When a decision is made based on noisy evidence, it is often a good strategy to take multiple samples of evidence up to a threshold before committing to a choice. Such process, termed bounded evidence accumulation, have successfully explained human and nonhuman behavior (speed and accuracy of choices) and neural recordings quantitatively. In this thesis, we exploit the quantitative relationship between evidence, choice, and reaction times (inverse of speed), to infer decision rules that are not reported directly. In Part I, we consider decisions based on one stream of evidence. In Chapter 2, we start by examining decisions that are not reported immediately but felt to be made at some point. We show that, in a perceptual decision-making task, we can predict the proportion of choices from the reported timing of covert decisions. We suggest that the awareness of having decided corresponds to the threshold-crossing of the accumulated evidence, rather than a post hoc inference or arbitrary report. For the type of decisions reported in Chapter 2 and many others, it has been suggested that the terminating threshold is not constant but decreases over time. In Chapter 3, we propose a method that estimates the threshold without any assumption on its shape. As a step toward more complex decisions, in Part II we consider decisions based on two streams of evidence. In Chapter 4, we summarize the results from human psychophysics experiments involving simultaneous motion-color judgments. The results suggest that information bearing on two dimensions of a decision can be acquired in parallel, whereas incorporation of information into a combined decision involves serial access to these parallel streams. Here, one natural question is how complete the seriality is. In Chapter 5, we propose a method to estimate the degree of seriality of two evidence accumulation processes. Another question is whether the two streams are acquired in parallel even when the stimulus viewing duration is not limited, and hence there is no apparent advantage to parallel acquisition given the serial evidence accumulation stage. In Chapter 6, we propose a method to estimate the probability of simultaneous acquisition of two evidence streams given the choice and evidence streams. Collectively, the work in this thesis presents new ways to study decision rules quantitatively given noninvasive measures such as the contents of the evidence stream(s), decision times, and the choice.

I defend the view that mental states have degrees of strength. Our pains are more or less intense, our mental imagery is more or less vivid, our visual perceptions are more or less striking, and our desires and thoughts are more or less gripping. Mental strength is a phenomenal magnitude shared by all conscious experiences that determines their degree of felt intensity. Mental strength, however, has been largely ignored over other aspects of mental states such as their representational contents, phenomenology, or type. Considering mental strength is crucial for illuminating philosophical discussions related to representationalism, the transparency of experiences, cognitive phenomenology, attention, and the structure and function of consciousness. I use mental strength to develop in detail a neuropsychologically plausible theory of introspection and its limits that is inspired by a signal detection theoretic model of perception. In the second half of the dissertation, I look into methodological issues concerning the neural correlates of consciousness such as controlling for performance capacity and stimulus strength, and what these methodological concerns reveal about our theories of consciousness and its function.

In the last decade, tremendous advances have been made in the effort to understand mind wandering, yet many questions remain unanswered. Chief among them is how mind wandering relates to learning. Insofar as mind wandering has been linked to poor learning, finding ways to reduce the propensity to mind wander could potentially improve learning. Two experiments were conducted to examine this. The first experiment evaluated how difficulty of the to-be-learned materials affected one’s tendency to mind wander and revealed that people mind wandered when there was a mismatch between their level of expertise and the difficulty of materials studied. The second experiment compared whether participants were more likely to mind wander in blocked or interleaved conditions and showed that participants were more likely to mind wander when materials were presented in a blocked fashion. Together, these results indicate that techniques such as studying materials specific to one’s own level of mastery or changing the way in which one studies might reduce mind wandering and improve learning. Of equal importance is the question of what happens on in the brain when a person mind wanders. While the effect of mind wandering on early sensory processing is known, the impact it has on learning-related processing is not. In two event-related potential (ERP) experiments, participants were asked to report whether they were mind wandering or not while studying materials they were later tested on. Analyses revealed that elaborative semantic processing – indexed by a late, sustained slow wave that was maximal at posterior parietal electrode sites – was attenuated when participants mind wandered. Crucially, the pattern when people were on task rather than mind wandering was similar to the subsequent memory effect previously reported by other memory researchers, suggesting that mind wandering disrupts the deep level of processing required for learning.

A fundamental question in the study of memory is: Why do we remember some events but forget others? It has been proposed that people preferentially remember motivationally relevant information, as these memories may be useful in guiding choices in the future, a framework called adaptive memory. This dissertation examined the brain mechanisms that support adaptive memory, specifically focusing on how memory is shaped by rewards and dopamine, using a combination of pharmacological manipulations and behavioral assays. First, we found that rewards retroactively prioritize memory for preceding neutral events, and consistent with models of hippocampal replay, two periods of consolidation are necessary for this effect: a period of rest immediately following encoding and overnight consolidation. Second, motivated by research showing that neurotransmitters, such as dopamine, potentiate motivationally relevant memories to endure over long durations, we administered d-amphetamine (a dopamine agonist) before encoding. We found that when hippocampus dependent memory is tested after a short delay, working memory best accounts for memory performance, but when tested after a long delay, d-amphetamine level directly predicts memory performance. And third, we tested how d-amphetamine modulates different memory systems after a delay, using two different behavioral paradigms in which participants learned about overlapping associations using either stimulus-response learning or deliberate associative encoding. In both experiments, we found that d-amphetamine during encoding enhanced test performance on the trained items a week later; however, we did not detect any evidence that d-amphetamine modulates the integration of the overlapping pairs. Together, the work reported in this dissertation suggests that memory for motivationally relevant information is prioritized, dopamine enhances performance across different memory and learning systems, the effect of both reward and dopamine on memory and learning emerge after consolidation, and dopamine does not bias the hippocampus to encode memories in an integrated manner.

Perceiver's use of thought suppression to maintain a consistent attitude toward another person ironically leads to nonlinear changes in their evaluations over time. In this study of interpersonal evaluation, 157 participants across three conditions (high-level mindset, low-level mindset, and control) observe the same person in seven counter-balanced videotaped social interactions depicting helpful, rude, and ambiguous behaviors. The high-level prime instructed participants to focus on the target's goals and intentions ; low-level participants focused on the target's specific concrete behaviors. High-level participants better resisted the influence of conflicting information by surpressing thoughts inconsistent with their initial evaluation of the target. From the dynamical systems perspective, such suppressed information over time becomes organized as an alternative attractor, nonconsciously influencing the perceiver's cognitive system, leading to change away from an initial attitude, as measured by the Mouse Paradigm procedure. / by Steven S. Parkin. / Thesis (M.A.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

This study examines teachers’ beliefs in the nature and malleability of intelligence, how these beliefs may vary in different academic domains, and whether those beliefs have any significant relationships with teachers’ self-efficacy beliefs, epistemological beliefs, and proposed interventions for struggling students. Findings showed that teachers exhibited a more fixed view of the nature of intelligence when survey items were framed in terms of math, not language arts or domain-general items. There was also evidence suggesting that teachers’ beliefs in the fixed entity nature of intelligence are significantly correlated with holding a traditional unidimensional conception of intelligence. However, little evidence was found indicating a relationship between teachers’ various beliefs and their proposed strategies for struggling students. The results have implications for research on lay conceptions of intelligence, and for teacher education curricula.

Improving outcomes for English language learners (ELLs) in secondary science remains an area of high need. The purpose of this study is to investigate bilingual knowledge organization in secondary science classrooms. This study involved thirty-nine bilingual students in three biology classes at a public high school in The Bronx, New York City. Methods included an in-class survey on language use, a science content and English proficiency exam, and bilingual free- recalls. Fourteen students participated in bilingual free-recalls which involved a semi-structured process of oral recall of information learned in science class. Free-recall was conducted in both English and Spanish and analyzed using flow-map methods. Novel methods were developed to quantify and visualize the elaboration and mobilization of ideas shared across languages. It was found that bilingual narratives displayed similar levels of organizational complexity across languages, though English recalls tended to be longer. English proficiency was correlated with narrative complexity in English. There was a high degree of elaboration on concepts shared across languages. Finally, higher Spanish proficiency correlated well with greater overlapping elaboration across languages. These findings are discussed in light of current cognitive theory before presenting the study’s limitations and future directions of research.

The number line is a versatile tool. When used in estimation, it can serve as a visual representation of number. This study evaluated the relationship between sorting numbers by magnitude and number line estimation performance. Fifty-eight participants in Grades 1, 2, and 3 estimated values on a 0-100 number line over four sessions. During two intervention sessions they sorted numbers into 5 categories either linearly or nonlinearly before they estimated the same target values. The linear group’s number line estimates had less error than the nonlinear group’s estimates at posttest. In particular, the participants who started with low numeracy scores in the linear group outperformed their counterparts in the nonlinear group on the number line estimation task. Computer-based number categorization supports computer-based number line estimation skills when numbers are categorized linearly. This finding extends the representational mapping hypothesis to computer-based scaffolds.

<p> Recent research has associated obesity with cognitive impairments and alterations in brain-derived neurotrophic factor (BDNF), with the majority of studies examining this in older adult or aging animals. To expand upon these efforts, two experiments were performed to examine the effects of diet-induced obesity (DIO) on spatial performance and hippocampal BDNF expression in young adult female and male rats. To expand upon these efforts, we examined these effects over dietary interventions of differing durations. To investigate these issues rats (female rats in Experiment 1 and male rats in Experiment 2) were assigned to either a standard chow condition or a DIO condition and remained on these diets for 4-, 8- or 12-weeks. Compared to their chow-fed counterparts, female DIO rats consumed significantly more average weekly calories, weighed significantly more, and exhibited significant alterations in glucose metabolism. However, these obesity-related physiological changes were not associated with concurrent impairments in spatial ability as measured using the Morris water maze, and only the 4-week DIO dietary intervention demonstrated a difference in hippocampal BDNF mRNA expression. Compared to their chow-fed counterparts, male DIO rats consumed significantly more average weekly calories than their chow-fed counterparts, weighed significantly more, and exhibited significant alterations in glucose metabolism. However, obesity-related physiological alterations were not associated with concurrent impairments in spatial ability or differences in BDNF mRNA expression, with the exception of the 12-week DIO animals performing significantly better than their chow-fed counterparts during the reversal probe trial on the final day of training. These findings were unexpected and will be discussed further later in the thesis. </p><p>

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