This programme of research, involving seven experiments, investigates Evans' (1980a; 1980b) revised version of the Dual Process theory of reasoning (Wason and Evans, 1975). A Type 2 process is characterised as verbal-rational and a Type I process as non-verbal and non-logical. Evans links the processes to two statistical components of observed reasoning performance. The Type I process reflects non-logical response biases and the Type 2 process reflects attention to the logical nature of the task. Six experiments employ a concurrent articulation (with or without a short-term memory load) methodology devised by Baddeley and Hitch (1974) for investigating their Working Memory model. Four experiments apply this technique to conditional reasoning tasks in an attempt to disrupt the verbal Type 2 process. Some weak evidence for the revised Dual Process theory is found. There is a tendency, marked in only one experiment, for concurrent articulation to inhibit logical performance, whilst having little effect on response biases. Unexpectedly, articulation conditions (without memory load) are characterised by faster responding than silent conditions. The results are inconsistent with Hitch and Baddeley's (1976) data and several features of their Working Memory model. Two further experiments repeat and extend their work. A number of important theoretical implications are discussed in the light of recent revisions to their theory (eg. Baddeley, 1983). A possible connection is drawn between Type I and Type 2 processes and dual memory codes (Paivio, 1971; 1983) and thought systems (Paivio, 1975) of a verbal and visual nature. The hypothesis that Type I processes may be associated with visual mechanisms is tested by introducing a factor into three experiments to induce use of a visual code. This does not affect the Type 1 process but facilitates lo3ical performance. These results are discussed in relation to the revised Dual Process theory. An explanation in terms of a recent tricoding model for processing of pictures and words (Snodgrass, 1980; 1984) is suggested.

La thèse met en lumière les conditions d’enseignement et d’apprentissage des mathématiques en langue seconde en étudiant avec précision l’articulation des savoirs mathématiques et des savoirs linguistiques. Elle traite le cas spécifique de l’enseignement des mathématiques en anglais dans un contexte CLIL et les séances expérimentales ont lieu en classes européennes de lycée. Le thème commun à ces séances est celui des preuves visuelles et multimodales. La Théorie des Situations Didactiques (TSD) offre un cadre théorique privilégié – notamment pour la construction des situations expérimentales - cadre qu’il a fallu compléter par des approches théoriques sémiotiques et linguistiques. Ainsi l’approche adoptée s’est révélée en adéquation avec la perspective actionnelle et la phraséodidactique a apporté de nombreux éléments permettant de mettre en relief le rôle de la phraséologie dans un enseignement intégré. Une focalisation particulière a dû être opérée sur les objets mathématiques et les processus d’abstraction mais aussi sur certains faits de langue. Les investigations ont permis d’affiner les descriptions des raisonnements produits tout en conservant une référence aux niveaux de milieux, au sens de la TSD. L’étude a nécessité de développer le concept de représentation et de décliner les représentations produites dans le contexte de la L2. Ce sont ces concepts et celui d’adidacticité, central dans la TSD, qui ont permis d’organiser les séances de manière optimale, en faisant apparaître le rôle essentiel joué par la perception active dans les processus de conceptualisation. / The purpose of this thesis is to investigate learning and teaching conditions of mathematics in English as a second language by closely examining how mathematical and language knowledge can fit together. This study deals with the specific case of CLIL teaching and the related experimental situations are performed in European classes in a French high school. The situations have a common topic, namely that of visual and multimodal proof. The theory of Didactical Situations is the central theoretical framework but our study has proven to be compatible with task-based pedagogy. Besides, phraseodidactics provided a useful and adequate auxiliary framework by shedding some light onto the essential role played by4phraseology. We particularly kept focused on mathematical objects and processes of abstraction but also on some specific language features. The concept of representation is central in our research works and thus had to be precisely defined. The success of our experimental situations owes a lot to the use of adidacticity, a central concept in TSD, and our focusing on the crucial part played by active perception during processes of conceptualisation. The purpose of one of the experimental situations (conducted in a second language) was to ensure that pupils divised, by themselves, a visual proof of an arithmetic property previously conjectured, carried out on the very level of schematisation an explicit generalisation and used real cubes to perform another type of proof, thus making the inductive step of the induction explicit.