A memory perspective on sensitive periods in language acquisition

Why are there sensitive periods for language learning? This question has generated much research interest, but remains a poorly understood yet fundamental scientific issue. We aim to tackle developmental differences in language acquisition skills from a novel memory based perspective. It is widely accepted that procedural memory, relying on phylogenetic structures like basal ganglia and cerebellum, matures at young age. Declarative memory functions in contrast rely on brain structures such as the medial temporal lobes and prefrontal cortex, becoming fully functional only later in life. The latter is more sensitive to proactive interference and forgetting, leading us to hypothesize that children, mainly procedural learners, are advanced language learners compared to adults, who also rely on declarative memory processing. In this study, children (12 years old) were compared to adults during serial-order learning of lexical sequences (the Hebb repetition paradigm), as laboratory analogue of novel word-form learning. We manipulated the amount of lexical overlap between sequences. Retention was investigated by having subjects relearn the sequences after two hours. Our results demonstrate that children show better offline savings. Adults in contrast are sensitive to forgetting, especially under interfering conditions. These findings suggest developmental memory differences underlying children’s superior word learning skills