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1
Duffield, Kasey Marie. "Perceptual Analysis of Children's Adaptation to an Electropalatography Sensor." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6817.
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The purpose of this study is to observe childrens adaptation to an electropalatographic (EPG) sensor. Sound recordings of six children between the ages of 7;0 and 9;11 sampled at 30-minute intervals over a two-hour period of wearing an EPG sensor were perceptually evaluated to quantify the children's adaptation over time. Twenty native speakers of American English evaluated the pronunciation of a series of words with embedded stops and fricatives produced with and without an EPG sensor in place. When collapsed over speaker and stimulus type, listener ratings decreased significantly after inserting the EPG sensor. Ratings then increased significantly after the sensor was in place for 30 minutes, and again after 60 minutes. No significant improvement in pronunciation was noted between the 60- and 120-minute test intervals, and adaptation did not reach preplacement levels until the sensor was removed. Mixed results were found in how speakers adapted across the different stimulus types. Adaptation was most consistent across speakers for the conversation conditions, but occurred most rapidly for /s/ and /k/. Speakers showed the best overall adaptation for the phoneme /t/ by the end of testing. These results are similar to several adaptation studies with adults, and the two studies with children. Results from this study will help speech pathologists effectively use EPG technology to help children accurately pronounce speech sounds, and to generalize these pronunciations to their normal speech.
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Abebe, Mekides Assefa. "Perceptual content and tone adaptation for HDR display technologies." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2285/document.
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Les technologies de capture et d'affichage d'images ont fait un grand pas durant la dernière décennie en termes de capacités de reproduction de la couleur, de gamme de dynamique et de détails des scènes réelles. Les caméras et les écrans à large gamme de dynamique (HDR: high dynamic range) sont d'ores et déjà disponibles, offrant ainsi plus de flexibilité pour les créateurs de contenus afin de produire des scènes plus réalistes.Dans le même temps, à cause des limitations des appareils conventionnels, il existe un gap important en terme de reproduction de contenu et d'apparence colorée entre les deux technologies. Cela a accentué le besoin pour des algorithmes prenant en compte ces considérations et assurant aux créateurs de contenus une reproduction cross-média fidèle.Dans cette thèse, nous focalisons sur l'adaptation et la reproduction des contenus à gamme de dynamique standard sur des dispositifs HDR. Tout d'abord, les modèles d'apparence colorée ainsi que les opérateurs de mappage tonal inverse ont été étudiés subjectivement quant à leur fidélité couleur lors de l'expansion de contenus antérieurs. Par la suite, les attributs perceptuels de clarté, chroma et saturation ont été analysés pour des stimuli émissifs ayant des niveaux de luminance de plus hautes gammes et ce en menant une étude psychophysique basée sur la méthode de mise à l'échelle de partitions. Les résultats expérimentaux ont permis de mener à la définition d'un nouvel espace couleur HDR efficace et précis, optimisé pour les applications d'adaptation de la gamme de dynamique. Enfin, dans l'optique de récupérer les détails perdus lors de captures d'images standard et d'améliorer la qualité perçue du contenu antérieur avant d'être visualisé sur un dispositif HDR, deux approches de correction des zones surexposées ou ayant subi un écrêtage couleur ont été proposées. Les modèles et algorithmes proposés ont été évalués en comparaison avec une vérité terrain HDR, menant à la conclusion que les résultats obtenus sont plus proches des scènes réelles que les autres approches de la littératureCamera and display technologies have greatly advanced in their capacities of reproducing color, dynamic range and details of real scenes in recent years. New and powerful high dynamic range (HDR) camera and display technologies are currently available in the market and, recently, these new HDR technologies offer higher flexibility to content creators, allowing them to produce a more precise representation of real world scenes.At the same time, limitations of conventional camera and display technologies mean that there is a significant gap in terms of content and color appearance reproduction between new and existing technologies. These mismatches lead to an increased demand for appearance studies and algorithms which take such under consideration and help content creators to perform accurate cross-media reproductions.In this thesis we mainly considered the adaptation and reproduction of standard dynamic range content towards HDR displays. First, existing color appearance models and reverse tone mapping operators were subjectively studied for their color fidelity during dynamic range expansion of legacy contents. Then perceptual lightness, chroma and saturation attributes were analyzed for emissive stimuli with higher range of luminance levels using adapted psycho-visual experimental setups based on the partition scaling method. The experimental results lead to a new, more efficient and accurate HDR color space, specifically optimized for dynamic range adaptation applications. Finally, to recover lost details and enhance the visual quality of legacy content before visualizing on an HDR display, two methods for color-clipping and over-exposure correction were introduced. The models and algorithms presented, were evaluated relative to HDR ground truth content, showing that our results are closer to the real scene than can be achieved with previous methods
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Erb, Julia [Verfasser]. "The neural dynamics of perceptual adaptation to degraded speech / Julia Erb." Leipzig : Max-Planck-Institut für Kognitions- und Neurowissenschaften, 2014. http://d-nb.info/1064777228/34.
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Barden, Katharine. "Perceptual learning of context-sensitive phonetic detail." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/241032.
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Although familiarity with a talker or accent is known to facilitate perception, it is not clear what underlies this phenomenon. Previous research has focused primarily on whether listeners can learn to associate novel phonetic characteristics with low-level units such as features or phonemes. However, this neglects the potential role of phonetic information at many other levels of representation. To address this shortcoming, this thesis investigated perceptual learning of systematic phonetic detail relating to higher levels of linguistic structure, including prosodic, grammatical and morphological contexts. Furthermore, in contrast to many previous studies, this research used relatively natural stimuli and tasks, thus maximising its relevance to perceptual learning in ordinary listening situations. This research shows that listeners can update their phonetic representations in response to incoming information and its relation to linguistic-structural context. In addition, certain patterns of systematic phonetic detail were more learnable than others. These findings are used to inform an account of how new information is integrated with prior experience in speech processing, within a framework that emphasises the importance of phonetic detail at multiple levels of representation.
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Tseng, Yuan-Chi. "Adaptation of image visual search strategies to utility given task and perceptual constraints." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505408.
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How do people adapt search strategies for finding visual images? An assumption in studies of rational behaviours is that the choice of strategies is shapec by rewards. Vision studies also find humans have a tendency to shift attention to the location that maximises information gain. However, it is unclear whether people would maximise information gain in circumstances where the cost of gaining information is likely to reduce its utility. In addition, information maximisation theories, derived from studies of a single saccade or search for a well-defined target with sequential optimal saccades, are unlikely to lead directly to an understanding of the bounds on visual search mechanisms in more complex and natural visual search settings, it is not known, for example, how people adapt basic elements of eye novement performance to changes in expected utility. Evidence from Experiments 1-4 showed that the selected strategy is sensitive to the display layout, i.e. the density and shape. Experiment 4 also observed that the choice of search strategy is associated with the expected number of alternatives in the search set. The follow-up diffusion based model showed how strategic control of thresholds for target and distractor recognition, in a gaze decision, could lead to the observed overall search behaviour in which participants balance the trade-off between the gaze duration and number of gazes. It also showed how saccade criteria are adapted to the number of alternatives. The findings of Experiment 5 supported the hypothesis that the micro-structure of the visual search process is adapted to a desire to maximise utility. The results showed that participants can trade time for value and that they can adjust gaze duration, and targeting, to the distribution of reward. The follow-up signal detection based model successfully predicted that adaptation generates optimal utility given the human visual and task constraints.
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Hunter, Elise Hansen. "Speech Adaptation to Kinematic Recording Sensors." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5728.
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This thesis examined the time course of speech adaptation prior to data collection when using an electromagnetic articulograph to measure speech articulator movements. The stimulus sentence and electromagnetic sensor placement were designed to be sensitive to changes in the fricatives /s/ and /ʃ/. Twenty native English speakers read aloud stimulus sentences before the attachment of six electromagnetic sensors, immediately after attachment, and again at 5, 10, 15 and 20 minutes after attachment. Participants read aloud continuously between recordings to encourage adaptation to the presence of the sensors. Audio recordings were rated by 20 native English listeners who were not part of the production study. After listening to five practice samples, these participants rated 150 stimuli (31 repeat samples) using a visual analog scale (VAS) with the endpoints labeled as precise and imprecise. An acoustic analysis of the recordings was done by segmenting the fricatives /s/ and /ʃ/ from the longer recording and computing spectral center of gravity and spectral standard deviation in Hertz. Durations of /s/, /ʃ/ and the sentence were also measured. Results of both perceptual and acoustic analysis revealed a change in speech precision over time, with all post attachment recordings receiving lower perceptual scores. Precision ratings beyond the ten minute recording remained steady. It can be concluded from the results that participants reached a height of adaptation after 10 minutes of talking with kinematic recording sensors attached, and that after the attachment of sensors, speech production precision did not at any point return to pre attachment levels.
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Haque, Serajul. "Perceptual features for speech recognition." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0187.
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Automatic speech recognition (ASR) is one of the most important research areas in the field of speech technology and research. It is also known as the recognition of speech by a machine or, by some artificial intelligence. However, in spite of focused research in this field for the past several decades, robust speech recognition with high reliability has not been achieved as it degrades in presence of speaker variabilities, channel mismatch condi- tions, and in noisy environments. The superb ability of the human auditory system has motivated researchers to include features of human perception in the speech recognition process. This dissertation investigates the roles of perceptual features of human hearing in automatic speech recognition in clean and noisy environments. Methods of simplified synaptic adaptation and two-tone suppression by companding are introduced by temporal processing of speech using a zero-crossing algorithm. It is observed that a high frequency enhancement technique such as synaptic adaptation performs better in stationary Gaussian white noise, whereas a low frequency enhancement technique such as the two-tone sup- pression performs better in non-Gaussian non-stationary noise types. The effects of static compression on ASR parametrization are investigated as observed in the psychoacoustic input/output (I/O) perception curves. A method of frequency dependent asymmetric compression technique, that is, higher compression in the higher frequency regions than the lower frequency regions, is proposed. By asymmetric compression, degradation of the spectral contrast of the low frequency formants due to the added compression is avoided. A novel feature extraction method for ASR based on the auditory processing in the cochlear nucleus is presented. The processings for synchrony detection, average discharge (mean rate) processing and the two tone suppression are segregated and processed separately at the feature extraction level according to the differential processing scheme as observed in the AVCN, PVCN and the DCN, respectively, of the cochlear nucleus. It is further observed that improved ASR performances can be achieved by separating the synchrony detection from the synaptic processing. A time-frequency perceptual spectral subtraction method based on several psychoacoustic properties of human audition is developed and evaluated by an ASR front-end. An auditory masking threshold is determined based on these psychoacoustic e?ects. It is observed that in speech recognition applications, spec- tral subtraction utilizing psychoacoustics may be used for improved performance in noisy conditions. The performance may be further improved if masking of noise by the tonal components is augmented by spectral subtraction in the masked region.
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TOLLNER, ALISON MARIE. "DIVIDED ATTENTION DURING ADAPTATION TO VISUAL-MOTOR ROTATION IN AN ENDOSCOPIC SURGERY SIMULATOR." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061235487.
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Banks, Briony. "Perceptual plasticity in adverse listening conditions : factors affecting adaptation to accented and noise-vocoded speech." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/perceptual-plasticity-in-adverse-listening-conditions-factors-affecting-adaptation-to-accented-and-noisevocoded-speech(c5227984-13b8-4e33-9233-5e1715cf8516).html.
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Adverse listening conditions can be a hindrance to communication, but humans are remarkably adept at overcoming them. Research has begun to uncover the cognitive and behavioural mechanisms behind this perceptual plasticity, but we still do not fully understand the reasons for variability in individual responses. The research reported in this thesis addressed several factors which would further this understanding. Study 1 examined the role of cognitive ability in recognition of, and perceptual adaptation to, accented speech. A measure of executive function predicted greater and more rapid perceptual adaptation. Vocabulary knowledge predicted overall recognition of the accented speech, and mediated the relationship between working memory and recognition accuracy. Study 2 compared recognition of, and perceptual adaptation to, accented speech with and without audiovisual cues. The presence of audiovisual cues improved recognition of the accented speech in noise, but not perceptual adaptation. Study 3 investigated when perceivers make use of visual speech cues during recognition of, and perceptual adaptation to, audiovisual noise-vocoded speech. Listeners’ eye gaze was analysed over time and related to their performance. The percentage and length of fixations on the speaker’s mouth increased during recognition of individual sentences, while the length of fixations on the mouth decreased as perceivers adapted to the noise-vocoded speech over the course of the experiment. Longer fixations on the speaker’s mouth were related to better speech recognition. Results demonstrate that perceptual plasticity of unfamiliar speech is driven by cognitive processes, but can also be modified by the modality of speech (audiovisual or audio-only). Behavioural responses, such as eye gaze, are also related to our ability to respond to adverse conditions. Speech recognition and perceptual adaptation were differentially related to the factors in each study and therefore likely reflect different processes; these measures should therefore both be considered in studies investigating listeners’ response to adverse conditions. Overall, the research adds to our understanding of the mechanisms and behaviours involved in perceptual plasticity in adverse listening conditions.
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Williams, Megan C. "A perceptual evaluation of the effect of a pseudopalate on voiceless obstruent production and motor adaptation /." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd2975.pdf.
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Williams, Megan Ann Cannon. "A Perceptual Evaluation of the Effect of a Pseudopalate on Voiceless Obstruent Production and Motor Adaptation." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/1724.
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Electropalatography (EPG) has proven to be a useful clinical and research tool for measuring tongue-to-palate contact. Research has shown sensorimotor adaptation to an EPG device may be possible following a short period of speech practice. This study was developed in order to better understand how a listeners' perception of speech clarity is effected by the presence of a relatively thin artificial pseudopalate in the speakers' oral cavity. Twenty listeners rated 220 speech stimuli on a visual analog scale ranging from normal to very distorted speech clarity. The stimuli included two different American English sentences. Speech clarity ratings were looked at as a function of the gender of the listener, the gender of the speaker, the type of speech sounds being heard, and the ability of the speakers to adapt their articulatory patterns over a period of 20 minutes. The results indicated that with the pseudopalate in place male speakers were generally rated by the listeners as having more distorted speech articulation than female speakers, especially for stop-loaded sentences. Overall, fricative-loaded sentences received higher articulation ratings than stop-loaded sentences. Finally, an adaptation period of 20 minutes showed significant improvement in speech articulation in comparison to ratings immediately following pseudopalate placement, however speech remained significantly distorted.
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Siciliano, Catherine. "Perceptual adaptation to binaurally mismatched frequency-to-place maps : implications for bilateral stimulation with cochlear implants." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/18930/.
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Simulations of monaural cochlear implants in normal-hearing listeners have shown that the deleterious effects of upward spectral shifting on speech perception can be overcome with training. This thesis examines whether the same is true when simulating bilateral stimulation. Can listeners adapt to upward-shifted speech information presented together with contralateral unshifted information? In two series of experiments, perceptual adaptation was investigated for both speech in quiet with a large interaural spectral mismatch, and speech in noise with a moderate interaural spectral mismatch. For speech in quiet, a six-channel dichotic sine-carrier vocoder simulated the binaurally mismatched frequency-to-place map. Odd channels were presented to one ear with an upward shift equivalent to a 6 mm basilar membrane distance, while even channels were presented to the contralateral ear unshifted. For speech in noise, the number of vocoded channels was increased to ten, and the upward spectral shift applied to the odd channels was decreased to 3.8 mm. Prior to vocoding, speech was combined with speech-shaped noise at a signal-to-noise ratio of 10 dB (or 0 dB for vowels). Listeners were trained with Connected Discourse Tracking for 5.3 hours or 10 hours, with the binaurally mismatched processor and/or just the shifted monaural bands. Speech perception was tested with sentence and vowel tests before, during and after training. Listeners showed adaptation to the upwardly shifted speech, but for nearly every speech test, intelligibility with the binaurally mismatched processor matched intelligibility with just the unshifted bands. Consistent with earlier findings with monaural spectral shifts, then, this research suggests that listeners are capable of adapting to a spectral shift, even in the presence of background noise. However, they appear to be resistant to integrating mismatches in frequency-place maps between the ears. A theory of “better ear” listening is proposed to account for this resistance. The findings are consistent with psychophysical studies of binaural hearing, which show maximal ITD and ILD sensitivity for similar interaural cochlear places. In optimizing bilateral cochlear implants for speech perception, it may thus be important to keep frequency-to-place maps similar in the two ears.
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Jaquet, Emma. "Perceptual aftereffects reveal dissociable adaptive coding of faces of different races and sexes." University of Western Australia. School of Psychology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0021.
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[Truncated abstract] Recent studies have provided evidence that face-coding mechanisms reference a norm or average face (Leopold, O`Toole, Vetter & Blanz, 2001; Rhodes & Jeffery, 2006). The central aim of this thesis was to establish whether distinct norms, and dissociable neural mechanisms code faces of different race and sex categories. Chapter 1 provides a brief introduction to norm based coding of faces, and reviews evidence for the existence of distinct norms for different races and sexes. Chapter 1 then introduces adaptation as a tool for investigating these ideas. Chapter 2 presents two adaptation studies that examined how faces of different races are coded. The aim of these studies was to determine whether dissociable neural mechanisms (or distinct face norms) code faces of different races. Chinese and Caucasian participants rated the normality of Caucasian and Chinese test faces, before and after adaptation to distorted faces of one race (e.g., 'contracted' Chinese faces; Experiment 1) or distorted faces of both races (e.g., 'contracted' Chinese faces and 'expanded' Caucasian faces; Experiment 2). Following adaptation to faces of one race, there were changes in perceived normality for faces of both races (i.e., perceptual aftereffects), indicating that common neural mechanisms code Chinese and Caucasian faces. However, aftereffects were significantly smaller in faces of the unadapted race suggesting some sensitivity to the race of faces. This sensitivity was also evident in Experiment 2. ... Some dissociability was also found in the coding of faces of different iv sexes. In Experiments 2 and 3, participants adapted to oppositely distorted faces of both sexes. Weak sex-selective aftereffects were found. Taken together, the findings suggest that male and female faces are coded by dissociable but not completely distinct neural populations. Chapter 4 examined whether the aftereffects reported for faces of different races or sexes reflected the adaptation of high-level neural mechanisms tuned to the social category information in faces, or earlier coding mechanisms tuned to simple physical differences between face groups. Chinese and Caucasian participants adapted to oppositely distorted face sets that were the same distance apart on a morph continua. The face sets were either from different race categories (e.g., contracted Chinese faces and expanded Caucasian faces), or from the same race category, (e.g., contracted Chinese faces and expanded caricatured Chinese faces). Larger opposite aftereffects were found when face sets were from different race categories, than when they were from the same race category suggesting that oppositely adapted neural mechanisms are tuned to social category differences rather than simple physical differences in faces. Together, these studies shed new light on how we code faces from different face categories. Specifically, the findings indicate that faces of different races and sexes are coded by both common and race- or sex-selective neural mechanisms. In addition, the findings are consistent with the possibility that race- and sex-selective norms and dimensions are used to code faces in face space. The implications of these findings and possible avenues for future research are discussed.
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Michael, Elizabeth. "Dissociable sources of uncertainty in perceptual decision making." Thesis, University of Oxford, 2016. http://ora.ox.ac.uk/objects/uuid:581e8fc9-1e12-4877-a89a-44cdc67c45e2.
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The natural world provides sensory systems with noisy and ambiguous information, which is often transformed into a more stable categorical percept. This thesis aims to investigate the nature of the neural representations in the visual system that support this transformation. To do so, we will employ a behavioural task that requires participants to average several independent sources of perceptual information. This task allows for the dissociation of two theoretically orthogonal sources of decision uncertainty: the mean distance of the perceptual information from a category boundary and the variability of the evidence under consideration. Behaviourally, both decreasing the mean distance to bound of information and increasing information variability are associated with increased errors and prolonged response times. We will present a computational model that can account for the independent behavioural effects of these two sources of uncertainty by assuming that categorical decisions are made on the basis of a probabilistic transformation of perceptual evidence. BOLD measurements demonstrate that these effects of mean and variability are supported by a partially dissociable network of brain regions. Electroencephalography demonstrates the differential influence of mean and variance in the pre- and post-decision period. Furthermore, we show that there is adaptation at the level of the perceptual representation to the information variance. Not only does this show that the visual system must represent information at the summary level, in addition to individual feature-based representation, but it also suggests that the costs associated with this form of perceptual uncertainty can be largely mitigated by the adoption of a more suitable representational range.
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Littman, Eric Marshall. "Adaptation to Simultaneous Multi-Dimensional Distortions." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1311961424.
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Aspeslagh, Sofie. "An investigation into the perceptual adaptation to spatialised multi-source acoustic environments in normal-hearing and hearing-impaired listeners." Thesis, University of the West of Scotland, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.739195.
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Glauert, Rebecca. "Body dissatisfaction and its relationship with the perceptual effects of exposure to bodies and attentional biases toward bodies." University of Western Australia. School of Psychology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0220.
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[Truncated abstract] Socio-cultural processes are often cited as one of the main causes of body dissatisfaction amongst women. Numerous studies have found that exposure to thin, idealized images in the media increases women's body dissatisfaction. The central aims of this thesis are to investigate how exposure to thin and fat bodies alters womens perceptions of body normality and body ideals, whether body dissatisfaction is related to these changes, and whether body dissatisfaction is associated with an attentional bias toward thin bodies. In Chapter 1 I review the main theories dominating body dissatisfaction research. In Chapter 2 I present two studies which investigate how exposure to thin and fat bodies influences perceptions of body normality and ideal body size. Women who varied on a measure of body dissatisfaction (Experiment 1 & 2) and awareness and acceptance of societal standards of beauty (Experiment 2) rated a range of computer generated bodies, varying in simulated BMI, for how normal (Experiment 1 & 2) and ideal they looked (Experiment 2). They were then exposed to either thin or fat bodies, and they re-rated the bodies. Increased levels of body dissatisfaction and internalisation of societal standards of beauty were related to a thinner most normal and ideal rated body, before any exposure, as well as a greater discrepancy between the most normal and ideal rated bodies. Both Experiments 1 & 2 revealed that brief exposure to thin or fat bodies altered women's perceptions of body normality and body ideal, where exposure to fat bodies made womens perceptions of a normal and ideal body fatter, and exposure to thin bodies, made perceptions of the most normal and ideal rated body thinner. ... In Chapter 5 I present normative data for the Body Shape Questionnaire-34 (a measure of dissatisfaction with body weight and shape) (Cooper et al, 1987) from an Australian university sample. Many researchers use university samples iv when investigating body dissatisfaction, so it is useful to have normative data for such a sample. One thousand and fifty two women aged between 16 and 30 completed the BSQ-34. A mean score of 94.4 (SD = 34.5) was found, with a range of 34-203. My scores are comparable with those found in an American undergraduate sample, and are significantly higher than those found in community, undergraduate and clinical samples in the UK and Italy. Results indicate that levels of body dissatisfaction may be higher in Australia than in the UK and Italy. Together, these studies provide some important new findings. 1) Body dissatisfaction and internalisation of societal standards of beauty are related to thinner body norms and ideals. 2) Women's perceptions of normal and ideal female body sizes can be readily altered by exposure to thin and fat bodies, and 3) women selectively attend to thin bodies, but the more dissatisfied she is with her own body, the less she attends to thin bodies. Potential implications of these results for the treatment of body dissatisfaction may include the incorporation of treatment programs which target not only unnaturally slim body ideals, but perceptions of what constitutes a normal body, as well as trying to alter selective attention toward thin bodies in the environment. The results may also highlight to the media that consistently showing ultra slim models will very likely affect women's perceptions of normal and ideal female body sizes.
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Graczyk, Emily Lauren. "Natural Perceptual Characteristics and Psychosocial Impacts of Touch Evoked by Peripheral Nerve Stimulation." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1522943665759439.
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Theodoni, Panagiota. "Fluctuations in perceptual decisions : cortical microcircuit dynamics mediating alternations in conscious visual perception." Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/145642.
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Fluctuations in perceptual decisions emerge when our brain confronts with ambiguous
sensory stimuli. For instance, our perception alternates between two conflicting images
when presented dichoptically to our eyes, allowing a dissociation of the sensory stimulation
from the conscious visual perception, and therefore providing a gateway to consciousness.
How does the brain work when it deals with such ambiguous sensory stimuli? We
addressed this question theoretically by employing a biophysically realistic attractor
network, by consistently reducing it to a four- variable rate- based model, and by extracting
analytical expressions for second- order statistics. We considered human behavioral and
macaque neurophysiological data collected when subjects were confronting with such
ambiguities. Our results show the relevance of neuronal adaptation in perceptual decision
making, as well as that it contributes to the speed- accuracy trade- off. Furthermore, our
findings affirm that both noise and neural adaptation operate in balance during the
fluctuating states of visual awareness and suggest that while adaptation in inhibition is not
relevant for the perceptual alternations, it contributes to the brain dynamics at rest. Finally,
we explain the observed neuronal noise- decorrelation during visual consciousness and
provide insights on the long- standing question: where in the brain rivalry is resolved.Les fluctuacions en les decisions perceptives sorgeixen quan el nostre cervell s'enfronta a estímuls sensorials ambigus. Per exemple, la nostra percepció alterna entre dues imatges contradictòries quan es presenten de forma dicòptica als nostres ulls, cosa que permet una dissociació de l'estimulació sensorial de la percepció visual conscient, i per tant proporciona una porta d'entrada a la consciència. Com funciona el cervell quan es tracta d'aquest tipus d'estímuls sensorials ambigus? Hem tractat aquesta qüestió de forma teòrica mitjançant l'ús d'una xarxa d'atractors biofísicament realista, reduint-la de forma consistent a un model de quatre variables basat en la freqüència, i extraient expressions analítiques pels estadístics de segon ordre. Hem emprat dades neurofisiològiques de comportament d'humans i macacos recollides quan els subjectes s'enfrontaven a aquest tipus d'ambigüitats. Els nostres resultats mostren la importància de l'adaptació neuronal en la presa de decisions perceptives i mostren la seva contribució a l'equilibri velocitat-precisió. D'altra banda, els nostres resultats confirmen que tant el soroll com l'adaptació neural operen en equilibri durant els estats fluctuants de consciència visual i suggereixen que, si bé l'adaptació en la inhibició no és rellevant per a les alternances de percepció, contribueix a la dinàmica del cervell en repòs. Finalment, expliquem la decorrelació del soroll neuronal observada durant la consciència visual i proporcionem noves idees en relació a l’antiga qüestió de en quin lloc del cervell es resol la rivalitat visual.
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Littman, Eric Marshall. "Prospective Control: Effect of Exploratory-task-generated-motion on Adaptation in Real and Virtual Environments." Oxford, Ohio : Miami University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1237518547.
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Bergerud, Donna Burgess. "Textbook adaptations for secondary students with learning disabilities /." Thesis, Connect to this title online; UW restricted, 1987. http://hdl.handle.net/1773/7793.
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Wolf, Christian Marc, and chris@adaptive-learning net. "Construction of an Adaptive E-learning Environment to Address Learning Styles and an Investigation of the Effect of Media Choice." RMIT University. Education, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080625.093019.
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This study attempted to combine the benefits of multimedia learning, adaptive interfaces, and learning style theory by constructing a novel e-learning environment. The environment was designed to accommodate individual learning styles while students progressed through a computer programming course. Despite the benefits of individualised instruction and a growing worldwide e-learning market, there is a paucity of guidance on how to effectively accommodate learning styles in an online environment. Several existing learning-style adaptive environments base their behaviour on an initial assessment of the learner's profile, which is then assumed to remain stable. Consequently, these environments rarely offer the learner choices between different versions of content. However, these choices could cater for flexible learning styles, promote cognitive flexibility, and increase learner control. The first research question underlying the project asked how learning styles could be accommodated in an adaptive e-learning environment. The second question asked whether a dynamically adaptive environment that provides the learner with a choice of media experiences is more beneficial than a statically adapted environment. To answer these questions, an adaptive e-learning environment named iWeaver was created and experimentally evaluated. iWeaver was based on an introductory course in Java programming and offered learning content as style-specific media experiences, assisted by additional learning tools. These experiences and tools were based on the perceptual and information processing dimension of an adapted version of the Dunn and Dunn learning styles model. An experimental evaluation of iWeaver was conducted with 63 multimedia students. The analysis investigated the effect of having a choice of multiple media experiences (compared to having just one static media experience) on learning gain, enjoyment, perceived progress, and motivation. In addition to these quantitative measurements, learners provided qualitative feedback at the end of each lesson. Data from 27 participants were sufficiently complete to be analysed. For the data analysis, participants were divided into two groups of high and low interest in programming and Java, then into two groups of high and low experience with computers and the Internet. Both group comparisons revealed statistically significant differences for the effect of choice. Having a choice of media experiences proved beneficial for learners with low experience but detrimental for learners with high experience or interest. These findings suggest that the effect of choice appears to be strongly influenced by the learner's background. It is hypothesised that encouraging a more active learner role in educational systems would expand the positive influence of choice to a wider range of learners. The study has contributed some weight to the argument that for certain groups of learners, it is more beneficial to view learning style as a flexible, rather than a stable construct. As a practical implication, it seems advisable to collect data on prior experience, interest, and the initial learning style distribution of the target audience before developing environments comparable to iWeaver. [See http://www.adaptive-learning.net/research/media.htm for media files associated with this thesis.]
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Vidal, Eloïse. "Étude et implémentation d'une architecture temps réel pour l'optimisation de la compression H.264/AVC de vidéos SD/HD." Thesis, Valenciennes, 2014. http://www.theses.fr/2014VALE0011/document.
Full textAbstract:
La vidéo sur IP a connu un essor rapide ces dernières années allant de la diffusion télévisuelle en haute qualité via des réseaux dédiés à la diffusion sur internet de contenus vidéo grand public. L’optimisation de l’encodage vidéo H.264/AVC permet aux différents acteurs du marché de se différencier en proposant des solutions pour réduire le débit nécessaire à la représentation d’un flux vidéo ainsi que pour améliorer la qualité perçue par les utilisateurs. C’est dans ce contexte de vidéo professionnelle en haute qualité que s’inscrivent ces travaux de thèse CIFRE réalisés au sein de l’entreprise Digigram, proposant des encodeurs vidéo temps réel pour des diffusions professionnelles en direct. Nous proposons deux solutions de prétraitement pour répondre aux problématiques du secteur de la distribution vidéo. Les deux solutions considèrent les caractéristiques du système visuel humain en exploitant un modèle de JND (Just Noticeable Distortion) définissant des seuils de perception en fonction d’une analyse du contenu des séquences vidéo à encoder. La première solution utilise un préfiltre adaptatif indépendant de l’encodeur, contrôlé par un modèle JND afin d'éliminer le contenu perceptuellement non pertinent et ainsi réduire le débit sans altérer la qualité ressentie. Une analyse approfondie de plusieurs filtres de la littérature, dont le filtre AWA (Adaptive Weighted Averaging) et le filtre bilatéral, nous a également amené à définir deux nouveaux filtres à support étendu qui permettent d’exploiter au mieux les corrélations dans les images haute définition. A l’aide de tests subjectifs, nous montrons que les préfiltres perceptuels proposés permettent en moyenne de diminuer le débit en sortie du codeur d'environ 20% pour une qualité constante en encodage VBR (débit variable) Intra et Inter-image. Finalement, une deuxième solution s’attache à améliorer la qualité perçue dans un contexte d’encodage CBR (débit constant) en intégrant un modèle JND dans l’une des implémentations de la norme H.264/AVC la plus reconnue, le codec x264. Une quantification adaptative perceptuelle est ainsi proposée permettant d’améliorer les performances du codec x264 en améliorant le codage de l’information de contour à moyen et bas débits en encodage intra et inter-imageThe use of digital video over IP has increased exponentially over the last years, due to the development of high-speed networks dedicated to high quality TV transmission as well as the wide development of the nonprofessional video webcast. Optimization of the H.264/AVC encoding process allows manufacturers to offer differentiating encoding solutions, by reducing the bandwidth necessary for transmitting a video sequence at a given quality level, or improving the quality perceived by final users at a fixed bit rate. This thesis was carried out at the company Digigram in a context of professional high quality video. We propose two solutions of preprocessing which consider the characteristics of the human visual system by exploiting a JND profile (Just Noticeable Distortion). A JND model defines perceptual thresholds, below which a distortion cannot be seen, according to the video content. The first solution proposes an adaptive pre-filter independent to the encoder, controlled by a JND profile to reduce the perceptually non-relevant content and so reduce the bitrate while maintaining the perceived quality. By analyzing the state-of-the-art literature, the AWA (Adaptive Weighted Averaging) and Bilateral filters have been selected. Then we define two new filters using a large convolution mask, which enable to better exploit correlations in high-definition video contents. Through subjective tests, we show that the proposed perceptual prefilters give an average bitrate reduction of 20% for the same visual quality in VBR (Variable Bitrate) H.264/AVC Intra and Inter encoding. Finally, the second solution enables to improve the perceived quality in CBR (Constant Bitrate) encoding, by integrating the JND profile into the x264 codec, one of the best implementation of the H.264/AVC standard. Thus, we propose a perceptual adaptive quantization which enhances the x264 performance by improving edge information coding in low and middle bitrate applications
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Sanchez, Gaëtan. "L'électrophysiologie temps-réel en neuroscience cognitive : vers des paradigmes adaptatifs pour l'étude de l'apprentissage et de la prise de décision perceptive chez l'homme." Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01058541.
Full textAbstract:
Aujourd'hui, les modèles computationnels de l'apprentissage et de la prise de décision chez l'homme se sont raffinés et complexifiés pour prendre la forme de modèles génératifs des données psychophysiologiques de plus en plus réalistes d'un point de vue neurobiologique et biophysique. Dans le même temps, le nouveau champ de recherche des interfaces cerveau-machine (ICM) s'est développé de manière exponentielle. L'objectif principal de cette thèse était d'explorer comment le paradigme de l'électrophysiologie temps-réel peut contribuer à élucider les processus d'apprentissage et de prise de décision perceptive chez l'homme. Au niveau expérimental, j'ai étudié les décisions perceptives somatosensorielles grâce à des tâches de discrimination de fréquence tactile. En particulier, j'ai montré comment un contexte sensoriel implicite peut influencer nos décisions. Grâce à la magnétoencéphalographie (MEG), j'ai pu étudier les mécanismes neuronaux qui sous-tendent cette adaptation perceptive. L'ensemble de ces résultats renforce l'hypothèse de la construction implicite d'un a priori ou d'une référence interne au cours de l'expérience. Aux niveaux théoriques et méthodologiques, j'ai proposé une vue générique de la façon dont l'électrophysiologie temps-réel pourrait être utilisée pour optimiser les tests d'hypothèses, en adaptant le dessin expérimental en ligne. J'ai pu fournir une première validation de cette démarche adaptative pour maximiser l'efficacité du dessin expérimental au niveau individuel. Ce travail révèle des perspectives en neurosciences fondamentales et cliniques ainsi que pour les ICM
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Saupe, Maya. "Perceptual adaptation to speech in calibrated noise." Thesis, 2020. https://hdl.handle.net/2144/40951.
Full textAbstract:
Perceptual adaptation to a talker allows listeners to efficiently resolve inherent ambiguities present in the speech signal introduced by the lack of a one-to-one mapping between acoustic signals and intended phonemic categories across talkers. In ideal listening environments, preceding speech context has been found to enhance perceptual adaptation to a talker. However, little is known regarding how perceptual adaptation to speech occurs in more realistic listening environments with background noise. The current investigation explored how talker variability and preceding speech context affect identification of phonetically-confusable words in adverse listening conditions. Our results showed that listeners were less accurate and slower in identifying mixed-talker speech compared to single-talker speech when target words were presented in multi-talker babble, and that preceding speech context enhanced word identification performance under noise both in single- and mixed talker conditions. These results extend previous findings of perceptual adaptation to talker-specific speech in quiet environments, suggesting that the same underlying mechanisms may serve to perceptually adapt to speech both in quiet and in noise. Both cognitive and attentional mechanisms were proposed to jointly underlie perceptual adaptation to speech, including an active control process that preallocates cognitive resources to processing talker variability and auditory streaming processes that support successful feedforward allocation of attention to salient talker-specific features.
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Ryan, Matthew P. "PRISM ADAPTATION: EFFECTS OF TARGET-TYPE AND PERFORMANCE FEEDBACK." 2011. http://hdl.handle.net/10222/14147.
Full textAbstract:
When wearing prism goggles that displace vision laterally, the initial pointing errors are rapidly corrected. When the goggles are removed after a sufficient period of prism adaptation (PA), there is an aftereffect in spatial responding in the opposite direction of the original displacement. In this study 24 participants were tested using a computerized PA procedure to explore the effects of displacement direction (left/right), type of feedback during adaptation (hand/indirect), and type of target (fixed/non-fixed) on pointing error during 180 PA trials and the time-course of the aftereffect when measured in two ways: Subjective Straight Ahead (SSA) pointing (proprioceptive guidance towards perceived straight-ahead) and Visual Open Loop (VOL) pointing (visual and proprioceptive performance when pointing toward a straight-ahead target).
During the initial stage of adaptation, all groups adjusted pointing in the opposite direction of prismatic displacement. Pointing error was similar for left and right goggle groups, but was more accurate and faster to stabilize with hand than indirect feedback. After pointing stabilized, the left-goggle/hand feedback group reached beyond targets (‘over-corrected’ pointing error), while other conditions failed to fully adjust pointing and remained ‘under-corrected’.
In all groups, SSA aftereffects were weak or absent, while VOL aftereffects endured for at least 40-minutes. VOL aftereffects were larger following hand-feedback at all post-PA latencies, and for left-goggle groups at early post-PA latencies. Target-type affected performance during the stabilized-phase of adaptation, but did not influence SSA or VOL aftereffects.
These results suggest that computerized PA had induced changes in vision but not proprioception, and provide novel evidence that the technology induced reliable aftereffects following both hand and indirect feedback PA. The results, when considered together with the study’s strengths and weaknesses, provide insight into how future studies might assess computerized-PA can be used to explore more complex attention and space representation process in healthy-normal and patients suffering from unilateral neglect.
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Heron, James, David J. Whitaker, Paul V. McGraw, and Kirill V. Horoshenkov. "Adaptation minimizes distance-related audiovisual delays." 2007. http://hdl.handle.net/10454/3810.
Full textAbstract:
NoA controversial hypothesis within the domain of sensory research is that observers are able to use visual and auditory distance cues to maintain perceptual synchrony - despite the differential velocities of light and sound. Here we show that observers are categorically unable to utilize such distance cues. Nevertheless, given a period of adaptation to the naturally occurring audiovisual asynchrony associated with each viewing distance, a temporal recalibration mechanism helps to perceptually compensate for the effects of distance-induced auditory delays. These effects demonstrate a novel functionality of temporal recalibration with clear ecological benefits.
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Hsiao, Pao-Yueh, and 蕭寶岳. "A Plastic Cortico-Striatal Circuit Model of Optimization and Adaptation in Perceptual Decision." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/96519430055047971321.
Full textAbstract:
博士國立清華大學
生物資訊與結構生物研究所
102
Decision optimization is a crucial ability that allows animals to interact with and to adapt to changing environments. Although many decision theories have been proposed to explain the process of finding best choices or the optimal decision, we are still lack of a detailed neural network model that explains how the nervous systems achieve optimization with preference given to speed or accuracy, and how the systems adapt to changes in the environment. The present study addresses the questions by proposing an integrated model that combines dopamine-modulated synaptic plasticity and a cotico-basal ganglia circuit model for perceptual decisions. In the integrated model, the cortical module detects signals and accumulates evidence, while the basal ganglia module acts as a threshold detector by disinhibiting the superior colliculus when the upstream cortical signal exceeds a certain level. Moreover, the synaptic strength between the cortex and striatum determines the decision threshold and is modulated by reward information through the release of dopamine. Our model shows that decision optimization and adaptation could be achieved via the interaction between the dopamine system and the cotico-basal ganglia circuit. In addition, the tendency to make fast or accurate decision can be explained in our model by dynamic balancing between the facilitating and depressing components of the dopamine dynamics. Specifically, the circuit model favors speed if we increase the phasic dopamine response to the reward prediction error, whereas the model favors accuracy if we reduce the tonic dopamine activity or the phasic dopamine responses to the estimated reward probability. The proposed model provides insight into the roles of different components of dopamine responses in decision adaptation and optimization in a changing environment.
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Nian-TingYang and 楊念庭. "A(n) (in)direct support for the perceptual expertise hypothesis of FFA: neural adaptation effects on bird experts." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/dqhg6s.
Full textAbstract:
碩士國立成功大學
心理學系
107
One of the unsolved debates in the prolonged exchanges between face specificity and perceptual expertise hypothesis of FFA has been on whether the BOLD activities in FFA for objects of expertise (e.g., cars) correlate with their (car experts’) behavioral expertise. While early studies found supporting evidence, later replication attempts by other labs did not. Until today, the reasons behind these disparate expertise-FFA correlation results remain unclear. To revisit, in the current study we recruit local bird experts, and examine from the flip side of the expertise-FFA correlation: whether there is an adaptation-like negative correlation between face selectivity (faces vs. objects) and bird expertise in their FFA. 17 Taiwanese birders and 17 American birds were both evaluated with behavioral expertise index (d’), and later scanned with various tasks, including FFA localizers (Taiwan only), passive viewing, 1-back location, 1-back and 2-back identity tasks, on blocked presentations of 4 stimuli: Own-race faces, familiar birds, unfamiliar birds, and common objects. While the localizer-defined r-FFA showed insignificant FFA-expertise correlations, be they ‘birds vs. objects’ or ‘birds only’, activities on face blocks shows strong negative correlation (r32 = -.565, p 〈 .001, BF- 0 = 142.878). In addition, when separating face blocks into ‘after-birds’ vs. ‘after-objects’ conditions, the former BOLD was more reduced with higher d’, and the latter more elevated overall, together further supporting the modulation of bird expertise onto activities for faces in FFA. Complementary whole-brain correlations with “faces vs. objects” contrasts showed adjacent right fusiform gyrus (rFG) regions, negatively d’-correlated, across all 4 tasks, whereas the “birds vs. objects” contrast showed positive rFG clusters only in PV and 1bID tasks, together suggesting the critical importance of choosing faces, not birds (or any other objects of expertise), as the target of the expertise-FFA correlation, for better chance of significance and localizer optimality. To conclude, our results provide clues to the mixed expertise-FFA correlation results, and demonstrate the face-bird interactions in rFG as further support of the Flexibility of mid-Fusiform Area (FFA, Tarr and Gauthier, Journal of cognitive neuroscience, 12(3), 495-504, 2000)
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Aubrais, Valérie. "Adaptation aux changements induits aux indices spectraux de l’audition spatiale chez l’humain." Thèse, 2013. http://hdl.handle.net/1866/10615.
Full textAbstract:
Dans le cas de perte auditive, la localisation spatiale est amoindrie et vient entraver
la compréhension de la parole et ce, malgré le port de prothèses auditives. La
présente étude modifie la forme de l’oreille externe d’individus à l’aide de silicone
afin d’induire des changements aux indices spectraux (HRTFs), similaires à ceux
causés par des prothèses auditives, et d’explorer les mécanismes perceptifs (visuel,
spectral, ou tactile) permettant d’alterner d’un nouvel ensemble à l’ensemble
originel de HRTFs une fois les prothèses enlevées. Les résultats démontrent que
les participants s’adaptent aux nouveaux HRTFs à l’intérieur de quatre séances
d’entraînement. Dès le retrait des prothèses, les participants reviennent à leur
performance originale. Il n’est pas possible de conclure avec les données présentes
si le changement d’un ensemble de HRTFs à un autre est influencé par un des
mécanismes de rétroaction perceptuelle étudié. L’adaptation aux prothèses perdure
jusqu’à quatre semaines après leur retrait.Spatial hearing contributes greatly to speech understanding in noisy environments. Hearing aids disturb all of the acoustic cues necessary for accurate sound localization and thus negate some of their benefits. This study addressed behavioral adaptation to changes in auditory spatial cues caused by changes similar to those induced by hearing aids. Spectral cues (HRTFs) were distorted by changing the shape of the outer ear with silicon molds. The present experiment was aimed at determining the perceptual modalities (visual, spectral or tactile) that might enable the switch from the modified to the original HRTFs once the molds were removed. Results indicate that participants were able to adapt within four training sessions. Participants immediately showed accurate sound localization when ear molds were removed. It was not possible to conclude whether the perceptual feedbacks had a major impact on the choice of the correct set of HRTFs to use. Adaptation to the modified HRTFs lasted weeks after their removal.
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Roy, Emmanuelle. "Le champ perceptuel du bien-être des frères et sœurs d'enfants diabétiques." Thèse, 2007. http://www.archipel.uqam.ca/748/1/D1595.pdf.
Full textAbstract:
Les frères et soeurs d'enfants atteints d'une maladie chronique doivent souvent composer avec des contraintes exigeantes, parfois nombreuses. De plus en plus de chercheurs s'intéressent à leur situation, particulièrement sous l'angle des problèmes qu'ils rencontrent (Berge & Patterson, 2004; Drotard & Crawford, 1985; Lobato, Faust, & Spirito, 1988). Cependant, les répercussions de la maladie sur les frères et soeurs ont surtout été examinées du point de vue des parents, ignorant les perceptions des principaux intéressés. Le diabète insulino-dépendant est une des principales maladies chroniques des enfants canadiens (Hanvey, Avard, Graham, Underwook, Campbell, & Kelly, 1994). Les symptômes physiques, de même que les soins qu'imposent le diabète, en interférant dans plusieurs aspects de la vie quotidienne des enfants atteints, ont immanquablement des effets sur leurs frères et soeurs et sur leurs parents (Barlow & Ellard, 2006). La présente étude vise à mieux comprendre ce que vivent les frères et soeurs d'enfants diabétiques en leur donnant la parole, et en faisant de la place au bien-être dans l'examen de leur expérience. Dans une optique de psychologie positive, la présente étude s'inspire de la théorie du champ perceptuel (Combs, Richards, & Richards, 1976) et de l'approche écologique du développement humain (Bronfenbrenner, 1979). Les objectifs de l'étude consistent à (a) décrire le champ perceptuel des enfants en matière d'adaptation au diabète de leur frère ou soeur en abordant les répercussions tant positives que négatives pouvant survenir, (b) analyser les perceptions des frères et soeurs quant aux échanges familiaux favorables au bien-être (Jutras, Normandeau, & Kalnins, 1997): comportements d'assistance, relations interpersonnelles positives, promotion de saines habitudes de vie, actes thérapeutiques, et (c) examiner les variations éventuelles dans les perceptions des enfants en fonction de variables individuelles ou familiales (genre, âge, revenu familial, durée du diabète, etc.).
Des entrevues individuelles semi-structurées ont été menées auprès de 55 frères et soeurs (8 à 17 ans) d'un enfant diabétique. Leurs réponses ont fait l'objet d'une analyse de contenu classique (L'Écuyer, 1990) avec accords interjuges. L'analyse révèle que les enfants ont une conception du diabète relativement élaborée: ils le décrivent en abordant les soins nécessaires et les contraintes engendrées, fournissant même des explications médicales. Si les enfants identifient plusieurs conséquences négatives à la maladie (contraintes dans l'alimentation et les activités, attention parentale accrue accordée à l'enfant diabétique), ils rapportent aussi leurs principales stratégies pour les affronter: tenter de conserver un bon moral et exprimer leurs besoins à leurs parents. Les enfants se montrent sensibles à ce que vivent leurs parents et sont capables d'identifier des conséquences positives du diabète dans leur vie. Les frères et soeurs se perçoivent comme des acteurs de bien-être pour l'enfant diabétique. Le soutien et le développement personnel émergent comme perspectives dominantes dans le champ perceptuel des enfants quant à leur adaptation à la maladie.
L'analyse des perceptions des enfants quant aux échanges familiaux favorables au bien-être selon l'approche de Jutras & al. (1997) indique que les comportements d'assistance et les relations interpersonnelles positives dominent. Globalement, il y a symétrie ou concordance dans les perceptions des types d'actions offertes et reçues par l'enfant, sauf pour la promotion de saines habitudes de vie avec la mère et les actes thérapeutiques avec l'enfant diabétique. L'analyse de la balance des échanges fait ressortir un surplus avec chaque parent, et un déficit avec l'enfant diabétique. L'analyse plus détaillée de la réciprocité souligne cependant que les frères et soeurs perçoivent l'apport de l'enfant diabétique à leur bien-être affectif. Les perceptions des enfants varient peu en fonction des variables examinées, sauf en ce qui concerne leur position de cadet ou d'aîné de l'enfant diabétique. Cette étude révèle l'importance particulière qu'occupent le soutien et le développement personnel dans le champ perceptuel des frères et soeurs d'enfants malades, suggérant qu'ils les associent dans un processus d'adaptation qui leur conférerait un sentiment de compétence et de valorisation. Les enfants se reconnaissent un rôle dans les soins de leur frère ou soeur diabétique et identifient la contribution de ce dernier à leur propre bien-être. Ils illustrent ainsi des mécanismes par lesquels l'acceptation de la situation, l'autocontrôle et l'altruisme peuvent se conjuguer pour faire de l'expérience des frères et soeurs d'un enfant malade une opportunité de croissance. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Bien-être, Fratrie, Diabète de type 1, Adaptation, Enfants.