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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.
11

What Explains a Semantic Unmasking Effect?

Ayars, Alisabeth January 2015 (has links)
Sanguinetti and Peterson (2013) found that masked words (e.g., "telephone") followed by a semantically related familiar silhouette (e.g., a silhouette of a telephone) were more likely to be perceived than words followed by an unrelated or novel silhouette, even though the words appeared prior to the silhouettes. This indicates that semantically related items can produce recovery of, or "unmask," earlier masked items. Sanguinetti and Peterson (2012) interpret their result in a framework proposed by Di Lollo, Enns, & Rensink (2000) which specifies feedback processing to play a role in hypothesis confirmation. According to Di Lollo et al., feedback processing in the visual system constitutes an iterative-loop system, directed at verification of hypotheses about perceptual stimuli. Sanguinetti and Peterson propose that the familiar silhouettes are able to confirm the hypothesis in the visual system that a semantically related word is present, via reentrant processing. At least two alternative explanations are available for the results. One alternative is that the semantically related silhouettes simply allow for retrieval of the episode of previously seeing the words (which is forgotten upon mask presentation), rather than causally contributing to their phenomenal consciousness. Another alternative is that the semantically related silhouettes allow participants to consciously infer what the word had been from a degraded perception. In Experiment 1, we showed that an attended feature of the words (i.e., their font) is not unmasked along with the semantics of the words—unmasked words appear in no identifiable font. This is evidence against the episodic retrieval hypothesis and supports Sanguinetti & Peterson's original interpretation, since the font of the words would be a component of the original episode of seeing the words. In Experiments 2a and 2b, we show that conscious recognition of the objects in the silhouettes is insufficient for the unmasking effect—reduction in silhouette exposure duration reduces the unmasking effect (Experiment 2a) even though silhouettes are equally recognizable (Experiment 2b). This rules out the inference explanation for the unmasking effect, since on this explanation unmasking would depend on whether the silhouettes are recognized and can therefore be employed in conscious inference. Independent theoretical contributions of these findings are discussed.
12

Detecting cluster bias in a multilevel item response model: A Monte Carlo evaluation of detection methods and consequences of ignoring cluster bias

Lee, Woo-yeol 22 March 2016 (has links)
Cluster bias in a multilevel item response model can be investigated by testing whether the within-level item discriminations are equal to the between-level item discriminations. However, in most multilevel item response model applications, the possibility of cluster bias is often ignored. Cluster bias detection methods using a multilevel item response model (the likelihood ratio test, Wald test, AIC, BIC, and saBIC) and the consequences of ignoring cluster bias are illustrated and discussed. Simulation results showed that all criteria performed well in detecting global cluster bias except the BIC with small sample sizes and high ICCs when some portion of the items exhibited cluster bias. For item cluster bias, the AIC outperformed the other criteria in the presence of partial cluster bias. When cluster bias was ignored, accuracy of item discrimination estimates and standard errors was mainly problematic. Implications of the findings and limitations are discussed.
13

Binding of Independent Contexts in Source Memory

Spitler, Samantha Nicole 21 April 2016 (has links)
Within the present study the binding between two independent source dimensions in a multidimensional source memory paradigm was investigated. Specifically, I examined stochastic dependence between the retrieval of each source dimension. Previous work has defined stochastic dependence as the higher probability of correct source retrieval for one dimension contingent on previous correct retrieval of a second source dimension, versus when contingent on incorrect retrieval of the second source dimension. Evidence is mixed as to whether item information within source dimensions must be encoded simultaneously in order to demonstrate eventual stochastic dependence. The present study tested the binding of two cross-modal source attributes (visual [left or right side of screen] and auditory [male or female voice]) over time by manipulating the lag between each independently-encoded source dimension. Source dimensions were encoded simultaneously or separately by two intervening encoding trials (separate condition). Based on the behavioral measures of binding, source dimensions presented more closely in time resulted in stochastic dependence in the context of remembering and not knowing. However, a multinomial model of response frequencies produced evidence of joint retrieval in the context of remembering for both the simultaneous and separate conditions. Because source dimensions were presented over time in some conditions, working memory capacity was measured as a potential predictor of stochastic dependence. However, working memory measures did not correlate with source memory performance. Future directions in examining this separate condition, stochastic dependence and individual differences in working memory capacity are discussed.
14

Examining the Role of Episodic and Semantic Networks in Anhedonia: Applying the Accessibility Model of Emotional Self-report to Psychometrically-defined Schizotypy

Mitchell, Kyle Robert 11 December 2015 (has links)
Individuals with schizophrenia exhibit a range of abnormalities in self-reported non-current experience of pleasure, but undisrupted current experience of pleasure. Several researchers have sought to address the mechanism of this deficit, yielding useful models of anhedonia. The accessibility model of emotional self-report suggests that deficits in hedonic response are due to differential activation of, and reliance upon, semantic and episodic memory systems. While this model has been proposed as an explanation of the deficits in hedonic response in schizophrenia, it has not been experimentally validated, and it remains to be seen whether the model will hold across the schizophrenia spectrum. The neurodevelopmental model of schizophrenia emphasizes the importance of understanding these deficits in individuals who are prone to psychosis, but may never manifest diagnosable disorder. The current study therefore sought to experimentally test the accessibility model of hedonic deficit in a sample of 92 individuals. Participants performed a task examining memory of emotionally valenced words designed to elicit semantically related emotional information. Overall, schizotypy was unrelated to abnormalities in memory performance in response to semantically congruent information. However, in disorganized schizotypy, semantic bias was a significant partial mediator of the relationship between schizotypy and current affective ratings. This result suggests the presence of abnormalities in semantic networks that contribute to differential current affective ratings to positively valenced stimuli.
15

Exploring the Nature of Memory Representations Underlying Priming of Pop-out in Visual Search

Bilge, Mustafa Taha 19 May 2016 (has links)
Participants respond to the target stimulus faster in a visual search task when the target item âpops outâ among distractor stimuli. Priming of pop-out refers to cases in which repetition of the pop-out feature (e.g., color) from the previous trials further speeds up visual search. Previous attempts at characterizing the memory representations underlying priming of pop-out put forward a specialized memory system evolved to benefit from the repetition of pop-out feature and location of stimuli in the environment (Maljkovic & Nakayama, 1994, 1996). In this dissertation, I primarily used behavioral measures (e.g., reaction time, RT) and event-related potentials (ERPs) (e.g., P3b) associated with working and long-term memory to demonstrate that priming of pop-out could be explained by these canonical memory systems. The results suggest that working memory representations guide attention and this guidance is modulated by the number of distractors. However, sequential repetitions of the pop-out feature modulate both long-term memory and working memory representations and these representations are strategically employed in guidance of attention. Further, repetition of target locations does not modulate either working or long-term memory representations; therefore different memory systems are employed for priming of the pop-out feature and location. Taken together, these results suggest that canonical memory systems, such as working memory and long-term memory, could explain priming of pop-out in particular and memory effects from previous trials that could permeate through the current trial in other visual search tasks in general.
16

The Role of Salience in Second Language Acquisition

Comeaux, Ian South 09 May 2016 (has links)
Abstract Cues to the actor role such as word order, noun animacy, case inflection and verb agreement vary in strength across languages. The competition model (CM; MacWhinney, 2005) suggests that adult L2 acquisition is difficult due to differences in cue strength between the native and target languages. Using a paradigm inspired by the CM, the present study examines whether salience plays a role in facilitating adjustments of cue strength during L2 learning. Native English speakers were exposed to an artificial language (via an actor-assignment task) which utilized four different cues: verb agreement, case marking, animacy, and word order. Word order, the strongest English cue, was the weakest relative to the other cues, requiring a shift in cue interpretation strategies. Salience was manipulated through the use of visual input enhancement (VIE). The two available morphological cues were presented with 1) no color contrast, 2) both marked with the same color contrast, or 3) each marked with a different color contrast. In Experiment 1, the cue hierarchy was dominated by the morphological cues (verb agreement > case marking > animacy > word order). It was found that VIE was effective in facilitating participant reliance upon the relevant cues, particularly so for the case marking cue. However, in Experiment 2, the cue hierarchy was rearranged so that a semantic cue was most the dominant (animacy > verb agreement > case marking > word order). With this hierarchy rearrangement, we failed to observe any benefit of VIE; participants continuously relied up the animacy cue. We conclude that VIE is a potentially effective tool for helping language learners adapt to the strength of cues in their target language. However, the efficacy of VIE seems limited 1) situations where it marks cues that are very high in the dominance hierarchy, and 2) to cues with low cognitive cost.
17

Effects of Various Seating Arrangements on Disruptive Classroom Behavior

Robichaux, Natalie Marie 09 May 2016 (has links)
Both class-wide behavioral interventions and antecedent strategies are commonly used to target disruptive behavior problems and improve classroom management. Typically, antecedent strategies precede behavioral interventions due to their proactive nature. Antecedent strategies, such as altering the classroom seating arrangement, may be more desirable to teachers than behavior interventions due to their simplicity and ability to be easily incorporated into existing routines. Past research, though limited, has demonstrated that row and column seating arrangements are associated with lower disruptions during independent work activities compared to group seating arrangements. In the first study, a multi-element design was used to compare rates of disruptive classroom behavior when utilizing three different seating arrangements (i.e., rows, pairs, and groups). Row and pair arrangements were associated with less disruptions than the group arrangement, and rows appeared slightly superior among all three. In the second study, rates of disruptive behavior were compared under three conditions: row and column seating, the Good Behavior Game, and both. All conditions resulted in decreased disruptive behaviors from baseline conditions (i.e., group seating arrangement). The greatest decreases were observed when the game was implemented, regardless of how the desks were arranged. Practical implications for decreasing disruptive behavior and directions for future research are discussed.
18

The Relationship Among Attention Deficit/Hyperactivity Disorder (ADHD) Subtypes, Oppositional Defiant Disorder (ODD), and Parenting Stress

Cannon, Megan 01 January 2013 (has links)
Attention-Deficit/Hyperactivity Disorder (ADHD) is one of the most common behavioral disorders diagnosed within childhood and affects approximately 9.5% of children in the United States. Additionally, approximately 35% to 60% of clinic-referred children will also meet the criteria for Oppositional Defiant Disorder (ODD). Increased levels of parenting stress are commonly experienced among parents of children diagnosed with ADHD and a number of factors contribute to this association. ADHD subtype has consistently presented itself as a factor; however, observing parenting stress levels between ADHD subtypes and ADHD with comorbid ODD within the same study has not been pursued in the literature. The present study utilized the Parenting Stress Index-Short Form (PSI/SF) to compare scores on the Total Stress, Parental Distress, and Parent-Child Dysfunctional interaction scales among mothers of children diagnosed with ADHD Predominantly Inattentive Type (ADHD-I), ADHD Combined Type (ADHD-C) and comorbid ADHD and ODD (ADHD/ODD). Following a One-Way Analysis of Covariance, a significant difference was found on the level of Total Stress reported by mothers of children diagnosed with ADHD/ODD when compared with mothers of children diagnosed with ADHD-C. No other significant differences were uncovered. Additionally, the current study attempted to gain a better understanding of the relationship between parenting stress and chronological age of the diagnosed child by observing the correlation between child age and the level of parenting stress reported by mothers of children diagnosed with ADHD, in addition to a comorbid diagnosis of ADHD and ODD. Pearson product-moment correlation coefficients were calculated between child age and the Total Stress and Difficult Child scales on the PSI/SF; however neither achieved statistical significance. Finally, the present study compared the correlations between child age and maternal scores on the Total Stress and Difficult Child scales on the PSI/SF among children with a sole diagnosis of ADHD, to those of children with a comorbid diagnosis of ADHD/ODD. Correlations within the ADHD/ODD group among child age and the Total Stress and Difficult Child scales were both in the negative direction. In contrast, the correlations within the ADHD group were both in a positive direction.
19

Prescription Privileges for Psychologists: General Practitioners' Attitudes and Referral Behaviors

Crabtree, Heather Jo 01 January 2011 (has links)
The purpose of this study was to assess General Practitioners' (GPs') and medical students' attitudes towards psychologists seeking prescription privileges and their willingness to refer patients to these professionals, as well as factors relating to these variables. Three hundred and thirty-eight GPs from a national sample, and 48 medical students from a private medical school in the southeastern United States participated in this online study. Participants were divided into two experimental groups, with one group receiving additional information regarding the educational and training experiences of prescribing psychologists and one group receiving no additional information. Participants completed a survey, which assessed: demographic variables, attitudes, referral behaviors, and personality factors. It was predicted that participants receiving additional information prior to survey completion would have more favorable attitudes and referral behaviors than those who did not receive the information. This prediction was confirmed for participants' attitudes, but not referral behaviors. Results also indicated that the majority of participants held unfavorable attitudes towards prescribing psychologists and were generally unwilling to refer patients to these professionals. However, contrary to the research hypothesis, GPs were found to have more favorable attitudes and referral behaviors than medical students. Additionally, analyses were conducted in order to use multiple variables (e.g., information condition, participant type, gender, age, practice setting, location, openness score) to predict participants' attitudes and referral behaviors. However, these factors were only found to account for a very small percentage of participants' attitudes and referral behaviors. In light of this study's results, future research is needed in order to further explore factors related to attitudes and referral behaviors of GPs. Future research should also investigate ways to improve communication and collaboration between medical professionals and psychologists.
20

Relationship of Reproductive Hormone Levels and Menstrual Distress With Indices of Stress

Feehely, Kristie DeBlasio 01 January 2009 (has links)
Previous research has found that hormone levels change throughout the phases of the menstrual cycle and can affect menstrual distress, however, with inconsistent results. Additionally, research has indicated that stress plays a role in menstrual distress symptoms. There has not been a comprehensive study to date which examines the relationship of reproductive hormone levels (e.g., progesterone, estradiol, LH and PRL) throughout all four phases of the menstrual cycle, while also studying menstrual distress symptoms and indices of stress. Participants include a community sample of women (N = 37) recruited at a university medical center in Mississippi who completed laboratory hormone assays, as well as the Menstrual Distress Questionnaire (Moos, 1968), the Weekly Stress Inventory (Brantley, Jones, Boudreaux, & Catz, 1997), and a global stress measure, throughout four phases of one menstrual cycle. Pearson correlations were conducted to test the potential relationships of hormone levels and indices of stress. The relationships between hormone levels and menstrual distress, as well as the relationships between menstrual distress and stress also were examined. Potential interactions were examined using multiple regressions. The role of menstrual distress in mediating the relationship between hormone levels and indices of stress also were considered and assessed using a series of multiple regression equations.

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