Sociolinguistic studies in Latin America generally deal with situations in which one of the official languages is in contact with an American Indian language, one of the major languages of immigration (German, Italian, Japanese), or one of the creole languages or dialects spoken in the Caribbean area. Except for the latter case, such studies have usually emphasized such processes as acculturation or assimilation, internal migrations, or social mobility.
A somewhat neglected research area is that of the coexistence of Spanish and Portuguese along the borders which Brazil shares with a number of Spanish-speaking nations. Just as it is an oversimplification to lump Brazil and its neighbors into a vaguely homogeneous “Latin” America, so also it would appear very risky to rely on the obvious linguistic similarities to generalize about communication between the two major speech communities.