  In this work, we use language modeling to investigate the factors that
influence code-switching. Code-switching occurs when a speaker alternates
between one language variety (the primary language) and another (the secondary
language), and is widely observed in multilingual contexts. Recent work has
shown that code-switching is often correlated with areas of high information
load in the primary language, but it is unclear whether high primary language
load only makes the secondary language relatively easier to produce at
code-switching points (speaker-driven code-switching), or whether
code-switching is additionally used by speakers to signal the need for greater
attention on the part of listeners (audience-driven code-switching). In this
paper, we use bilingual Chinese-English online forum posts and transcripts of
spontaneous Chinese-English speech to replicate prior findings that high
primary language (Chinese) information load is correlated with switches to the
secondary language (English). We then demonstrate that the information load of
the English productions is even higher than that of meaning equivalent Chinese
alternatives, and these are therefore not easier to produce, providing evidence
of audience-driven influences in code-switching at the level of the
communication channel, not just at the sociolinguistic level, in both writing
and speech.
