The first- and second-language age of acquisition effect in first- and second-language book reading

- L1 and L2 AoA were investigated in an eye movement corpus of bilingual reading.
- Both L1/L2 AoA influence L2 fixation times: earlier learned words were read faster.
- This finding supports the two main AoA hypotheses (mapping and semantic).

The age of acquisition (AoA) effect in first/monolingual language processing has received much attention in psycholinguistic research. However, AoA effects in second language processing were only investigated rarely. In the current study, we investigated first (L1) and second language (L2) AoA effects in a combined eye tracking and mega study approach. We analyzed data of a corpus of eye movements to assess the time course of AoA effects on bilingual reading. We found an effect of L2 AoA in both early and late measures of L2 reading: fixation times were faster for words that were learned earlier in L2. This suggests that the L2 AoA effect has an influence throughout the entire L2 reading process, analogous to the L1 AoA effect. However, we are also the first to find an early effect of L1 AoA on L2 processing: if the L1 translation of the L2 word was learned earlier, the L2 word was also read faster. We discuss the implications of these findings for two important hypotheses that offer an explanation for the AoA effect: the mapping and semantic hypothesis. We propose that the current results suggest an integration between these accounts.