Interpersonal Coordination Dynamics in Psychotherapy: A Systematic Review

Coordination is a general phenomenon that emerges in physical, biological, and psychological systems (Turvey 1990). It is the ways in which components and processes of a system change together over time (Butner et al. 2014) and it can take many forms (Butler 2011). For example, the pendulums of clocks on a wall move in time and in relative phase to each other when they share a physical medium (Strogatz and Stewart 1993), and when people swing pendula together they share oscillatory patterns and bi-directionally influence each other (Butner et al. 2005). During human interaction, there is evidence that we coordinate our movements (Abney et al. 2015), communicative behaviors (Louwerse et al. 2012), neural activity (Likens et al. 2014), physiology (Palumbo et al. 2016), and voices (Imel et al. 2014; Reich et al. 2014) with others.

Integrative approaches to psychotherapy have increasingly argued for considering psychotherapy as a dynamical system (Gelo and Salvatore 2016; Schiepek et al. 2015). The general notion here is that there is a psychotherapy system consisting of at least the patient and the therapist, each with their own sub-systems (e.g., cardiovascular, neural, etc.) that reciprocally influence each other as they interact. From this perspective, the ways in which system components coordinate are crucial for effective functioning.

While there are many plausible starting points from which to investigate psychotherapy, we focus on interpersonal coordination as a form of coordination where a variable measured from the patient and from the therapist change together in systematic ways over time. We refer to the term coordination as it is used in the field of coordination dynamics (Kelso 2009; Turvey 1990), which is superordinate to more specifically operationalized forms of coordination such as synchronization or alignment (Butner et al. 2014). Not only has there been some evidence that interpersonal coordination matters in psychotherapy in certain modalities (Ramseyer and Tschacher 2011), but there has also been more general interactional benefits of coordinating with others such as increased affiliation (Hove and Risen 2009), increased cooperative tendencies (Wiltermuth and Heath 2009), and increased pro-social behaviors and attitudes (Rennung and Göritz 2016). While there is a growing body of literature examining the benefits of interpersonal coordination, the explanation for its functionality during psychotherapy is still limited (cf. Koole and Tschacher 2016).

One plausible explanation for why interpersonal coordination has an important role in psychotherapy is that it could be a manifestation of common factors; factors that occur in psychotherapy independent of treatment type, which have shown to be drivers of therapy effectiveness and are typically conveyed through social interaction (Messer and Wampold 2002). Relatedly, movement coordination has been associated with working alliance (Koole and Tschacher 2016) and physiological coordination has been related to empathic responding (Marci et al. 2007), both of which are often considered common factors. Furthermore, it has been argued that it is not only the working alliance that it is important, but also the ‘real’ relationship that is evidenced by emotional coordination between therapist and patient (Liebovitch et al. 2011; Peluso et al. 2012). In relationships broadly, there is compelling evidence for physiological co-regulation (Butler and Randall 2013), which may also apply to psychotherapeutic contexts. Another plausible explanation is polyvagal theory, which describes how coordinated physiological responding between patient and therapist may provide the bio-behavioral basis for feelings of safety that allow the therapeutic relationship to progress and flourish (Geller and Porges 2014). And, lastly, social mentality theory prescribes that in adopting a caregiving role, therapists may be biologically predisposed to attune and coregulate others in their caring/caregiving relationships (Gilbert 2019), such as those early caregiver relationships that help infants to regulate their physiology and behavior (e.g., Evans and Porter 2009; Hofer 1994). Thus, while there are a number of theoretical explanations for how interpersonal coordination may function, a systematic review of these findings in psychotherapy is warranted.

In our review, we focus on interpersonal coordination during psychotherapeutic interactions in any modalities that have been examined including movement, physiology, vocalizations, language, and behaviors, and any psychotherapy processes or outcomes measures of coordination that the modalities have been linked with. It is our aim that an integrative set of findings on interpersonal coordination dynamics during psychotherapy can inform a richer understanding of psychotherapeutic interactions and human interaction, more broadly. In doing so, we also aim to form a basis for improving the research and practice of psychotherapy by providing some tentative recommendations for further evaluation.

We conducted a systematic literature review following existing models and guidelines (Okoli and Schabram 2010; Palumbo et al. 2016). The goal was to retrieve all articles published in English peer-reviewed journals relating to interpersonal coordination occurring in psychotherapeutic contexts that were published no later than December 2016. An additional search was conducted on August 20, 2019. We chose our search terms based on prior literature searches and articles a priori deemed as relevant. Searches were conducted separately based on the following overarching terms: Physiological, behavioral, interpersonal, and dyadic. For each of these terms, the search algorithm was connected to the following terms with an AND statement: synchron* OR coordination OR covariation OR coherence OR linkage OR contagion OR attune* OR alignment OR mimic* AND psychotherap* OR counseling OR psychiatry. Asterisks denote that the search engine will include permutations of the specified root. Searches based on these keywords were conducted in PsychInfo and PubMed. Additionally, once articles were identified as relevant and meeting the eligibility criteria below, a reverse citation search was conducted using Google Scholar. Eligibility and exclusion criteria are listed below. Limitations of the review, by definition, are that articles outside of our search terms, time-period, or eligibility criteria were not included.

Additional details of the search and retrieval process as well as the information extracted are available upon request. Forty-three articles were included in this systematic review and denoted by asterisks in the References section.

In the following, we provide descriptive summaries of the studies to provide an overview of the therapy types included in the studies, the gender composition of the dyads, the disorders and issues of patients, the methods used to quantify coordination, and the different timescales that were included in the analyses. Note that the values may sum to more than the total number of included articles because, for example, multiple disorders could have been included or multiple methods could have been employed.

While we have collated the extant findings on interpersonal coordination in psychotherapy, a number of critical questions remain unanswered if the aim is to explain its functionality during psychotherapy. On these grounds, we highlight a number of issues for consideration in future research. In the following, we propose four general shortcomings and three critical questions identified by this review. Note that while we refer to these as shortcomings here, we in no way diminish the value of the groundbreaking work included in this review.

With regards to coordination of different modalities in face-to-face interaction in the context of psychotherapy, some fundamental, critical questions remain unanswered. First, an underlying question regarding the link between coordination and the quality of interpersonal relationships remains as follows: Is there a larger construct underpinning interpersonal coordination, is it capturing multiple constructs, or is coordination its own construct relevant directly for psychotherapy? For example, is coordination of movement and language underpinning the therapeutic relationship (Ramseyer and Tschacher 2011; Reich et al. 2014) and coordination in physiology capturing the ‘real’ emotional relationship (Peluso et al. 2012)? Or, are these constructs better reflected in the questionnaires and ratings systems designed to capture them? If the former is the case, then perhaps coordination is something that is more foundational to social interaction (Dale et al. 2013; Fusaroli et al. 2014a, b) in a way that allows these relationships to flourish (cf. Bohl 2015). Alternatively, coordination may simply be reflective of particular common factors or social mentalities and competencies associated with social roles (Gilbert 2019) or they could reflect evolutionary processes that facilitate feelings of safety in social interactions (Geller and Porges 2014). Future work that proposes changes in the relationships between these variables based on the effectiveness of the treatment may be one useful way forward for assessing the functionality of coordination in psychotherapy (Rocco et al. 2016).

Relatedly, we propose a second overall critical question regarding the link between coordination and symptomatology: What critical aspects of psychotherapy bring about change in patient behavior and symptomatology and does coordination play a role in this change? The fundamental goal of psychotherapy is to create a change in a patient’s patterns of thought, behavior, and/or emotion that is remedial for a patient’s disorder, problem, or concern (Wampold and Imel 2015). While this review shows a general link between coordination in some modalities and change in symptomatology, it is not clear how coordination functions toward bringing about psychotherapeutic change, particularly when the needs of clients can be so diverse. Indeed, an approach that emphasizes points of psychotherapeutic change as a basis for understanding individual psychotherapy effectiveness has been described elsewhere (Gelo and Salvatore 2016). Our emphasis on how interpersonal coordination corresponds to patterns of psychotherapeutic change could readily be incorporated into such an approach.

Finally, we propose a fundamental question that remains unanswered in the literature regarding the link between different modalities, namely: What is the relationship across modalities? While a few of the studies examined cross-modality relationships, in considering the patient and therapist as a dynamical system, there ought to be systematic relationships between measures derived from the various modalities (Gelo and Salvatore 2016; Schiepek et al. 2015). The dotted lines in Fig. 2 makes it apparent the lack of research examining relationship between modalities, and note that neurophysiological measures, to a large extent, have been unexamined. One approach to this question is exemplified in Gorman et al. (2016) who examined the relationship between neurophysiology and language styles in a teamwork context. Another example involves a study of couples therapy in which a method was advanced that links coordination in vocal pitch with physiology across three interlocutors (Butner et al. 2017). Answering this question could highlight the cascading effects that permeate the multi-scale psychotherapeutic system (cf. Kelty-Stephen et al. 2013) and highlight key modalities of influence, for example, how the behavior of one person may be driving both the behavior and physiology of another (cf. Crowell et al. 2017). This may have also practical utility in selection of important measures for actual psychotherapy sessions that are incorporated as therapeutic tools (Imel et al. 2017; Schiepek et al. 2015).

Data from a well-designed study could provide preliminary answers to these questions. Such a study would include a measure from each of the modalities included in this review (and shown in Fig. 1), each of the psychotherapy process and outcome measures, and account for longitudinal change within and across sessions. The important aspect here is that many of the studies focused only on the relationship between specific modalities with particular outcomes or processes while excluding others. While there are many valid reasons for doing so, both theoretically and pragmatically, the cost is that there are potentially important interconnections and relationships between measures that are omitted (see Fig. 1 for example), thus precluding answers to the aforementioned questions. Such a study will likely need to incorporate machine learning methods for coordination-based feature extraction across multiple measures (e.g., Chanel et al. 2013). While this type of study is a necessary precursor to the practical implications listed below, we still find the potential practical implications worth stating here as motivation for conducting such challenging, yet potentially rewarding research.

All of the measures from this review can be grouped according to whether they are forms of computer- or human-based assessment (Imel et al. 2017). Whereas studies that rely on physiological measures or use automated processes to extract movement patterns from videos are examples of computer-based assessments, studies that require human responses or evaluations of behavior such as joystick ratings of interpersonal dimensions are human-based assessments. In many ways, the study of psychotherapy and longitudinal human interaction quickly becomes a big data problem where there is an increasing need for more computer-based assessments. Such methods not only allow for quicker assessments of more data, but they also open up possibilities for using technology to enhance the interaction (Imel et al. 2017). In the present context, one crucial goal involves working toward the adoption of near-real time measures of coordination, whether in bodily movements, physiology, or communication patterns, to apply meaningful feedback to the interaction itself (cf. Gorman et al. 2012; Schiepek et al. 2015; Wiltshire et al. 2020). Of course, much work remains to be done prior to advancing this effort, such as how these specific technologies can be used to scaffold specific aspects of the interaction (cf. Fiore and Wiltshire 2016; Wiltshire and Fiore 2014), although having this goal may contextualize the types of interpersonal coordination studies conducted on psychotherapy in the future.

Not only could measures of coordination become a focus for feedback during psychotherapy sessions, but perhaps first and foremost, they could become a focus for the training of psychotherapists. With all the apparent benefits of various forms of coordination, it may be a fruitful endeavor to consider what aspects of extant therapist training coincide with these findings and could be targeted as training opportunities. For example, therapists in training could undergo pitch and behavioral matching training or activities meant to align interlocutors’ physiology (Ferrer and Helm 2013); or, perhaps, even dyadic practices that focus on increasing affective awareness, mentalization capacities (Singer and Engert 2019), and neurofeedback that encourages empathy (Järvelä et al. 2019). Activities of this nature, while not substitutes for current forms of training, may give therapists additional interactional strategies that allow them to become more aware of the ways in which they coordinate with patients, which in turn, may contribute to better psychotherapeutic outcomes. The benefits of such training remain to be seen, although there is reasonable motivation to explore these possibilities given the extant findings.

Advancing the empirical work in this area will have practical implications for theory building as well. On the one hand, these studies show that coordination matters in psychotherapy, but studies in other contexts are beginning to show that more coordination is not necessarily better and may be largely contingent upon context (Abney et al. 2015; Miles et al. 2017; Timmons et al. 2015). It may be that better therapeutic outcomes are achieved with an optimum amount of coordination (cf. Harrison and Stergiou 2015; Ramseyer 2011; Wiltshire et al. 2018) that occurs at the right time and that is in a specific modality or at the right level of analysis (Koole and Tschacher 2016). In some cases, the optimum coordination, may in fact be no coordination at all to achieve a specific interaction/therapeutic goal including, for example, interpersonal dynamics that temporarily rupture the therapeutic relationship (e.g., Colli and Lingiardi 2009). Such efforts to identify more nuanced aspects of interpersonal coordination as they relate to the particular needs of the client, different therapeutic contexts, diagnoses, personality traits, and personal/therapeutic/interactional goals, will contribute more largely to understanding and enriching theory about interpersonal coordination during human interaction.