Achilleas Kostoulas

Applied Linguistics & Language Teacher Education

Complexity Theory & Language Development: A review of Ortega & Han (2017)

If you’ve been following this blog long enough, you will likely know that I have a keen interest in complexity theory and its implications for language teaching and learning. That’s why I was quite excited when I was asked to review Complexity Theory and Language Development. This volume, which has been edited by Lourdes Ortega and ZhaoHang Han, brings together ten papers by some of most prominent scholars in the field.

The review has just appeared in the Linguist List, and what follows below is a revised, and hopefully more accessible version, with some extra content and hyperlinks, and language that is somewhat less pretentious.

The review

Cover Page of Complexity Theory and Language Development
Complexity Theory and Language Development

The edited volume Complexity Theory and Language Development (Lourdes Ortega & ZhaoHong Han, editors) is a collection of 10 chapters, fronted by brief introductory comments by the editors, which has been compiled in celebration of Professor Diane Larsen-Freeman for her seminal work advancing Complexity Theory in applied linguistics. The contributions that make up the collection explore different ways in which Complexity Theory has been applied to the field, or can be used to inform it. 

Summary of Contents

Complexity Theory: The Lessons Continue

Following brief editorial comments and chapter summaries (pp. 1-10), the collection begins with an authoritative discussion of Complexity Theory by Diane Larsen-Freeman (Chapter 1: “Complexity Theory: The Lessons Continue”, pp. 11-50). The key takeaway from this detailed chapter is that complexity can most usefully function as a metatheory in applied linguistics. Whereas most theories and methods in applied linguistics refer directly to the empirical world, complexity can serve a valuable role by connecting them, as a shared conceptual frame.

Larsen-Freeman begins by tracing connections between Complexity Theory and its antecedents in the physical and social sciences, as well as philosophy. She also usefully positions complexity in relation to post-modern thinking, with which there is much overlap, but also important theoretical difference. Many readers will also be interested in the discussion of how Larsen-Freeman’s own thinking about complexity has evolved since her seminal contributions in the 1990s. 

In addition to describing how complexity perspectives developed, Larsen-Freeman’s chapter provides readers with a helpful state-of-the-art account of Complexity Theory in language development research. By listing an extensive range of publications that have used complexity to investigate topics ranging from L1 acquisition to World Englishes, she provides ample evidence of an ongoing paradigm shift in applied linguistics. This is followed by a manifesto-like statement of 30 maxims about language, language learners and users, and language learning, which constitute a broad framework for the emerging Complexity paradigm.

Extract of Larsen-Freeman (2017)
This list of assumptions that underlie complexity thinking, by Diane Larsen-Freeman, is one of the highlights of the book.

The chapter concludes by discussing three major challenges associated with applying complexity thinking to linguistics research. The first challenge (non-duality) refers to the unhelpful tendency to think of the phenomena that interest us in applied linguistics as if they are binary distinctions (you can follow up on this by watching this video). The second challenge is the difficulty of framing a system for study without destroying its meaningful connections to its context (for a practical example, you might want to read this extract from my own book, A Language School as a Complex System). The third issue, generalisability, refers to the difficulty reconciling the idea that each complex system has a unique configuration, which lies at the core of complexity, with the quest for knowledge that is relevant to wide audiences, which is a fundamental mandate of scientific work. 

Complexity Theory and Dynamic Systems Theory: Same or Different

The second chapter in the collection (“Complexity Theory and Dynamic Systems Theory: Same or Different”, pp. 51-58) is a short contribution by Kees de Bot, which juxtaposes two strands of complexity-informed thinking. The first one, Complexity Theory, developed from systems theory and the work of scholars like Bateson and Morin, whereas the second one, Dynamic Systems Theory, is an adaptation of work in mathematics that traces its origins to Poincaré and Mandelbrot, and was actively developed by researchers based at the University of Groningen (the ‘Groningen group’).

Complexity Theory Dynamic Systems Theory
Conceptual originsSystems theory (e.g., Bateson, Morin)Mathematics (e.g.,
Poincaré, Mandelbrot)
DevelopmentAnglo-SaxonGroningen Group

Although the two terms appear to “have been used in peaceful cohabitation” (p. 52), and have tended to be used interchangeably in the literature, de Bot points out that “labels and terms matter” (p. 56) and argues that the use of the term Complex Dynamic Systems Theory (CDST), which brings the two perspectives together, affords greater conceptual clarity. 

Neural Complexity Meets Lexical Complexity

Chapter 3, by John H. Schumann, is entitled “Neural Complexity Meets Lexical Complexity: An Issue both in Language and in Neuroscience” (pp. 59-78). In this chapter, Schumann addresses issues in neurobiology that might be usefully conceptualised under a complexity lens.

One such example is degeneracy, which means that the same output or brain function can be produced by structurally different brain mechanisms. Schuman notes that similar ‘many-to-one’ correspondences exist in language, and offers synonymy as an example. He also notes that mismatches between the neurological instantiation of emotions, their phenomenological experience and their lexical representation raises similar issues. He goes on to suggest that the existence of parallel problems in different disciplinary areas (neurobiology and linguistics) is likely due to the fact that “both the brain and the lexicon of human language are complex and dynamic” (p. 75).

Building on this, and drawing on Larsen-Freeman’s view of complexity as a metatheory, Schumann concludes that Complexity Theory can help us better understand discrepancies between “the non-material world of words … and the material worlds” (p. 76).

Conceptualising Learner Characteristics in a Complex Dynamic World

In Chapter 4 (“Conceptualising Learner Characteristics in a Complex Dynamic World”, pp. 79-96), Zoltán Dörnyei takes a focused look into how Complexity Theory has informed individual differences (ID) research in second language acquisition.

Early ID research in Second Language Acquisition (SLA) aspired to identify the enduring characteristics of learners, such as aptitude or motivation, which had an impact on language learning outcomes. Such a perspective, Dörnyei explains, has tended to ignore that learner characteristics are not as discrete or as stable as early research would suggest.

To better account for the interconnectedness and variation of the IDs,
Dörnyei describes a conceptual framework that he developed with Stephen Ryan (Dörnyei & Ryan 2015). This model places the learner’s narrative identity at the centre, and relates it to dispositional traits and characteristic adaptations, as well as factors connected to the human nature, the learning situation and cultural parameters.

As Dörnyei suggests, this revised view on IDs allows for “continuity with past findings in personality psychology” regarding differentiation (p. 93), but it also highlights the dynamism and emergent nature of the narratively constructed self. 

The Emerging Need for Methods Appropriate to Study Dynamic systems

The next contribution (Chapter 5: “The Emerging Need for Methods Appropriate to Study Dynamic systems: Individual Differences in Motivational Dynamics”, pp. 97-122) explores methodological responses to the challenges associated with studying complex dynamic systems.

In the chapter, Peter D. MacIntyre, Emily MacKay, Jessica Ross and Esther Abel review 12 different research methods, drawing on the studies reported in Dörnyei et al.’s (2015) edited collection on motivational dynamics. Their wide-ranging review spans from relatively familiar designs (e.g., longitudinal qualitative interviews, triangulation in mixed-methods research, Q methodology) to more novel approaches, like retrodictive qualitative modelling or qualitative comparative analysis. These methods, it is argued, are particularly appropriate to answering the process-oriented questions that are likely to be asked by researchers working in the Complexity Theory paradigm. 

Lost in State Space?

Chapter 6, by Wander Lowie, is entitled “Lost in State Space? Methodological Considerations in Complex Dynamic Theory Approaches to Second Language Development Research” (pp. 123-141).

Similarly to MacIntyre et al. (above), this contribution also makes a distinction between product-oriented and process-oriented research, and suggests that the latter is a better match for the complexity paradigm. Lowie argues that “the most appropriate method of analyses of development over time will have to involve nonlinear analyses of longitudinal case studies” (p. 125, my emphasis). Such studies, he suggests, satisfy multiple theoretical requirements for complexity-informed research, namely:

  • They explicitly include a temporal dimension in the research design;
  • They generate high density of observations which help to better capture intra-learner variability;
  • They facilitate the study of interactions between the subsystems that collectively produce the phenomenon under investigation.

Longitudinal case studies are hard to generalise, however (see also Larsen-Freeman’s comments about generalisablity). To counter such criticism, Lowie stresses that after individualised developmental trajectories are discovered, these findings can be used to tease out underlying theory; besides, the importance of generalising to larger populations may be overstated. 

Complex Dynamics Systems Theory: Lessons to be Learned

The following chapter (Chapter 7: “Complex Dynamics Systems Theory: Lessons to be Learned”, pp. 143-162) focuses on pedagogical implications of adopting a complexity-informed perspective in language development. In this chapter, Marjolijn Verspoor puts forward a “data-usage-based (DUB)” theory of language, according to which the building blocks of language are “Form-Use-Meaning-Mappings”, ranging from individual lexemes (words) to conventionalised multi-word sequences.

In addition to a complexity-informed view on language, she also advocates a complexity-informed methodology, or “DUB instruction”, which she compares and contrasts to communicative language teaching with reference to pedagogical principles derived from Lightbown and Spada (2013). The chapter concludes by exemplifying this approach using a teaching method described as Film and Language Integrated Learning. 

Language Destabilisation and (Re-)Learning from a Complexity Perspective

Examples of how existing research can be reinterpreted using Complex Systems Theory as a meta-theoretical lens can be found in Chapter 8, entitled “Language Destabilisation and (Re-)Learning from a Complexity Perspective” (pp. 163-183).

In this chapter, Conny Optiz describes four studies that looked into different aspects of language acquisition and attrition, and which spanned different timescales ranging from weeks to years. For each study, readers are presented with background information and a summary of key findings.

Table summarising findings on language acquisition and attrition (from Optiz 2017)
Table summarising findings from four studies of language acquisition and attrition, from Chapter 8, by Connie Optiz.

This description leads to a synthesis of findings, where Optiz argues that:

  1. the language systems of multilingual users keep changing;
  2. the magnitude of variation is associated with the timescale of change;
  3. variation does not appear to have a linear relation to the amount of effort users invest in the language.

She also suggests that the development of the language system also resembles complex systems in two more important ways. Firstly, it appears to be sensitive to its initial conditions, as can be expected in complex systems. Secondly, she argues the linguistic activity of the language users both shapes the context of language use and is constrained by it. Again, this seems to relate to the reciprocal shaping influences commonly observed in complex systems. 

A Neuropsycholinguistic Approach to Complexity

The instability of language systems is also the focus of Barbara Köpke’s chapter (Chapter 9: “A Neuropsycholinguistic Approach to Complexity: Bi/multilingual Attrition and Aphasia as Destabilization”, pp. 191-208). By combining the explanatory potential of linguistics, psycholinguistics and neuroscience, Köpke advances a view of language as an adaptive system that is prone to destabilisation.

Three such examples of destabilising processes are discussed, namely:

  • L1 attrition among neurologically unimpaired bilingual speakers;
  • learning an additional language; and
  • developing an acquired language disorder, such as aphasia.

Köpke synthesizes findings from the applied linguistics literature on this topic, and concludes that they highlight the adaptive potential of the brain, and suggest that adaptation is “a permanent and fundamental mechanism guiding both human behaviour and its biological grounding” (pp. 202-203). 

Energy Conservation in SLA: The Simplicity of a Complex Adaptive System

The final chapter in this collection (Chapter 10: “Energy Conservation in SLA: The Simplicity of a Complex Adaptive System”, pp. 209-231) brings together the insights of a linguist (ZhaoHong Han) and two astrophysicists (Gang Bao and Pail Wiita), in order to “explain and predict L2 ultimate attainment” (p. 210).

To achieve this, the authors put forward a theory of energy conservation (“Energy Conservation Theory in L2”, ECT-L2), which is analogous to the Law of Conservation of Energy in classical physics. In their discussion, they identify parallels between kinetic energy and motivation and aptitude, centrifugal energy and the linguistic distance between the L1 and L2, and potential energy and L1 interference (“traction”). They then express these forms of energy mathematically, by means of four formulae that they use explain three scenarios of language acquisition.

Diagram depicting "Theory of Energy Conservation in L2"
Chapter 10 used elegant diagrams and advanced mathematical notation, but it was not always easy to follow.

The authors suggest that despite apparent differences, their theory is complementary to Complexity Theory, with complexity accounting for moment-to-moment phenomena, and ECT-L2 providing a macroscopic view. They also claim that “none of the extant theories in SLA has achieved this level of sophistication” and confidently assert that “ECT-L2 could allows us to predict ultimate attainment” in SLA (p. 225). 


Considering the increasing popularity of complexity in applied linguistics and language education, this volume makes a very timely contribution. Its most important strength is that it convincingly advances the view of Complexity Theory as a meta-theory that can provide much needed coherence in the field by specifying “what is meaningful and meaningless, acceptable and unacceptable, central and peripheral as theory … and as method” (Overton 2007: 154, cited in this volume: 21). This is a thesis argued very compellingly in Chapter 1, and the ensuing contributions provide ample evidence of how Complexity Theory can provide a shared conceptual space that brings together insights from diverse sub-disciplines studying of language and language learning. Such connections are not always seamless, and the diversity of the contributions that make up the volume alerts us to subtle differences in underlying ontologies, methodological orientations and terminological preferences. The editors’ decision not to iron out these differences, despite some potential for confusion, seems particularly astute, as it helps to highlight the theoretical depth and nuance of the complexity paradigm. 

Who is this book for?

Overall, I believe that this volume would be especially helpful to advanced readers with an interest in complexity and its implications for studying language development, whether their focus is on the acquisition or attrition of the first or second language. Chapter 1, in particular, is an indispensable read, which is likely to exercise considerable influence in shaping future developments in the field. Chapter 2 also serves a useful orienting purpose, whereas Chapters 8 and 9 provide readers with interesting examples of how language can be conceptualised as an adaptive system. Together, these four chapters provide a helpful conceptual overview of Complexity Theory. 

Chapters 3 and 9 might primarily appeal to researchers with a focus on neurolinguistics, while readers whose interests lie in second language learning and teaching will likely find Chapters 4 (on individual differences) and 7 (on complexity-informed pedagogy) especially useful. For readers with an interest in developing research methods that are compatible with the ontological tenets of Complexity, Chapter 5 provides a useful entry point that showcases different methodological options, and Chapter 6 offers useful epistemological guidance.

Chapter 10, which uses mathematical methods to explain and predict language learning outcomes is an interesting addition to the collection. To be perfectly honest, I found it hard to follow the chapter, which used advanced mathematic notation, and I cannot tell whether the mathematical model described can provide a viable alternative to empirical observation as a means for predicting learning outcomes. However, reading the chapter left me wondering whether the model (or such models) could inform the design of computer simulations that can be used for time-series analyses, which can then be juxtaposed to actual empirical data. Moreover, the chapter illustrates the potential for interdisciplinary crossover made possible by a metatheory. 

While this volume will doubtless be a valuable read for academics and students who are already familiar with Complexity Theory, more casual readers might find it relatively challenging at times. Larsen-Freeman’s detailed chapter provides readers with useful support in this regard, but its main purpose seems to be to recapitulate theoretical developments and sustain momentum, rather than to provide a detailed introduction. A final chapter synthesising the common themes that unite the contributions would have been a welcome addition. 

In summary

Overall, this collection achieves two important aims, which are close to the heart of all scholars working in the complexity paradigm. Firstly, it invites readers to reflect on the “range of questions, methods and answers” that Complexity Theory generates when applied to linguistic inquiry (p. 9). The contributions that make up this volume do this in ways that consistently engage the readers’ intellect, even if they do not always prompt unconditional agreement. Secondly, it pays a very fitting tribute to the scholarship of Diane Larsen-Freeman, in whose honour and celebration the volume was compiled. 

Some final words…

I hope you found these thoughts useful, or at least I hope that I have managed to convey a sense of interest in complex systems theory. I have, in recent years, become increasingly convinced that complexity is a useful way forward in studying language education, and it was for this reason very pleasing to see several contributions in this book putting the theory to good use – and even stretching the occasional boundary. Whether you agree with this assessment, or feel that you want to voice an objection, I would very much welcome your insights in the comments section below.

If you would like to read more about how complexity is used in language education, I have written a few blog posts over the years where I try to make it accessible. You can find them by following this link, and I hope you enjoy engaging with them.



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3 responses to “Complexity Theory & Language Development: A review of Ortega & Han (2017)”

  1. eflnotes avatar

    Thanks for putting a version of your review here Achilleas. Are there any notes addressing critiques of DST in language learning in the book?

    1. Achilleas Kostoulas avatar

      Hi! Glad you enjoyed this. I’m afraid there’s not much in terms of criticism in this book, which is to be expected, I guess, given its nature and the author lineup. But I have something in mind which is not published yet, and I’ll send it to you when it’s ok to share.

      1. eflnotes avatar

        oh great look fwd to that, good luck with the publishing process!

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