Matching Items (72)
Description
The human brain controls a person's actions and reactions. In this study, the main objective is to quantify reaction time towards a change of visual event and figuring out the inherent relationship between response time and corresponding brain activities. Furthermore, which parts of the human brain are responsible for the reaction time is also of interest. As electroencephalogram (EEG) signals are proportional to the change of brain functionalities with time, EEG signals from different locations of the brain are used as indicators of brain activities. As the different channels are from different parts of our brain, identifying most relevant channels can provide the idea of responsible brain locations. In this study, response time is estimated using EEG signal features from time, frequency and time-frequency domain. Regression-based estimation using the full data-set results in RMSE (Root Mean Square Error) of 99.5 milliseconds and a correlation value of 0.57. However, the addition of non-EEG features with the existing features gives RMSE of 101.7 ms and a correlation value of 0.58. Using the same analysis with a custom data-set provides RMSE of 135.7 milliseconds and a correlation value of 0.69. Classification-based estimation provides 79% & 72% of accuracy for binary and 3-class classication respectively. Classification of extremes (high-low) results in 95% of accuracy. Combining recursive feature elimination, tree-based feature importance, and mutual feature information method, important channels, and features are isolated based on the best result. As human response time is not solely dependent on brain activities, it requires additional information about the subject to improve the reaction time estimation.
ContributorsChowdhury, Mohammad Samin Nur (Author) / Bliss, Daniel W (Thesis advisor) / Papandreou-Suppappola, Antonia (Committee member) / Brewer, Gene (Committee member) / Arizona State University (Publisher)
Created2019
Description
Self-control has been shown to be an important influence behind a variety of risk and protective behaviors, such as substance abuse. Although prior research points to the existence of multiple dimensions of self-control, this concept is not consistently defined and frequently only studied as a conglomerate in clinical research. The current study sought to examine how two experimental manipulations of subcomponents of self-control (motivation and self-efficacy) affect real-world consumptive behavior after accounting for executive function. Additionally, the validity and reliability of a brief state survey measure of perceived self-control capacity, internal motivation, and external motivation was tested. The goal was to examine how basic scientific principles involved in self-control translate into clinically relevant behaviors, which may inform understanding of momentary lapses in self-control behavior, potentially leading to novel prevention and intervention efforts. 94 college students completed a 1-2 hour laboratory protocol during which they completed survey and laboratory-based tasks of self-control and related behaviors, executive function, and ad libitum alcohol consumption. Results showed that the self-efficacy manipulation successfully increased perceived self-control capacity, although this did not lead to a significant reduction in consumption. The motivation manipulation neither increased motivation nor reduced consumption in this sample. However, the brief state survey measure of self-control subcomponents demonstrated strong test-retest reliability and distinction from trait self-control, demonstrating its viability for use in future research. By elucidating the relationships between specific mechanisms of self-control, laboratory-based tasks and manipulations, and real-world consumptive behaviors, prevention and intervention efforts for problems such as alcohol abuse may be tailored to the needs of the individual and made more impactful and cost-effective.
ContributorsPapova, Anna (Author) / Corbin, William R. (Thesis advisor) / Brewer, Gene (Committee member) / Karoly, Paul (Committee member) / McClure, Samuel (Committee member) / Arizona State University (Publisher)
Created2020
Description
The ability to inhibit a planned but inappropriate response, and switch to executing a goal-relevant motor response, is critically important for the regulation of motor behaviors. Inhibition and switching could be mediated by various control mechanisms. Proactive control uses contextual information (cues) to plan the response for the target stimulus (probe) based on the expectation of a response inhibition or switching stimulus combination. Previous work has reported the involvement of several brain areas associated with proactive inhibition and switching, e.g., dorsolateral prefrontal cortex, anterior cingulate cortex, inferior frontal junction, and pre-supplementary motor area. However, how these areas interact and their functional role in different types of cognitive control is still debated. An AX-version of the continuous performance task (AX-CPT) was used to examine proactive inhibition and switching of motor actions. In a typical AX-CPT trial, a contextual cue stimulus is presented, followed by a probe stimulus after a specific inter-stimulus interval. As part of a trial sequence, if a target cue and target probe are presented, a target response is to be provided when the probe is observed. Otherwise, a non-target response is to be provided for all other stimuli. A behavioral switching AX-CPT experiment (48 subjects) was conducted to explore the parameters that induce a proactive shift in the motor response. Participants who performed the AX-CPT task with relatively shorter interstimulus interval predominantly and consistently exhibited proactive control behavior. A follow-up pilot study (3 subjects) of response inhibition versus response switching AX-CPT was performed using 256-channel high-density electroencephalography (HD-EEG). HD-EEG was used to identify the time course of cortical activation in brain areas associated with response inhibition. It was observed that one out of three participants used a proactive strategy for response switching based on probe response error and probe response reaction time. Instantaneous amplitude spatial maps obtained from HD-EEG revealed cortical activity corresponding to conflict between proactively-prepared incorrect responses and reactively-corrected goal-relevant responses after the probe was presented.
ContributorsMysore, Archana Shashidhar (Author) / Santello, Marco (Thesis advisor) / Blais, Christopher (Committee member) / Brewer, Gene (Committee member) / Tillery, Stephen Helms (Committee member) / Arizona State University (Publisher)
Created2020
Description
This study examined the effects of different constructed response prompts and text types on students’ revision of misconceptions, comprehension, and causal reasoning. The participants were randomly assigned to prompt (self-explain, think-aloud) and text type (refutational, non-refutational) in a 2x2, between-subjects design. While reading, the students were prompted to write responses at regular intervals in the text. After reading, students were administered the conceptual inventory of natural selection (CINS), for which a higher score indicates fewer misconceptions of natural selection. Finally, students were given text comprehension questions, and reading skill and prior knowledge measures. Linear mixed effects (LME) models showed that students with better reading skill and more prior knowledge had a higher CINS score and better comprehension compared to less skilled students, but there were no effects of text type or prompt. Linguistic analysis of students’ responses demonstrated a relationship of prompt, text, and reading skill on students’ causal reasoning. Less skilled students exhibited greater causal reasoning when self-explaining a non-refutational text compared to less skilled students prompted to think-aloud, and less skilled students who read the refutational text. The results of this study demonstrate a relationship between reading skill and misconceptions in natural selections. Furthermore, the linguistic analyses suggest that less skilled students’ causal reasoning improves when prompted to self-explain.
ContributorsWatanabe, Micah (Author) / McNamara, Danielle S. (Thesis advisor) / Brewer, Gene (Committee member) / Firetto, Carla (Committee member) / Arizona State University (Publisher)
Created2020
Description
Aortic aneurysms and dissections are life threatening conditions addressed by replacing damaged sections of the aorta. Blood circulation must be halted to facilitate repairs. Ischemia places the body, especially the brain, at risk of damage. Deep hypothermia circulatory arrest (DHCA) is employed to protect patients and provide time for surgeons to complete repairs on the basis that reducing body temperature suppresses the metabolic rate. Supplementary surgical techniques can be employed to reinforce the brain's protection and increase the duration circulation can be suspended. Even then, protection is not completely guaranteed though. A medical condition that can arise early in recovery is postoperative delirium, which is correlated with poor long term outcome. This study develops a methodology to intraoperatively monitor neurophysiology through electroencephalography (EEG) and anticipate postoperative delirium. The earliest opportunity to detect occurrences of complications through EEG is immediately following DHCA during warming. The first observable electrophysiological activity after being completely suppressed is a phenomenon known as burst suppression, which is related to the brain's metabolic state and recovery of nominal neurological function. A metric termed burst suppression duty cycle (BSDC) is developed to characterize the changing electrophysiological dynamics. Predictions of postoperative delirium incidences are made by identifying deviations in the way these dynamics evolve. Sixteen cases are examined in this study. Accurate predictions can be made, where on average 89.74% of cases are correctly classified when burst suppression concludes and 78.10% when burst suppression begins. The best case receiver operating characteristic curve has an area under its convex hull of 0.8988, whereas the worst case area under the hull is 0.7889. These results demonstrate the feasibility of monitoring BSDC to anticipate postoperative delirium during burst suppression. They also motivate a further analysis on identifying footprints of causal mechanisms of neural injury within BSDC. Being able to raise warning signs of postoperative delirium early provides an opportunity to intervene and potentially avert neurological complications. Doing so would improve the success rate and quality of life after surgery.
ContributorsMa, Owen (Author) / Bliss, Daniel W (Thesis advisor) / Berisha, Visar (Committee member) / Kosut, Oliver (Committee member) / Brewer, Gene (Committee member) / Arizona State University (Publisher)
Created2020
Description
This study focuses on the properties of binaural beats (BBs) compared to Monaural beats (MBs) and their steady-state response at the level of the Superior Olivary Complex (SOC). An auditory nerve stimulator was used to simulate the response of the SOC. The simulator was fed either BBs or MBs stimuli to compare the SOC response. This was done for different frequencies at twenty, forty, and sixty hertz for comparison of the SOC response envelopes. A correlation between the SOC response envelopes for both types of beats and the waveform resulting from adding two tones together was completed. The highest correlation for BBs was found to be forty hertz and for MBs it was sixty hertz. A Fast Fourier Transform (FFT) was also completed on the stimulus envelope and the SOC response envelopes. The FFT was able to show that within the BBs presentation the envelopes of the original stimuli showed no difference frequency. However, the difference frequency was present in the binaural SOC response envelope. For the MBs, the difference frequency was present within the stimulus and the monaural SOC response envelope.
ContributorsCrawford, Taylor Janay (Author) / Brewer, Gene (Thesis advisor) / Zhou, Yi (Committee member) / Azuma, Tamiko (Committee member) / Arizona State University (Publisher)
Created2021
Description
The current study explores the extent to which different processing strategies affect comprehension accuracy and integration of information across multiple texts. Reading comprehension of single texts is a difficult task, in which the challenges are compounded by the need to integrate information across texts. Processing strategies, such as self-explanation and source-evaluation, help reduce the challenges that readers face when attempting to comprehend texts. Self-explanation has been a successful strategy for coherence-building processes in single text comprehension, but the benefits for supporting inter-textual comprehension have not yet been explored. Source-evaluation supports identification of different sources, which helps resolve inconsistencies between texts; yet it remains unclear whether sourcing alone supports comprehension within as well as between texts. Think-aloud is a strategy intended to encourage further processing of the text without providing any explicit comprehension strategy. The differences between these two strategies prompts questions regarding the adequacy of either strategy for supporting inferencing and integration within and across texts. In this study, participants (n=80) were randomly assigned to one of three strategy conditions: self-explanation, source-evaluation, or think-aloud. Students read four texts after which they completed three types of open-ended comprehension questions (i.e., textbase, intra-textual inference, and inter-textual inference), a source memory task, and individual difference measures. Prior knowledge and reading skill were strongly correlated (r = .65) and showed moderate correlations (r = .31 to .60) with participants’ comprehension accuracy, total number of integrations within their responses, and their memory for sources. Participants were more likely to respond accurately and demonstrate integrations across texts for the text-based questions in comparison to the more challenging inference questions. There was a marginal effect of condition on comprehension question accuracy, wherein participants who self-explained responded more accurately than those who engaged in the think-aloud task. In addition, those in the self-explanation or source-evaluation conditions recalled more sources than those in the think-aloud condition. There were no significant differences in performance between the self-explanation and the source-evaluation conditions. Overall, the results of this study indicate that encouraging students to self-explain and/or evaluate sources while they read multiple documents enhances comprehension and memory for sources.
ContributorsPerret, Cecile Aline (Author) / McNamara, Danielle S (Thesis advisor) / Brewer, Gene (Committee member) / Glenberg, Arthur (Committee member) / Arizona State University (Publisher)
Created2021
Description
In the study of the human brain’s ability to multitask, there are two perspectives: concurrent multitasking (performing multiple tasks simultaneously) and sequential multitasking (switching between tasks). The goal of this study is to investigate the human brain’s ability to “multitask” with multiple demanding stimuli of approximately equal concentration, from an electrophysiological perspective different than that of stimuli which don’t require full attention or exhibit impulsive multitasking responses. This study investigates the P3 component which has been experimentally proven to be associated with mental workload through information processing and cognitive function in visual and auditory tasks, where in the multitasking domain the greater attention elicited, the larger P3 waves are produced. This experiment compares the amplitude of the P3 component of individual stimulus presentation to that of multitasking trials, taking note of the brain workload. This study questions if the average wave amplitude in a multitasking ERP experiment will be the same as the grand average when performing the two tasks individually with respect to the P3 component. The hypothesis is that the P3 amplitude will be smaller in the multitasking trial than in the individual stimulus presentation, indicating that the brain is not actually concentrating on both tasks at once (sequential multitasking instead of concurrent) and that the brain is not focusing on each stimulus to the same degree when it was presented individually. Twenty undergraduate students at Barrett, the Honors College at Arizona State University (10 males and 10 females, with a mean age of 18.75 years, SD= 1.517) right handed, with normal or corrected visual acuity, English as first language, and no evidence of neurological compromise participated in the study. The experiment results revealed that one- hundred percent of participants undergo sequential multitasking in the presence of two demanding stimuli in the electrophysiological data, behavioral data, and subjective data. In this particular study, these findings indicate that the presence of additional demanding stimuli causes the workload of the brain to decrease as attention deviates in a bottleneck process to the multiple requisitions for focus, indicated by a reduced P3 voltage amplitude with the multitasking stimuli when compared to the independent. This study illustrates the feasible replication of P3 cognitive workload results for demanding stimuli, not only impulsive-response experiments, to suggest the brain’s tendency to undergo sequential multitasking when faced with multiple demanding stimuli. In brief, this study demonstrates that when higher cognitive processing is required to interpret and respond to the stimuli, the human brain results to sequential multitasking (task- switching, not concurrent multitasking) in the face of more challenging problems with each stimulus requiring a higher level of focus, workload, and attention.
ContributorsNeill, Ryan (Author) / Brewer, Gene (Thesis director) / Peter, Beate (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The locus coeruleus-norepinephrine system (LC-NE) has been argued to play a vital role in task engagement and attention control by the adaptive gain theory (Aston-Jones & Cohen, 2005). One of the central claims of this theory is that tonic LC activity exhibits a quadratic relationship with task performance. Pupil dynamics have been correlated to LC-NE activity via primate intracranial recordings in ways that provide evidence for the adaptive gain theory. Due to the small size and location of the LC, less is known about LC functioning in humans, leading to a desire to find valid, noninvasive psychophysiological proxies to study this structure. In this paper we performed a replication of Murphy, Robertson, Balsters, & O’Connell (2011) to gather evidence on whether pupil fluctuations and the P3 event-related potential are viable markers for measuring tonic and phasic LC-NE activity in humans. A sample of 33 subjects from the Arizona State University human subjects pool provided usable electroencephalogram and pupillometry data collected during an auditory oddball task. Our analyses largely correspond with those found in Murphy et al. (2011) showing some evidence that pupillometry and P3 can be utilized when studying the LC. Moving forward we will reproduce the full set of analyses from Murphy et al. (2011) with our dataset.
ContributorsStrayer, Deanna L. (Author) / Brewer, Gene (Thesis director) / Robison, Matthew (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This autoethnography is the culmination of years of migraine research and self-experimentation with alternative medicine to treat Hemiplegic Migraine (HM). HM is a rare phenomenon that is commonly misdiagnosed as a stroke or epilepsy disorder since the symptoms can include partial unilateral paralysis or weakness, visual disturbances, unilateral headache, vomiting, and trouble speaking. There is no known cure for HM, and current migraine medications can be accompanied by adverse side effects at an expensive cost. Alternative medicine, such as dietary supplementation, meditation, and positive thinking are potential options for working in relationship with HM episodes. This thesis explores HM as a personally transformative experience by learning to grow from pain.
ContributorsSchramm, Emily (Author) / Cloutier, Scott (Thesis director) / Brewer, Gene (Committee member) / School of Life Sciences (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05