Le but de la présente recherche est d’étudier l’influence de la séparation spatiale entre des marqueurs auditifs statiques sur la discrimination de la durée. Dans ce contexte, une surestimation de cette dernière en fonction de l’augmentation de la distance entre les marqueurs des intervalles temporels est fréquemment observée. Il s’agit de l’effet kappa. Bien que démontré en modalité tactile et visuelle, aucune étude ne le met clairement en évidence avec une méthode expérimentale équivalente pour l’audition. Afin de préciser son implication et de tenter d’établir les limites temporelles et spatiales de sa manifestation pour cette modalité, dix participants doivent comparer deux intervalles temporels vides délimités par trois stimuli auditifs statiques séparés par une distance variant, en ratios, de 1:1:1 à 1:1:2 (1 = 0,90 m et 2 = 1,80 m). Ce type de tâche correspond à la méthode des stimuli constants. Les standards utilisés sont de 160 ms et de 320 ms. Généralement, les résultats obtenus indiquent qu'il n'y a pas d'effet kappa avec les paramètres utilisés. Au contraire, une tendance à percevoir les intervalles temporels comme étant plus courts lorsqu’ils sont délimités par des marqueurs séparés par une plus grande distance est observée.

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La charge de travail élevée et le manque de temps pour répondre aux besoins des patients peuvent engendrer un certain stress chez les infirmières novices, stress qui peut affecter négativement la prestation des soins. De plus, ces infirmières novices expérimentent un niveau de stress élevé dans les six premiers mois d’embauche. Toutefois, très peu d’études ont exploré la perception du stress et la perception de la qualité des soins dispensés aux patients chez les infirmières novices. L’objectif principal de la présente étude consiste à décrire la relation entre la perception d’infirmières novices du stress vécu et la perception de la qualité des soins. Un devis descriptif corrélationnel exploratoire à l’aide d’une enquête a été retenu. Cette étude s’appuie sur le cadre conceptuel de Firth-Cozens (2001). Les données sur la perception du stress ont été recueillies par le biais de l’échelle de stress perçu Perceived Stress Scale 10 version française de Belllinghausen et al. (2009) ainsi que par la dimension reconnaissance du stress du Safety Attitudes Questionnaire. Quant aux données sur la perception de la qualité des soins, elles ont été obtenues par le biais de l’instrument de mesure le Victorian Patient Satisfaction Questionnaire version infirmière (Leggat et al., 2010) et par la dimension climat de sécurité du Safety Attitudes Questionnaire. Les résultats révèlent que les infirmières novices reconnaissent qu’elles sont stressées. Elles ont conscience qu’une charge de travail excessive peut nuire à leur performance. Toutefois, elles minimisent l’impact du stress et de la fatigue sur la qualité de leurs soins. Elles ont aussi le sentiment qu’elles ne peuvent pas discuter des erreurs commises. De plus, il y a une faible corrélation négative non significative entre la perception du stress et la perception de la qualité des soins (r=-0,183 p=0,067). Cependant, un lien théorique subsiste entre les deux variables (Firth-Cozens, 2001). D’autres études sont nécessaires afin de démontrer un lien empirique entre la perception du stress et la perception de la qualité des soins chez les infirmières novices.

published_or_final_version / abstract / Psychology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Psychology / Doctoral / Doctor of Philosophy

Contemporary computational models of motion perception assume that in processing continuous or near-continuous motion information, the visual system measures spatial displacement in retinal coordinates over a series of time-varying images. Additional three-dimensional information possessed by the system purportedly does not influence this low-level motion analysis. The present research investigated the influence of static three-dimensional distance information recovered from binocular disparity on the perceived direction of motion. It was assumed that if a stereoscopic display context influenced perceived motion direction, the apparent velocity of a moving element would increase in order to traverse the greater apparent distance. This would be reflected in a predictable pattern of errors when the true angular velocity was the same, slower or faster than that of the standard. The stimuli consisted of random-dot stereograms depicting surfaces at varying distances and orientations. In one stereoscopic display, the disparity information indicated a surface sloping smoothly in depth from crossed to uncrossed disparity. The second display contained two fronto-parallel planes at discrete distances from the observed. Motion stimuli were single element translating horizontally and presented monocularly to the observer's right eye. Experiment 1 compared differential velocity judgments in the contexts of the sloped surface and a control condition at zero disparity. The results indicated an overall increase in the perceived velocity of the element moving in the context of the sloped surface. The pattern of results was replicated in experiment 2, but an additional effect of the relative positions of the two surfaces also was obtained. Experiment 3 explored the case of two discrete fronto-parallel planes, one at crossed disparity and the other at uncrossed disparity. This experiment also produced a position effect, but indicated that the perceived distance of the two planes did not differentially affect observer's velocity judgments. It was concluded that in some cases, the metric of motion analysis could be affected by three-dimensional information recovered from binocular disparity. The particular case discovered in these experiments was a surface that appeared to slope smoothly in depth. Discrete depth planes produced no such effect.

Selective attention is a filtering system that focuses on relevant information in our environment while irrelevant information is suppressed. The two well-known components of selective attention, facilitation and inhibition, work hand in hand to aid the processing of relevant information. The main theme of the present thesis was to study the inhibitory component of visual selective attention using stimuli such as motion and shape in a rapid serial visual presentation. Therefore, the first three experimental chapters investigated how relevant motion and shape information are processed and perceived in the presence of similar irrelevant information. The findings showed that first order visual motion detection is impaired in the presence of distracters and this inhibition of distracters is generated in a bottom-up manner. The findings were, however, not straightforward. The findings from Experiments 6-10 showed that distracter information (shape) influences shape target detection only when distracters are made salient and the perceptual load of the task is moderately difficult. Collectively, the findings in this present thesis suggest that there may be more than one kind of inhibition generated for different kinds of stimuli.

This thesis explores the effect of vocal affect expression on communicative effectiveness. Two studies examined whether positive speaker affect facilitates the encoding and decoding of the message, combining methods from Phonetics and Psychology.

Although there is extensive evidence that auditory spatial processing can adapt to changes in auditory spatial cues both in infancy and adulthood, the mechanisms underlying adaptation appear to differ across species. Whereas barn owls compensate for unilateral hearing loss throughout development by learning abnormal mappings between cue values and spatial position, adult mammals seem to adapt by ignoring the acoustical input available to the affected ear and learning to rely more on unaltered spatial cues. To investigate these differences further, ferrets were raised with a unilateral earplug and their ability to localize sounds was assessed. Although these animals did not fully compensate for the effects of an earplug, they performed considerably better than animals that experienced an earplug for the first time, indicating that adaptation had taken place. We subsequently found that juvenile-plugged (JP) ferrets learned to adjust both cue mappings and weights in response to changes in acoustical input, with the nature of these changes reflecting the expected reliability of different cues. Thus, the auditory system may be able to rapidly update the way in which individual cues are processed, as well as the way in which different cues are integrated, thereby enabling spatial cues to be processed in a context- specific way. In attempting to understand the mechanisms that guide plasticity of spatial hearing, previous studies have raised the possibility that changes in auditory spatial processing may be driven by mechanisms intrinsic to the auditory system. To address this possibility directly, we measured the sensitivity of human subjects to ITDs and ILDs following transient misalignment of these cues. We found that this induces a short-term recalibration that acts to compensate for the effects of cue misalignment. These changes occurred in the absence of error feedback, suggesting that mutual recalibration can occur between auditory spatial cues. The nature of these changes, however, was consistent with models of cue integration, suggesting that plasticity and integration may be inextricably linked. Throughout the course of this work, it became clear that future investigations would benefit from the application of closed-field techniques to the ferret. For this reason, we developed and validated methods that enable stimuli to be presented to ferrets over earphones, and used these methods to assess ITD and ILD sensitivity in ferrets using a variety of different stimuli. We found that the Duplex theory is able to account for binaural spatial sensitivity in these animals, and that sensitivity is comparable with that found in humans, thereby confirming the ferret as an excellent model for understanding binaural spatial hearing.

Call number: LD2668 .T4 1959 P37