WHY IS LANGUAGE LEARNING SO SLOW IF INFANTS ARE SUCH RAPID LEARNERS?
Human infants show a striking capacity for extracting statistical regularities in language. This process, called statistical learning, is thought to bootstrap acquisition of language. Critically, studies of statistical learning test infants in the minutes following familiarization, but long-term memory formation unfolds over hours and days, with little work investigating retention of statistical learning. This creates a critical gap in the literature given how little we know about how single or multiple learning experiences translate into permanent knowledge. Furthermore, different memory systems with vastly different encoding and retention profiles emerge at different points in development, with the underlying memory system dictating the fidelity of the memory trace hours later. I describe the scant literature on retention of statistical learning, the learning and retention properties of memory systems as they apply to statistical learning, and the development of these memory systems. I propose that different memory systems support retention of statistical learning in infants and adults, suggesting an explanation for the slow pace of natural language acquisition in infancy. I discuss the implications of this position for child and adult language acquisition.