<p>For over 50 years, the Satisfaction of Search effect, and more recently known as the Subsequent Search Miss (SSM) effect, has plagued the field of radiology. Defined as a decrease in additional target accuracy after detecting a prior target in a visual search, SSM errors are known to underlie both real-world search errors (e.g., a radiologist is more likely to miss a tumor if a different tumor was previously detected) and more simplified, lab-based search errors (e.g., an observer is more likely to miss a target ‘T’ if a different target ‘T’ was previously detected). Unfortunately, little was known about this phenomenon’s cognitive underpinnings and SSM errors have proven difficult to eliminate. However, more recently, experimental research has provided evidence for three different theories of SSM errors: the Satisfaction account, the Perceptual Set account, and the Resource Depletion account. A series of studies examined performance in a multiple-target visual search and aimed to provide support for the Resource Depletion account—a first target consumes cognitive resources leaving less available to process additional targets. </p><p>To assess a potential mechanism underlying SSM errors, eye movements were recorded in a multiple-target visual search and were used to explore whether a first target may result in an immediate decrease in second-target accuracy, which is known as an attentional blink. To determine whether other known attentional distractions amplified the effects of finding a first target has on second-target detection, distractors within the immediate vicinity of the targets (i.e., clutter) were measured and compared to accuracy for a second target. To better understand which characteristics of attention were impacted by detecting a first target, individual differences within four characteristics of attention were compared to second-target misses in a multiple-target visual search. </p><p>The results demonstrated that an attentional blink underlies SSM errors with a decrease in second-target accuracy from 135ms-405ms after detection or re-fixating a first target. The effects of clutter were exacerbated after finding a first target causing a greater decrease in second-target accuracy as clutter increased around a second-target. The attentional characteristics of modulation and vigilance were correlated with second- target misses and suggest that worse attentional modulation and vigilance are predictive of more second-target misses. Taken together, these result are used as the foundation to support a new theory of SSM errors, the Flux Capacitor theory. The Flux Capacitor theory predicts that once a target is found, it is maintained as an attentional template in working memory, which consumes attentional resources that could otherwise be used to detect additional targets. This theory not only proposes why attentional resources are consumed by a first target, but encompasses the research in support of all three SSM theories in an effort to establish a grand, unified theory of SSM errors.</p> / Dissertation

There are at least two types of response to stimuli: an automatic response that happens before conscious thought (a Type 1 response) and a deliberative, intentional response (a Type 2 response). These responses are related to behavior associated with the affective loading of the stimulus presented. Prior research has shown, for example, that a Type 1 tendency to spend more time looking at fear-provoking stimuli is associated with higher levels of general anxiety, while a Type 2 tendency to spend more time looking away from happy faces is associated with higher levels of depressive symptoms. Some stimuli categories elicit mixed responses, indicated by discrepant Type 1 and Type 2 responses. For example, alcoholics in recovery tend to look toward alcohol-themed pictures in the first 200 milliseconds, then look away. This suggests that alcoholics in recovery have an automatic draw to alcohol that is overridden by the conscious application of a cognitive schema to avoid alcohol. Sexual response studies to date have measured Type 1 and Type 2 responses separately; however, no study has yet measured both types of response within the same person. This study was the first to examine both Type 1 and Type 2 responses to erotic stimuli within the same individual as a test of within-individual variation of attentional responses to sexual stimuli. Results do not support a connection between either attentional bias or conflicting Type 1 and Type 2 responses and sexual desire or distress. Implications of these non-findings are discussed in theoretical and methodological contexts, and future research is suggested.

Objectives: Due to a number of conceptual and methodological limitations, existing research has provided only equivocal evidence that deficits/biases in attentional control (AC) are causally implicated in depressive rumination and/or that Cognitive Control Training (CCT) can be used to remediate such vulnerabilities. By using a well-validated training task and ensuring adequate training exposure, the current study aimed to examine the hypothesis that daily CCT would reduce rumination and improve mood among participants with elevated ruminative disposition. Method: Using a multiple baseline design (MBD), eight high-ruminating university participants rated their daily levels of rumination and mood before and after the randomly-determined introduction of daily CCT, designed to enhance their level of AC. Daily ratings were compared before and after the introduction of CCT, using systematic visual analysis and randomisation tests for significance at the group level. Results: No evidence was found to support the hypothesis that daily CCT reduces rumination and/or improve mood. While participants improved in their performance within the CCT across the training period, there was no evidence of near- or far-transfer, visual analysis revealed no impact of the introduction of daily training, and all group-level analyses were non-significant (p ≥ .05). Conclusion: Despite addressing a number of conceptual/methodological concerns, the current study provides no further support for AC theories of rumination or the use of CCT-based treatments for depression. Such conclusions must be interpreted in light of other methodological limitations, however, including the use of a non-clinical sample and the use of MBD to detect delayed treatment effects.

The suggestion that bilinguals show enhanced cognitive control compared to monolinguals in certain aspects of executive function has received much contention. While this has been explained as a result of the extensive training in bilinguals having to manage the conflict that arises from their concurrently active langauges, others have argued that the superiority in executive control is attenuated when background variables such as immigration status, education and general cognitive ability is taken into account. This thesis was motivated by the general question: How is executive control influenced by differing bilingualism experiences? To this end, we compared attentional control performance in bilinguals and monolinguals on the Attention Network Test, the auditory Elevator task (Test of Everyday Attention), and the number Stroop task. The main aim of the thesis was to examine the role of two bilingualism factors: (i) interactional context (defined in the Adaptive Control Hypothesis, Green & Abutalebi, 2013), which pertains to how bilinguals switch between their languages, and (ii) linguistic distance, which refers to the extent of similarity between the bilingual's languages. The comparison between Edinburgh monolinguals, Edinburgh late bilinguals, Edinburgh early bilinguals, and Singapore early bilinguals as differentiated by their interactional context revealed better performance in bilinguals on two specific test components. Singapore bilinguals, who came from a dual-language and dense code-switching context, showed enhanced conflict resolution on the Attention Network Test, whilst Edinburgh late bilinguals, who were from a single-language context, were better on the Elevator reversal subtest tapping on attentional switching. The results thus suggest differential effects of interactional context on attentional control. We further compared task performance of bilinguals with related or distant L1-L2 combinations as defined by the linguistic and orthography overlap between their two languages. The data did not support a role of linguistic distance on attentional control. Edinburgh bilinguals studying an Indo-European language performed similarly to those studying the non Indo-European languages of Chinese and Japanese. In Singapore bilinguals, English-Chinese bilinguals also did not differ from English-Malay bilinguals on any of the test components. We supplemented the investigation by further examining if the factors of test-order and age could impact on how differences between monolinguals and bilinguals are exhibited. Our results suggest that monolinguals may show an improvement in attentional control after relatively short periods of engagement in experimental tasks, whilst bilinguals did not receive this boost. Test order may therefore partly explain the inconsistencies in literature regarding the claimed bilingual advantage. The comparison between older and younger adults also implied an effect of age. In young adults, bilinguals outperformed monolinguals on the Elevator reversal subtest of auditory switching, whereas the advantage shown in older bilinguals was on visual attentional orienting. The results across the various themes are reviewed and discussed with relevance to the current standing in the field, and suggestions for future research directions are put forth.

Emotional eating behavior is characterized by eating a large amount of calorie dense sweet and/or high fat foods in an attempt to control, cope with, or avoid negative emotions. Numerous factors are likely to contribute to emotional eating behavior, including attentional factors, such as rumination and avoidance coping. Rumination based emotional eating (attention focused on negative stimuli while mindlessly eating) is often utilized to improve mood while dwelling on problems. However, for those inclined to escape/avoid troublesome thoughts, another type of emotional-eating pattern may be used. By focusing attention on food, emotional eating is believed to distract individuals from negative emotions. However, along with avoiding distressing thoughts, a strong attentional focus on food may also lead to diminished attention resources and subsequently the missing of self-preserving thoughts (e.g. dietary restraint or satiety). While Denke & Lamm (2015) explored neural mechanisms underlying rumination based emotional eating, to the best of our knowledge, no one has investigated the neural correlates underlying avoidance based emotional eating. This study examined how attentional sub-processes contribute to emotional eating behavior among female participants in a task designed to explore escape type emotional-eating behavior. Dense-array EEG and a version of the canonical attentional blink task were used to ascertain the neural correlates underlying the attentional sub-processes and how attentional activation differs for emotional eaters vs. non-emotional eaters. Findings do not support the food fixation escape type emotional-eater hypothesis, but do indicate task validity.

Emotional Stroop task results have been shown to be inconsistent throughout the literature due to a multitude of factors including both stimulus and population factors. There are also several theories to explain the emotional Stroop effects, including the attentional control theory (Eysenck et al., 2007). This theory states that anxiety consumes attentional and memory resources, resulting in impairment in executive functions, and thus cognitive performance is lowered. Recently, Owens et al. (2014) reported that the effects of anxiety on cognitive performance might be moderated by working memory capacity (WMC). The present study explored whether Owens et al.'s (2014) paradigm fit the Stroop data. It also explored the role that WMC had in recognition memory for emotional and neutral words. Processing efficiency during the Stroop task and anxiety was expected to show a positive relationship for High WMC and a negative relationship for Low WMC. Furthermore, memory for emotional words were expected to be better for Low WMC due to longer processing times for emotional words. The results showed that WMC did not improve the model for both the emotional Stroop and the surprise recognition memory task, thereby contradicting Owens et al.'s (2014) proposed paradigm. Furthermore, an increase of anxiety scores showed a decrease in memory for emotional words but only for Low WMC.

There is more information in the visual environment than we can process at a given time, and as a result selective attention mechanisms have developed that allow us to focus on information that is relevant to us while ignoring information that is not. It is often assumed that our ability to overcome distraction by irrelevant information in the environment requires conscious, effortful processing, and traditional theories of selective attention have emphasized the role of an observer's explicit intentions in driving this control. At the same time, effortful control on the basis of explicit processes may be maladaptive when the behaviors to be executed are complex and dynamic, as is the case with many behaviors that we carry out on a daily basis. One way to increase the efficiency of this process would be to store information regarding past experiences with a distracting stimulus, and use this information to control distraction upon future encounters with that particular stimulus. The focus of the current thesis was to examine such a "learned control" view of distraction, where experience with particular stimuli is the critical factor determining whether or not a salient stimulus will capture attention and distract us in a given situation. In Chapters 2 through 4, I established a role for task-specific learning in the ability of observers to overcome attentional capture, showing that experience with particular attributes of distracting stimuli and the context in which the task was performed led to a predictable decrease in capture. In Chapter 5, I examined the neural basis of these learned control effects, and the results suggest that neocortical and medial temporal lobe learning mechanisms both contribute to the experience-dependent modulation of attentional capture observed in Chapters 2-4. Based on these results, a model of attentional capture was proposed in which experience with particular stimulus attributes and their context critically determine the ability of salient, task-irrelevant information to capture attention and cause distraction. I conclude that although explicit processes may play some role in this process under some conditions, much of our ability to overcome distraction results directly from past experience with the visual world.

The ability to navigate with limited vision is a skill that is often employed in our daily lives. Navigating without vision to a remembered target has previously been studied. However, not much is known about the attention required to perform blind navigation. We examined the effect of aging and presence of obstacles on the attentional demands of blind navigation. We evaluated reaction time, navigation errors and average walking speed in an 8 meter walking path, with or without obstacles, in the absence of vision. Results showed that older participants had increased reaction time and increased linear distance travelled as opposed to young participants, that obstacles increased reaction time and decreased average walking speed in all participants, and that emitting the reaction time stimulus early in the trial increased the linear distance travelled. Interpretation of the results suggests that aging and presence of obstacles augments the attentional demands of blind navigation.

The research focuses on the role of top-down influences on selective attention across the attentional visual field. The attentional visual field is the subset of the visual field in which attentional processes take place. The size of the attentional visual field is relatively large compared to the areas considered by most empirical studies of visual attention to date. Three possible forms of top-down influence are examined: 1) the expectation of the size of the area in which the target is likely to occur; 2) the expectation of the direction in which the target is likely to occur; and 3) existing unconscious bias in the spatial distribution of attention. Results from Experiment 1 suggest that participants modify the size of the attended area according to their expectation of the location of the target. Experiment 2 demonstrates that focus of attention can be oriented toward the expected target direction. Experiment 3 reveals that, even when no conscious control is involved, the distribution of attention is biased toward certain areas. Theoretical considerations are discussed, including the introduction of a simple statistical model to assist in conceptualizing the modifications of the distribution of attention over the attentional visual field. Practical applications of the results are also discussed.

The research focuses on the role of top-down influences on selective attention across the attentional visual field. The attentional visual field is the subset of the visual field in which attentional processes take place. The size of the attentional visual field is relatively large compared to the areas considered by most empirical studies of visual attention to date. Three possible forms of top-down influence are examined: 1) the expectation of the size of the area in which the target is likely to occur; 2) the expectation of the direction in which the target is likely to occur; and 3) existing unconscious bias in the spatial distribution of attention. Results from Experiment 1 suggest that participants modify the size of the attended area according to their expectation of the location of the target. Experiment 2 demonstrates that focus of attention can be oriented toward the expected target direction. Experiment 3 reveals that, even when no conscious control is involved, the distribution of attention is biased toward certain areas. Theoretical considerations are discussed, including the introduction of a simple statistical model to assist in conceptualizing the modifications of the distribution of attention over the attentional visual field. Practical applications of the results are also discussed.