There is a clearly established division of functional processing between left and right hemispheres of the brain, with the pattern showing robust consistency across individuals. The finding of functional differences between the hemispheres of the brain raises two important questions: First, what mechanisms gave rise to the lateralized biases in processing function? Second, what are the consequences of functional asymmetry of cognitive processing in the human brain on our everyday behaviour? Examining the mechanisms that give rise to cerebral lateralization, Experiments 1 and 2 tested the assumption that there is a causal relationship in the degree and direction of lateralization between left- and right-hemisphere dominant tasks. In experiment 1, this relationship between left-hemisphere processing of speech sounds and right-hemisphere processing of emotional vocalizations was examined using dichotic listening tasks. An overall complementary pattern of lateralization was observed across participants, but no significant relationship was found for degree of lateralization of speech and emotional vocalization processing within individuals. These results support the view that functions in the left and right hemispheres are independently lateralized. In Experiment 2 we examined the relationship pattern in degree of lateralization between linguistic processing and melody recognition using dichotic-listening tasks. The expected left-hemisphere advantage was observed for the linguistic processing task, but the expected right-hemisphere advantage was not observed for the melody recognition task, precluding an informative assessment of complementarity between the two tasks. The division of processing between the two hemispheres of the brain has been shown to result in lateralized performance advantages and behavioural biases. Examining these consequences of lateralization, Experiments 3 through 6 explored the influence of lateral biases on everyday behaviour. Experiments 3 and 4 examined the influence of asymmetries in facial attractiveness on posing biases. Despite evidence suggesting that the right side of the face is found to be more attractive, professional modeling photographs examined in Experiment 3 revealed a leftward posing bias suggesting that asymmetries in facial attractiveness are not dominant in influencing posing behaviour, even when the purpose of the image is to highlight attractiveness. Experiment 4 controlled for image selection biases by examining posing behaviour directly and revealed a rightward posing bias when participants were asked to emphasize their attractiveness. Experiments 5 and 6 examined the influence of lateralized cognitive processing demands on seating preferences. Experiment 5 investigated the real-world seating patterns of theatre patrons during actual film screenings. It was found that, when processing expectations relied on right-hemisphere dominant processes, such as emotional, facial, or visuospatial processing, people were more likely to choose a seat to the right side of the room. Experiment 6 was designed to test two competing theories that have attempted to explain seating biases: one posits that expectation of processing demand drives the bias; the other posits that basic motor asymmetries drive the bias. Through naturalistic observation, I recorded classroom-seating choices of university students using photographs. When processing expectations relied on left-hemisphere dominant processes, such as linguistic processing, people were more likely to choose seats on the left side of the classroom; this finding contrasts the right side bias observed in theatre seating studies, providing evidence that expectation of processing demands influences the seating bias. Addressing the mechanisms that guide the evolution of lateralization, no support for the assumption of a causal relationship between complementary left-and right-lateralized cognitive functions was found. Additionally, examination of asymmetries in everyday behaviours such as seating and posing provide evidence that the lateralization of cognitive functions has a direct influence on human behaviour and interaction with the environment.

Purpose: The aim of this research was to examine the relationship between stuttering and bilingualism to hemispheric asymmetry for the processing and production of language. Methods: A total of 80 native speakers of German were recruited for the study, ranging in age from 15 to 58 years. Out of those 80 participants, 40 participants were also proficient speakers of English as a second language (L2). The participants were organised into four speaker groups (20 per group) according to language ability and speech status, consisting of monolinguals who stutter (MWS), monolinguals who do not stutter (MWNS), bilinguals who stutter (BWS), and bilinguals who do not stutter (BWNS). Each of the four groups comprised 12 males and 8 females. All participants completed a battery of behavioural assessments measuring functional cerebral hemispheric asymmetry during language processing and production. The behavioural tests included (1) a dichotic listening paradigm, (2) a visual hemifield paradigm, and (3) a dual-task paradigm. Results: Overall, the results showed no significant differences in language lateralisation between participant groups on the three behavioural tests. However group differences were identified in regard to executive functions on the visual hemifield and dual-task paradigms. Both bilingual groups showed significantly faster reaction times and fewer errors than the two monolingual groups on the visual hemifield paradigm. The bilingual groups also performed similarly on the dual-task paradigm, while the MWS group tended to show greater task disruption. No meaningful relationship was found between stuttering severity and the majority of results obtained for the test conditions. However, all four language modalities were found to correlate significantly with results obtained for the visual hemifield and dual-task paradigms, suggesting that performance on these tests increased with higher L2 proficiency. Conclusion: Although no differences in language lateralisation were found, it appears that bilingualism had a greater influence on functional cerebral hemispheric processing than stuttering. A prevailing finding was that bilingualism seems to be able to offset deficits in executive functioning associated with stuttering. Brain reserve and cognitive reserve are thought to have a close interrelationship with the executive control system. Cognitive reserve may have been reflected in the present study, resulting in a bilingual cognitive advantage. Hence, the results of the present study lend support to previous findings implicating the benefits of bilingualism.

The main focus of this investigation was to examine the automaticity of facial expression recognition through valence judgments in a modified photo-word Stroop paradigm. Positive and negative words were superimposed across male and female faces expressing positive (happy) and negative (angry, sad) emotions. Subjects categorized the valence of each stimulus. Gender biases in judgments of expressions (better recognition for male angry and female sad expressions) and the valence hypothesis of hemispheric advantages for emotions (left hemisphere: positive; right hemisphere: negative) were also examined. Four major findings emerged. First, the valence of expressions was processed automatically (robust interference effects). Second, male faces interfered with processing the valence of words. Third, no posers' gender biases were indicated. Finally, the emotionality of facial expressions and words was processed similarly by both hemispheres.

Over twenty years of research have examined the cognitive consequences of positive affect states, and suggested that positive affect leads to a broadening of cognition. However, this research has primarily examined positive affect that is low in approach motivational intensity (e.g. contentment). In my program of research, I have systematically examined positive affect that varies in approach motivational intensity, and found that positive affect high in approach motivation (e.g. desire) narrow cognition, whereas positive affect low in approach motivation broaden cognition. In this dissertation, I will review past models and present a motivational dimension model of affect that expands understanding of how affective states influence attentional and cognitive breadth. I then review a body of research that has varied the motivational intensity of positive and negative affect and found that affect of low motivational intensity broadens cognitive processes, whereas affect of high motivational intensity narrows cognitive processes. Furthermore, a bi-directional link exists between attentional narrowing and approach motivation, such that a narrowed attentional focus to appetitive stimuli causes greater approach motivation than a broadened attentional focus.

This experiment investigated lateralized hemispheric regulation of the autonomic nervous system (ANS) among high anxious and nonanxious university undergraduate men using a novel laboratory paradigm. Specifically, this three phase paradigm entailed the administration of a verbal fluency (left frontal) and nonverbal fluency (right frontal) task with or without the threat of a painful stimulus (cold pressor) to high anxious and nonanxious participants. Thus, the cerebrums are hypothesized to be engaged in a dual-task experience requiring the regulation of the ANS and concurrent performance on the verbal or the nonverbal fluency measure. Given the literature which supports relative right hemisphere activation among anxious individuals, it was hypothesized that high anxious men would (1) demonstrate greater physiological arousal to the cold pressor, (2) perform relatively worse on nonverbal fluency measures and demonstrate greater difficulty regulating cardiovascular functioning, and (3) demonstrate relatively lower nonverbal fluency scores and increased physiological arousal when presented with the nonverbal fluency task and cold pressor stimulus simultaneously. The results are evaluated using three perspectives: Heller's (1993) hypothesis, Kinsbourne's Functional Cerebral Distance principle, and lateralized regulation of the sympathetic and parasympathetic nervous system. The results only partially supported the right hemisphere activation hypothesis for anxious individuals, as many of the significant results were counter to hypotheses. Specifically, high anxious men demonstrated lower verbal fluency scores and greater heart rate during the combined stimulus of the cold pressor and verbal fluency task. The data are supportive of relative anterior deactivation among high anxious men. The discussion extends the findings to present questions regarding cerebral regulation of the ANS. Future experiments which may add to the current understanding of lateralized regulation of the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) are suggested. / Ph. D.

No description available.

Sixty right-handed men, half classified as anxious without depressive symptoms, the other half as nonanxious, participated in a tachistoscopic study of the influence of anxiety without depression on hemispheric processing of Ekman and Friesen's (1976) happy, angry, and neutral emotional faces. Results were counter to hypotheses, where anxious subjects' reaction times to affective valences were slower than nonanxious subjects. Additionally, anxious subjects failed to demonstrate a negative affective bias for neutral stimuli. Results are discussed in terms of arousal theory, where anxious subjects may be considered overaroused for the tachistoscopic task, thereby exhibiting slower reaction times to affective stimuli. More specific neuropsychological hypotheses for anxious individuals without depression versus nonanxious individuals in terms of concurrent anterior dysfunction and posterior hyperarousal are discussed. / Master of Science

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Les épilepsies bénignes partielles idiopathiques de l'enfant sont associées à un pronostic favorable, car les crises sont rares et disparaissent à l'adolescence. La nature bénigne de ces syndromes est remise en question en raison de difficultés d'apprentissage et de déficits cognitifs subtils, fréquemment rapportés dans cette population. Nous étudions l’incidence des décharges épileptiques inter-critiques sur la cognition, et observons leurs influences sur l’organisation cérébrale et les fonctions cognitives. Nous proposons des épreuves informatisées, à des patients avec des pointes centro-temporales (EPCT) principalement localisées à l'un des deux hémisphères et occipitales de type Panayiotopoulos (SP), afin d'évaluer des compétences verbales, visuo-spatiales, visuo-attentionnelles, ainsi que trois processus d’imagerie mentale visuelle jamais étudiés dans ces syndromes. Les données comportementales renforcent l’idée d’une spécificité des perturbations selon la latéralisation hémisphérique des pointes inter-critiques et confirment leur incidence sur l’organisation de l’asymétrie hémisphérique fonctionnelle associée aux fonctions étudiées. Par ailleurs, nous montrons que le SP a une incidence particulièrement négative sur les processus d'imagerie mentale visuelle, compétences centrales pour la réussite scolaire de l’enfant et l’enrichissement de son imaginaire. Nos résultats sont en adéquation avec la remise en question actuelle de la nature bénigne de ces épilepsies sur le plan cognitif. Comparer les déficits et l’asymétrie hémisphérique fonctionnelle selon la localisation principale des pointes procure de nouveaux arguments pour un impact spécifique des manifestations inter-critiques, car seuls les mécanismes cognitifs sous-tendus par les régions concernées sont perturbés. Cela apporte des éléments d’explications sur les difficultés d'apprentissages signalés chez ces enfants, et incite à proposer des aménagements pédagogiques. / Benign idiopathic partial epilepsies of children are associated with a favorable prognosis because of rare seizure and usually recovery during adolescence. The benign nature of these syndromes is questioned because of learning difficulties and subtle cognitive deficits, frequently reported in this population. We study the incidence of the epileptic discharges on the cognition, and observe their influences on brain organization and cognitive functions. We propose computerized tests to patients with centrotemporal spikes (BECT) mainly localized in one of both hemispheres and occipital discharges, Panayiotopoulos syndrome (PS), to estimate verbal, visuo-spatial and visuo-attentional skills, as well as three visual imagery processes still never studied in these syndromes. Behavioural data strengthen the idea of a specific disturbances according to the hemispheric lateralization of the discharges and confirm their incidence on the organization of the functional hemispheric asymmetry associated with the studied functions. Furthermore, we show that PS has a particularly negative impact on the visual imagery process, important skills in the child's academic success and enrichment of his imagination. Our results are consistent with the current questioning of the benign nature of epilepsy on the cognitive level. Compare the deficits and the functional hemispheric asymmetry according to the main localization of discharges gets new arguments for a specific impact of the epileptiform activity, because only the cognitive mechanisms underlain by the concerned regions are disrupted. This provides evidence to explain the learning difficulties identified in these children, and encourages them to provide educational facilities.

No description available.