Developmental trajectories of control of verbal and non-verbal interference in speech comprehension in monolingual and multilingual children

Research on speech comprehension in noise indicates that a multilinguistic experience may confer advantages in filtering out verbal interference, an effect observed both in children acquiring two or more languages since birth (Filippi, Morris, Richardson, a al., 2015) and in second language learner adults (Filippi, Leech, Thomas, a al., 2012). A possible interpretation for this advantage is that the multilingual mind is "trained" to control interference from the language not in use. This constant effort may support optimization of cognitive resources that are necessary for successfully selecting, processing and interpreting complex linguistic information. The present study aimed to extend this line of research by including a non-verbal interference condition. 209 typically developing children (132 English monolinguals and 77 multilinguals from different linguistic backgrounds) carried out a sentence interpretation task in the presence of verbal and non-verbal interference. We found no evidence for a reliable group difference in our data. Instead, findings indicated that background cognitive ability and socioeconomic status were the best indicators of successful control of interference, irrespective of whether participants were bilingual or monolingual. These findings are discussed in the light of previous research and, more widely, on the account of the current debate on the bilingual advantage.