The purpose of this thesis is to study how to overcome difficulties one typically encounters when solving non-negative inverse problems by standard Krylov subspace methods. We first give a theoretical background to the non-negative inverse problems. Then we concentrate on selected modifications of Krylov subspace methods known to improve the solution significantly. We describe their properties, provide their implementation and propose an improvement for one of them. After that, numerical experiments are presented giving a comparison of the methods and analyzing the influence of the present parameters on the behavior of the solvers. It is clearly demonstrated, that the methods imposing nonnegativity perform better than the unconstrained methods. Moreover, our improvement leads in some cases to a certain reduction of the number of iterations and consequently to savings of the computational time while preserving a good quality of the approximation.

The present study investigates the use of impoliteness in American presidential debates, analyzing whether the use of impoliteness strategies has increased, whether this varies depending on the candidate’s status as an incumbent or a challenger and if Donald Trump is an outlier when compared to his peers. To conduct this study, a total of 12 debates from the last 6 elections (2000-2020) were analyzed. The analysis used Culpeper’s (1996) framework as its base, specifically looking at the frequency and variability in the usage of face-attacks along with a set of output/micro-strategies from Garcia-Pastor (2008) typically used in the primary presidential debates as well as instances of overlaps and interruptions. The results showed, based on nearly all of the measured variables, that there was a significant increase in the 2016 and the subsequent 2020 debates when compared to the preceding ones. Furthermore, there were clear differences found in the incumbent presidents’ strategy choice and frequency when compared to their opponents as the former would typically be more defensive, using less impoliteness. Trump strayed from this established pattern by being vastly more aggressive than his incumbent predecessors. He additionally scored the highest in nearly all of the measured variables, this, in conjunction with the noticeable difference in his use of overlapping speech, as well as direct face-attacks, leads to the conclusion that he is an outlier in his use of impoliteness and a likely catalyst for the increase seen in the 2016-2020 debates.

Spoken language is produced with a great deal of variability with which listeners must be able to cope. One source of variation is coarticulation, which is due to articulatory planning and transitions between segments. Recently, the temporal features of coarticulation were investigated during a picture/spoken-word matching task by using spliced stimuli carrying either congruent or incongruent subphonemic cues at the CV juncture (Archibald & Joanisse, 2011). ERPs were recorded with attention paid to the phonological mapping negativity (PMN) (Connolly & Phillips, 1994; Newman & Connolly, 2004) – a prelexical response sensitive to violations of phonological expectations. Results found that the PMN varied in response to coarticulation violations and concluded that phonetic features in spoken words influence prelexical processing during word recognition. Using a written-/spoken-word paradigm, Arbour, 2012 controlled phonological shape by using onsets that were either fricatives or stops, hypothesizing that coarticulatory information would be differentially processed due to their temporal differences. Findings supported the PMN’s sensitivity to coarticulation but also showed that temporal and physical differences between onsets modulated the effect. These results raise the question of whether acoustic distance between vowels will modulate prelexical processing of speech as reflected by the PMN amplitude: the focus of the current study. Words were organized into minimal sets such that all onset/coda combinations appeared with each vowel provided that English words resulted. Vowels were one of /i, u, æ, ɑ/, maximizing acoustic distance (height and backness). Data from 20 subjects indicate that the PMN is sensitive to the degree of difference between the original and post-splice vowels. When the number of distinctive features changing is greater, the result is an earlier, more robust PMN. This suggests that the rate of speech recognition is not static but dynamic, and is dependent on likeness of subphonemic features. / Thesis / Master of Science (MSc)

Previous studies have found that behavioral and P300 responses to speech are influenced by linguistic cues in the stimuli. Research has found conflicting data regarding the influence of phonemic characteristics of stimuli in the mismatch negativity (MMN) response. The current investigation is a replication of the study designed by Tampas et al. (2005), which studied the effects of linguistic cues on the MMN response. This current study was designed to determine whether the MMN response is influenced by phonetic or purely acoustic stimuli, and to expand our knowledge of the scalp distribution of processing responses to within- and across-category speech and nonspeech stimuli. The stimuli used in this study consisted of within-category synthetic speech stimuli and corresponding nonspeech frequency glides. Participants consisted of 21 (11 male and 10 female) adults between the ages of 18 and 30 years. A same/different discrimination task was administered to all participants. Data from behavioral responses and event-related potentials (MMN and P300) were recorded. Results provided additional evidence that the MMN response is influenced by linguistic information. MMN responses elicited by the nonspeech contrasts had more negative peak amplitudes and longer latencies than MMN responses elicited by speech contrasts. Brain maps of t scores for speech vs. nonspeech contrasts showed significant differences in areas of cognitive processing for all contrast pairs over the left hemisphere near the temporal and parietal areas. The present investigation confirms that there are significant differences in the cortical processing of speech sounds vs. nonspeech sounds.

The mismatch negativity (MMN) response, a passively-elicited component of the auditory event-related potential (ERP), reflects preattentive identification of infrequent changes in acoustic stimuli. In the current study, the MMN response was examined closely to determine what extent natural speech sounds evoke the MMN. It was hypothesized that a significant MMN response results during the presentation of deviant stimuli from which spectral energy within formant bands critical to vowel identification has been removed. Localizations of dipoles within the cortex were hypothesized to yield information pertaining to the processing of formant-specific linguistic information. A same/different discrimination task was administered to 20 adult participants (10 female and 10 male) between the ages of 18 and 26 years. Data from behavioral responses and ERPs were recorded. Results demonstrated that the MMN may be evoked by natural speech sounds. Grand-averaged brain maps of ERPs created for all stimulus pairs showed a large preattentive negativity. Additionally, amplitudes of the MMN were greatest for pairs of auditory stimuli in which spectral energy not corresponding to formant frequencies was digitally eliminated. Dipoles reconstructed from temporal ERP data were located in cortical areas known to support language and auditory processing. Significant differences between stimulus type and reaction time were also noted. The current investigation confirms that the MMN response is evoked by natural speech sounds and provides evidence for a theory of preattentive formant-based processing of speech sounds.

Moderate-to-severe traumatic brain injury (M/S TBI) can affect an individual's ability to perform daily tasks. For example, individuals with M/S TBI are more likely to commit errors on tasks such as making a meal or wrapping a present. The neural processes involved in such errors are poorly understood. Studies suggest that neurophysiologic markers of cognitive control and error processing may be helpful in gaining additional insight into errors on naturalistic action tasks. Unfortunately, previous experimental methods left a methodological gap which limited the use of neurophysiological markers in the study of naturalistic action. Several recent studies in healthy adults have suggested one method of bridging the gap by having individuals observe another person's errors. The current study was the first study to employ the method in a TBI population as a possible means of gaining additional insight into the detrimental effects of M/S TBI on the performance of naturalistic actions. In order to gain additional insight into the effects of M/S TBI on the completion of naturalistic tasks I used two neurophysiologic markers of cognitive control and error processing. They were the observer error related negativity (oERN) and the P300 components of the scalp-recorded event-related potential (ERP). I hypothesized that individuals with M/S TBI would demonstrate error-specific changes in the two oERN and P300 that would correlate with self-reported difficulties in daily functioning. The study consisted of two experiments. One compared 15 individuals with M/S TBI to 17 demographically similar healthy controls on an error related naturalistic action based picture task. The second compared an overlapping sample of 16 individuals with M/S TBI to 16 demographically similar controls as they watched a confederate complete the Erikson flanker task, a commonly used task in the study of electrophysiological markers. Accuracy (error vs. correct) and group (M/S TBI vs. control) effects were analyzed using 2 x 2 repeated measures ANOVAs on ERP amplitude and latency. Pearson product-moment correlations were calculated to evaluate the relationship between the P300 and oERN and measures of self-reported executive functioning (Frontal Systems Behavior Scale, FrSBe) and neuropsychological measures. Findings supported a difference between the control and M/S TBI groups in how errors were processed during the naturalistic actions based picture task. There was an interaction between group membership and response accuracy (error vs. correct) on P300 amplitude and P300 latency. Controls demonstrated reduced P300 amplitude and latency on error trials compared to correct trials. Individuals with M/S TBI did not demonstrate a significant difference between correct trials and error trials on P300 amplitude and latency. The amplitude and latency of the P300 were correlated with self-reported functional difficulties in individuals with M/S TBI but not control participants. A Fisher's r -- z analysis indicated that correlations differed significantly between groups; however, an outlier was identified in the correlational data. Removal of the outlier data led to non-significant results in the Fisher's r -- z analysis. Taken together, results of the picture task supplied evidence that for individuals with M/S TBI differences in neurophysiologic markers between groups could be explained by reduced adaptation to complexity or by possible deficits in a secondary error processing pathway for complex errors. Future research could focus on better defining the functional relationship between P300 amplitude and latency and increased errors in naturalistic actions following M/S TBI. Observation of the flanker task did not elicit oERN waveforms from either healthy controls or from individuals with M/S TBI. The results could be due to problems with the current task, but also raised some concerns about previous studies using the flanker task which employed a slightly different methodology requiring participants to count errors. The current study did not require participant to count errors. As a whole, the study supplied partial support for using electrophysiological markers of error processing to gain additional understanding increased errors in the performance of naturalistic actions following M/S TBI.

The human brain is highly responsive to (deviant) sounds violating an auditory regularity. Respective brain responses are usually investigated in situations when the sounds were produced by the experimenter. Acknowledging that humans also actively produce sounds, the present event-related potential study tested for differences in the brain responses to deviants that were produced by the listeners by pressing one of two buttons. In one condition, deviants were unpredictable with respect to the button-sound association. In another condition, deviants were predictable with high validity yielding correctly predicted deviants and incorrectly predicted (mispredicted) deviants. Temporal principal component analysis revealed deviant-specific N1 enhancement, mismatch negativity (MMN) and P3a. N1 enhancements were highly similar for each deviant type, indicating that the underlying neural mechanism is not affected by intention-based expectation about the self-produced forthcoming sound. The MMN was abolished for predictable deviants, suggesting that the intention-based prediction for a deviant can overwrite the prediction derived from the auditory regularity (predicting a standard). The P3a was present for each deviant type but was largest for mispredicted deviants. It is argued that the processes underlying P3a not only evaluate the deviant with respect to the fact that it violates an auditory regularity but also with respect to the intended sensorial effect of an action. Overall, our results specify current theories of auditory predictive processing, as they reveal that intention-based predictions exert different effects on different deviance-specific brain responses.

The auditory system is able to recognize auditory objects and is thought to form predictive models of them even though the acoustic information arriving at our ears is often imperfect, intermixed, or distorted. We investigated implicit regularity extraction for acoustically intact versus disrupted six-tone sound patterns via event-related potentials (ERPs). In an exact-repetition condition, identical patterns were repeated; in two distorted-repetition conditions, one randomly chosen segment in each sound pattern was replaced either by white noise or by a wrong pitch. In a roving-standard paradigm, sound patterns were repeated 1–12 times (standards) in a row before a new pattern (deviant) occurred. The participants were not informed about the roving rule and had to detect rarely occurring loudness changes. Behavioral detectability of pattern changes was assessed in a subsequent behavioral task. Pattern changes (standard vs. deviant) elicited mismatch negativity (MMN) and P3a, and were behaviorally detected above the chance level in all conditions, suggesting that the auditory system extracts regularities despite distortions in the acoustic input. However, MMN and P3a amplitude were decreased by distortions. At the level of MMN, both types of distortions caused similar impairments, suggesting that auditory regularity extraction is largely determined by the stimulus statistics of matching information. At the level of P3a, wrong-pitch distortions caused larger decreases than white-noise distortions. Wrong-pitch distortions likely prevented the engagement of restoration mechanisms and the segregation of disrupted from true pattern segments, causing stronger informational interference with the relevant pattern information

L’objectif de ce travail était d’examiner la spécificité fonctionnelle du traitement et des représentations des hauteurs musicales. À cette fin, ce traitement a été comparé à celui des phonèmes de la parole, d’une part, et aux associations spatiales évoquées par des séquences ordonnées, d’autre part. Nos quatre études avaient pour point commun d’adapter à un nouvel objet de recherche des méthodes bien établies en psychologie cognitive. Ainsi, nous avons exploité la tâche de classification accélérée (Etude 1) de Garner (1974), l’analyse des conjonctions illusoires en mémoire (Etude 2), l’additivité de la composante mismatch negativity (MMN) des potentiels évoqués (Etude 3) et l’observation d’associations spatiales de codes de réponse (Etude 4). Les trois premières études, menées chez des participants non-musiciens, portaient sur la spécificité de traitement des hauteurs par rapport à celui des phonèmes au sein de stimuli chantés. Les deux premières études ont mis en évidence un effet surprenant de la nature des phonèmes sur leurs interactions avec le traitement des mélodies : les voyelles apparaissaient plus intégrées à la mélodie que les consonnes. Ceci était vrai à la fois lors du traitement en temps réel de non-mots chantés (Etude 1) et au niveau des traces en mémoire de ces mêmes non-mots (Etude 2, utilisant une tâche de reconnaissance à choix forcé permettant la mise en évidence de conjonctions illusoires). Cette dissociation entre voyelles et consonnes quant à leur intégration avec les traitements mélodiques ne semblait pas causée par des caractéristiques acoustico-phonétiques telles que la sonorité. Les résultats de la troisième étude indiquaient que les MMNs en réponse à des déviations de hauteur et de voyelle n’étaient pas additives et que leur distribution topographique ne différait pas selon le type de déviation. Ceci suggère que, même au niveau pré-attentionnel, le traitement des voyelles n’est pas indépendant de celui des hauteurs. Dans la quatrième étude, nous avons comparé le traitement des hauteurs musicales à un autre domaine : la cognition spatiale. Nous avons ainsi montré que les non-musiciens comme les musiciens associent les notes graves à la partie inférieure et les notes aiguës à la partie supérieure de l’espace. Les deux groupes liaient aussi les notes graves au côté gauche et les notes aiguës au côté droit, mais ce lien n’était automatique que chez les musiciens. Enfin, des stimuli musicaux plus complexes (intervalles mélodiques) n’évoquaient ces associations spatiales que chez les musiciens et ce, uniquement sur le plan horizontal. Ces recherches contribuent de plusieurs manières à la compréhension de la cognition musicale. Premièrement, nous avons montré que les consonnes et les voyelles diffèrent dans leurs interactions avec la musique, une idée à mettre en perspective avec les rôles différents de ces phonèmes dans l’évolution du langage. Ensuite, les travaux sur les représentations spatiales des hauteurs musicales ouvrent la voie à un courant de recherche qui aidera à dévoiler les liens potentiels entre habiletés musicales et spatiales. / The purpose of this work was to examine the functional specificity of musical pitch processing and representation. To this aim, we compared musical pitch processing to (1) the phonological processing of speech and (2) the spatial associations evoked by ordered sequences. The four studies described here all use classical methods of cognitive psychology, which have been adapted to our research question. We have employed Garner’s (1974) speeded classification task (Study 1), the analysis of illusory conjunctions in memory (Study 2), the additivity of the mismatch negativity (MMN) component of event-related potentials (Study 3), as well as the observation of spatial associations of response codes (Study 4). The three first studies examined, in non-musician participants, the specificity of pitch processing compared to phoneme processing in songs. Studies 1 and 2 revealed a surprising effect of phoneme category on their interactions with melodic processing: vowels were more integrated with melody than were consonants. This was true for both on-line processing of sung nonwords (Study 1) and for the memory traces of these nonwords (Study 2, using a forced-choice recognition task allowing the occurrence of illusory conjunctions). The difference between vowels and consonants was not due to acoustic-phonetic properties such as phoneme sonority. The results of the third study showed that the MMN in response to pitch and to vowel deviations was not additive and that its brain topography did not differ as a function of the kind of deviation. This suggests that vowel processing is not independent from pitch processing, even at the pre-attentive level. In the fourth study, we compared pitch processing to another domain: spatial cognition. We showed that both musicians and non-musicians map pitch onto space, in that they associate low-pitched tones to the lower spatial field and high-pitched tones to the higher spatial field. Both groups of participants also associated low pitched-tones with the left and high-pitched tones with the right, but this association was automatic only in musicians. Finally, more complex musical stimuli such as melodic intervals evoked these spatial associations in the horizontal plane only in musicians. This work contributes to the understanding of music cognition in several ways. First, we have shown that consonants and vowels differ in their interactions with music, an idea related to the contrasting roles of these phonemes in language evolution. Second, the work on the spatial representation of pitch opens the path to research that will help uncover the potential links between musical and spatial abilities.

Il est peu de notions aussi vastes que celle du non-savoir, mais le flou du caractère nécessairement négatif de sa définition s’accompagne tout de même du sentiment que la source de ce qui ne peut qu’être déterminé négativement par la pensée (non, cela n’est pas le savoir) ne peut qu’être positive. Notion à l’applicabilité infinie, parce qu’en elle vient s’abîmer tout ce qui ne peut tenir dans l’espace de la maîtrise relative à ce dont on peut dire : je sais de quoi il s’agit. Est non-savoir tout ce qui se rapporte au bouillonnement pulsionnel de la vie et à l’échéance fatale de la mort. Ce qui pousse l’homme au meurtre, au génocide, à la guerre et à la violence révolutionnaire se confond avec un contenu affectif et identitaire qui ne peut être ramené au savoir sans laisser de reste. Mais tenter de comprendre ce qui échappe à l’entendement est cela même qui relance sans cesse la réflexion comprise comme cœur du savoir. Le savoir se montre ainsi sous une extrême dépendance face à son Autre. À la lumière de cette hypothèse devant beaucoup aux découvertes de la psychanalyse, le présent mémoire s’est donné pour objectif de jeter un regard frais sur quelques grandes tensions sociopolitiques de l’Histoire; mais il a d’abord fallu évaluer philosophiquement la possibilité d’un concept de non-savoir. Des champs identitaires majeurs — révolutions totalitaires ou démocratiques, bouleversements ou synergies culturelles — sont ainsi analysés sous l’angle d’une économie pulsionnelle qui s’inscrit dans une interaction perpétuelle avec ce qui s’ébauche ici comme une économie du rapport entre non-savoir et savoir. Est ainsi produite une esquisse des rapports possibles entre la vie pulsionnelle de l’homme, le savoir institutionnel et le monde sociopolitique. / Few notions are as vast as that unknowing; but the imprecise nature of its definition is nonetheless accompagnied by the implication that what offers itself only negatively to the mind has a positive source. The applicability of the notion of unknowing is infinite; it swallows up all that resists the mastery indicated by statements about that which is. Unknowing encompasses all that belongs to the boiling drive of life and to the faceless moment of death. What leads human beings to murder, to genocide, to war and to revolutionnary violence is bound up with an affective content of identification that cannot be subsumed by knowledge without leaving a residue. Yet attempting to understand what exceeds the mind’s grasp serves as the motor of mental reflection at the heart of knowledge production itself. In this sense, knowledge is inescapably dependent on its « other ». In light of this hypothesis drawn from the domain of psychoanalysis, this thesis aims to reexamine the conceptual underpinnings of basic sociopolitical tensions in History. The conceptual impetus driving major identity movements — such as totalitarian or democratic revolutions and cultural disruptions or synergies — is analysed in terms of a libidinal or drive-oriented economy which is in perpetual interaction with what this thesis characterizes as an economy of the relation between knowing and unknowing, between knowledge and its negation.