Learning from a transactional distance: a systematic review of distance education for second and foreign language learning

Conventionally, the education of languages and most disciplines are delivered in classrooms, where teachers and learners communicate and interact in face-to-face, real-time and physical settings. The norm of conventional education (CI) has been revolutionised by the coronavirus disease of 2019 (COVID-19), a global pandemic that circumscribed physical and in-person interaction, and leading to an unprecedented and worldwide suspension of classroom teaching. To minimise the prolonged disruption to education, distance education (DE) has become the normative practices of teaching and learning, which are often conducted via web-based and computerised media and technology so that teachers and learners could communicate from a virtual distance. The popularisation of DE has attracted far-reaching interest from stakeholders of education to contemplate the role of DE in the wake of the pandemic. On the one hand, some perceive the pandemic as a catalyst of paradigmatic shift from CI to DE, while others are sceptical of the effectiveness of DE. In view of this controversy, this paper aims to examine the effectiveness of DE in the field of second and foreign language learning (SLL/FLL) by conducting a systematic review that synthesises empirical evidence, and with a rigorous and transparent methodology that ensures reliability, validity and overall quality of findings.
Although DE came into existence over a century ago, it is a complicated domain in which there is an absence of universal standardisation in defining, categorising, evaluating or theorising the concepts and applications. By addressing these four issues, this paper laid the foundation for conducting the systematic review in manner of conceptual and theoretical consistency, preciseness and clarity. Firstly, based on a detailed and comprehensive review of literature, this paper defines DE as an ‘umbrella concept’ encompassing a composition of widely accepted definitions that are collectively applicable to an extensive variety of contexts. Secondly, this paper categorises DE by three modes of synchrony: the asynchronous, synchronous, and blended modes. The asynchronous and synchronous modes could be conceptualised by separate schools of thoughts in areas of media and technology, pedagogy and philosophy, and the blended mode combines the two divergent modes into the design and practice of DE. Thirdly, the effectiveness of the three modes could be compared according to four groups of results, including the outcome of second language (L2) learning, perception and attitude of teachers and learners, motivation of learners, and the emotion of learners. Finally, this paper adopts the theoretical framework of the transactional distance theory (TDT), which has over five decades of theoretical development and empirical investigations. TDT is arguably qualified as a global theory that compendiously encapsulates various media and technology, pedagogy and philosophy, and converges with other theories and concepts in the field of DE. TDT hypotheses an inverse relationship between the level of transactional distance (TD) and the degree of effectiveness in DE. TD is conceptualised as the barrier between teachers and learners that prohibits learning in DE, and as the function of three variables: the level of structure (or rigidity) of the DE course (i.e. How rigid or flexible is the course in catering to the individual needs of learners?); the level of dialogue between teachers and learners, and learners and contents (i.e. How interactive is the course?); and the level of learner autonomy (i.e. To what extent are learners capable of learning independently and making learning decisions for themselves?)
This paper aims to address three research questions, including the extent to which different DE modes (i.e. asynchronous, synchronous and blended) are effective in SLL/FLL of DE, the extent to which TD levels are different across the DE modes, and the relationship between the levels of TD and effectiveness of the DE modes. Based on the aforesaid review of current knowledge that addresses the conceptual, empirical and theoretical issues in the field of DE, there are three hypotheses of the research questions. Firstly, owing to the difference in media and technology, philosophy and pedagogical approach, the magnitude and types of outcome are likely to vary according to the synchrony of instruction (i.e. DE categories). Secondly, TD levels in each DE mode could be different depending on the instructional design and implementation of SLL/FLL in DE. Since the blended mode might demonstrate the benefits of both asynchronous and synchronous modes, and is generally favoured in the current generation of DE, it is hypothesised that the blended mode is more likely to yield more positive outcomes. Thirdly, TD is a barrier to learning and is inversely correlated with the effectiveness of DE, and a similar relationship is hypothesised to manifest in SLL/FLL of DE.
An elaborate methodology was designed based on the best practices of comparable systematic reviews, while adapting to the circumstances of this study. A systematic process of database search and flow of studies was followed, and articles were screened based on a standardised set of inclusion and exclusion criteria. The included studies are empirical studies that have been peer-reviewed, examined at least two DE modes (i.e. synchronies), complied with the definitions synthesised in the literature review, and satisfied a reasonable standard of weight of evidence (WOE) to ensure the quality of research. The process of screening, reviewing, documenting and confirming the included articles were conducted by a reviewer and two checkers to increase inter-rate and intra-rater reliability of the findings.
Following the procedures set out in the methodology, 31 articles were winnowed from the original sample of 308 articles on the basis of relevance to the current study, adequacy of details and clarity, validity and quality of findings (WOE), and inter-rater and intra-rater reliability. Published in the span of two decades, the body of research exhibits a representative sample of empirical investigations, embodying a diverse variety of characteristics, backgrounds and contexts, countries and regions, educational settings, L1s and L2s, L2 skills and proficiency levels, research design, data collection methods, lengths of investigation, participant types, sample sizes, types and concurrent applications of media and technology, and measurements in the categories of L2 learning, perception and attitudes, emotion and motivation.
By comparing the TD levels, scores of TD variables, measurements and results of L2 courses conducted in three DE modes, a number of distinct findings were observed. The blended mode was associated with the lowest levels of TD and the higher proportion of positive results, whereas the asynchronous mode exhibited a higher levels of TD but a smaller proportion of positive results In contrast, the synchronous mode was associated with the highest levels of TD and the lowest proportion of positive results. Last but not least, the number of media and technology concurrently applied was greatest in courses conducted in the blended mode, followed by the asynchronous mode, and the least in the synchronous mode. These findings affirm the hypotheses of the three research questions. It could be concluded that there is cogent evidence to associate DE modes with TD levels and the results of DE courses. Finally, the limitations of the systematic review, recommendations and the possible future of DE are discussed.

Keywords: transactional distance theory
e-learning
synchronous learning
educational technology
foreign language learning
blended learning
COVID-19
second language learning
distance education
asynchronous learning