Toward a set of design principles for decoding training: A systematic review of studies of English as a foreign/second language listening education

Listening is a major challenge for many English as a foreign language (EFL)/English as a second language (ESL) learners. Many learners find it difficult to immediately process and segment an ongoing stream of sounds. Decoding training is one of interventions that have been used to assist EFL/ESL learners. This paper reviewed empirical studies of the effectiveness of decoding training in developing EFL/ESL learners' listening. We examined the following four major factors: (a) the types of instructional activities used; (b) the effects of decoding training on student listening outcomes; (c) the main instructional enablers of decoding training; and (d) the main instructional barriers to decoding training. The two activities most frequently used for decoding training were dictation and pronunciation instruction. A meta-analysis of 13 intervention studies showed an overall significant effect in favor of decoding training over non-decoding instruction for listening education (Hedges's g = 0.553, CI = 0.348-0.759, 95% confidence interval, p = 0.000), with no evidence of publication bias. Two theoretical frameworks, cognitive learning theory and the attention, relevance, confidence, and satisfaction model, were used to synthesize 33 studies to analyze the common elements that promote and hinder the development of learners' decoding skills. We proposed a set of design principles for decoding training that are expected to enhance the effectiveness and efficiency of decoding training in EFL/ESL listening education.