La Bretagne est traversée par une frontière linguistique séparant historiquement la Basse-Bretagne de langue celtique (le breton) et la Haute-Bretagne de langue romane (le gallo). En zone frontalière, la différence linguistique sert de support à des représentations stéréotypées de l’Autre et de sa langue. Bien que la limite ait longtemps été mouvante, que des échanges aient toujours eu lieu et que les histoires familiales mêlent fréquemment des personnes originaires des deux côtés, deux groupes présentés comme étanches sont constitués de longue date, les « Bretons » et les « Gallos ». En créant une altérité en apparence évidente, la frontière linguistique permet aux uns et aux autres, dans un double mouvement, de se différencier de leurs voisins et de s’identifier à leur groupe. L’analyse des représentations fait apparaître une forte asymétrie, nettement en faveur des Bas-Bretons et du breton, tandis que les Hauts-Bretons et le gallo sont souvent ignorés, voire font l’objet d’un franc mépris. Cette asymétrie va de pair avec une survalorisation de la Basse-Bretagne dans les discours sur l’identité bretonne face à une Haute-Bretagne fréquemment occultée. De nos jours, ces représentations anciennes continuent à influer sur les pratiques, le gallo faisant l’objet d’une faible mobilisation et ses locuteurs obtenant peu de moyens susceptibles d’aider à inverser le mouvement de déclin. La frontière est source de tensions au sein du mouvement de revitalisation des langues de Bretagne, qu’on la considère obsolète ou que l’on souhaite s’appuyer sur elle pour faire respecter un territoire et revendiquer des droits linguistiques. / Brittany is divided by a language boundary that has historically separated Lower Brittany, where the Celtic language of Breton is spoken, from Upper Brittany, where people speak the Romance language of Gallo. In the border zone, this linguistic difference is used in support of stereotypical representations of the Other and his/her language. Although the boundary has long been instable, although exchanges have always taken place, and although family histories frequently mix people originating on either side, discourses have long invoked two groups constituted as hermetic: “Bretons” and “Gallos.” By creating a readily visible axis of alterity, the linguistic boundary permits people on either side to differentiate themselves from their neighbors and, simultaneously, to identify with their own group. Analyses of these representations reveal a marked asymmetry, clearly in favor of Lower Bretons and the Breton language, while Upper Bretons and Gallo are often ignored, or even made objects of open disdain. This asymmetry corresponds to an overvaluation of Lower Brittany in discourses about Breton identity, which frequently leaves Upper Brittany elided. At present, these longstanding representations continue to influence practices, Gallo being the object of less social mobilization and its speakers receiving less assistance in reversing language shift. The border is the source of tensions at the heart of Brittany’s language revitalization movement, whether one considers it to be obsolete or uses it to gain respect for a territory or to claim language rights

This thesis consists of two studies together with a preliminary study, focusing on the issue of ingroup representation of the &uuml / lk&uuml / c&uuml / group. The first study, addressing the problems of stereotype content, stereotype accuracy, and stereotype consensus, was based on in-depth interviewing with twenty members of the &uuml / lk&uuml / c&uuml / group. It was hypothesized that the group members, when their social identities were salient, would locate the ingroup within a chronic way of looking at the world, namely the perceived context. The accuracy of stereotypes and the stereotype consensus commonly observed among group members depended upon the efficiency of this perceived context as an explanation. Moreover, the favorability of stereotype content also derived heavily from this perceived context. The second study, based on two hundreds &uuml / lk&uuml / c&uuml / group members, examined the effects of target group (ingroup, close outgroup, distant outgroup), type of attributes (favorable, unfavorable), comparative context (intragroup, intergroup with close outgroup, intergroup with distant outgroup, multigroup), and level of identification with the ingroup (high-identifiers, low-identifiers) on the perceptions of homogeneity. A number of hypotheses were tested and the following results were found: First, group members perceived the ingroup as more positively homogeneous than both the close and the distant outgroup. Moreover, the close outgroup was perceived as more positively homogeneous than the distant outgroup. In fact, the distant outgroup was perceived as negatively homogeneous. Second, group members perceived both the ingroup and the close outgroup as more positively homogeneous in terms of unfavorable attributes than in terms of favorable ones. On the contrary, they tended to perceive the distant outgroup as more negatively homogeneous in terms of favorable attributes than in terms of unfavorable ones. Third, the above perceptions were less accentuated in the intragroup context, while they were more accentuated in the multigroup context. Fourth, the above perceptions were more accentuated for the high-identifiers than for the low-identifiers. Apart from these main effects, a number of complicated interactions were also discovered and these results were discussed with reference to the relevant literature.