At some time or another, many readers of this volume have shaken their heads in amazement at overhearing speakers who were carrying out a conversation in two languages, apparently freely drawing from both linguistic systems at will. Some readers themselves produce such conversations regularly. Such naturally occurring conversations on everyday topics are the subject of this study.
These conversations are frequent all over the world wherever the participants are bilinguals, from Puerto Rican secretaries rapidly alternating Spanish and English while strolling on lunch-break on the sidewalks of New York City, to Kikuyu market vendors in Nairobi, Kenya, judiciously adding phrases in Luo to their Swahili while wooing a Luo-speaking customer, to university professors in Tamil Nadu, India, interchanging English and Tamil when relating what happened at a recent academic conference.
The research question which this book addresses is the following: when speakers alternate between two linguistic varieties, how free is this alternation from the structural point of view? That is, are there structural constraints on codeswitching, and, if so, what are those constraints? An additional question which the study answers indirectly is: do the social functions of codeswitching control in any way the types of structures occurring?
From the sociolinguistic point of view, codeswitching of languages offers bilinguals a way to increase their flexibility of expression, going beyond the style-switching of monolinguals. That is, switching is a means to index the nuances of social relationships by exploiting the sociopsychological associations of the languages employed (cf. Myers-Scotton, 1993).