Note:

This study investigated electroencephalographic differences related to cue (central left- or right-directed arrows) in a covert endogenous visual spatial attention task patterned after that of Hopf and Mangun (2000). This was done with the intent of defining the timing of components in relation to cognitive processes within the cue-target interval. Multiple techniques were employed to do this. Event-related potentials (ERPs) were examined using Independent Component Analysis. This revealed a significant N1, between 100:200 ms post-cue, greater contralateral to the cue. Difference wave ERPs, left minus right cue-locked data, divulged significant early directing attention negativity (EDAN) at 200:400 ms post-cue in the right posterior which reversed polarity in the left posterior. Temporal spectral evolution (TSE) analysis of the alpha band revealed three stages, (1) high bilateral alpha precue to 120 ms post-cue, (2) an event related desynchronization (ERD) from approximately 120 ms: 500 ms post-cue, and (3) an event related synchronization (ERS) rebound, 500: 900 ms post-cue, where alpha amplitude, a measure of activity, was highest contralateral to the ignored hemifield and lower contralateral to the attended hemifield. Using a combination of all of these components and scientific literature in this field, it is possible to plot out the time course of the cognitive events and their neural correlates. / by Edward Justin Modestino. / Vita. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

Age-related cognitive decline is a growing public health issue as increases in life expectancy are expected to substantially raise the prevalence of cognitive impairment and dementia. An estimated 46.8 million individuals are currently living with dementia, with the global prevalence expected to double every 20 years. Emerging evidence suggests that ambient air pollution from traffic and other sources may be an important risk factor for cognitive decline in addition to its association with other cardiovascular and neurological outcomes. The aim of this dissertation was to first investigate the association between long-term exposure to ambient air pollution and cognitive decline among older adults in an urban population within Northern Manhattan. I then set out to assess specific mechanisms involved in the association between long-term exposure to ambient air pollution and cognitive decline, specifically investigating the ApoE4 allele, age, and current smoking behavior as effect modifiers of the association between long-term exposure to ambient air pollution and cognitive decline. I found evidence of an adverse effect of ambient air pollution on the cognitive functioning of older adults. Overall, exposure to higher levels of ambient air pollution was highly predictive of lower cognitive scores, but at baseline only. Contrary to the current hypothesis, limited evidence was found for an association between estimates of air pollution and trajectories of cognitive decline. The patterns of effect were similar across pollutant types and cognitive domains in this aging, urban population. I found strong evidence of effect modification by smoking status, where contrary to the hypothesis; the overall effects of ambient air pollution on cognition and cognitive decline were stronger among individuals who never smoked. The impact of effect modification by age category was most prominent in the memory and language cognitive domains. Among individuals less than 75 years old at baseline, there was a stronger association between a one IQR increase in air pollutants and cognitive domain scores at baseline as compared to individuals 75 years and older. I did not observe conclusive evidence of an association between air pollution and cognition in models stratified by APOE-4 status. To my knowledge, this is the largest study to analyze the association of ambient air pollution on cognition and cognitive decline over time in a racially and ethnically diverse sample. These results further support the current evidence on the role of air pollution on accelerated cognitive aging and brain health.

Despite the burgeoning literature documenting the effects of breast-feeding on cognition and educational attainment over the past several decades, there remains important gaps in our knowledge regarding whether this relationship is dictated by sociodemographic factors. The current investigations, which examined the literature on the effects of breast-feeding on cognition and educational attainment in children, adolescents, and older adults addressed these gaps. Chapter 2 was an up-to-date global systematic review of population studies in individuals ≤ 25 years and ≥ 25 years of age. Results indicate that the majority of published studies conducted by researchers demonstrated a positive relationship between the effect of breast-feeding on cognitive outcomes and educational attainment. Additionally, findings highlighted the importance of possible confounders and how adjusting for them can change the relationship between breast-feeding and cognition and educational attainment. Chapter 3 investigated the breast-feeding-cognition/educational attainment relationship across race, as well as whether mother-child stimulation might mediate this relationship. The National Longitudinal Study of Adolescent to Adult Health (Add Health) was used to examine the effect of being breast-fed or not, and duration on cognitive outcomes and grade point average (GPA). Results indicate that individuals who were breast-fed had slightly higher GPAs and performance on both a vocabulary test and a number recall test compared to adolescents who were not breast-fed. There was an effect for race, but no interaction between race and breast-feeding. Mother-child stimulation had a limited effect on the relationship between breast-feeding and cognitive outcomes and GPA. Chapter 4 explored whether the effect observed in adolescence persists into older adulthood. The Reasons for Geographic and Racial Differences in Stroke (REGARDS) Cohort was used to examine this relationship in adults age ≥ 45 years. The covariates included sex of adolescent, race (Black or White), maternal education, paternal education, maternal smoking history, number of other children mother has, resident location (urban/not-urban), and a financial adversity index. This was a composite score consisting of yes or no responses to (1) do you have health insurance, (2) have you been employed within the past 12 months, (3) are you on public assistance, and (4) do you have enough money to pay your bills? Results show that self-report history of being breast-fed did not current predict performance on cognitive tests. Additionally, neither race nor sex moderated this relationship between breast-feeding and cognition. Overall, evidence from the review and two studies highlight the important of assessing the effect of breast-feeding on cognition and educational attainment in populations with varying confounding factors, however, while some of the results are inconsistent with our hypothesis, replication is clearly essential to further explore the possible underlying mechanism.

In this dissertation I study how different cognitive constraints affect individuals' belief formation process, and the consequences of these constraints on behavior. In the first chapter I present laboratory experiments designed to test whether subjects' inability to perform more rounds of iterated deletion of dominated strategies is due to cognitive limitations, or to higher order beliefs about the rationality of others. I propose three alternative explanations for why subjects might not be doing more iterations of dominance reasoning. First, they might have problems computing iterated best responses, even when doing so does not require higher order beliefs. Second, subjects might face limitations in their ability to generate higher order beliefs. Finally, subjects' behavior might not be limited by cognitive limitations, but rather justified by their beliefs about what others will play. I design two experiments in order to test these hypothesis. Findings from the first experiment suggest that most subjects' strategies (about 66%) are not the result of their inability to compute iterated best responses. I then run a second experiment, finding that about 70% of the subjects' behavior come from limitations in their ability to iterate best responses and generate higher order beliefs at the same time, while for the other 30% their strategies are a best response to higher order beliefs that others are not rational. In the second chapter I study whether a Sender in a Bayesian Persuasion setting (Kamenica and Gentzkow, 2011) can benefit from behavioral biases in the way Receivers update their beliefs, by choosing how to communicate information. I present three experiments in order to test this hypothesis, finding that Receivers tend to overestimate the probability of a state of the world after receiving signals that are more likely in that state. Because of this bias, Senders' gains from persuasion can be increased by ``muddling the water'' and making it hard for Receivers to find the correct posteriors. This contradicts the theoretical result that states that communicating using signal structures is equivalent to communicating which posteriors these structures induce. Through analysis of the data and robustness experiments, I am able to discard social preferences or low incentives as driving my results, leaving base-rate neglect as a more likely explanation. The final chapter studies whether sensory bottlenecks, as oppose to purely computational cognitive constraints, are important factors affecting subjects' inference in an experiment that mimics financial markets. We show that providing redundant visual and auditory cues about the liquidity of a stock significantly improves performance, corroborating previous findings in neuroscience of multi-sensory integration, which could have policy implications in economically relevant situation.

<p>  </p> <p>Individual differences in cognitive effort-based decision-making can reveal the variety of decision strategies used in action valuations. For example, factors such as how challenging an action is or how much reward can be gained are often considered when weighing how valuable an action is. Experiment 1 considers task preferences offered at different demand levels (i.e., the degree of challenge) to determine whether decision-making strategies are related primarily to 1) demand levels, 2) individual capability, or 3) task components. Results suggest that participants’ decisions were primarily driven by task options rather than their performance. Experiment 2 then compares task preferences in different incentive-related conditions. While the majority of decisions were in the predicted direction (favoring lower demand levels and higher monetary amounts), there were individual differences that suggested valuations of both task options as well as incentive conditions. The results of these experiments suggest individuals use various decision strategies involving factors that may have been overlooked in past research. These findings challenge the assumption that task preferences are primarily related to how challenging an action is and instead suggest that preferences may be highly susceptible to experimental design factors as well as factors intrinsic to the individual.</p>

The study focuses on the everyday problem solving processes of a group of community activists in a rural setting in the Eastern Cape Province of South Africa. It aims to uncover: first, the local knowledge of the participants of the study with reference to the concepts problem and problem solving; second, the participants' group problem solving procedure; and third, the dialectical interrelation between the participants' knowledge and practice with reference to everyday group problem solving. It is contended that the mainstream cognitive approach and the cross-cultural tradition are inappropriate for the study of everyday cognitive processes. A ‘situated cognition’ approach, based on the notions of activity and cultural mediation, is proposed as a theoretical framework for the study. The ontological and epistemological assumptions underpinning the empirical study were derived from a scientific realist and a hermeneutical paradigm. Data for the inquiry into the local knowledge of the participants was collected through individual interviews. The data was interpreted, using the grounded theory techniques of constant comparison, coding and compiling theoretical diagrams. Data for the inquiry into the participants' group problem solving practice consisted of video-taped group problem solving processes. This data was analysed, using a multi layered process of progressively deeper interpretation, employing a reading guide technique. Analysis of the research data revealed that the participants perceived a problem as an impediment to satisfactory participation in society. Problem solving was considered as an emotive, cognitive and inter-active process, involving particular role players. This process had a certain structure, involved attitudes and actions and relied on particular resources. Successful problem solving was perceived to result in restoration of social equilibrium. The group problem solving procedure used by the participants consisted of a process of developing a common understanding and group consensus. The strategies employed in the process, the roles played by the participants, the rules adhered to by the participants and the structure underlying the process were all congruent with these aims. There was a mutually reinforcing interrelation between knowledge and practice with reference to the participants’ problem solving.

Indiana University-Purdue University Indianapolis (IUPUI) / Down syndrome (DS), a genetic disorder that affects ~1 in 700 live births, is caused by trisomy of human chromosome 21 (Hsa21). Individuals with DS are affected by a wide spectrum of phenotypes which vary in severity and penetrance. However, cognitive and skeletal impairments can be commonly observed in all individuals with DS. To study these phenotypes, we utilized the Ts65Dn mouse model that carries three copies of approximately half the gene orthologs found on Hsa21 and exhibit similar phenotypes as observed in humans with DS. Individuals with DS and Ts65Dn mice have deficits in bone mineral density (BMD), bone architecture, bone strength, learning and memory. Over-expression of DYRK1A, a serine-threonine kinase encoded on Hsa21, has been linked to deficiencies in DS bone homeostasis and cognition. Epigallocatechin-3-gallate (EGCG), an aromatic polyphenol found in high concentrations in green tea, is a selective inhibitor of DYRK1A activity. Normalization of DYRK1A activity by EGCG therefore may have the potential to ameliorate skeletal and cognitive deficits. We hypothesized that supplements containing EGCG obtained from health food stores/ online vendors will not be as effective as EGCG from a chemical company in correcting bone deficits associated with DS. Our results suggest that EGCG improves the bone mineral density of trisomic femurs significantly better than the supplements while the EGCgNOW supplement from NOW FOODS improves trabecular and cortical bone structure. The results from HPLC analysis of supplements showed the presence of other catechins in EGCgNOW and degradation analysis revealed the rapid degradation of supplements. Therefore we hypothesize that the presence of EGCG degradation products and other green tea catechins in supplements may play a role in the differential skeletal effects we observed. We further hypothesized that a three week treatment of adolescent mice with EGCG will lead to an improvement in the learning and memory deficits that are observed in trisomic animals in comparison to control mice. However, our results indicate that three weeks of low-dose EGCG treatment during adolescence is insufficient to improve hippocampal dependent learning and memory deficits of Ts65Dn mice. The possibility remains that a higher dose of EGCG that begins at three weeks but lasts throughout the behavioral test period may result in improvement in learning and memory deficit of Ts65Dn mice.