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The McGurk effect is an illusion that occurs when an auditory /ba/ is combined with a visual /ga/. The two stimuli fuse together which leads to the perception of /da/, a sound in between /ba/ and /ga/. The purpose of this study was to determine whether music performance and visual arts majors process mismatched auditory and visual stimuli, like the McGurk effect, differently. Nine syllable pairs were presented to 10 native English speakers (5 music performance majors and 5 visual arts majors between the ages of 18 and 28 years) in a four-forced-choice response paradigm. Data from event-related potentials were recorded for each participant. Results demonstrate that there are differences in the electrophysiological responses to viewing the mismatched syllable pairs. The /ga/ phoneme in the music performance group produced more differences while the /da/ phoneme produced more differences in the visual arts group. The McGurk effect is processed differently in the music performance majors and the visual arts majors; processing begins in the earliest latency epoch in the visual arts group but in the late latency epoch in the music performance group. These results imply that the music performance group has a more complex decoding system than the visual arts group. It also may suggest that the visual arts group is better able to integrate the visual and auditory information to resolve the conflict when mismatched signals are presented.

Positive affect is generally associated with improvements in cognitive abilities; however, few studies have addressed positive affect and its relation to specific cognitive control processes. Previous research suggests positive affect conditions are more flexible/distractible states, suggesting cognitive control processes are perhaps decreased in context maintenance and increased in conflict detection/resolution. To measure the cognitive control processes, specific components of the scalp-recorded event-related potentials (ERPs) called the cue slow wave (context maintenance), the N450 (conflict detection), and conflict SP (conflict resolution) were acquired in response to an affective single-trial, cued-Stroop task. Participants were presented with pleasant, neutral, and unpleasant images prior to Stroop instruction (i.e., respond to "color" or "word") and response. Participants had greater accuracy during the pleasant condition when given a longer delay for extra time to process the high conflict task, t(36) = 3.09, p = .004, 95% CI (0.07, 0.02) compared to the unpleasant condition. Additionally, the unpleasant condition resulted in greater context maintenance than pleasant (increased cue-related slow wave amplitude; t(40) = 2.38, p = .02). Unpleasant conditions were associated with greater conflict resolution processes (as measured by the conflict SP) with high conflict trials, t(40) = 2.55, p = .015; whereas pleasant did in congruent trials, t(40) = 2.707, p = .010. Findings suggest negative affective states increase participants' focus on the task in avoidance of the distracting unpleasant picture. Our findings lay the foundation for understanding the differences between state and trait affect on cognitive control processes.

Long-term declarative memory depends on pattern separation, which reduces the degree of overlap between similar representations, to maintain memory specificity, and on pattern completion, which occurs when a degraded cue is used to retrieve a previously stored memory. Previous studies aimed at evaluating the underlying neuronal substrates of these computational processes have used a mnemonic discrimination paradigm and fMRI to focus on the hippocampus, to the exclusion of cortical processing. We aim to investigate the influences extra-hippocampal processes have on pattern separation in the following two studies. Study 1. Computational models of pattern completion suggest it occurs cortically and results in generalized memories whereas pattern separation occurs in the hippocampus and results in memory specificity. It is unknown how the incongruity of these two neuronal processes is resolved. Many studies evaluating the neuronal correlates of pattern separation have used fMRI to evaluate activity in the hippocampus. The sluggish time resolution of fMRI and the restricted spatial focus leave room for considerable differences between pattern completion and pattern separation to go undetected. Here, we use encephalography (EEG) and an event-related potential (ERP) analysis to examine neuronal activity during pattern separation and pattern completion to investigate whether or not cortical processing is employed to resolve the discrepancy between these two neuronal processes. We largely did not observe differences between the ERPs associated with pattern separation and pattern completion. Failure to identify neuronal differences could result from the bulk of neuronal processing differentiating between the two processes occurring deeper in the brain than can be measured by ERPs. Study 2. Extrinsic rewards contingent on memory performance can boost memory and learning. However, the effects of extrinsic rewards on memory specificity, particularly in regards to the process of pattern separation, are not well understood. In this behavioral study, we evaluate how extrinsic rewards affect behavioral performance in a task that taxes pattern separation. Our data show that rewards given for participation at the time of encoding boost mnemonic discrimination between target-lure pairs while rewards given for memory performance at the time of retrieval do not. We hypothesize this is because pattern separation is an encoding dependent process. This boost in discriminability is only seen when the rewarded stimuli are blocked together in separate blocks from the non-rewarded stimuli. When the rewarded and non-rewarded stimuli are interspersed within blocks, discriminability does not significantly differ between the rewarded and non-rewarded trials. Overall, performance was better when rewards were contingent on performance than when rewards independent of performance, although this difference is eliminated when attention during encoding is controlled.

PURPOSE: This study examined the effect of different intensities of acute exercise on attention allocation to visual food cues, postexercise energy intake, and subjective measures of hunger in women. METHODS: This crossover study utilized treatment conditions that were randomized and counter-balanced. Fifty-two adult women, 18-29 years, were compared under three separate conditions: no exercise, 45 min of moderate-intensity exercise at 3.9 METs and 22.5 min of vigorous-intensity exercise at 7.8 METs. To measure attention allocation to visual food cues, participants were shown a passive viewing task consisting of a continual stream of pictures of food (high and low calorie) and nonfood stimuli while brain activity was monitored using an EEG. The late positive potential (LPP) component of the scalp-recorded event-related potential (ERP) was used for data analysis. Postexercise food intake was measured during an ad libitum snack offered at the end of each condition. Subjective ratings of appetite were measured before and immediately after each condition using a visual analog scale (VAS). RESULTS: No significant differences for LPP were found for the condition (no exercise, moderate exercise or vigorous exercise) by picture type (high calorie, low calorie or nonfood) interaction (P = 0.184). Total kcal intake did not differ among the different exercise conditions (P = 0.19). However, even though energy intake did not differ among exercise conditions, low-energy-dense foods were consumed at higher rates compared to high-energy-dense foods after the vigorous (P = 0.0005) and moderate exercise conditions (P = 0.02) compared to the nonexercise condition. Findings from the VAS indicate the moderate exercise session resulted in significantly higher ratings of hunger when compared to the nonexercise (P = 0.04) and vigorous exercise sessions (P = 0.0046). There was also a significant condition (no exercise, moderate exercise or vigorous exercise) by period (pre- or postexercise) interaction found in postexercise ratings of hunger (P = 0.018). The moderate exercise condition reported higher levels of hunger after exercise (P = 0.0002). In addition, findings from the VAS also indicated energy for the moderate exercise condition increased postexercise (P = 0.006) and was higher than either the nonexercise (P = 0.011) or the vigorous exercise conditions (P = 0.017). CONCLUSION: The results of this study demonstrate that an acute bout of moderate exercise may increase subjective hunger and overall energy without increasing the neural response to visual food cues or postexercise energy intake. Furthermore, it also shows that an acute bout of vigorous exercise did not alter neural response to visual food cues, hunger or energy intake postexercise.

This dissertation evaluated whether Visual Working Memory (VWM) is a distinct memory system or if it is an activated state of Visual Long Term Memory (VLTM). These two positions suggest different roles for VLTM representations in the performance of VWM. If VWM representations are an activated state of VLTM representations, it seems plausible that strong VLTM representations should facilitate VWM performance. However, if the two representations are actually distinct, it seems less likely that a facilitation interaction between VLTM and VWM representations should be observed. Five experiments were conducted in which participants learned a set of trained stimuli over two days of training. Participant performance with the trained stimuli was compared to performance with novel stimuli on a subsequent VWM change detection task to determine the plausibility of VLTM-VWM interactions. The first and second experiments revealed a LTM facilitation effect that could not be explained by priming, but the third experiment suggested that this facilitation effect was mediated by non-visual representations. The fourth and fifth experiments parceled out the contributions of non-visual memory representations, and failed to demonstrate any evidence of VLTM-VWM performance interactions. These results, in conjunction with other examples from the literature, all converged on the conclusion that VLTM-VWM facilitation interactions are relatively implausible. As such, it was concluded that VWM and VLTM representations are discreet.

A model proposed by Holroyd and Coles (2002) stating that error related negativity (ERN) is caused by a decrease in mesencephalic dopamine output to the ACC was tested. A group of individuals with Parkinson's disease (N = 16) and an age and education matched group free from neurological disorder (N = 16) completed a card guessing task where the magnitude of monetary penalties and rewards for incorrect and correct answers was varied by block. Individuals with Parkinson's disease were tested after an overnight washout from dopamingeric medications. The amplitude of the mid-frontal negativity elicited by feedback was analyzed with spatial and temporal principal components analyses. Dipole source analyses were also performed. Analyses revealed no significant differences in the mid-frontal negativity amplitude between the two groups. In addition, the magnitude of consequence and the validity of response had no significant effects on fERN amplitude although there was a trend for higher magnitude consequences to be associated with larger fERN amplitude. Dipole analyses indicated the source of the mid-frontal negativity fell into the cingulate, specifically the cingulate gyrus. The results suggest that the mid-frontal negativity elicited by feedback indicating an error was made remains intact in individuals with Parkinson's disease. This does not support predictions made by Holroyd and Coles' model in regard to this group unless disruptions to the system that produces the fERN do not occur until later stages in the disease. An additional finding was a late positive potential for the error trials which began approximately 450 milliseconds after feedback and continued throughout the epoch. The ramifications of this wave are discussed.

Both theoretical models and empirical evidence implicate the combined influences of high emotional reactivity and low emotional regulation to exacerbation in children's stuttering behavior (e.g., Conture, Walden, Arnold, Graham, Hartfiled, Karrass, 2006; Conture & Walden, 2012; Karrass et al., 2006). Attentional control is a key factor in both the development and implementation of emotional regulation (Bell & Calkins, 2012; Rueda, Posner, & Rothbart, 2004). The purpose of this study was to investigate attentional control along the distraction process in children who stutter using two event-related potential (ERP) experimental tasks: auditory-auditory distraction and visual search. Eight school-age children who stutter (CWS) and eight school-age children who do not stutter (CWNS) were recruited in this study. Using a Go/No Go paradigm, children in this study were asked to discriminate tone duration in the auditory-auditory distraction task and detect specific visual targets in the visual search task in both the auditory and visual tasks. Behavioral measures included reaction time (RT), hit rate (HR, accuracy) and false alarm (FA), while electrophysiological measures included the peak latency and mean amplitude of the mismatch negativity (MMN), P3a, N2pc and reorientation negativity (RON), and N2pc. Each ERP component reflects a specific stage along the distraction process: automatic scanning and change detection (MMN), involuntary orientation to deviants (P3a), attentional filtering (N2pc) and voluntary attentional reorientation (RON). The first three components are involved in the sensory/perceptual processing, while the last component is involved in the goal-directed processing (cognitive control for distraction compensation). These behavioral and ERP results were correlated with temperament data obtained from parent-report questionnaires. There were three main findings. First, CWS, but no CWNS, exhibited a P600 and increased peak latency of the late phase of RON (lRON). The P600 is elicited by violations in rule-governed sequences or the effect of encountering unexpected stimuli, while the lRON reflects evaluation of task-relevant information and motor preparation. The existence of P600 suggests that CWS return and re-evaluate deviants, perhaps due to reduced inhibitory control. As a result, CWS are delayed to start the attentional process reflected by lRON. Second, CWS exhibited a higher rate of false alarms in the auditory-auditory distraction task; this finding confirmed the notion of less efficiency in inhibitory control for CWS. Third, similar to previous research findings, our temperament data also revealed that CWS tended to exhibit relatively high negative affect in combination with relatively low effortful and attentional control, compared to their fluent peers. Taken together, present findings corroborate previous observations of relatively high emotional reactivity and relatively low efficiency in emotional regulation for CWS, including attentional and inhibitory control. Further, our results reveal that the low attentional control in CWS may result from less efficiency in the goal-directed processing for distraction compensation.

The current study evaluates the effectiveness of a Brain-Computer Interface (BCI) system that operates by detecting a P300 elicited by one of four randomly presented stimuli (i.e., YES, NO, PASS, END). Two groups of participants were tested. The first group included three ALS patients that varied in degree of disability, but all retained the ability to communicate; the second group included three Non-ALS controls. Each participant participated in ten experimental sessions during a period of approximately 6 weeks. Sessions were conducted either at the participant's home or in the lab. During each run the participant's task was to attend to one stimulus and disregard the other three. Stimuli were presented auditorily, visually, or in both modes. Additionally, on each run, the experimenter would either tell the participant which stimulus to focus on, or ask the participant a question and the participant would focus on the correct "YES/NO" answer to the question. Overall, for each participant, the ERPs elicited by the target stimuli could be discriminated from the non-target stimuli; however, less variability was observed in the Non-ALS group. Comparing across sessions, the within session variability was lower than across session variability. In addition, waveform morphology varied as a function of the presentation mode, but not in a similar pattern for each participant. Offline and simulated online classification algorithms conducted using step-wise discriminant analysis produced results suggesting the potential for online classification performance at levels acceptable for communication. Future investigations will begin to focus on testing online classification performance with real-time feedback, and continuing to examine stimulus properties to determine how to maximize P300 amplitude for individual users.

Word recognition is based on the complex interplay of bottom up processing of acoustic input and corresponding top-down processing based on linguistic redundancies (i.e., contextual cues). Friedrich and Kotz (2007) investigated the timeline of integrating top-down and bottom-up processes among young adults with normal hearing using sentences presented in quiet. As a follow-up study, also with young adults with normal hearing (Experiment 1 of this dissertation), we used sentences embedded in multi-talker background noise and found similar results to Friedrich and Kotz (2007); but, with the use of principal component analysis (PCA) unveiled additional effects of phonological and semantic integration of spoken sentences presented in background noise. These past studies provide evidence of the time course of bottom-up and top-down mechanisms among young adult listeners in quiet and in noise; however, it is unknown if a similar pattern would be present among older adult listeners, which was the primary goal of the dissertation. In Experiment 2, we aimed to elucidate the time-course, and behavioral and neural correlates of word recognition primed by speech-in-noise in older adults with near normal hearing (i.e., thresholds ≤ 25 dB-HL through 3000 Hz and minimal high frequency hearing loss). Older adults often report difficulty understanding speech in the presence of background noise. Degradation in peripheral and central auditory processing along with age-related cognitive decline has been hypothesized as reasons why older adults struggle in the presence of noise.