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This dissertation examines the impact of stimulus and response similarity on response selection. Traditional models of response selection invoke a central processor that operates like a look-up table by matching the perceptually classified stimulus (e.g., green square) to the specified response (e.g., right button press). The look-up property of response selection affords the system the ability to map any stimulus onto any response, even if that stimulus-response has never been paired before. Under such an approach, the degree of perceptual similarity or dissimilarity that exists among stimuli in the environment should have little effect on central operations, the similarity or dissimilarity of the motor response executed in response to a stimulus should not influence response selection, and no interaction between stimulus and response features is permitted, given that stimulus features affect the encoding process, and response features affect the output process, but not response selection itself. Eight studies examine the influence of stimulus and response similarity during response selection. The first two experiments establish the interaction across different task demands between stimulus and response similarity. The interaction was not the result of perceptual difficulty (Experiment 3) and was extended to a new set of stimuli (Experiment 4). A consequence of the design in Experiments 1 - 4 was that response condition was confounded with response configuration. In one of the response conditions the target location had three competitors on one side of it compared to the other condition where the target had one competitor on one side and two others on the other side. Experiments 5 and 6 examined the separate roles that response configuration and response metrics had on the interaction between stimulus and response similarity. The mechanism that produced the interaction was the result of competition between partially activated stimulus-response alternatives. Experiments 7 and 8 further explored the role of competition during response selection by turning to traditional response selection methodologies that introduce competition through either the presentation of irrelevant stimulus information or through presenting the stimulus along an irrelevant spatial dimension. These data have broad implications for models of RS. To account for the ability to pair any stimulus modality with any response modality dominant accounts of RS assume that central operations are performed by a generic set of processes that operate over representations that are stripped of metric information (amodal representations). Response selection works as a look-up table that receives a categorized stimulus as an input and returns an abstract response code as output. This type of model cannot produce an interaction between stimulus and response similarity and thus, the present data provide a serious challenge to these types of models. Finally, the data provide evidence that the metric relationship between stimuli and response matter and influence response selection. The co-activation of stimulus-response alternatives are at a level of representation that includes both stimulus and response properties. A framework is presented that captures key aspects of the data.

abstract: Political party identification has an immense influence on shaping individual attitudes and processes of reasoning to the point where otherwise knowledgeable people endorse political conspiracies that support one's political in-group and simultaneously disparage an out-group. Although recent research has explored this tendency among partisans, less is known about how Independents respond in comparison. Previous research fails to identify the Independent as a unique type of voter, but rather categorizes this group as ostensibly partisan, not a separate phenomenon to investigate. However, most Independents purport neutrality and, by recent polls, are becoming a substantial body worthy of concerted focus. Many questions arise about who Independents really are. For example, do all who identify as Independent behave in a similar manner? Are Independents ideologically different than what is represented by a partisan label? Is the Independent category a broad term for something entirely misunderstood? A thorough investigation into the greater dynamics of the political environment in the United States is an enormous undertaking, requiring a robust interdisciplinary approach beyond the focus and intent of this study. Therefore, this study begins the journey toward understanding these phenomena; do Independents, as a whole, uniformly respond to statements about political conspiracy theories? To explore these possibilities, explicit responses are bypassed to evaluate the implicit appeal of political conspiracy theories. An action dynamics (mouse-tracking) approach, a data rich method that records the response process, demonstrates Independents are not in fact a homogeneous group, but rather seem to fall into two groups: non-partisan leaning and partisan leaning. The analysis exposes that relative to the baseline and control stimuli: (1) Non-leaning Independents reveal an increased susceptibility to implicitly endorse bi-partisan directed conspiracy theories when compared to leaners. (2) Republican-leaners demonstrate a stronger susceptibility to endorse right-wing aligned conspiracy theories (against Barack Obama), similar to Republican partisans. (3) Democrat-leaners, unlike Democrat partisans, do not demonstrate any particular susceptibility to implicitly endorse either right/left-wing aligned conspiracy theories (against Barack Obama or George W. Bush). Drawing from major theories from social, political, and cognitive psychology will contribute to an understanding of these phenomena. Concluding remarks include study limitations and future directions. / Dissertation/Thesis / Masters Thesis Psychology 2017

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Most models of auditory word recognition describe the activation of lexical items in a continuous and graded manner. Much evidence in favor of these models comes from the visual-world paradigm, using either eye fixations or computer cursor trajectories as dependent measures. In particular, Spivey, Grosjean and Knoblich (2005) relied on their observation of unimodality in the distribution of cursor trajectories to argue in favor of a single cognitive process consistent with a continuous model of lexical activation. The present study addresses two questions: (1) whether the logic of inferring the number of cognitive processes from distributional analyses can be extended to a different dependent variable – reaction times, and (2) how robust the distribution of cursor trajectories is to changes in cursor speed (mouse gain). In Experiment 1, eye movements and reaction times were recorded in a visual-world paradigm and reaction times were modeled using ex-Gaussian curve-fitting. Participants responded slower to trials with a phonological competitor presented alongside the target than to trials with a control image presented alongside the target. Crucially, this difference was manifested as a shifting of the distribution rather than as a skewing of the distribution and lends additional support for a continuous model of lexical activation. Experiment 2 measured eye and mouse movements concurrently in a similar visual-world task to investigate the relationship between these two dependent measures at the level of the individual trial. In addition, Experiment 2 manipulated the speed of the cursor (mouse gain) between subjects. The low mouse gain served to reduce the effect of phonological competition. Moreover, the shape of the distribution of cursor trajectories across phonological competitor and control conditions was indistinct with low mouse gain, while the shape of the distributions across the two conditions differed with high mouse gain. This effect of mouse gain shows that the distribution of cursor trajectories is not robust to changes in mouse gain. Moreover, it raises questions about the strength of the linking hypothesis necessary to interpret the distribution of cursor trajectories.

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Conduire un véhicule dans le brouillard requiert d’intégrer de l’information visuelle bruitée avec des attentes sur la scène routière pour rechercher des indices visuels importants pour la navigation. Les tâches d’identification et de recherche visuelle peuvent être vues comme des processus de prise de décision où l’information est accumulée et où des attentes sur l’objet et son contexte sont intégrées. L’accumulation d’information est souvent modélisée comme un processus passif. Cette thèse vise à mettre en avant des mécanismes actifs, intégrant les attentes sur la cible (sur sa position, sur son identité) et de l’information sensorielle dégradée (e.g., brouillard). Nous avons employé le paradigme de mouse-tracking, permettant d’inférer des aspects dynamiques du processus de prise de décision via les mouvements de la souris d’ordinateur. L’Étude 1 évalue l’effet du contexte dans la catégorisation de cible et suggère un compromis entre rapidité et exactitude de l’accumulation d’évidence pouvant être vu comme influençant activement la décision. Mais elle n’évalue pas directement la collecte active d’évidence. Les Études 2 et 3 incluent la mesure de la détection et vérification de la cible via les mouvement des yeux lors de la recherche visuelle dans des scènes dégradée. Les attentes sur la localisation (Étude 2) et sur l’identité de la cible (Étude 3) sont manipulées. Ces études éclairent les contributions de la détection et de la vérification dans l’accumulation d’évidence pour la réponse cible absente et cible présente. Pour conclure, nous proposons une ébauche de modèle de prise de décision intégrant une dynamique entre accumulation d’évidence et système oculomoteur. / Driving a vehicle in the fog requires the integration of noisy visual information with expectations about the visual road scene, in order to search for visual clues important for navigating. The visual search and identification of relevant objects can be seen as decision-making processes where sensory information is accumulated and where the expectations about the target object and its context are integrated. The accumulation of information is often modelled as a passive process. This thesis focuses on the contribution of active mechanisms integrating expectations about the target (its identity, its location) with degraded sensory information (with fog or artificial noise). We used the mouse-tracking paradigm, allowing to infer dynamic aspects of the decision-making process through a computer mouse movements. Study 1 evaluates the effect of the context for categorizing a target and suggests a trade-off between the speed and accuracy of the evidence accumulation process which can be seen as actively influencing the decision. But this study cannot directly evaluate the active collection of evidence. In Studies 2 and 3, target detection and verification are directly measured through eye movements during visual search tasks in visually degraded scenes. We manipulated the expectations about the location (Study 2) and the target’s identity (Study 3). These studies emphasize the contributions of the detection and verification processes in the accumulation of evidence toward the target present and target absent responses. In conclusion, we propose the draft of a decision-making model which integrates the dynamics between the accumulation of evidence, and the oculomotor system.