring the Relationship between Long-Term Memory and Attention through Attentional Templates

Goldstein, Rebecca Rose 29 June 2016 (has links)
It is assumed that the contents of visual working memory (VWM) guide attention. This notion has been challenged by work which has demonstrated that multiple searches for the same target changes contralateral delay activity (CDA), an event-related potential that is the putative marker of the amount of information maintained in VWM. It has been suggested that the disappearance of the CDA with an invariable target marks the transfer of the attentional template from VWM storage to long-term memory (LTM) storage. Therefore, LTM may guide attention in many situations where it has previously been assumed that VWM guides attention. However, while the transfer of attentional template from VWM to LTM is demonstrated through a decrease in the amplitude of the CDA, this shift has not been accompanied by a corresponding behavioral change in response times. The purpose of the present study was to test the hypothesis that a LTM template leads to faster performance than a VWM template (the LTM template hypothesis). Two experiments were conducted to explore this hypothesis. In Experiment 1, the LTM template hypothesis was examined by comparing performance between two different groups of subjects: the first group searched for a target that changed on every trial (variable) while the second group searched for a target that was invariable across trials. In Experiment 2, one group of subjects searched for both the variable and invariable targets. The results showed that a LTM template (invariable target search) leads to faster performance than a VWM template (variable target search). Roughly six times as many trials were required for an effect on performance compared to the number of trials required for an effect in CDA amplitude. Eye tracking results suggest the change in performance is due to more efficient search initiation and target verification.
42

Cognitive Processes in the Perception of Actions and Agents

Baker, Lewis John 29 June 2016 (has links)
Sensory input from the social world is often bustling and chaotic, and yet human beings typically comprehend events with ease. Evidence suggests that the perceptual system uses social cues to guide awareness to relevant actions, objects and spatial locations. In three studies, I demonstrate some of the cognitive processes involved in the perception of actions and agents. Chapter 1 tests the limitations of our ability to perceive ongoing activity, finding that event perception requires limited-capacity resources that tax encoding of properties when viewing two events in parallel. Chapter 2 explores the limits of a proposed system that rapidly calculates anotherâs perspective, revealing a heuristic signal that oneâs visuospatial access to an attended set of objects may be privileged. Chapter 3 then tests whether social agents guide visual attention, finding a curious tendency to search regions of space unseen by another agent. Combined, these studies illustrate mechanisms that guide awareness in the real world.
43

Understanding Attachment and Perceptions of Orphan Caregivers in Institutional Care in Kenya

Miller, Leanne R. 08 October 2015 (has links)
<p> This concurrent nested mixed methods study assessed institutional caregivers&rsquo; perception on their role as caregivers and caregivers&rsquo; attachment orientation in Kenya. Additionally, the study looked for a connection between attachment and perception. Participants were 15 female caregivers, 8 from a government institution and 7 from a nongovernment institution. Data from a semi-structured interview indicated that caregivers, regardless of attachment, were emotionally invested in the children&rsquo;s wellbeing, felt a sense of duty, and stated their job was challenging but rewarding. ECR-R assessed attachment and found that attachment varied slightly between institutions. The most significant difference was between institutions with 4 secure caregivers in the nongovernment institution and only 1 secure caregiver in the government institution. A slight relationship between attachment and perception was found as all secure caregivers indicated they believed both physical and emotional needs of children were essential. Results indicate additional cultural studies on attachment and perception are warranted.</p>
44

Concurrent and Short-term Prospective Relations of Attention and Inhibition to Emotion Regulation and Depressive Symptoms in Children

Samanez Larkin, Silvia Patricia 26 May 2015 (has links)
Identifying cognitive and emotional risk factors that contribute to the onset, maintenance, and recurrence of depression is crucial for developing interventions for treatment and prevention. Poor executive function skills may be vulnerabilities for the development of depression through their effect on emotion regulation. The purpose of this study was to explore specific executive function skills that may be related to adaptive emotion regulation abilities, with the ultimate goal of identifying psychological mechanisms that confer risk for the development of depression. Children, ages 8 to 17, completed behavioral and self-report measures of executive function assessing attentional control and inhibitory control, and self-report measures of emotion regulation and depressive symptoms. Results showed that better self-reported attentional control was associated with lower depressive symptoms and better emotion regulation. Better behavioral and self-reported inhibitory control were associated with lower depressive symptoms and with better emotion regulation. Additionally, better emotion regulation was associated with lower levels of depressive symptoms controlling for behavioral and self-reported measures of executive function. No evidence was found for statistical mediation by emotion regulation of the relation between executive function and depressive symptoms, however. The study demonstrated significant relations among executive function, emotion regulation, and depressive symptoms. Future studies are needed to clarify the direction of these associations, so that interventions can be developed that target specific executive functions and emotion regulation skills for the purpose of reducing the likelihood of depression.
45

A Novel Measure of Effect Size for Mediation Analysis

Lachowicz, Mark Joseph 26 May 2015 (has links)
Mediation analysis has become one of the most popular statistical methods in the social sciences. However, currently available effect size measures for mediation have limitations that restrict their usage to special cases. The goal of this research was to develop a general measure of effect size for mediation analysis that was applicable to a wide variety of models while maintaining the properties of a good effect size estimate. It will be shown how modification of a currently existing effect size measure for simple three-variable mediation models results in a novel effect size measure with properties suitable for general applicability. A matrix method will be proposed for obtaining the measure from complex mediation models and its use will be demonstrated for special cases. In addition, a novel method of variance decomposition using the measure will be proposed which allows for unique and shared contributions of sets of predictors and mediators to be examined in complex mediation models. Finally, two simulation studies will be conducted to examine 1) the properties of the statistic across various population models and 2) the finite sampling properties of the statistic in a multiple mediator model.
46

A Bayesian approach to abbreviated MMPI's accuracy.

Blair, Gary Russell. January 1990 (has links)
This study compared the performance of three abbreviated MMPIs, the Mini-Mult, the FAM, and the MMPI-168 as well as the MMPI, in their ability to predict diagnosis, in their ability to emulate the MMPI, and in their utility with the Gilberstadt and Duker prototype system. Most of the previous research had used the one, two or three highest profile scale matches from the short to long forms to assess code type compatibility instead of an actual typing system. Further, most of the prior studies had used traditional maximum likelihood statistical measures to assess performance. Posterior probabilities calculated from Bayes' rule were used as the primary measure here. Both the original norms and new prediction equations calculated from the sample data for the three short forms were used for all three tests, with a sample size of 578 male veteran inpatients for the Mini-Mult and FAM, and a sample size of 358 for the MMPI-168. The new equations generally outperformed the original ones by most measures, but the trends were similar in both conditions. There was little code type agreement between the short forms and the full MMPI, even though they usually had high scale-to-scale correlations and similar scale means. Part of the reason for this was the low rate of typing on any test, around 30%. Another reason was the low rate of high point correspondence between the short and full forms. A normal code with all clinical scales less than or equal to 70 T-scores performed best, although it is not part of the prototype system. All of the short forms had high valid and false negative rates for the code types with respect to the MMPI's code types. Diagnoses, as set by clinicians and recorded from each case's psychology service file, formed the external performance criteria. Across tests, few code types tended to be associated with a particular diagnosis and diagnoses weren't basically associated with code types. Trying to match diagnoses predicted by the code types with file diagnoses yielded only about a .10 overall probability of a match across tests, including the MMPI, under the most strict conditions. Liberalizing the conditions could bump the hit rates to about .70. The MMPI-168 with new equations was the best short form and outperformed the full MMPI in some conditions. Limitations of this study, some possible implications, and future research are discussed.
47

Some spatial characteristics of behavior: A new technology.

Robles-Sotelo, Elias. January 1990 (has links)
A methodology consisting of an experimental chamber, operational definitions of behavior categories, and methods for quantitative analysis of the use of space by small rodents is presented. The chamber consists of a large open box in which the location of the animal was determined by a grid of 24 x 24 infrared beams. Recording was achieved by sampling every 5 seconds, and storing the status of the 48 photosensors in a disk file for later analysis. Each sample produced a binary matrix with 576 cells identifying the location of the animal at that time. From this sequence of matrices a number of behaviors were defined and described. Exploration was measured as the cumulative percentage of unique cells visited by the subject during the observation period. Monotonically decelerating curves were found, with exploration during the first day in the chamber significantly different from that on the following three days, according to the Kolmogorov-Smirnov test. Time allocation was measured as the relative frequency of visits to individual cells computed for various time intervals. Three dimensional charts with spatial location along the X and Y axis, and relative frequency in the Z axis were used to represent time allocation to space or "spatial preference". These surfaces were transformed into vectors and compared with the same goodness-of-fit test. The operational definition of time allocation as well as the methods for comparing the surfaces were found adequate to reliably describe nesting and patrolling patterns of Ratus Norvegicus. Finally, activity was defined as the amount of space visited as a function of time. This measure of rat of location change was computed in 15 min. intervals for 15 consecutive nights. A consistent 3-hour cycle of activity was detected using ARIMA methods. The cycle was accurately described and predicted with a model containing one periodic and one nonperiodic components. The usefulness of this nonintrusive technology for digitizing behavior in space is discussed in terms of possible applications to studies on learning, behavioral pharmacology, and ethology.
48

The relationship of measures of job satisfaction to work/nonwork preference, life satisfaction, and mental health in Black and White workers.

Clemens, Camille. January 1990 (has links)
This study examines how the relationship between job satisfaction and measures of life satisfaction, mental health and work/non-work preferences differ for Black and White workers. Subjects consist of 128 employees from a large West Coast veteran's hospital. Results found Black workers' mental health scores were significantly related to income level and their work/non-work preference. For White workers, no significant relationships were found to exist. Also, Black and White workers reported no significant difference in overall level of job satisfaction.
49

Implicit and explicit memory for verbal stimuli presented during sleep.

Wood, James Michael. January 1990 (has links)
The present study explored the possibility of implicit memory for verbal information presented during sleep. Nineteen subjects in the experimental condition each spent one adaptation and two experimental nights in the sleep laboratory. On one experimental night they were presented with two lists of cued homophones (e.g. tortoise-hare) over earphones during REM or Stage 2 sleep and tested immediately afterward. On the other experimental night they were presented with two lists of category-instance pairs (e.g. bird-cardinal). In most cases, the lists were presented five times. For comparison, 12 control subjects came to the laboratory during the day and while awake underwent the same procedures as the sleeping subjects. All subjects were eliminated from the data analysis who had not been presented with two cued-homophone and two category-instance lists. The final data analysis included 10 sleeping subjects and 12 waking controls. For these subjects, all items were eliminated for which the subject had shown arousal or was in an inappropriate sleep stage before, during, or in the fifteen seconds immediately after stimulus presentation. A repeated measures ANOVA followed by a posteriori comparisons indicated that, contrary to what had been predicted, subjects in the experimental condition showed no sleep learning effects on either the homophone or the category-instance tests, although control subjects did. Consistent with earlier studies, recall for words presented during sleep was found in a few cases, but only when presentation was soon followed by arousal. These findings strongly suggest that semantic priming does not occur for verbal material presented during REM or Stage 2 sleep. The possibility of structural priming during sleep is also discussed. Past sleep learning studies are critically reviewed, and recommendations are made regarding the topics and methodology of future sleep learning experiments. In particular, a recommendation is made for additional research on quasi sleep learning, that is, learning for information presented immediately prior to arousal.
50

The self-preoccupation of depressives.

Pritchard, Barbara Ellen Angelo January 1990 (has links)
The study of depression has recently focused on interpersonal aspects of the disorder. Specifically, it has been suggested that depressed persons may engage in behavior which has an aversive impact on others. The social psychology literature has found that self-preoccupation, largely manifested in inappropriately high self-disclosure, results in being viewed negatively by others. The present study was an attempt to link these two areas by assessing whether depressed persons are self-preoccupied, and if so, whether such self-preoccupation has a negative interpersonal impact. Three groups of female subjects, composed of depressed outpatients, nondepressed outpatients, and normal controls (N = 36), engaged in face-to-face dyads with randomly selected females. Behavioral and observer ratings of self-preoccupation were taken, as well as self-report measures of interpersonal impact. Depressives were found to be excessively self-preoccupied. However, this behavior did not have the expected aversive impact on others. Possible explanations for these findings were discussed. Directions for future research were presented.

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