The age of acquisition effect in processing second language words and its relationship with the age of acquisition of the first language

The present study investigated the age of acquisition (AoA) effect in processing second language (L2) words and how it is related to the AoA of the corresponding first language (L1) words. We adopted a lexical decision task in three experiments. The filler words were orthographically illegal in Experiment 1 to elicit more word form processing, while Experiment 2 used legal fillers to shift the bias toward semantic processing. In Experiment 3, we used a larger amount of stimuli containing more longer words with legal fillers. Our results showed that L2 AoA has a weak effect at the orthographical processing level and a stable effect at the semantic processing level. The L1 AoA modulates the L2 AoA effect at the semantic processing level, which is more likely to appear in long words. These results suggest that it is important to take bilingual representation and activation into consideration to explain the L2 AoA effect.