What are the effects of non-balanced bilingualism on cognitive performance? And how do proficient, non-native speakers acquire and use lexical, syntactic and semantic information during sentence processing? Whilst there is growing research on these topics, there is no firm consensus on how to answer these questions. In the literature on cognitive effects of bilingualism, this lack of consensus has even resulted in radically opposing views and a heated debate. In this thesis, I seek to provide a balanced treatment of the literature and to address the above-mentioned questions by employing behavioral and neurophysiological paradigms. First, using a structural priming paradigm, I examine how proficient, non-native speakers of different native language backgrounds (Romance and Germanic) acquire lexically-specific syntactic restrictions of non-alternating verbs in English. Results from these experiments suggest that, although non-native speakers partially acquire lexically-specific syntactic restrictions, their knowledge is not native-like. Moreover, transfer from the first language does not seem to play a role in the acquisition of the relevant restrictions. Second, using Event-Related Potentials (ERPs) I examine whether proficient non-native Spanish-English speakers draw on different forms of semantic information such as relatedness and animacy incrementally during sentence comprehension. Results of these experiments suggest that, while relatedness facilitates processing (indexed by N400s) in both native and non-native speakers, effects of animacy are smaller in non-native speakers, relative to native speakers. Third, I employ a series of auditory attentional tasks and measures of lexical access and verbal fluency to assess cognitive functions in non-balanced bilinguals with different levels of language proficiency. Results show a bilingual advantage in inhibitory control and a non-significant trend towards bilingual better performance in attentional switching, and the groups exhibit similar performance on verbal fluency. Results of all the studies are discussed in the context of the existing literature on cognitive performance in bilinguals and accounts of language processing in native and non-native speakers and suggestions for future research are provided.

The aim of the current series of experiments was to further explore the boundary conditions of the recognition memory old/new effect in the context of the recognition/associative recall task (Rugg, Schloerscheidt, Doyle, Cox, & Patching, 1996). The study by Rugg et al. was replicated and extended by manipulating both the semantic relatedness between study items and the timing of recall. Eventrelated potentials (ERPs) were recorded from 17 scalp electrode sites during performance of a recognition/associative recall task. Forty participants were visually presented with four blocks of 50 word pairs which were either unrelated (Experiments 1 and 2) or weakly semantically related (Experiments 3 and 4). Participants were instructed to form an association between the members of each word pair. At test, the first members of each pair were visually presented intermixed with a similar number of unstudied items. Participants were required to discriminate (i.e., recognise) previously studied items (old) from new items. Participants were also required to recall the study associate for words judged old, and to provide confidence levels for each recognition decision on a 3-point scale. Recall was either immediate (Experiments 1 and 3) or delayed (Experiments 2 and 4). Relative to ERPs to new items, the ERPs elicited by words correctly recognised and for which the associate was correctly recalled exhibited a positive-going shift between 500-800 ms poststimulus onset. The effect was maximal at posterior temporal-parietal electrode sites (the parietal old/new effect). Although the effect was not lateralised to the left hemisphere, this result may be due to the variability in encoding strategies employed by the participants. Behavioural data consistently indicated that response confidence is confounded with response category. The ERP results also revealed that the old/new effect is not evident following the experimental control of response confidence, and that immediate recall is associated with a negative-going shift at posterior electrode sites between 800-1100 ms poststimulus onset. Manipulating the semantic relatedness between the word pairs did not influence the distribution of the old/new effect. The results are discussed in terms of the view that the parietal old/new effect reflects neural activity associated with the recollection of specific previous experiences, and may reflect retrieval processes supported by the medial temporal lobe memory system (Moscovitch, 1992, 1994; Squire, 1992; Squire, Knowlton, & Musen, 1993). It is suggested that future research extend the current findings by examining the influence of response confidence in alternative recognition memory paradigms.

The electroencephalogram (EEG) reflects summated, slow post-synaptic potentials of cortical neurons. Sensory, motor or cognitive events (such as a fast-rising sensory stimulus, a brisk self-paced movement or a stimulus-triggered cognitive task) can elicit transient changes in the ongoing human EEG, called event-related potentials (ERPs). ERPs are widely used in clinical practice, and believed to reflect the activity of the sensory system activated by the stimulus (for example, laser-evoked potentials are used to substantiate the neuropathic nature of clinical pain conditions). When ERPs are elicited by pairs or trains of stimuli delivered at short inter-stimulus intervals (ISIs), the magnitude of the ERP elicited by the repeated stimuli is markedly reduced, a phenomenon known as response decrement. While the interval between two consecutive stimuli becomes longer, the reduced response is recovered. Thus, this phenomenon has been traditionally interpreted in terms of neural refractoriness of generators of ERPs ("neural refractoriness hypothesis"). This thesis, however, challenges this neural refractoriness hypothesis by describing the results of manipulating the preceding events of the eliciting stimulus. The first study examined the effect of variable and short ISIs on sensory ERPs, delivering trains of auditory and electrical stimuli with random ISIs ranging from 100 to 1000ms. In the second study, pairs of laser stimuli were presented in two comparable conditions. In the constant condition, the ISI was identical across trials in each block, while in the variable condition, the ISI was variable across trials. By directly comparing ERPs elicited by laser stimulation, this study aimed to explore whether lack of saliency in the eliciting stimulus could explain the response decrement during stimulus repetition. Finally, the third study tested the hypothesis that the reduced eliciting ERPs would recover if saliency were introduced by changing the modality of the preceding event. Thus, trains of three stimuli (S1-S2-S3) with 1s ISI were presented; S2 was either same or different in modality as S1 and S3 in each block. Results from these three experiments demonstrate that this "refractoriness hypothesis" does not hold, and suggest that the magnitude of ERPs is only partly related to the magnitude of the incoming sensory input, and instead largely reflects neural activities triggered by salient events in the sensory environment. These results are important for the correct interpretation of ERPs in both physiological and clinical studies.

The direction in which another is looking at triggers a spontaneous orienting of attention towards gaze direction in the viewer. However, whether the facial expression displayed by the gazing individual modulates this attention orienting is unclear. In this thesis, the modulation of gaze-oriented attention with facial expressions was explored in non-anxious individuals at the behavioral level and at the neural level using Event-Related Potentials (ERP). In the gaze-cueing paradigm used, a dynamic face cue averting gaze and expressing an emotion was presented, followed by a lateral, to-be-localized target. At the behavioral level, a faster response to targets appearing at the gazed-at location (congruent targets) than to targets appearing opposite to the gazed-at location (incongruent targets) was observed (Chapters 3-5). This so-called Gaze Orienting Effect (GOE) was enhanced with fearful, angry and surprised expressions relative to neutral and happy expressions and was driven by emotional differences in response speed to congruent targets (Chapters 3-5). These effects could not be attributed to better discrimination of those emotions when presented with an averted gaze (Chapter 2). These results confirm the impact of fear and surprise on gaze-oriented attention in non-anxious individuals and demonstrate, for the first time, a similar impact for angry expressions. All the emotions enhancing the GOE signal an evolutionary relevant stimulus in the periphery, are threat-related and carry a negative valence, which suggests that one of these attributes (or all combined) is driving the emotional modulation of gaze-oriented attention (surprise is treated like fear in the context of fearful expressions). In Chapter 4, the effect of the dynamic cue sequence on these GOE modulations was investigated. An emotional modulation of the GOE was found only when the gaze shift preceded the emotional expression, but not when the emotion was expressed before gaze shift or when expression and gaze shift were simultaneous. These results highlight the importance of using a sequence closer to real life situations (we usually orient attention before reacting to an object in the environment) in studying the modulation of the GOE with emotions. At the neural level, we investigated the ERPs associated with gaze-oriented attention at target presentation and at cue presentation (Chapters 3 and 5). Confirming previous reports, the amplitude of a target-triggered P1 ERP component was larger in the congruent than in the incongruent condition, reflecting enhanced processing of gaze-congruent targets. In addition, cue-triggered ERPs previously observed in response to arrow cues, were investigated. An Early Directing Attention Negativity (EDAN) and an Anterior Directing Attention Negativity (ADAN) were found, indexing respectively attention-orienting to the cued location and maintenance of attention at the cued location. This is the first study to report both EDAN and ADAN components in response to gaze cues. These results show clear markers of attention orienting by gaze at the neural level, during both cue and target processing. Neither EDAN nor ADAN was modulated by emotion. The congruency effect on P1 was enhanced for fearful, surprised and happy faces compared to neutral faces in Chapter 3 but no differences between the emotions were found in Chapter 5. Thus, the emotional modulation of the brain processes involved in gaze-oriented attention is very weak and protracted or occurs mainly between target onset and response to target. The relationships between participants’ autistic traits and their emotional modulation of gaze-oriented attention were also investigated. Results showed a negative correlation with the GOE to happy upright faces and with the P1 congruency effect, which suggests that individuals with more severe autistic traits are less sensitive to the impact of social emotions like joy. The implication of these results for attention orienting in general and for individuals with Autism Spectrum Disorder is discussed. Together, the findings reported in this thesis clarify the behavioral and neural processes involved in gaze oriented attention and its modulation by facial expression in addition to demonstrating a relationship between gaze oriented attention, its modulation with social emotions and autistic traits.

The direction in which another is looking at triggers a spontaneous orienting of attention towards gaze direction in the viewer. However, whether the facial expression displayed by the gazing individual modulates this attention orienting is unclear. In this thesis, the modulation of gaze-oriented attention with facial expressions was explored in non-anxious individuals at the behavioral level and at the neural level using Event-Related Potentials (ERP). In the gaze-cueing paradigm used, a dynamic face cue averting gaze and expressing an emotion was presented, followed by a lateral, to-be-localized target. At the behavioral level, a faster response to targets appearing at the gazed-at location (congruent targets) than to targets appearing opposite to the gazed-at location (incongruent targets) was observed (Chapters 3-5). This so-called Gaze Orienting Effect (GOE) was enhanced with fearful, angry and surprised expressions relative to neutral and happy expressions and was driven by emotional differences in response speed to congruent targets (Chapters 3-5). These effects could not be attributed to better discrimination of those emotions when presented with an averted gaze (Chapter 2). These results confirm the impact of fear and surprise on gaze-oriented attention in non-anxious individuals and demonstrate, for the first time, a similar impact for angry expressions. All the emotions enhancing the GOE signal an evolutionary relevant stimulus in the periphery, are threat-related and carry a negative valence, which suggests that one of these attributes (or all combined) is driving the emotional modulation of gaze-oriented attention (surprise is treated like fear in the context of fearful expressions). In Chapter 4, the effect of the dynamic cue sequence on these GOE modulations was investigated. An emotional modulation of the GOE was found only when the gaze shift preceded the emotional expression, but not when the emotion was expressed before gaze shift or when expression and gaze shift were simultaneous. These results highlight the importance of using a sequence closer to real life situations (we usually orient attention before reacting to an object in the environment) in studying the modulation of the GOE with emotions. At the neural level, we investigated the ERPs associated with gaze-oriented attention at target presentation and at cue presentation (Chapters 3 and 5). Confirming previous reports, the amplitude of a target-triggered P1 ERP component was larger in the congruent than in the incongruent condition, reflecting enhanced processing of gaze-congruent targets. In addition, cue-triggered ERPs previously observed in response to arrow cues, were investigated. An Early Directing Attention Negativity (EDAN) and an Anterior Directing Attention Negativity (ADAN) were found, indexing respectively attention-orienting to the cued location and maintenance of attention at the cued location. This is the first study to report both EDAN and ADAN components in response to gaze cues. These results show clear markers of attention orienting by gaze at the neural level, during both cue and target processing. Neither EDAN nor ADAN was modulated by emotion. The congruency effect on P1 was enhanced for fearful, surprised and happy faces compared to neutral faces in Chapter 3 but no differences between the emotions were found in Chapter 5. Thus, the emotional modulation of the brain processes involved in gaze-oriented attention is very weak and protracted or occurs mainly between target onset and response to target. The relationships between participants’ autistic traits and their emotional modulation of gaze-oriented attention were also investigated. Results showed a negative correlation with the GOE to happy upright faces and with the P1 congruency effect, which suggests that individuals with more severe autistic traits are less sensitive to the impact of social emotions like joy. The implication of these results for attention orienting in general and for individuals with Autism Spectrum Disorder is discussed. Together, the findings reported in this thesis clarify the behavioral and neural processes involved in gaze oriented attention and its modulation by facial expression in addition to demonstrating a relationship between gaze oriented attention, its modulation with social emotions and autistic traits.

In infancy, the ability to tell the difference between two faces within a category (e.g., species, race) that is infrequently experienced declines from 6 to 9 months of age (Kelly et al., 2009, 2007; Pascalis et al., 2005; Pascalis, de Haan, & Nelson, 2002; Scott & Monesson, 2009). This decline in the ability to distinguish faces is known as "perceptual narrowing" and has recently been found to be absent when infants are given experience matching a face with an individual-level proper name between 6 to 9 months of age (Scott & Monesson, 2009). Additionally, individual-level experience between 6 and 9 months of age has led to neural changes at 9 months of age (Scott & Monesson, 2010). It is currently unclear whether brief, early experience between 6 and 9 months leads to sustained behavioral advantages and lasting neural changes. In order to answer these questions, the current study recruited and tested children who previously participated in a face training study when they were infants (Scott & Monesson, 2009, 2010). Findings revealed that individual-level experience with faces during the first year of life: 1) resulted in faster reaction time for faces outside of the trained category, and 2) led to more adult-like neural representations of faces outside of the trained category 3-4 years later. These results suggest that experience with individual-level learning in the first year of life is generalized to visually similar, but environmentally relevant face categories.

Over the last 30 or more years evidence has accumulated in favour of the view that memory is not a unitary faculty; rather, it can be subdivided into a num- ber of functionally independent subsystems. Whilst dividing memory phenomena into these distinct subsystems has undoubtedly advanced our understanding of memory as a whole, the approach of studying subsystems in isolation fails to address potential interactions between them. Over the last few decades there has been a gradual increase in the number of studies attempting to move be- yond dissociation by characterising functional interactions between subsystems of memory. The main aim of this thesis was to contribute to this endeavour, by examining interactions between two specific subsystems that are positioned on opposite sides of the declarative and non-declarative divide in long-term mem- ory: priming and episodic recognition. Event-Related Potentials (ERPs) were employed to monitor neural markers of repetition priming and episodic memory during recognition tests with masked priming of test cues. In the standard pro- cedure, half of the studied and unstudied test trials began with a brief (48ms) masked repetition of the to-be-recognized word prior to the onset of test items; the remaining unprimed trials were preceded by the word “blank”. The pattern of priming effects across experiments was reasonably consistent, with differences between experiments directly related to the intended manipulations. In contrast to priming effects, the pattern of memory effects was variable across experiments, demonstrating that the engagement of explicit recognition signals is influenced by the outcome of implicit processing, and suggesting that interactions between priming and explicit retrieval processes do occur. Taken together, results from experiments reported in this thesis indicate (1) that under certain circumstances, priming is sufficient to support accurate recognition and does not necessitate changes in memory performance, (2) that mid-frontal old/new effects indexing familiarity are not merely driven by repeated access to semantic information, and (3) that priming influences neural correlates of recollection by speeding their onset. Overall, the data clearly demonstrate that there are multiple potentially interacting routes to recognition.

La reconnaissance experte de l'expression faciale est cruciale pour l'interaction et la communication sociale. Le comportement, les potentiels évoqués (ERP), et les techniques d’oculométrie peuvent être utilisés pour étudier les mécanismes cérébraux qui participent au traitement visuel automatique. La reconnaissance d'expressions faciales implique non seulement l'extraction d'informations à partir de caractéristiques faciales diagnostiques, stratégie qualifiée de traitement local, mais aussi l'intégration d'informations globales impliquant des traitements configuraux. Des nombreuses recherches concernant le traitement des informations faciales émotionnelles il apparaît que l’interaction des traitements locaux et configuraux pour la reconnaissance des émotions est mal comprise. La complexité inhérente à l'intégration de l'information faciale est mise en lumière lorsque l'on compare la performance de sujets sains et d’individus atteints de schizophrénie, car ces derniers ont tendance à s’attarder sur quelques éléments locaux, parfois peu informatifs. Les différentes façons d'examiner les visages peuvent avoir un impact sur la capacité socio-cognitive de reconnaître les émotions. Pour ces raisons, cette thèse étudie le rôle des caractéristiques diagnostiques et configurales dans la reconnaissance de l'expression faciale. En plus des aspects comportementaux, nous avons donc examiné la dynamique spatiale et temporelle des fixations à l’aide de mesures oculométriques, ainsi que l’activité électrophysiologique précoce considérant plus particulièrement les composantes P100 et N170. Nous avons créé de nouveaux stimuli des esquisses par une transformation numérique de portraits photos en esquisses, pour des visages exprimant colère, tristesse, peur, joie ou neutralité, issus de la base Radboud Faces Database, en supprimant les informations de texture du visage et ne conservant que les caractéristiques diagnostiques (yeux et sourcils, nez, bouche). Ces esquisses altèrent le traitement configural en comparaison avec les visages photographiques, ce qui augmente le traitement des caractéristiques diagnostiques par traitement élémentaire, en contrepartie. La comparaison directe des mesures neurocognitives entre les esquisses et les visages photographiques exprimant des émotions de base n'a jamais été testée, à notre connaissance. Dans cette thèse, nous avons examiné (i) les fixations oculaires en fonction du type de stimulus, (ii) la réponse électrique aux manipulations expérimentales telles que l'inversion et la déconfiguration du visage. Concernant, les résultats comportementaux montrent que les esquisses de visage transmettent suffisamment d'information expressive (compte tenu de la présence des caractéristiques diagnostiques) pour la reconnaissance des émotions en comparaison des visages photographiques. Notons que, comme attendu, il y avait un net avantage de la reconnaissance des émotions pour les expressions heureuses par rapport aux autres émotions. En revanche, reconnaître des visages tristes et en colère était plus difficile. Ayant analysé séparément les fixations successives, les résultats indiquent que les participants ont adopté un traitement plus local des visages croqués et photographiés lors de la deuxième fixation. Néanmoins, l'extraction de l'information des yeux est nécessaire lorsque l'expression transmet des informations émotionnelles plus complexes et lorsque les stimuli sont simplifiés comme dans les esquisses. Les résultats de l’électroencéphalographie suggèrent également que les esquisses ont engendré plus de traitement basé sur les parties. Les éléments transmis par les traits diagnostiques pourraient avoir fait l'objet d'un traitement précoce, probablement dû à des informations de bas niveau durant la fenêtre temporelle de la P100, suivi d'un décodage ultérieur de la structure faciale dans la fenêtre temporelle de la N170. / Proficient recognition of facial expression is crucial for social interaction. Behaviour, event-related potentials (ERPs), and eye-tracking techniques can be used to investigate the underlying brain mechanisms supporting this seemingly effortless processing of facial expression. Facial expression recognition involves not only the extraction of expressive information from diagnostic facial features, known as part-based processing, but also the integration of featural information, known as configural processing. Despite the critical role of diagnostic features in emotion recognition and extensive research in this area, it is still not known how the brain decodes configural information in terms of emotion recognition. The complexity of facial information integration becomes evident when comparing performance between healthy subjects and individuals with schizophrenia because those patients tend to process featural information on emotional faces. The different ways in examining faces possibly impact on social-cognitive ability in recognizing emotions. Therefore, this thesis investigates the role of diagnostic features and face configuration in the recognition of facial expression. In addition to behavior, we examined both the spatiotemporal dynamics of fixations using eye-tracking, and early neurocognitive sensitivity to face as indexed by the P100 and N170 ERP components. In order to address the questions, we built a new set of sketch face stimuli by transforming photographed faces from the Radboud Faces Database through the removal of facial texture and retaining only the diagnostic features (e.g., eyes, nose, mouth) with neutral and four facial expressions - anger, sadness, fear, happiness. Sketch faces supposedly impair configural processing in comparison with photographed faces, resulting in increased sensitivity to diagnostic features through part-based processing. The direct comparison of neurocognitive measures between sketch and photographed faces expressing basic emotions has never been tested. In this thesis, we examined (i) eye fixations as a function of stimulus type, and (ii) neuroelectric response to experimental manipulations such face inversion and deconfiguration. The use of these methods aimed to reveal which face processing drives emotion recognition and to establish neurocognitive markers of emotional sketch and photographed faces processing. Overall, the behavioral results showed that sketch faces convey sufficient expressive information (content of diagnostic features) as in photographed faces for emotion recognition. There was a clear emotion recognition advantage for happy expressions as compared to other emotions. In contrast, recognizing sad and angry faces was more difficult. Concomitantly, results of eye-tracking showed that participants employed more part-based processing on sketch and photographed faces during second fixation. The extracting information from the eyes is needed when the expression conveys more complex emotional information and when stimuli are impoverished (e.g., sketch). Using electroencephalographic (EEG), the P100 and N170 components are used to study the effect of stimulus type (sketch, photographed), orientation (inverted, upright), and deconfiguration, and possible interactions. Results also suggest that sketch faces evoked more part-based processing. The cues conveyed by diagnostic features might have been subjected to early processing, likely driven by low-level information during P100 time window, followed by a later decoding of facial structure and its emotional content in the N170 time window. In sum, this thesis helped elucidate elements of the debate about configural and part-based face processing for emotion recognition, and extend our current understanding of the role of diagnostic features and configural information during neurocognitive processing of facial expressions of emotion.

H προβολή υποσυνείδητων μηνυμάτων είναι η διαδικασία έκθεσης ερεθισμάτων κάτω από το κατώφλι της συνειδητοποίησης. Με τον τρόπο αυτό μπορεί να επηρεαστούν οι σκέψεις, τα συναισθήματα και ενέργειες του ανθρώπου. Η υποσυνείδητη αντίληψη συμβαίνει όταν οι πληροφορίες αποθηκεύονται στο ανθρώπινο μυαλό, χωρίς ο δέκτης να έχει συνειδητά επίγνωση του προβλήματος. Οι πληροφορίες φτάνουν στο μυαλό, γιατί ενώ δεν είναι συνειδητά αντιληπτές, γίνονται αντιληπτές από το υποσυνείδητο κομμάτι του εγκεφάλου. Αντικείμενο της παρούσας διπλωματικής εργασίας είναι η αποτίμηση των πιθανών διαφορών στις καταγραφές ηλεκτροεγκεφαλογραφήματος (ΕΕG) και προκλητών δυναμικών (ERPs) κατά την υποβολή ενός ατόμου σε οπτικά υποσυνείδητα ερεθίσματα σε σύγκριση με καταγραφές χωρίς ερέθισμα. Στην εργασία χρησιμοποιήθηκε ένα ερευνητικό πρωτόκολλο το οποίο εξετάζει το πώς επηρεάζουν τα υποσυνείδητα ερεθίσματα τη λήψη αποφάσεων και την εγκεφαλική λειτουργία. Στο πρώτο μέρος της εργασίας (κεφάλαια 1 και 2) γίνεται μια συνοπτική αναφορά στις κυριότερες μεθόδους απεικόνισης εγκεφάλου, όπως το ηλεκτροεγκεφαλογράφημα και την λειτουργική απεικόνιση Μαγνητικού Συντονισμού καθώς και στον συνδυασμό τους για πιο ικανοποιητικά αποτελέσματα. Το κεφάλαιο 3 αναφέρεται κυρίως σε θέματα σχετικά τα προκλητά δυναμικά, καθώς και την υποσυνείδητη αντίληψη. Στο κεφάλαιο 4 περιγράφεται η πειραματική διαδικασία και η μετρητική διάταξη που χρησιμοποιήθηκε καθώς και η παρουσίαση της επεξεργασίας των μετρήσεων μέσω του eeglab. Τέλος, στο κεφάλαιο 5 παρουσιάζονται τα αποτελέσματα της επεξεργασίας σε διαγράμματα προκλητών δυναμικών και φασματικής ισχύος καθώς επίσης και τα συμπεράσματα της εργασίας αυτής. / The display of subliminal messages is the process of stimuli exposure below the threshold of awareness. Through this procedure the thoughts, feelings and actions of a human can be influenced. The subliminal perception occurs when information stored in the human mind without the receiver being consciously aware of it. The information reaching the brain is perceived by the subconscious part of the brain. The object of this diploma thesis is to assess the possible differences in electroencephalogram (EEG) and event - related potentials (ERPs) recordings during the presentation of visual subliminal stimuli compared to non – subliminal conditions. A protocol that examines how subliminal stimuli influence the decision making and the cerebral operation is used. In the first part of the thesis (chapters 1 and 2) there is a brief review of the main brain imaging methods such as EEG and fMRI as well as the combination of them. Chapter 3 reveals issues about event - related potentials and mostly about subliminal perception. In chapter 4, the experiment and the measuring devices used are described, and there is also a presentation of the analysis by using the eeglab. Finally, chapter 5 includes the results of analysis on event - related potential and spectral power graphs, as well as the conclusions of this work.

La présente étude vise à approfondir les connaissances relatives aux mécanismes neuronaux qui sous-tendent la maintenance de sons variant en hauteur dans la mémoire auditive à court terme (MACT), plus précisément lors de sa saturation. À cet effet, la technique des potentiels reliés aux évènements (PRE) en électrophysiologie a été utilisée. La sélection des participants s’est déroulée par l’entremise de deux expériences comportementales : l’une était une tâche de discrimination et l’autre, une tâche qui évaluait l’habileté générale des participants à réussir une tâche similaire à celle de l’expérience principale en électroencéphalographie (EEG). Les résultats comportementaux de notre tâche en EEG ont montré que la performance diminuait de façon significative plus la charge en mémoire augmentait (séquences de 2, 4, 6 et 8 sons) et que l’estimation de la capacité de la MACT mesurée par K augmentait entre 2 et 4 sons pour atteindre un plafond à 4 sons (effet plafond). Le K maximum étant de 2.84 sons, l’empan mnésique (EM) auditif semble être près de 3 sons. Les résultats électrophysiologiques ont montré que la composante électrophysiologique reliée à la maintenance de sons en MACT, la Sustained Anterior Negativity (SAN), était modulée par le nombre de sons à maintenir : son amplitude augmentait de 2 à 4 sons et ce, jusqu’à l’atteinte d’un plafond à 4 sons. Ces résultats suggèrent que la maintenance de sons additionnels dans la MACT n’est plus possible après sa saturation. Nous soutenons donc que la SAN est un index électrophysiologique de l’activité neuronale associée à la maintenance d’items auditifs dans la MACT et que son amplitude est un bon indicateur de la capacité individuelle de la MACT, estimée par K. Des résultats post-hoc ont démontré que les musiciens et les non-musiciens tendent à avoir des différences au niveau de la SAN, sans pour autant modifier l’effet de charge en mémoire. Une analyse qualitative et quantitative de l’utilisation des stratégies mnésiques ont permis de clarifier leur implication et leur nature au sein d’une tâche cognitive de mémoire, plus précisément en audition. Pour conclure, l’ensemble de ces résultats suggère également que la SAN est reliée à la maintenance de sons dans la MACT et ainsi, un bon indicateur de sa capacité. / The aim of the current study is to further understand, through the use of event-related potentials (ERPs), the neural mechanisms that underlie the maintenance of pitch in auditory short-term memory (ASTM) after reaching the memory span. Two behavioral experiments were used to help perform the selection of the participants: the first one was an evaluation of the acoustic discrimination and the second one was a general evaluation of participants’ ability to succeed to a similar task of the one that will be used in the electrophysiological (EEG) part of the experiment. Behavioral results from the EEG task showed a significant decrease in accuracy when the load increased (sequences of 2, 4, 6 and 8 tones). The estimation of the memory capacity (named K), increased from load 2 to 4 and reached a plateau after 4 tones. The maximum K represented 2.84 tones; the auditory span seems to be around 3 tones. Experimental results showed that the ERP component related to the maintenance of tones in ASTM, as measured by the Sustained Anterior Negativity (SAN), was modulated by the load. More specifically, its amplitude increased when the load increased (from 2 to 4) and reached a plateau at load 4. These results suggest that the maintenance of additional tones in ASTM is not possible after its saturation. Thus, the SAN appears to be an adequate electrophysiological index of neuronal activity related to the maintenance of tones in ASTM, and its amplitude appears to be predicted by K. Post-hoc results showed that musician and non-musicians tend to have some differences in their electrophysiological results; however, no change related to the load effect was observed. Finally, a qualitative and quantitative analysis was done to investigate the impact of the use of different mnemonic strategies in ASTM. Taking together, our results support that the SAN component is related to the maintenance of tones in ASTM and can be considerate as a good indicator of its capacity.