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Source memory revealed through eye movements and pupil dilation

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Current theoretical debate, crossing the bounds of memory theory and mental imagery, surrounds the role of eye movements in successful encoding and retrieval. Although the eyes have been shown to revisit previously-viewed locations during retrieval, the functional role of these

Current theoretical debate, crossing the bounds of memory theory and mental imagery, surrounds the role of eye movements in successful encoding and retrieval. Although the eyes have been shown to revisit previously-viewed locations during retrieval, the functional role of these saccades is not known. Understanding the potential role of eye movements may help address classic questions in recognition memory. Specifically, are episodic traces rich and detailed, characterized by a single strength-driven recognition process, or are they better described by two separate processes, one for vague information and one for the retrieval of detail? Three experiments are reported, in which participants encoded audio-visual information while completing controlled patterns of eye movements. By presenting information in four sources (i.e., voices), assessments of specific and partial source memory were measured at retrieval. Across experiments, participants' eye movements at test were manipulated. Experiment 1 allowed free viewing, Experiment 2 required externally-cued fixations to previously-relevant (or irrelevant) screen locations, and Experiment 3 required externally-cued new or familiar oculomotor patterns to multiple screen locations in succession. Although eye movements were spontaneously reinstated when gaze was unconstrained during retrieval (Experiment 1), externally-cueing participants to re-engage in fixations or oculomotor patterns from encoding (Experiments 2 and 3) did not enhance retrieval. Across all experiments, participants' memories were well-described by signal-detection models of memory. Source retrieval was characterized by a continuous process, with evidence that source retrieval occurred following item memory failures, and additional evidence that participants partially recollected source, in the absence of specific item retrieval. Pupillometry provided an unbiased metric by which to compute receiver operating characteristic (ROC) curves, which were consistently curvilinear (but linear in z-space), supporting signal-detection predictions over those from dual-process theories. Implications for theoretical views of memory representations are discussed.

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Date Created
2012

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Cognitive control processes underlying continuous and transient monitoring processes in event-based prospective memory

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A converging operations approach using response time distribution modeling was adopted to better characterize the cognitive control dynamics underlying ongoing task cost and cue detection in event based prospective memory (PM). In Experiment 1, individual differences analyses revealed that working

A converging operations approach using response time distribution modeling was adopted to better characterize the cognitive control dynamics underlying ongoing task cost and cue detection in event based prospective memory (PM). In Experiment 1, individual differences analyses revealed that working memory capacity uniquely predicted nonfocal cue detection, while proactive control and inhibition predicted variation in ongoing task cost of the ex-Gaussian parameter associated with continuous monitoring strategies (mu). In Experiments 2A and 2B, quasi-experimental techniques aimed at identifying the role of proactive control abilities in PM monitoring and cue detection suggested that low ability participants may have PM deficits during demanding tasks due to inefficient monitoring strategies, but that emphasizing importance of the intention can increase reliance on more efficacious monitoring strategies that boosts performance (Experiment 2A). Furthermore, high proactive control ability participants are able to efficiently regulate their monitoring strategies under scenarios that do not require costly monitoring for successful cue detection (Experiment 2B). In Experiments 3A and 3B, it was found that proactive control benefited cue detection in interference-rich environments, but the neural correlates of cue detection or intention execution did not differ when engaged in proactive versus reactive control. The results from the current set of studies highlight the importance of response time distribution modeling in understanding PM cost. Additionally, these results have important implications for extant theories of PM and have considerable applied ramifications concerning the cognitive control processes that should be targeted to improve PM abilities.

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Date Created
2015

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A Mechanistic Account of the Relation between Working Memory Capacity and Fluid Intelligence

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Working memory capacity and fluid intelligence are important predictors of performance in educational settings. Thus, understanding the processes underlying the relation between working memory capacity and fluid intelligence is important. Three large scale individual differences experiments were conducted to determine

Working memory capacity and fluid intelligence are important predictors of performance in educational settings. Thus, understanding the processes underlying the relation between working memory capacity and fluid intelligence is important. Three large scale individual differences experiments were conducted to determine the mechanisms underlying the relation between working memory capacity and fluid intelligence. Experiments 1 and 2 were designed to assess whether individual differences in strategic behavior contribute to the variance shared between working memory capacity and fluid intelligence. In Experiment 3, competing theories for describing the underlying processes (cognitive vs. strategy) were evaluated in a comprehensive examination of potential underlying mechanisms. These data help inform existing theories about the mechanisms underlying the relation between WMC and gF. However, these data also indicate that the current theoretical model of the shared variance between WMC and gF would need to be revised to account for the data in Experiment 3. Possible sources of misfit are considered in the discussion along with a consideration of the theoretical implications of observing those relations in the Experiment 3 data.

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2018

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Decoding the ERP/Behavior Link: A Trial-Level Approach to the NoGo-N200 Component

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In most of the work using event-related potentials (ERPs), researchers presume the function of specific components based on the careful manipulation of experimental factors, but rarely report direct evidence supporting a relationship between the neural signal and other outcomes. Perhaps

In most of the work using event-related potentials (ERPs), researchers presume the function of specific components based on the careful manipulation of experimental factors, but rarely report direct evidence supporting a relationship between the neural signal and other outcomes. Perhaps most troubling is the lack of evidence that ERPs correlate with related behavioral outcomes which should result, at least in part, from the neural processes that ERPs capture. One such example is the NoGo-N2 component, an ERP component elicited in Go/NoGo paradigms. There are two primary theories regarding the functional significance of this component in this context: that the signal represents response inhibition and that the component reflects conflict. In this paper, a trial-level method of analysis for the relationship between ERP component potentials and downstream behavioral outcomes (in this case, response accuracy) using a multi-level modeling framework is proposed to provide discriminatory evidence for one of these theories. Following a description of the research on the NoGo-N2, preliminary data supporting the conflict monitoring theory are presented, noting important limitations. Next, an EEG simulation study is presented in which NoGo-N2 data are generated with a known relationship to fabricated reaction time data, showing that, with added levels of complexity and noise within the data, the MLM approach is consistently successful at extracting the known relationships that occur in real NoGo-N2 data. Next, using independent components analysis (ICA) to extract spatiotemporal components that best represent the signal of interest, a well-powered analysis of the relationship between the NoGo-N2 and response accuracy is used to provide strong discriminatory evidence for the conflict monitoring theory of the NoGo-N2. Finally, implications for the NoGo-N2, as well as all ERP components, are discussed with a focus on how this approach can and should be used. the paper concludes with potential expansions of this approach to areas beyond identifying the function of ERP components.

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Date Created
2019

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I Can’t Stand Thinking Anymore: An Analysis of Directed Attention on Posture

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Maintaining upright balance and postural control is a task that most individuals perform everyday with ease and without much thought. Although it may be a relatively easy task to perform, research has shown that changes in cognitive (or “attentional”)

Maintaining upright balance and postural control is a task that most individuals perform everyday with ease and without much thought. Although it may be a relatively easy task to perform, research has shown that changes in cognitive (or “attentional”) processes are reflected in the movements of sway. The purpose of this dissertation is to understand the relationship between attention and posture when attention is directly or indirectly shifted away from posture. Using a dual-task paradigm, attention was shifted directly by instructing participants to prioritize the balance task (minimize sway in a unipedal stance) or prioritize the cognitive task (minimize errors in an auditory n-back task) and indirectly by changing the difficulty level of the cognitive task (0-back vs. 2-back task). Postural sway was assessed using sample entropy (SampEn), standard deviation, (SD) and sway path (SP) of trunk movements to measure the regularity, variability, and overall distance of sway travelled, respectively. Dual-task behavior was examined when participants were in a controlled (i.e., non-fatigued) state (Experiment 1), in a state of physical fatigue (Experiment 2), and in a state of mental fatigue (Experiment 3). Across all three experiments, indirectly shifting attention away from posture in the more difficult 2-back task induced less regularity (higher SampEn) and variability (smaller SD) in postural sway. Directly shifting attention away from posture, by prioritizing the cognitive task, induced less regularity (higher SampEn) and a longer path length (higher SP) in Experiment 1, however this effect was not significant for the fatigued participants in Experiments 2 and 3. Neither physical fatigue (Experiment 2) or mental fatigue (Experiment 3) negatively affected postural sway or cognitive performance. Overall, the findings from this dissertation contribute to the relationship between movement regularity and attention in posture, and that the postural behavior that emerges is sensitive to methods in which attention is manipulated (direct, indirect) and fatigue (physical, mental).

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Date Created
2019