Introduction

Human beings are remarkable language learners who can easily learn and master several languages throughout their lives. Most of us have met people who can switch from one language to another within the same conversation, or children as young as four or five who can use one language with their mother, another with their father, and yet another with their kindergarten teacher. Multilingualism is, no doubt, a common achievement for many people around the world.

The increasing spread of multilingualism and the importance of language within society has led several scholars to investigate multilingual behaviour over the years, as evidenced by the strong tradition of work on sociolinguistic and educational aspects of multilingualism (Abu-Rabia, 1998; Baetens Beardsmore and Kohls, 1988; Bhatia, 2004; Bild and Swain, 1989; Brohy, 2001; Cenoz and Genesee, 1998; Cenoz et al., 2001; Clyne et al., 2004; Cummins, 2001; Dagenais and Day, 1998; Edwards, 1994; Jaspaert and Lemmens, 1990; Kramsch, 2006; Leman, 1990; Muñoz, 2000; Oksaar, 1983; Pandey, 1991). Research on the cognitive and psycholinguistic aspects of multilingualism has instead been much slower to appear. With the exception of a few early studies (Chamot, 1973; Chandrasekhar, 1978; Gulutsan, 1976; Haggis, 1973; Lococo, 1976; Tulving and Colotla, 1970; Vildomec, 1963), it is only in the 1980s that multilinguals' processes begin to be examined closely and systematically, reaching the effect of raising a general awareness among scholars that multilinguals are learners and speakers of their own who should not be compared to L2 learners without some careful vigilance.

At present most studies on multilinguals' acquisition and production processes can be found in academic journals, edited volumes, conference proceedings or unpublished M.A. or Ph.D. theses.