Quantifiable Aspects of Language Acquisition

This paper investigates the quantifiable aspects of language acquisition such as the amount of input (perceived speech material) and vocabulary size. In light of the disillusionment of language education methodology in the 20th century with the search for an ideal method of language learning, the need for a new theoretical framework that will account for the available research data is emphasized. Stephen Krashen’s theory of second language acquisition is described as the most significant contribution to this end. Krashen’s hypotheses of acquisition and learning, natural order, monitor, comprehensible input and emotional filter are discussed. It is theorized that statistical processing of language input by the brain lies at the core of language acquisition. Reference is made to evidence from first language acquisition and polyglots’ study of foreign languages confirming this statement. The requirements for optimal input are examined, leading to the question of sufficient input quantity (measured by the number of words). Relevant data from first language acquisition, corpus linguistics and polyglottery is presented. Then, the question of vocabulary size corresponding to different levels of language competence is addressed by reference to estimates found in polyglot literature, exam-based research and online sources. In conclusion, it is argued that reaching an intermediate level in foreign language skills (B1– B2 in the European framework), requires the input of about one million words while mother tongue acquisition in childhood requires several dozen times more. This result can serve as a reference point for language education curriculum and materials development. On this basis, some practical recommendations for the improvement of language education are proposed, namely the need for talking with children more, calculating input in the learning process, using audio and video materials more widely, stimulating extensive reading, encouraging students to perceive information on topics of interest in a foreign language, and working with their motivation. Finally, the importance of further quantitative studies on language acquisition is underscored.