Dr. Chuchu Li, UCSD, presents in person and over zoom (password lingcol).
In real life, bilinguals spontaneously switch languages when conversing with other bilinguals, even though numerous laboratory studies have revealed robust language switching costs even when switching is voluntary or predictable. One reason is that some words are more accessible in the other language, and accessibility-driven switches can be cost-free in isolated word production (e.g., single picture naming; Kleinman & Gollan, 2016). However, in connected speech but not in isolated word production, bilinguals tend to select a default language (such that most words are produced in this language). The violation of default language selection may elicit switch costs even when language switching is driven by lexical accessibility. To test whether and when bilinguals pay such costs, we measured bilinguals’ speech onset latency as well as the production duration of each word until the switch word. Spanish-English bilinguals described arrays of moving pictures in English that began with a complex phrase (e.g., [The shoe and the mesa] moved above the cloud) or a simple phrase (e.g., [The shoe] moved above the mesa and the cloud). In sentences beginning with a complex phrase, production durations of “shoe” and “and” were longer on switch than nonswitch trials. However, in sentences beginning with a simple phrase, speech rate was not affected by language switching until “mesa” itself was produced. Speech durations reveal broader switch costs than speech onsets; switches driven by lexical accessibility can be cost free only if they match default language selection, which operates on the phrase, the default scope of planning.