Cross-language negative priming remains intact,while positive priming disappears: evidence for two sources of selective inhibition

In the current experiments, within- and between-language primed lexical decision tasks with Twi-English bilinguals were used. The aim was to explore the priming effects produced by attended and ignored words, in an effort to draw theoretical and empirical parallels and differences between the mechanisms of excitation and inhibition and to isolate the different circumstances in which these mechanisms operate in bilingual language processing. In the within-language (Twi) experiment, facilitatory (positive) priming resulted when a prime word and subsequent probe target word were identical, whereas delayed decisions to probe targets (negative priming) ensued when the ignored prime word was conceptually identical to the subsequent probe target word. In contrast, while the between-language (Twi-English) experiments replicated the ignored repetition negative priming effect, no evidence of positive priming was observed. These between-language findings undermine episodic retrieval models of selective attention that discount inhibitory processes in negative priming paradigms. Instead, our findings substantiate inhibition-based accounts by showing that there are two sources of inhibition operating at the local word and global language levels of abstraction. The findings also support bilingual language representations in which the words of the two languages are integrated.