Society is based on communication, for which speech is the most prevalent medium. In day to day interactions we talk to each other, but it is not only the words spoken that matters, but the emotional delivery as well. Extracting emotion from speech has therefore become a topic of research in the area of speech tasks. This area as a whole has in recent years adopted a Self- Supervised Learning approach for learning speech representations from raw speech audio, without the need for any supplementary labelling. These speech representations can be leveraged for solving tasks limited by the availability of annotated data, be it for low-resource language, or a general lack of data for the task itself. This thesis aims to evaluate the performances of a set of pre-trained speech models by fine-tuning them in different multilingual environments, and evaluating their performance thereafter. The model presented in this paper is based on wav2vec 2.0 and manages to correctly classify 86.58% of samples over eight different languages and four emotional classes when trained on those same languages. Experiments were conducted to garner how well a model trained on seven languages would perform on the one left out, which showed that there is quite a large margin of similarity in how different cultures express vocal emotions, and further investigations showed that as little as just a few minutes of in-domain data is able to increase the performance substantially. This shows promising results even for niche languages, as the amount of available data may not be as large of a hurdle as one might think. With that said, increasing the amount of data from minutes to hours does still garner substantial improvements, albeit to a lesser degree. / Hela vårt samhälle är byggt på kommunikation mellan olika människor, varav tal är det vanligaste mediet. På en daglig basis interagerar vi genom att prata med varandra, men det är inte bara orden som förmedlar våra intentioner, utan även hur vi uttrycker dem. Till exempel kan samma mening ge helt olika intryck beroende på ifall den sägs med ett argt eller glatt tonfall. Talbaserad forskning är ett stort vetenskapligt område i vilket talbaserad känsloigenkänning vuxit fram. Detta stora tal-område har under de senaste åren sett en tendens att utnyttja en teknik kallad själv-övervakad inlärning för att utnyttja omärkt ljuddata för att lära sig generella språkrepresentationer, vilket kan liknas vid att lära sig strukturen av tal. Dessa representationer, eller förtränade modeller, kan sedan utnyttjas som en bas för att lösa problem med begränsad tillgång till märkt data, vilket kan vara fallet för sällsynta språk eller unika uppgifter. Målet med denna rapport är att utvärdera olika applikationer av denna representations inlärning i en flerspråkig miljö genom att finjustera förtränade modeller för känsloigenkänning. I detta syfte presenterar vi en modell baserad på wav2vec 2.0 som lyckas klassifiera 86.58% av ljudklipp tagna från åtta olika språk över fyra olika känslo-klasser, efter att modellen tränats på dessa språk. För att avgöra hur bra en modell kan klassifiera data från ett språk den inte tränats på skapades modeller tränade på sju språk, och evaluerades sedan på det språk som var kvar. Dessa experiment visar att sättet vi uttrycker känslor mellan olika kulturer är tillräckligt lika för att modellen ska prestera acceptabelt även i det fall då modellen inte sett språket under träningsfasen. Den sista undersökningen utforskar hur olika mängd data från ett språk påverkar prestandan på det språket, och visar att så lite som endast ett par minuter data kan förbättra resultet nämnvärt, vilket är lovande för att utvidga modellen för fler språk i framtiden. Med det sagt är ytterligare data att föredra, då detta medför fortsatta förbättringar, om än i en lägre grad.

Modern day society is vastly complex, with information and data constantly being posted, shared, and collected everywhere. There is often an abundance of massive amounts of unlabeled data that can not be leveraged in a supervised machine learning context. Thus, there exists an incentive to research and develop machine learning methods which can learn without labels. Selfsupervised learning (SSL) is a newly emerged machine learning paradigm that aims to learn representations that can later be used in domain specific downstream tasks. In this degree project three SSL models based on the Simple Framework for Contrastive Learning of Visual Representations (SimCLR) are evaluated. Each model aims to learn sleep deprivation related representations on magnetoencephalography (MEG) measurements. MEG is a non-invasive neuroimaging technique that is used on humans to investigate neuronal activity. The data was acquired through a collaboration with Karolinska Institutet and Stockholm University, where the SLEMEG project was conducted to study the neurophysiological response to partial sleep deprivation. The features extracted by the SSL-models are analyzed both qualitatively and quantitatively, and also used to perform classification and regression tasks on subject labels. The results show that the evaluated Signal- and Recording SimCLR models can learn sleep deprivation related features, whilst simultaneously learning other co-occuring information also. Furthermore, the results indicate that the learned representations are informative and can be utilized for multiple downstream tasks. However, it is noted that what has been learned is mostly related to subject-specific individual variance, which leads to poor generalization performance on classification and regression downstream tasks. Thus, it is believed that the models would perform better with access to more MEG data, and that source localized MEG data could remove part of the individual variance that is learned. / Den moderna dagens samhälle är enormt komplext, information och data blir konstant postat, delat, och insamlat överallt. På grund av det så finns det ofta ett överflöd av massiva mängder omärkt data some inte kan användas i ett övervakat maskininlärnings-sammanhang. Därmed finns det ett incitament att forska om och utveckla maskininlärningsmetoder som kan lära modeller utan tillgång till märkningar. Självövervakad inlärning (SSL) är en modern metod som nyligen har fått mycket fokus, vars mål är att lära sig representationer av datat som sedan kan användas i domänspecifika nedströmsuppgifter. I det här examensarbetet så är tre SSL metoder evaluerade där de alla strävar efter att lära sig representationer relaterat till sömndeprivering på magnetoencefalografi (MEG) mätningar. MEG är en icke-invasiv metod som används på människor för att undersöka neuronal aktivitet. Datat var förvärvat genom ett sammarbeta med Karolinska Institutet och Stockholms Universitet, där SLEMEG studien hade blivit genomförd för att studera neurofysiologisk respons på sömndeprivering. De av SSL-modellerna extraherade särdragen är analyserade både kvalitativt samt kvantitativt, och sedan använda för att genomföra klassificerings och regressions-uppgifter. Resultaten visar på att de evaluerade Signal- och Recording SimCLR modellerna kan lära sig särdrag relaterade till sömndepriverad, men samtidigt också lära sig annan samförekommande information. Dessutom så indikerar resultaten att de lärda representationerna är informativa och kan då användas i flera olika nedströmsuppgifter. Dock så noteras det att det som blivit inlärt är mestadels relaterat till individ-specifik varians, vilket leder till dålig generaliseringsprestanda. Således är det trott att modellerna hade presterat bättre med tillgång till mer MEG data, samt att källlokalisering av MEG datat hade kunnat ta bort en del av den individuella variansen som blir inlärd.

In recent years the wide availability of high-resolution satellite images has made the remote monitoring of water resources all over the world possible. While the detection of open water from satellite images is relatively easy, a significant percentage of the water extent of wetlands is covered by vegetation. Convolutional Neural Networks have shown great success in the task of detecting wetlands in satellite images. However, these models require large amounts of manually annotated satellite images, which are slow and expensive to produce. In this paper we use self-supervised training methods to train a Convolutional Neural Network to detect water from satellite images without the use of annotated data. We use a combination of deep clustering and negative sampling based on the paper ”Unsupervised Single-Scene Semantic Segmentation for Earth Observation”, and we expand the paper by changing the clustering loss, the model architecture and implementing an ensemble model. Our final ensemble of self-supervised models outperforms a single supervised model, showing the power of self-supervision. / Under de senaste åren har den breda tillgången på högupplösta satellitbilder möjliggjort fjärrövervakning av vattenresurser över hela världen. Även om det är relativt enkelt att upptäcka öppet vatten från satellitbilder, täcks en betydande andel av våtmarkernas vattenutbredning av vegetation. Lyckligtvis kan radarsignaler tränga igenom vegetation, vilket gör det möjligt för oss att upptäcka vatten gömt under vegetation från satellitradarbilder. Under de senaste åren har Convolutional Neural Networks visat stor framgång i denna uppgift. Tyvärr kräver dessa modeller stora mängder manuellt annoterade satellitbilder, vilket är långsamt och dyrt att producera. Självövervakad inlärning är ett område inom maskininlärning som syftar till att träna modeller utan användning av annoterade data. I den här artikeln använder vi självövervakad träningsmetoder för att träna en Convolutional Neural Network-baserad modell för att detektera vatten från satellitbilder utan användning av annoterade data. Vi använder en kombination av djup klustring och kontrastivt lärande baserat på artikeln ”Unsupervised Single-Scene Semantic Segmentation for Earth Observation”. Dessutom utökar vi uppsatsen genom att modifiera klustringsförlusten och modellarkitekturen som används. Efter att ha observerat hög varians i våra modellers prestanda implementerade vi också en ensemblevariant av vår modell för att få mer konsekventa resultat. Vår slutliga ensemble av självövervakade modeller överträffar en enda övervakad modell, vilket visar kraften i självövervakning.

Le trouble du spectre de l'autisme (TSA) est un trouble neurodéveloppemental caractérisé par des interactions sociales atypiques. L’hyperscanning est une technique émergente permettant l'enregistrement simultané de l'activité cérébrale de plusieurs individus lors d'interactions sociales. Dans cette étude, des données d'EEG hyperscanning issues de participants autistes et neurotypiques seront traitées par des techniques d’apprentissage profond (AP), améliorées par l'apprentissage auto-supervisé (AAS) pour analyser et discerner des schémas indicatifs de TSA. L'AP est utilisé pour extraire des schémas à partir des données brutes de l'EEG, réduisant la dépendance à l'ingénierie de caractéristiques manuelles, puis l’AAS est appliqué aux des données EEG non étiquetées. Cependant, malgré le potentiel des techniques d’AP, leur application au TSA reste largement inexplorée, notamment en hyperscanning. Afin de combler cette lacune, nous avons adapté et personnalisé des techniques d'AAS proposée par Banville et al., (2020), en incorporant deux encodeurs AP distincts entraînés pour extraire des caractéristiques significatives à partir de données EEG individuelles, et affinés dans un modèle d’AP de classificateur binaire. Des comparaisons ont été réalisées avec des encodeurs initialement aléatoires et des caractéristiques extraites manuellement des données EEG utilisées comme entrées pour un modèle de régression logistique. Le classificateur binaire entraîné sur des caractéristiques apprises par AAS surpasse systématiquement le classificateur de régression logistique et les encodeurs initialisés aléatoirement, atteignant une précision de 78 %, comparable à la performance la plus élevée rapportée par Banville et al. (2020) de 79,4 %. Nos résultats soulignent l'importance des représentations acquises à partir de signaux EEG individuels dans l'architecture multi-cerveaux adaptée à la classification d’EEG hyperscanning. Cette étude encourage ainsi l’utilisation des modèles d’AP dans les analyses d’EEG hyperscanning, notamment pour le développement d'outils de diagnostic et d'interventions plus précis et efficaces pour les personnes autistes, et ce même avec un nombre limité d'échantillons de données. / Autism spectrum condition (ASC) is a neurodevelopmental condition characterized by atypical social interactions. Traditional research on ASC has primarily focused on individual brain signals, but the emerging technique of hyperscanning enables simultaneous recording of multiple individuals' brain activity during social interactions. In this study, we leverage hyperscanning EEG data and employ Deep Learning (DL) techniques, augmented by self-supervised learning (SSL), to analyze and discern patterns indicative of ASC. DL is utilized to extract patterns from raw EEG data, reducing the reliance on manual feature engineering. SSL further enhances DL's efficacy by training on unlabeled EEG data, particularly useful when labeled datasets are limited. Despite the potential of DL techniques, their application in ASC diagnosis and treatment, particularly in hyperscanning, remains largely unexplored. This project aimed to bridge this gap by analyzing hyperscanning EEG data from autistic and neurotypical participants. Specifically, we adapted and customized SSL techniques proposed by Banville et al., incorporating two distinct DL embedders. These embedders are trained to extract meaningful features from single-brain EEG data and finetuned within a binary classifier DL model using hyperscanning EEG data from autistic and control dyads. Baseline comparisons were conducted with supervised, randomly initialized embedders, and hand-engineered features extracted from hyperscanning EEG using as inputs to a logistic regression model. Notably, the binary classifier trained on SSL-learned features consistently outperforms the logistic regression classifier and randomly initialized embedders, achieving an accuracy of 78%. This accuracy is comparable to Banville et al.'s highest reported performance of 79.4%. Our results underscore the significance of representations acquired from individual EEG signals within the multi-brain architecture tailored for hyperscanning EEG classification. Moreover, they hold promise for broader utilization of DL models in hyperscanning EEG analyses, especially for developing more accurate and efficient diagnostic tools and interventions for autistic individuals, even with limited data samples available.

Hlavným zámerom tejto diplomovej práce bola automatická segmentácia lézií sklerózy multiplex na snímkoch MRI. V rámci práce boli otestované najnovšie metódy segmentácie s využitím hlbokých neurónových sietí a porovnané prístupy inicializácie váh sietí pomocou preneseného učenia (transfer learning) a samoriadeného učenia (self-supervised learning). Samotný problém automatickej segmentácie lézií sklerózy multiplex je veľmi náročný, a to primárne kvôli vysokej nevyváženosti datasetu (skeny mozgov zvyčajne obsahujú len malé množstvo poškodeného tkaniva). Ďalšou výzvou je manuálna anotácia týchto lézií, nakoľko dvaja rozdielni doktori môžu označiť iné časti mozgu ako poškodené a hodnota Dice Coefficient týchto anotácií je približne 0,86. Možnosť zjednodušenia procesu anotovania lézií automatizáciou by mohlo zlepšiť výpočet množstva lézií, čo by mohlo viesť k zlepšeniu diagnostiky individuálnych pacientov. Našim cieľom bolo navrhnutie dvoch techník využívajúcich transfer learning na predtrénovanie váh, ktoré by neskôr mohli zlepšiť výsledky terajších segmentačných modelov. Teoretická časť opisuje rozdelenie umelej inteligencie, strojového učenia a hlbokých neurónových sietí a ich využitie pri segmentácii obrazu. Následne je popísaná skleróza multiplex, jej typy, symptómy, diagnostika a liečba. Praktická časť začína predspracovaním dát. Najprv boli skeny mozgu upravené na rovnaké rozlíšenie s rovnakou veľkosťou voxelu. Dôvodom tejto úpravy bolo využitie troch odlišných datasetov, v ktorých boli skeny vytvárané rozličnými prístrojmi od rôznych výrobcov. Jeden dataset taktiež obsahoval lebku, a tak bolo nutné jej odstránenie pomocou nástroju FSL pre ponechanie samotného mozgu pacienta. Využívali sme 3D skeny (FLAIR, T1 a T2 modality), ktoré boli postupne rozdelené na individuálne 2D rezy a použité na vstup neurónovej siete s enkodér-dekodér architektúrou. Dataset na trénovanie obsahoval 6720 rezov s rozlíšením 192 x 192 pixelov (po odstránení rezov, ktorých maska neobsahovala žiadnu hodnotu). Využitá loss funkcia bola Combo loss (kombinácia Dice Loss s upravenou Cross-Entropy). Prvá metóda sa zameriavala na využitie predtrénovaných váh z ImageNet datasetu na enkodér U-Net architektúry so zamknutými váhami enkodéra, resp. bez zamknutia a následného porovnania s náhodnou inicializáciou váh. V tomto prípade sme použili len FLAIR modalitu. Transfer learning dokázalo zvýšiť sledovanú metriku z hodnoty približne 0,4 na 0,6. Rozdiel medzi zamknutými a nezamknutými váhami enkodéru sa pohyboval okolo 0,02. Druhá navrhnutá technika používala self-supervised kontext enkodér s Generative Adversarial Networks (GAN) na predtrénovanie váh. Táto sieť využívala všetky tri spomenuté modality aj s prázdnymi rezmi masiek (spolu 23040 obrázkov). Úlohou GAN siete bolo dotvoriť sken mozgu, ktorý bol prekrytý čiernou maskou v tvare šachovnice. Takto naučené váhy boli následne načítané do enkodéru na aplikáciu na náš segmentačný problém. Tento experiment nevykazoval lepšie výsledky, s hodnotou DSC 0,29 a 0,09 (nezamknuté a zamknuté váhy enkodéru). Prudké zníženie metriky mohlo byť spôsobené použitím predtrénovaných váh na vzdialených problémoch (segmentácia a self-supervised kontext enkodér), ako aj zložitosť úlohy kvôli nevyváženému datasetu.

Extraire une représentation de tous les facteurs de haut niveau de l'état d'un agent à partir d'informations sensorielles de bas niveau est une tâche importante, mais difficile, dans l'apprentissage automatique. Dans ce memoire, nous explorerons plusieurs approches non supervisées pour apprendre ces représentations. Nous appliquons et analysons des méthodes d'apprentissage de représentations non supervisées existantes dans des environnements d'apprentissage par renforcement, et nous apportons notre propre suite d'évaluations et notre propre méthode novatrice d'apprentissage de représentations d'état. Dans le premier chapitre de ce travail, nous passerons en revue et motiverons l'apprentissage non supervisé de représentations pour l'apprentissage automatique en général et pour l'apprentissage par renforcement. Nous introduirons ensuite un sous-domaine relativement nouveau de l'apprentissage de représentations : l'apprentissage auto-supervisé. Nous aborderons ensuite deux approches fondamentales de l'apprentissage de représentations, les méthodes génératives et les méthodes discriminatives. Plus précisément, nous nous concentrerons sur une collection de méthodes discriminantes d'apprentissage de représentations, appelées méthodes contrastives d'apprentissage de représentations non supervisées (CURL). Nous terminerons le premier chapitre en détaillant diverses approches pour évaluer l'utilité des représentations. Dans le deuxième chapitre, nous présenterons un article de workshop dans lequel nous évaluons un ensemble de méthodes d'auto-supervision standards pour les problèmes d'apprentissage par renforcement. Nous découvrons que la performance de ces représentations dépend fortement de la dynamique et de la structure de l'environnement. À ce titre, nous déterminons qu'une étude plus systématique des environnements et des méthodes est nécessaire. Notre troisième chapitre couvre notre deuxième article, Unsupervised State Representation Learning in Atari, où nous essayons d'effectuer une étude plus approfondie des méthodes d'apprentissage de représentations en apprentissage par renforcement, comme expliqué dans le deuxième chapitre. Pour faciliter une évaluation plus approfondie des représentations en apprentissage par renforcement, nous introduisons une suite de 22 jeux Atari entièrement labellisés. De plus, nous choisissons de comparer les méthodes d'apprentissage de représentations de façon plus systématique, en nous concentrant sur une comparaison entre méthodes génératives et méthodes contrastives, plutôt que les méthodes générales du deuxième chapitre choisies de façon moins systématique. Enfin, nous introduisons une nouvelle méthode contrastive, ST-DIM, qui excelle sur ces 22 jeux Atari. / Extracting a representation of all the high-level factors of an agent’s state from level-level sensory information is an important, but challenging task in machine learning. In this thesis, we will explore several unsupervised approaches for learning these state representations. We apply and analyze existing unsupervised representation learning methods in reinforcement learning environments, as well as contribute our own evaluation benchmark and our own novel state representation learning method. In the first chapter, we will overview and motivate unsupervised representation learning for machine learning in general and for reinforcement learning. We will then introduce a relatively new subfield of representation learning: self-supervised learning. We will then cover two core representation learning approaches, generative methods and discriminative methods. Specifically, we will focus on a collection of discriminative representation learning methods called contrastive unsupervised representation learning (CURL) methods. We will close the first chapter by detailing various approaches for evaluating the usefulness of representations. In the second chapter, we will present a workshop paper, where we evaluate a handful of off-the-shelf self-supervised methods in reinforcement learning problems. We discover that the performance of these representations depends heavily on the dynamics and visual structure of the environment. As such, we determine that a more systematic study of environments and methods is required. Our third chapter covers our second article, Unsupervised State Representation Learning in Atari, where we try to execute a more thorough study of representation learning methods in RL as motivated by the second chapter. To facilitate a more thorough evaluation of representations in RL we introduce a benchmark of 22 fully labelled Atari games. In addition, we choose the representation learning methods for comparison in a more systematic way by focusing on comparing generative methods with contrastive methods, instead of the less systematically chosen off-the-shelf methods from the second chapter. Finally, we introduce a new contrastive method, ST-DIM, which excels at the 22 Atari games.

Stena Recycling is one of the leading recycling companies in Sweden and at their facility in Halmstad, 300 tonnes of refuse are handled every day where aluminium is one of the most valuable materials they sort. Today, most of the sorting process is done automatically, but there are still parts of the refuse that are not correctly sorted. Approximately 4\% of the aluminium is currently not properly sorted and goes to waste. Earlier works have investigated using machine vision to help in the sorting process at Stena Recycling. However, consistently through all these previous works, there is a problem in gathering enough annotated data to train the machine learning models. This thesis aims to investigate how machine vision could be used in the recycling process and if pre-training models using self-supervised learning can alleviate the problem of gathering annotated data and yield an improvement. The results show that machine vision models could viably be used in an information system to assist operators. This thesis also shows that pre-training models with self-supervised learning may yield a small increase in performance. Furthermore, we show that models pre-trained using self-supervised learning also appear to transfer the knowledge learned from images created in a lab environment to images taken at the recycling plant.

<p dir="ltr">Several incidents report misuse of synthetic speech for impersonation attacks, spreading misinformation, and supporting financial frauds. To counter such misuse, this dissertation focuses on developing methods for speech forensics. First, we present a method to detect compressed synthetic speech. The method uses comparatively 33 times less information from compressed bit stream than used by existing methods and achieve high performance. Second, we present a transformer neural network method that uses 2D spectral representation of speech signals to detect synthetic speech. The method shows high performance on detecting both compressed and uncompressed synthetic speech. Third, we present a method using an interpretable machine learning approach known as disentangled representation learning for synthetic speech detection. Fourth, we present a method for synthetic speech attribution. It identifies the source of a speech signal. If the speech is spoken by a human, we classify it as authentic/bona fide. If the speech signal is synthetic, we identify the generation method used to create it. We examine both closed-set and open-set attribution scenarios. In a closed-set scenario, we evaluate our approach only on the speech generation methods present in the training set. In an open-set scenario, we also evaluate on methods which are not present in the training set. Fifth, we propose a multi-domain method for synthetic speech localization. It processes multi-domain features obtained from a transformer using a ResNet-style MLP. We show that with relatively less number of parameters, the proposed method performs better than existing methods. Finally, we present a new direction of research in speech forensics <i>i.e.</i>, bias and fairness of synthetic speech detectors. By bias, we refer to an action in which a detector unfairly targets a specific demographic group of individuals and falsely labels their bona fide speech as synthetic. We show that existing synthetic speech detectors are gender, age and accent biased. They also have bias against bona fide speech from people with speech impairments such as stuttering. We propose a set of augmentations that simulate stuttering in speech. We show that synthetic speech detectors trained with proposed augmentation have less bias relative to detector trained without it.</p>

Ces dernières années, le domaine de l’apprentissage profond a connu des progrès énormes dans des applications allant de la génération d’images, détection d’objets, modélisation du langage à la réponse aux questions visuelles. Les approches classiques telles que l’apprentissage supervisé nécessitent de grandes quantités de données étiquetées et spécifiques à la tâches. Cependant, celles-ci sont parfois coûteuses, peu pratiques, ou trop longues à collecter. La modélisation efficace en données, qui comprend des techniques comme l’apprentissage few-shot (à partir de peu d’exemples) et l’apprentissage self-supervised (auto-supervisé), tentent de remédier au manque de données spécifiques à la tâche en exploitant de grandes quantités de données plus “générales”. Les progrès de l’apprentissage profond, et en particulier de l’apprentissage few-shot, s’appuient sur les benchmarks (suites d’évaluation), les métriques d’évaluation et les jeux de données, car ceux-ci sont utilisés pour tester et départager différentes méthodes sur des tâches précises, et identifier l’état de l’art. Cependant, du fait qu’il s’agit de versions idéalisées de la tâche à résoudre, les benchmarks sont rarement équivalents à la tâche originelle, et peuvent avoir plusieurs limitations qui entravent leur rôle de sélection des directions de recherche les plus prometteuses. De plus, la définition de métriques d’évaluation pertinentes peut être difficile, en particulier dans le cas de sorties structurées et en haute dimension, telles que des images, de l’audio, de la parole ou encore du texte. Cette thèse discute des limites et des perspectives des benchmarks existants, des fonctions de coût (training losses) et des métriques d’évaluation (evaluation metrics), en mettant l’accent sur la modélisation générative - les Réseaux Antagonistes Génératifs (GANs) en particulier - et la modélisation efficace des données, qui comprend l’apprentissage few-shot et self-supervised. La première contribution est une discussion de la tâche de modélisation générative, suivie d’une exploration des propriétés théoriques et empiriques des fonctions de coût des GANs. La deuxième contribution est une discussion sur la limitation des few-shot classification benchmarks, certains ne nécessitant pas de généralisation à de nouvelles sémantiques de classe pour être résolus, et la proposition d’une méthode de base pour les résoudre sans étiquettes en phase de testing. La troisième contribution est une revue sur les méthodes few-shot et self-supervised de détection d’objets , qui souligne les limites et directions de recherche prometteuses. Enfin, la quatrième contribution est une méthode efficace en données pour la description de vidéo qui exploite des jeux de données texte et vidéo non supervisés. / In recent years, the field of deep learning has seen tremendous progress for applications ranging from image generation, object detection, language modeling, to visual question answering. Classic approaches such as supervised learning require large amounts of task-specific and labeled data, which may be too expensive, time-consuming, or impractical to collect. Data-efficient methods, such as few-shot and self-supervised learning, attempt to deal with the limited availability of task-specific data by leveraging large amounts of general data. Progress in deep learning, and in particular, few-shot learning, is largely driven by the relevant benchmarks, evaluation metrics, and datasets. They are used to test and compare different methods on a given task, and determine the state-of-the-art. However, due to being idealized versions of the task to solve, benchmarks are rarely equivalent to the original task, and can have several limitations which hinder their role of identifying the most promising research directions. Moreover, defining meaningful evaluation metrics can be challenging, especially in the case of high-dimensional and structured outputs, such as images, audio, speech, or text. This thesis discusses the limitations and perspectives of existing benchmarks, training losses, and evaluation metrics, with a focus on generative modeling—Generative Adversarial Networks (GANs) in particular—and data-efficient modeling, which includes few-shot and self-supervised learning. The first contribution is a discussion of the generative modeling task, followed by an exploration of theoretical and empirical properties of the GAN loss. The second contribution is a discussion of a limitation of few-shot classification benchmarks, which is that they may not require class semantic generalization to be solved, and the proposal of a baseline method for solving them without test-time labels. The third contribution is a survey of few-shot and self-supervised object detection, which points out the limitations and promising future research for the field. Finally, the fourth contribution is a data-efficient method for video captioning, which leverages unsupervised text and video datasets, and explores several multimodal pretraining strategies.