Due to the rapid growth of Internet technology, universities and higher educational institutions around the world are investing heavily in web-based learning systems to support their traditional teaching and to improve their students’ learning experience and performance. However, the success of an e-learning system depends on the understanding of certain antecedent factors that influence the students’ acceptance and usage of such e-learning systems. Previous research indicates that technology acceptance models and theories may not be applicable to all cultures as most of them have been developed in the context of developed countries and particularly in the U.S. So far little research has investigated the important role that social, cultural, organizational and individual factors may play in the use and adoption of the e-learning systems in the context of developing countries and more specifically there is almost absence of this type of research in Lebanon. This study aims to fill this gap by developing and testing an amalgamated conceptual framework based on Technology Acceptance Model (TAM) and other models from social psychology, such as Unified Theory of Acceptance and Use of Technology (UTAUT) and TAM2 that captures the salient factors influencing the user adoption and acceptance of web-based learning systems. This framework has been applied to the study of higher educational institutions in the context of developing as well as developed countries (e.g. Lebanon and UK). Additionally, the framework investigates the moderating effect of Hofstede’s four cultural dimensions at the individual level and a set of individual differences on the key determinants that affect the behavioural intention to use e-learning. A total of 1197 questionnaires were received from students who were using web-based learning systems at higher educational institutions in Lebanon and the UK with opposite scores on cultural dimensions. Confirmatory Factor Analysis (CFA) was used to perform reliability and validity checks, and Structural Equation Modeling (SEM) in conjunction with multi-group analysis method was used to test the hypothesized conceptual model. As hypothesized, the findings of this study revealed that perceived usefulness (PU), perceived ease of use (PEOU), subjective norms (SN), perceived quality of work Life (QWL), self-efficacy (SE) and facilitating conditions (FC) to be significant determinants of behavioural intentions and usage of e-learning system for the Lebanese and British students. QWL; the newly added variable; was found the most important factor in explaining the causal process in the model for both samples. Our findings proved that there are differences between Lebanese and British students in terms of PEOU, SE, SN, QWL, FC and AU; however no differences were detected in terms of PU and BI. The results of the MGA show that cultural dimensions as well as demographic factors had a partially moderated effect on user acceptance of e-learning. Overall, the proposed model achieves acceptable fit and explains for 68% of the British sample and 57% of the Lebanese sample of its variance which is higher than that of the original TAM. Our findings suggest that individual, social, cultural and organisational factors are important to consider in explaining students’ behavioural intention and usage of e-learning environments. The findings of this research contribute to the literature by validating and supporting the applicability of our extended TAM in the Lebanese and British contexts and provide several prominent implications to both theory and practice on the individual, organizational and societal levels.

Previous research has focused on developmental trends in parent-adolescent conflict without extensively describing individual differences in conflict. The current study tested child factors, parent factors, contextual factors, and adolescence-specific factors as concurrent correlates and longitudinal predictors of parent-adolescent conflict. Participants include 218 mother-child dyads, adolescents’ mean age (11years, 11months). Parent and adolescent data was collected during the summers following the adolescents’ 5th and 6th grade years. All four groups of variables were associated with parent-adolescent conflict. The child group of factors emerged as the most consistent group of variables concurrently and longitudinally.

In der Metakontrastmaskierung wird die Sichtbarkeit des ersten Stimulus (Target) durch das Auftreten eines zweiten Stimulus (Maske) reduziert. Zwei Maskierungsfunktionen (MF) treten hauptsächlich auf: Typ A, wenn die Sichtbarkeit mit ansteigender SOA zumimmt, und Typ-B, wenn die Sichtbarkeit in kurzer und langer SOA hoch ist und auf ein Minimum in mittlerer SOA abfällt. In fünf Studien wurde systematisch untersucht welchen Einfluss experimentelle Parameter auf das Auftreten der MF haben. Je länger die Maske im Verhältnis zum Target präsentiert wird, desto weiter verschiebt sich das Minimum der MF hin zu kürzerer SOA und desto mehr ähnelt sie einer Typ-A-MF (monoton ansteigend). Die Maskierung ist in kleinen Stimuli stärker als in großen Stimuli, sowohl im Zentrum als auch in der Peripherie. Bei beiden Stimulusgrößen findet bei der kürzesten SOA die stärkste Maskierung statt. MF unterscheiden sich nicht, wenn sich die Vorhersagbarkeit der Präsentationsorte der Stimuli unterscheidet. Scheinbewegungen werden in langen SOAs eher wahrgenommen als in kurzen SOAs. Darüber hinaus wurden inter-individuelle Unterschiede gefunden, die Einblicke in die Mechanismen erlauben, die in der Metakontrastmaskierung beteiligt sind. Einige Versuchspersonen zeigen eine Typ-A-MF und berichten Scheinbewegungen in der Abfolge der Stimuli wahrzunehmen, hauptsächlich in langen SOAs. Andere zeigen eine Typ-B-MF und berichten negative Nachbilder in Form des Tagets im Inneren der Maske wahrzunehmen, hauptsächlich in kurzen SOAs. Typ-A- und Typ-B-Versuchspersonen unterscheiden sich in ihrer Top-Down-Verarbeitung der Stimuli, nicht aber in ihrer Bottom-Up-Verarbeitung. Zwei Prozesse stellten sich heraus, die in der Verarbeitung der Metakontraststimuli beteiligt sein könnten. Nach der Integrations-Segregations-Theorie steht die getrennte (segregierte) Wahrnehmung zweier Stimuli, die Scheinbewegungen ermöglicht, mit dem Segregationsprozess in Zusammenhang. Dagegen steht die gleichzeitige (integrierte) Wahrnehmung zweier nacheinander folgender Stimuli mit dem Integrationsprozess in Zusammenhang. Da Prozess 1 stark mit einer Typ-A-MF verknüpft ist, einhergehend mit der Wahrnehmung von Scheinbewegungen, könnte dieser Prozess dem Segregationsprozess entsprechen. Da Prozess 2 stark mit einer Typ-B-MF verknüpft ist, einhergehend mit der Wahrnehmung negativer Nachbilder, könnte dieser Prozess dem Integrationsprozess entsprechen. Es wird angenommen, dass diese beiden Prozesse an der bewussten Wahrnehmung des Targets in der Metakontrastmaskierung beteiligt sind.

Les humains virtuels en interaction homme machine sont aujourd’hui établis comme un objet de recherche à part entière. Leurs comportements pensés pour différentes applications sont basés sur les routines d’interaction entre humains. Bien que les humains virtuels aient souvent un corps représenté graphiquement, les recherches actuelles souffrent de deux limitations majeures qui dégradent la crédibilité de l’expérience des utilisateurs : les comportements corporels modélisés manquent d’interactivité sociale et ne prennent pas en compte les différences interindividuelles. Les développements récents en Sciences Humaines promeuvent une approche plus intégrative avec en son cœur le rôle constitutif de l’interaction sociale. La position centrale et interdisciplinaire des humains virtuels dans ce nouvel agenda de recherche est particulièrement importante : ils sont à la fois une manière de mieux étudier les différents phénomènes d’interactions sociales (comme outil expérimental) et une solution potentielle à des défis sociétaux (comme applications). L’objectif principal de cette thèse est de combiner les apports et valoriser les synergies établies entre les sciences de l’informatique et les sciences humaines, afin d’appréhender le rôle modérateur des différences interindividuelles dans le contrôle et la régulation des interactions corporelles. L’objectif à plus long terme de cette contribution vise à développer des humains virtuels interactifs à l’interface de ces domaines, avec l’idée que les besoins des deux champs de recherches contraindraient de manière positive les propositions futures. Pour limiter le cadre de cette thèse, nous nous sommes concentrés sur les mouvements du corps (les aspects statiques du corps ou les autres modalités ne sont pas considérées), sur les mécanismes de couplages bas niveaux et le rôle modérateur des différences interindividuelles avec comme objectif de proposer des prototypes d’humains virtuels comme preuve de concept (plutôt que des logiciels fonctionnels complets) incluant des modèles d’interaction corporelle dyadique. Notre méthodologie peut être résumée en quatre étapes principales. Premièrement, les modèles et hypothèses liant les processus d’interaction sociale aux différences interindividuelles résultent d’une double revue de littérature en sciences de l’informatique et sciences humaines. Ces différences interindividuelles identifiées comme pertinentes apparaissant faiblement associées théoriquement, notre seconde étape consista à étudier leurs associations lors d’une étude à grande échelle. Troisièmement, les interactions corporelles ont été analysées dans deux études de cas qui présentent des intérêts applicatifs et expérimentaux. Dans les deux cas, des corpus multimodaux d’interactions corporelles dyadiques ont été collectés et associés à des mesures de différences interindividuelles. La phase finale fut de développer des prototypes d’humains virtuels inspirés par les analyses précédentes et basés sur les données collectées. Le modèle général portant sur la prise en compte des différences interindividuelles se révèle en accord avec les données collectées (questionnaires d’auto-évaluation) : les relations entre dispositions d’orientations pro-sociales, d’empathie et de régulation émotionnelle furent confirmées. Les deux études de cas validèrent partiellement les hypothèses initiales : certaines différences interindividuelles modulèrent les processus d’interaction corporelle. Ces études contribuent à la définition de modèles d’humains virtuels interactifs parcimonieux. La principale contribution critique de ces deux études de cas au rôle modérateur des différences interindividuelles dans le modèle proposé est la nécessité de prendre en considération le contexte de la tâche avant de définir les hypothèses. L’intégration de ces différences interindividuelles identifiées dans les études de cas aux modèles informatiques interactifs est incluse dans les directions de recherches futures. / In human computer interaction, virtual humans are now established as a specific object of research. They build on human to human interaction routines to serve various application goals. Although Virtual Humans (VH) have bodies, current researches suffer from two major limitations which impair the experienced credibility: modeled bodily behaviors lack of social interactivity and do not account for individual differences. Recent developments in human sciences call for a more integrative approach with at its heart the constitutive role of social interaction. Of particular importance is the central and interdisciplinary position of virtual humans in this new research agenda: they are both a way to better investigate the various socially interactive phenomena (VH as experimental tools) and potential solutions for societal challenges (VH as applications). The main goal of this PhD thesis is to contribute to both computer and human sciences by studying together bodily interaction and individual differences. Central to this study is the long term objective to develop interactive virtual humans at the interface of these domains, with the idea that requirements from both fields would constrain positively future propositions. To limit the scope of the thesis, we focused on body movements (not considering static bodily aspects or other modalities), low level coupling mechanisms and the moderating role of individual differences with the aim to propose proof of concept of virtual human prototypes (rather than complete functional software) embedding full body dyadic interaction models. Our research methodology can be summarized in four main steps. First, models and hypotheses linking social interaction processes and individual differences emerged from a review of the literature in both computer and human sciences. As the identified relevant individual differences appeared barely theoretically associated, our second step aimed at investigating their interrelatedness in a large scale study. Thirdly, bodily interactions were analyzed in two case studies which present application and experimental interests. In both cases, corpuses were collected with full body interacting dyads and individual differences measured. The final phase was to develop virtual human prototypes inspired by previous analyses and based on the collected data. The proposed general model of individual differences was shown to be consistent with real word data (collected by self-report questionnaires): dispositions in pro-social orientations, empathy and emotion regulation were closely related. The two case studies partially confirmed our initial hypotheses: various individual differences modulated the bodily interactive processes. These studies enabled the definition of parsimonious virtual human interactive models. The main critical contribution of the two case studies to the proposed model of individual differences is the clear necessity to take into consideration the task context before drawing any hypotheses. Future directions of research are proposed including an integration of individual differences identified in case studies.

O presente estudo teve como objetivo investigar a associação da trajetória e do nível de estabilização ao final da fase de estabilização no desempenho da fase de adaptação. Participaram do experimento cem sujeitos de ambos os sexos, entre 10 e 12 anos de idade. Os sujeitos realizaram uma tarefa seriada de rastreamento de sinais luminosos. O experimento constou de duas fases: estabilização (120 tentativas) e adaptação (40 tentativas). Para a fase de estabilização foi utilizada uma sequência de 5 estímulos (4-2-5-3-1) com intervalo de 800 ms entre os mesmos. Para a fase de adaptação foram alterados: o intervalo entre os estímulos (700 ms) e a ordem dos estímulos (4-2-5-1-3). As variáveis do estudo foram: a) nível de estabilização alcançado ao final da fase de estabilização, b) trajetória do desempenho individual na fase de estabilização, e c) trajetória do desempenho individual na fase de adaptação. As análises estatísticas constaram de: análise de variância não paramétrica de Friedman - para detectar as diferenças no desempenho entre os blocos de tentativas; análise de cluster - para agregar os sujeitos com desempenho semelhante tanto na fase de estabilização (final e trajetória) quanto de adaptação (trajetória); análise de correlação por meio do coeficiente de contingência - para analisar a relação entre o desempenho na adaptação e os níveis de estabilização (final e trajetória). A análise com todos os sujeitos indicou: a) melhora do desempenho a partir de 50 tentativas de prática e manutenção do novo nível de desempenho ao longo da fase de estabilização e b) com a modificação na tarefa o desempenho diminuiu, mas voltou aos mesmos patamares do final da estabilização após 30 tentativas. A partir da análise de cluster os participantes foram agrupados em 6 subgrupos para o nível de estabilização final (CO-C; 1AO; 1A-2AO; 2A-3AO; 3A; 4A-5A) e 2 subgrupos para as trajetórias ao longo da fase de estabilização (C-1A; 1A-5A). Os níveis de estabilização final e da trajetória ao longo da estabilização apresentaram-se associados ao desempenho da fase de adaptação. Mais especificamente, foi observado que o subgrupo com trajetórias apenas com respostas corretas ao longo da fase de estabilização manteve o mesmo nível de desempenho na fase de adaptação. No subgrupo com trajetórias com respostas antecipatórias ao longo da fase de estabilização, 60% dos sujeitos mantiveram o mesmo nível de desempenho na fase de adaptação e os demais apresentaram trajetórias com respostas predominantemente corretas. Além disso, considerando o nível de estabilização ao final da fase de estabilização, os resultados permitiram discutir que é necessário alcançar pelo menos três respostas antecipatórias na sequência para apresentar respostas antecipatórias na adaptação, pois os subgrupos com menos de 3RA na composição das suas sequências apresentaram apenas respostas corretas na adaptação. Com base nestes resultados, pode-se inferir que parte da heterogeneidade do desempenho apresentado na fase de adaptação esta associado às diferenças individuais, visto que sujeitos submetidos ao mesmo regime de prática apresentaram comportamentos díspares ao longo da fase de estabilização e adaptação / The present study aimed to investigate the association of the trajectory and the level stabilization at the end of the stabilization phase on the performance of the adaptation phase. A hundred subjects of both gender, between 10 and 12 years old, participated in the experiment. Subjects performed a serial tracking task light signals. The experiment consisted of two phases: stabilization (120 trials) and adaptation (40 trials). For the stabilization phase a 5 stimulus sequence (4-2-5-3-1) with an interval of 800 ms between them. For the adaptation phase were changed: the interval between stimulus (700 ms) and order of stimulus (4-2-5-1-3). The variables of the study were: a) stabilization level reached at the end of the stabilization phase, b) trajectory of individual performance in the stabilization phase. These variables were based on results in the stabilization phase. Statistical analyzes consisted of: non-parametric analysis of variance Friedman - to detect differences in performance between blocks of trials, cluster analysis - to aggregate the subjects with similar performance both in the stabilization phase (final and trajectory) and adaptation (trajectory); correlation analysis through contingency coefficient - to examine the relationship between performance in adaptation and the stabilization levels (final and trajectory). The analysis with all subjects showed: a) performance improvement from 50 trials of practice and maintain the new level of performance throughout the stabilization phase and b) with changes in the task performance decreased, but returned to the same levels as the end of the stabilization after 30 attempts. From the cluster analysis participants were grouped into 6 subgroups for final stabilization level (CO-C; 1AO; 1A-2AO; 3AO-2A, 3A, 4A, 5A), and 2 subgroups for trajectories along the stabilization phase (C-1A, 1A-5A). Final stabilization level and trajectory along the stabilization presented themselves associated with the performance in the adaptation phase. More specifically, it was observed that the subgroup trajectory with only correct answers along the stabilization phase showed no change in performance in adaptation phase. In the subgroup trajectories with only anticipatory answers along the stabilization phase, maintained the same level of performance in the adaptation phase and the others presented trajectories with correct answers. Moreover, considering the level of stabilization at the end of the stabilization phase, the results allowed to discuss that is needed to achieve at least three anticipatory responses in the sequence to display anticipatory responses in adaptation, because the subgroups under 3RA in the composition of their sequences showed only correct responses in adaptation. Based on these results, can be inferred that some of the heterogeneity of performance presented in the adaptation phase is associated with the individual differences, whereas subjects submitted to the same practice regimen showed disparate behaviors during the stabilization and adaptation phase

A presença de diferenças individuais no desempenho motor de crianças e jovens da mesma faixa etária é um aspecto relatado por grande parte da literatura. O presente estudo escolheu o modelo de capacidades perceptivo-motoras para explorar estas diferenças e focou na questão de níveis diferenciados de maturação do sistema nervoso central (SNC). Uma vez que a maioria dos estudos sobre capacidades perceptivo-motoras investiga adultos e não se conhece como o nível do SNC influencia a associação entre as capacidades e desempenho motor. Com isso, o presente estudo teve como objetivo investigar a associação entre as capacidades perceptivo-motoras e o desempenho de tarefas motoras em sujeitos de 7 e 13 anos de idade. A amostra refere-se aos sujeitos que fizeram parte do estudo de Crescimento e Desenvolvimento Motor Longitudinal Misto de Muzambinho-MG. Foram selecionados 110 sujeitos, contrabalanceados em termos de sexo e idade. As capacidades perceptivo-motoras analisadas foram a de coordenação multimembros (CM), timing coincidente (TC), tempo de reação (TR) e tempo de movimento (TM), por sua vez as tarefas motoras analisadas foram correr, rebater e receber. Para a análise da correlação foi utilizado o teste de Spearman, uma vez que não houve distribuição normal. Os resultados indicaram que o desempenho do correr se associou a CM tanto para os 7 anos (ρ=-0,33) quanto para 13 anos (ρ=-0,34). Por sua vez, o desempenho do receber se associou com a CM (ρ=0,41) e TR (ρ=-0,41) para os 7 anos, mas apenas com a CM (ρ=0,29) para os 13 anos. E o desempenho do rebater não se associou com nenhuma das capacidades perceptivo-motoras analisadas. Com base nestes resultados, pode-se inferir que o desempenho em tarefas motoras típicas da infância é associado as capacidades perceptivo-motoras, mas o nível maturacional do sistema nervoso central pode ser um aspecto que interfere nesta associação. Estes resultados permitem identificar um campo de investigação promissor para entender as diferenças individuais que ocorrem no desempenho de crianças e jovens / The presence of individual differences in motor performance of children and teenagers of the same age group is a reported aspect for much of the literature. This study chose the model of perceptual-motor abilities to explore these differences and focused on issue of different central nervous system development levels (CNS). Since most of the studies investigate perceptual-motor abilities in adults and it is not known how the CNS level affects the association between ability and motor performance. This study aimed to investigate the association between perceptual-motor abilities and performance of motor tasks in individuals of 7 and 13 years old. The sample refers to subjects who participated in the study of mixed longitudinal motor growth and development in the city of Muzambinho - Minas Gerais/Brazil. It was selected 110 individuals, balanced in terms of gender and age. The perceptual-motor abilities analysed were the multilimb coordination (MC), coincident timing (CT), reaction time (RT) and movement time (TM) in turn analysed motor tasks were running, batting and receiving. For the correlation analysis it was used the Spearman\'s test, since there were no normal distribution. The results related to the running performances were associated with MC for both 7 years old (p = -0.33) and for 13 years old (p = -0.34). In turn, the receiving performances were associated with the MC (p = 0.41) and RT (p = -0.41) for 7 years old, but only with the MC (p = 0.29) for the 13 year old. Moreover, the batting performances were not associated with any of the perceptual-motor abilities analysed. Based on these results, we can infer that the performance in typical motor tasks of childhood is associated with the perceptual-motor abilities, but the maturity level of the central nervous system can be an aspect that interferes in this association. These results identify a promising field of research to understand individual differences occurring in the performance of children and teenagers

Thesis advisor: Liane Young / Research in three parts used behavioral methods and fMRI to shed light on the nature of moral norms and situate them within a broader understanding of how people deploy cognition to navigate the social world. Results revealed that moral norms in two clusters: {1} “universal-rights norms” (i.e., values focused on universal rights to be unharmed and treated as an equal); and {2} “group-elevating norms” (i.e., loyalty, reciprocity, obedience to authority, and concern about purity) predicted prosocial and antisocial moral judgments, interpersonal orientations, and behaviors through cognitive mechanisms including representations of causation and theory of mind (ToM). Five studies reported in Part 1 demonstrated that universal-rights norms were positively associated with prosociality (equal allocations and willingness to help); whereas group-elevating norms were robustly positively associated with antisocial interpersonal orientations (Machiavellianism and Social Dominance Orientation). Three studies in Part 2 showed that group-elevating norms predicted antisocial moral judgments including stigmatization and blame of victims. In contrast, universal-rights values were associated with sensitivity to victims’ suffering and blame of perpetrators. Experimentally manipulating moral focus off of victims and onto perpetrators reduced victim-blaming by reducing perceptions of victims as causal and increasing perceptions of victims as forced. Effects of group-elevating norms on victim-blaming were likewise mediated by perceptions of victim causality and forcedness, suggesting that intervening on focus constitutes one way to modulate effects of moral norms on moral judgments. Four studies in Part 3 examined moral diversity within the domain of fairness and revealed that group-elevating and universal-rights norms are differentially reflected in conceptions of fairness as reciprocity, charity, and impartiality. Reciprocity and charity warranted being clustered together as person-based fairness due to their shared motivational basis in consideration of the unique states of individuals and emotion, and their robust, overlapping recruitment of neural activity indicative of ToM in PC, VMPFC and DMPFC. Impartiality, which favored no particular individual, constituted person-blind fairness, due to its reliance on standard procedures rather than the unique states of individuals or emotion, and its failure to recruit PC, VMPFC and DMPFC. In terms of fairness and moral praiseworthiness, these three allocative processes cleaved along a different line. Person-blind impartiality was rated most fair and highly moral, and person-based fairness broke apart into: charity, deemed highly moral and labeled by the most empathic participants as fair; and reciprocity, which was lowest in fairness and moral praiseworthiness ratings and most esteemed by Machiavellian individuals and those who made a greater number of self-interested allocations. Enhanced activity in LTPJ for unfairness generally, and in judgment of reciprocity in particular, pointed to a role for ToM in moral evaluation of these different conceptions of fairness. Findings across Parts 1-3 have meta-ethical implications. Reduced endorsement of universal-rights norms and increased endorsement of group-elevating norms conferred risk for antisocial judgments, interpersonal orientations and behaviors, suggesting that universal-rights norms and group-elevating norms may differ in their capacity to produce moral outcomes. Results demonstrating a role for ToM and representations of causality in the effects of moral norms on moral judgments deserve focus in future research. It will be important to determine how deeply moral values imbed into individuals’ cognitive architecture, and the extent to which effects of moral values can be modulated via interventions on basic cognition. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.

Chez l'homme, la voix facilite les interactions sociales par la transmission d’informations sur l'identité de la personne, ses émotions ou sa personnalité. En particulier, l'identité du locuteur peut être automatiquement extraite même lorsque le message et l'état émotionnel varient, ce qui suggère des mécanismes cognitifs et cérébraux partiellement dissociables pour ces processus. Cependant, la reconnaissance d'une voix familière ou la discrimination entre deux locuteurs sont, pour certains sujets, non seulement non-automatiques, mais même impossibles. Ce déficit, lorsqu'il se manifeste dès la naissance, est appelé phonagnosie du développement et constitue la contrepartie auditive de la prosopagnosie (déficit de reconnaissance des visages). Dans le domaine visuel, il a été proposé que les sujets affectés par la prosopagnosie du développement représentent des cas extrêmes dans la distribution des capacités de reconnaissance de visages. A l’inverse, des "super-reconnaisseurs" des visages se situaient à l’opposé de cette distribution.Comme la distribution des capacités de reconnaissance de la voix dans la population générale était encore inconnue, le premier objectif de cette thèse a été d'en étudier les différences individuelles au moyen d'un court test - le Glasgow Voice Memory Test (GVMT). Les résultats obtenus ont reflété une large variabilité interindividuelle dans les capacités de reconnaissance des voix: parmi une cohorte de 1120 sujets, il y avait à la fois des sujets avec des performances significativement en dessous de la moyenne (potentiels phonagnosiques) et des "super-reconnaisseurs" des voix. Cette variabilité individuelle comportementale semblerait se refléter au niveau cérébral, comme révélés par l'imagerie par résonance magnétique fonctionnelle (IRMf) : en fait, il a été montré précédemment qu'il existait une variabilité interindividuelle considérable dans le signal BOLD (blood-oxygen level dependent) lié à la voix dans les zones temporales de la voix (TVAs). Ces régions sont situées sur le bord supérieur des sulcus/gyrus temporal supérieur (STS/STG) et montrent une activation préférentielle pour les sons vocaux plutôt que non vocaux. Le deuxième objectif de ce travail fut de mieux caractériser le lien entre les mécanismes comportementaux et neuronaux sous-tendant la variabilité interindividuelle dans les processus de reconnaissance des voix. Pour cela, nous avons examiné comment la perception de la voix modulait la connectivité fonctionnelle entre les TVAs, constituant le "noyau" du réseau de perception de la voix, et les régions frontales également sensibles aux voix, constituant une extension de ce réseau. Les résultats ont montré qu'il y avait une connectivité fonctionnelle positive dans l'ensemble du réseau et que la connectivité fonctionnelle fronto-temporelle et fronto-frontale droite augmentait avec les scores obtenus lors du GVMT.Pour compléter ce travail, nous avons réalisé une autre étude IRMf en utilisant des analyses multivariées, afin de clarifier les corrélats neuronaux de la reconnaissance du locuteur mais aussi le lien entre sensibilité cérébrale à la voix et capacités de reconnaissance du locuteur. Pour cela, des sujets ayant des capacités de reconnaissance vocale hétérogènes ont été soumis à la fois à une tâche d'identification du locuteur et à une tâche d'écoute passive de sons vocaux et non vocaux. Les résultats ont confirmé que l’identification du locuteur s’effectuait via un réseau étendu de régions, incluant les TVAs mais aussi des régions frontales. De plus, nous avons observé que le score de classification voix/non-voix dans le STS droit permettait de prédire les capacités d'identification des locuteurs.Dans l'ensemble, ces résultats suggèrent que les capacités de reconnaissance vocale varient considérablement d'un individu à l'autre et que cette variabilité pourrait être le reflet de profils d’activité cérébrale différents au sein du réseau de la perception de la voix. / In humans, voice conveys heterogeneous information such as speaker’s identity, which can be automatically extracted even when language content and emotional state vary. We hypothesized that the ability to recognize a speaker considerably varied across the population, as previously observed for face recognition. To test this hypothesis, a short voice recognition test was delivered to 1120 subjects in order to observe how voice recognition abilities were distributed in the general population. Since it has been previously observed that there exists a considerable inter-individual variability in voice-elicited activity in temporal voice areas (TVAs), regions along the superior temporal sulcus/gyrus (STS/STG) that show preferentially activation for voices than other sounds, the second aim of this work was then to better characterize the link between the behavioral and neural mechanisms underlying inter-individual variability in voice recognition processes through functional magnetic resonance imaging (fMRI). The results of a first fMRI study showed that functional connectivity between frontal and temporal voice sensitive regions increased with voice recognition scores obtained at a voice recognition test. Another fMRI study showed that speaker’s identity was treated in an extended network of regions, including TVAs but also frontal regions and that voice/non-voice classification accuracy in right STS increased with speaker identification abilities. Altogether, these results suggest that voice recognition abilities considerably vary across subjects and that this variability can be mirrored by different neural profiles within the voice perception network.

Studies have shown that human infants can integrate the multisensory attributes of their world and, thus, have coherent perceptual experiences. Multisensory attributes can either specify non-arbitrary (e.g., amodal stimulus/event properties and typical relations) or arbitrary properties (e.g., visuospatial height and pitch). The goal of the current study was to expand on Walker et al.'s (2010) finding that 4-month-old infants looked longer at rising/falling objects when accompanied by rising/falling pitch than when accompanied by falling/rising pitch. We did so by conducting two experiments. In Experiment 1, our procedure matched Walker et al.'s (2010) single screen presentation while in Experiment 2 we used a multisensory paired-preference procedure. Additionally, we examined infants' responsiveness to these synesthetic-like events at multiple ages throughout development (four, six, and 12 months of age). ... In sum, our findings indicate that the ability to match changing visuospatial height with rising/falling pitch does not emerge until the end of the first year of life and throw into doubt Walker et al.'s (2010) claim that 4-month-old infants perceive audiovisual synesthetic relations in a manner similar to adults. / by Nicholas Minar. / Thesis (M.A.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Our everyday world consists of people and objects that are usually specified by dynamic and concurrent auditory and visual attributes, which is known to increase perceptual salience and, therefore, facilitate learning and discrimination in infancy. Interestingly, early experience with faces and vocalizations has two seemingly opposite effects during the first year of life, 1) it enables infants to gradually acquire perceptual expertise for the faces and vocalizations of their own race and, 2) it narrows their ability to discriminate the faces of other-race faces (Kelly et al., 2007). It is not known whether multisensory redundancy might help older infants overcome the other-race effect reported in previous studies. The current project investigated infant discrimination of dynamic and vocalizing other-race faces in younger and older infants using habituation and eye-tracking methodologies. Experiment 1 examined 4-6 and 10-12-month-old infants' ability to discriminate either a native or non-native face articulating the syllable /a/. Results showed that both the 4-6- and the 10-12-month-olds successfully discriminated the faces,regardless of whether they were same- or other-race faces. Experiment 2 investigated the contribution of auditory speech cues by repeating Experiment 1 but in silence. Results showed that only the 10-12-month-olds tested with native-race faces successfully discriminated them. Experiment 3 investigated whether it was speech per se or sound in general that facilitated discrimination of the other-race faces in Experiment 1 by presenting a synchronous, computer-generated "boing" sound instead of audible speech cues. Results indicated that the 4-6-month olds discriminated both types of faces but that 10-12-month-olds only discriminated own-race faces. These results indicate that auditory cues, along with dynamic visual cues, can help infants overcome the effects of previously reported narrowing and facilitate discrimination of other-race static, silent faces. Critically, our results show that older infants can overcome the other race-effect when dynamic faces are accompanied by speech but not when they are accompanied by non- speech cues. Overall, a generalized auditory facilitation effect was found as a result of multisensory speech. Moreover, our findings suggest that infants' ability to process other- race faces following perceptual narrowing is more plastic than previously thought. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection