Introduction
Psychological interventions are subject to rigorous scientific evaluation in order to demonstrate evidence of efficacy and effectiveness (Hagermoser Sanetti and Kratochwill, Reference Hagermoser Sanetti and Kratochwill2014; Kratochwill and Stoiber, Reference Kratochwill and Stoiber2002). Practitioners of psychological therapies are commonly required by regulatory bodies to base their practice upon an evidence base, which includes independent scientific evaluation (e.g. Health and Care Professions Council, 2012; National Association of School Psychologists, 2010). The premise for this ‘evidence-based’ practice is twofold: first, it is ethically appropriate that clients should be protected from harm, and should reasonably expect that the practitioner has justifiable grounds to believe that intervention will effect remediation or improvement; second, all stakeholders (e.g. client, employer, service delivery setting, regulator) may reasonably assume that the psychological intervention or therapy will be delivered in an optimally effective and efficient way (Anderson, Reference Anderson2006; Frederickson, Reference Frederickson2002).
Kratochwill and Stoiber (Reference Kratochwill and Stoiber2002) highlight principal criteria for confirmatory evaluation of an intervention programme, including effect size, specificity of effect, consistency, and coherence of intervention–outcome relationships with explicit evaluation of programme theory (cf. Bickman, Reference Bickman and Bickman1987). At the same time, the authors acknowledge that psychological therapists are not mere ‘technicians’ following intervention manuals and evaluation protocols, and so any framework for practice evaluation must be sufficiently flexible to take account of a variety of therapeutic modalities, practice delivery structures and settings (cf. Christensen et al., Reference Christensen, Carlson and Valdez2002). The Procedural and Coding Manual for Review of Evidence-Based Interventions, sponsored by the American Psychological Association Division 16 and the Society for the Study of School Psychology, has been shown to be a useful framework for evaluating interventions (Lewis-Snyder et al., Reference Lewis-Snyder, Kratochwill and Stoiber2002; Steele Shernoff et al., Reference Steele Shernoff, Kratochwill and Stoiber2002). More recently, the concept of ‘treatment integrity’ has been utilized to encapsulate different ways in which different psychological intervention and therapies can be validly and consistently evaluated (Century and Cassata, Reference Century, Cassata, Hagermoser Sanetti and Kratochwill2014; Hagermoser Sanetti and Kratochwill, Reference Hagermoser Sanetti and Kratochwill2014). Such overarching frameworks and concepts challenge innovators, researchers and practitioners to account for the effectiveness of interventions to a set of broadly agreed standards. In this way, new interventions can move from exploratory phases to broader evaluations of a clearly specified ‘core’ intervention, and then in turn to context-specific evaluations of the specified core intervention (Frederickson, Reference Frederickson2002; Salkovskis, Reference Salkovskis, Aveline and Shapiro1995). The paper explores the evolution of theory and practice of motivational interviewing (MI), moving on to explore the relationship of this to the pursuit of evidence for its efficacy.
Theoretical and practice developments in MI
Background to MI
The background, history and development of MI are described by Miller and Rose (Reference Miller and Rose2009). Initially atheoretical, MI arose from within clinical practice and was formulated by Miller's interactions with a group of Norwegian psychologists working with clients with alcohol difficulties. Verbalizing the approaches used allowed development of a conceptual model of working, which thereafter became the basis for MI. Miller (Reference Miller1983) later published a reduced version of this – the first appearance of MI in academic literature.
Miller and Rose (Reference Miller and Rose2009) described how Miller continued to progress his thinking, developing a ‘Drinker's Check-up’ (DCU), which allowed MI to be combined with personal feedback from standardized measures of drinking behaviours (Miller and Sovereign, Reference Miller, Sovereign, Loberg and Miller1989). Miller then collaborated with Stephen Rollnick, a UK-based healthcare specialist, to publish the seminal text Motivational Interviewing: Preparing People to Change Addictive Behaviour (Miller and Rollnick, Reference Miller and Rollnick1991). Subsequent versions of the core MI text were published (Miller and Rollnick, Reference Miller and Rollnick2002; Reference Miller and Rollnick2012a), each presenting new dimensions to this evolving field. Central to all three editions was the notion of exploring ambivalence and strengthening commitment to change behaviour. While Miller and Rollnick (Reference Miller and Rollnick1991) focused on change processes, the second edition provided a more coherent central framework of a ‘spirit’, and refined principles (Miller and Rollnick, Reference Miller and Rollnick2002).
Miller and Rollnick (Reference Miller and Rollnick2012a) note in their preface to the third edition, Motivational Interviewing: Helping People Change that ‘Quite a lot is different in this edition, and more than 90% is new’ (p. vii). Table 1 below considers the development of the core constructs of MI over the three volumes, with significant revisions between the 2002 and 2012 editions presenting fundamental changes to the core structure of MI. The extent to which these amendments have actually affected the operationalization of MI is not clear, and this issue may warrant further research.
Table 1. Comparisons of the definitions, spirit and principles across the three editions of Motivational Interviewing (Miller and Rollnick, Reference Miller and Rollnick1991, Reference Miller and Rollnick2002, Reference Miller and Rollnick2012a)
Efficacy
Within the fields of healthcare and addiction in particular, MI has continued to expand and to develop an increasing evidence base, and has yielded more than 1000 peer reviewed publications and 200 randomized clinical trials (Miller and Rollnick, Reference Miller and Rollnick2010). Lundahl et al. (Reference Lundahl, Moleni, Burke, Butters, Tollefson, Butler and Rollnick2013) explored MI use in medical care settings by undertaking systematic review and meta-analysis of randomized controlled trials. Overall, MI showed beneficial effects across 48 included studies, 63% of outcome comparisons yielding statistically significant results in favour of MI interventions. However, interestingly fidelity was inversely related to outcome, to such an extent that studies measuring fidelity produced lower effect sizes that those that did not. Lundahl et al. (Reference Lundahl, Moleni, Burke, Butters, Tollefson, Butler and Rollnick2013) proposed this to be ‘cause for sobering reflection’, but also suggested that outcomes may indicate ‘MI is easy to implement in real-world settings and has positive effects for patients even without time-intensive supervision of fidelity monitoring’ (p. 166).
Barnett et al. (Reference Barnett, Sussman, Smith, Rohrbach and Spruijt-Metz2012) reviewed 39 studies in which MI was used as an intervention for adolescent substance use, including within their design a quality evaluation of the MI intervention, in terms of manual use, training and supervision availability and maintenance of fidelity. Interestingly two of the studies presented none of these quality measures, yet both produced positive outcomes. This was not always true for studies demonstrating a higher quality MI intervention. Burke et al. (Reference Burke, Arkowitz and Menchola2003) found previously that studies conducted within William Miller's clinic produced higher effect sizes than those conducted elsewhere; the authors called for additional research into the efficacy of MI in its pure form, suggesting difficulties in disentangling contributions made by the relative components of adaptations of MI (AMIs).
Dray and Wade (Reference Dray and Wade2012) noted that when MI efficacy was evaluated with clients with eating disorders, one factor that made it difficult to draw conclusions was inconsistency in delivery. They suggested a need for future research to evaluate the efficacy of manual-based MI interventions, although this is inconsistent with the flexible, responsive and person-centred approach advocated by MI's proponents (Miller and Rollnick, Reference Miller and Rollnick2012a). Britt et al. (Reference Britt, Hudson and Blampied2004) summarized applications of MI within health settings, concluding that despite promising evidence for its effectiveness, further clarity about how MI is effective and what elements of MI are essential was needed. Furthermore, they called for additional guidance on structuring sessions and identifying which specific motivational intervention would benefit which client group.
Theory of MI
Defending its atheoretical nature, Miller (Reference Miller1999) contended that MI was derived from practice, stating ‘it was drawn out of me’ (p. 2). Indeed, no direct reference to MI theory was made by Miller and Rollnick (Reference Miller and Rollnick2012a). Apodaca and Longabaugh (Reference Apodaca and Longabaugh2009) noted that while theories underlying MI are rich, they have yet to be integrated into a comprehensive philosophy.
Previously, two theoretical models have been proposed for underpinning MI – the Transtheoretical Model (TTM) and Self-Determination Theory (SDT). These will now be briefly discussed in turn.
The Transtheoretical Model
Miller and Rollnick (Reference Miller and Rollnick1991) originally linked MI to the Transtheoretical Model (TTM) of Change (DiClemente and Prochaska, Reference DiClemente and Prochaska1982), acknowledging its usefulness in understanding client behaviour and guiding therapist action. Miller and Rollnick (Reference Miller and Rollnick1991) positioned the TTM as a helpful model and to date it has been the most significant theoretical structure supporting MI. The TTM has been used alongside MI in a number of contexts, including eating disorders (Dray and Wade, Reference Dray and Wade2012), educational disaffection (Atkinson and Woods, Reference Atkinson and Woods2003), self-harm (Kamen, Reference Kamen2009) and smoking cessation (Erol and Erdogan, Reference Erol and Erdogan2008). Indeed, Atkinson (Reference Atkinson and McNamara2014) argued that to practitioners using MI in educational settings it offered a central framework to enable understanding of the principles and spirit of MI (Miller and Rollnick, Reference Miller and Rollnick2002). McNamara (Reference McNamara2009) suggested that for education professionals:
‘. . .the techniques of Motivational Interviewing have been profoundly influential in helping people change and that the TTM has enabled the practice of Motivational Interviewing to be carried out with a degree of precision which might have otherwise not been the case’ (p. 211).
McNamara (Reference McNamara2014) further suggested that the absence of a structure like the TTM may limit MI use within the discipline of education.
However, the TTM is not a theory and offers, in itself, no explanatory power. It has been criticized for its lack of conceptual and theoretical derivation (Wilson and Schlam, Reference Wilson and Schlam2004) and for the fact that its oversimplified presentation has led to poor assessment and intervention practice by clinicians over-reliant on its structure (West, Reference West2005). However, its centrality to the original dissemination of MI practice (Miller and Rollnick, Reference Miller and Rollnick1991) means that it might have been influential in the development of practice, as a heuristic for determining the focus and pace of MI as an intervention. Further exploration of the extent to which practitioners still reference the TTM in guiding MI practice may help to establish the ways in which MI and the TTM are currently associated.
Self-Determination Theory
Previously there has been support for the notion that SDT (cf. Ryan and Deci, Reference Ryan and Deci2000) could provide underlying theoretical explanations for the effectiveness of MI. Markland et al. (Reference Markland, Ryan, Tobin and Rollnick2005) proposed that SDT could offer a coherent framework for understanding the processes and efficacy of MI, while Vansteenkiste and Sheldon (Reference Vansteenkiste and Sheldon2006) highlighted potentially mutual benefits of an alliance for both MI and SDT, suggesting respective advantages of theoretical and practical grounding. While Vansteenkiste and Sheldon (Reference Vansteenkiste and Sheldon2006) were not explicit about how SDT might support MI practice, Markland et al. (Reference Markland, Ryan, Tobin and Rollnick2005) offered a SDT foundation for the approaches used within MI sessions (p. 821). However, Miller and Rollnick (Reference Miller and Rollnick2012b) proposed that while SDT held potential for supporting MI, they would not develop a systematic integration.
The need for theoretical stability
Despite earlier interest, neither the TTM nor SDT have influenced recent theory and practice developments, and indeed Miller and Rollnick (Reference Miller and Rollnick2002, Reference Miller and Rollnick2009) have increasingly distanced MI from the TTM. Barnett et al. (Reference Barnett, Sussman, Smith, Rohrbach and Spruijt-Metz2012) surmised that the search to understand mechanisms of change has been ad hoc, proposing that ‘A theory-based approach to determine mechanisms of change in MI theory is needed’ (p. 1332). Indeed, the role of underpinning theory is more widely acknowledged as potentially advantageous to evidence-based programme development, effective programme adaptation, anticipation of potential intervention risks, and ethical application within a practitioner's field of competence (Bickman, Reference Bickman and Bickman1987; Bumbarger, Reference Bumbarger, Sanetti and Kratochwill2014; Hagermoser Sanetti and Kratochwill, Reference Hagermoser Sanetti and Kratochwill2014; Kratochwill and Stoiber, Reference Kratochwill and Stoiber2002; McGivern and Walter, Reference McGivern, Walter, Hagermoser Sanetti and Kratochwill2014; Rossi and Freeman, Reference Rossi and Freeman1993). One possibility is that the principles, processes and spirit (see Table 1), while not offering a well-defined set of steps to clinical practice, do provide a guiding protocol, which implies a theoretical perspective that is never fully articulated. However, given that the core structure of MI is still in development (Miller and Rollnick, Reference Miller and Rollnick2012a) and the rationale for changes are difficult to understand, particularly given the evidence for the efficacy of MI under its previous format (Miller and Rollnick, Reference Miller and Rollnick2002; Miller and Rose, Reference Miller and Rose2009), such elements ostensibly lack a clearly evidenced coherence to support a high level of treatment integrity (cf. King and Bosworth, Reference King, Bosworth, Hagermoser Sanetti and Kratochwill2014).
While development is expected within contemporary practice, it could be argued that MI is now over 30 years old and should have had opportunity to achieve theoretical stability. Were there to be in future greater impetus for theoretical underpinning, it might also be useful to consider other theories that could support understanding of the change processes which are fundamental to MI, such as social-cognitive theory (cf. Bandura, Reference Bandura2001).
Practice
Complexity of MI practice
Miller and Rollnick (Reference Miller and Rollnick2009) purported that ‘MI is not easy’ (p. 135), noting it involves a complex skill set which cannot be mastered via training alone, but through ongoing practice with feedback and coaching. The complexity of MI is evident in the recent writings of Miller and Rollnick (Reference Miller and Rollnick2012a) with the glossary running to 10 pages and boasting over 150 terms. These include practice acronyms such as CATS (Commitment, Activation and Taking Steps) and DARN (Desire, Ability, Reason and Need); alongside the central skills of OARS (Open questions, Affirmation, Reflection, Summary). There is an additional plethora of techniques, including the elegantly titled ‘Bouquet’, ‘Equipoise’, ‘Goldilocks Principle’ and ‘Smoke Alarms’. Internalizing such extensive practitioner guidance, alongside the definitions, spirit and processes offers significant challenges for new MI practitioners, particularly those who lack regular practice opportunities, or access to ongoing training and supervision.
Previously, models and structures have been proposed to complement MI, potentially offering guidance and direction to practitioners. These include the Drinker's Check-up (Miller and Sovereign, Reference Miller, Sovereign, Loberg and Miller1989); the Menu of Strategies (Rollnick et al., Reference Rollnick, Heather and Bell1992); Motivational Enhancement Therapy (MET) (Miller et al., Reference Miller, Zweben, DiClemente and Rychtarik1994), FRAMES (Miller and Sanchez, Reference Miller, Sanchez, Howard and Nathan1994); a framework for negotiating behaviour change with ambivalent clients (Rollnick et al., Reference Rollnick, Mason and Butler1999) and guidance for the ‘competent novice’ (Rollnick et al., Reference Rollnick, Butler, Kinnersley, Gregory and Nash2010). Despite orchestrating many of these approaches, Rollnick and Miller (Reference Rollnick and Miller1995) were keen to separate MI from what they refer to as ‘related methods’. For example, in reference to their framework for negotiating behaviour change (Rollnick et al., Reference Rollnick, Mason and Butler1999), Rollnick et al. (Reference Rollnick, Miller and Butler2008) note in Health Behaviour Change, that ‘Cautious about diluting or simplifying motivational interviewing beyond recognition, we all but avoided any reference to it’ (p. viii).
The reason why clear structures have not been maintained or developed might be exemplified by the Menu of Strategies (Rollnick et al., Reference Rollnick, Heather and Bell1992), which remains arguably the best-defined generic MI protocol. It was developed as a brief MI approach for use in medical settings, following practitioner feedback about losing direction when trying to undertake MI. However, despite the rationale of practitioner need and the well-defined phases described by Rollnick et al. (Reference Rollnick, Heather and Bell1992), the approach has had limited application within MI practice. Indeed, the second and third editions of Motivational Interviewing Miller and Rollnick (Reference Miller and Rollnick2002, Reference Miller and Rollnick2012a) make no reference to the approach, although the structure has appealed to practitioners (Atkinson and Woods, Reference Atkinson and Woods2003; McCambridge and Strang, Reference McCambridge and Strang2003, Reference McCambridge and Strang2004).
Rollnick and Miller (Reference Rollnick and Miller1995) questioned whether the spirit of MI could be captured within the Menu of Strategies and other brief intervention models. They cautioned against similar methods being described as MI, instead propagating the importance of distinguishing the mechanisms by which interventions work from the specific methods designed to encourage behaviour change. Miller and Rollnick (Reference Miller and Rollnick2009) reflected that the impetus for this had been the observation of formulaic practice, suggesting that this was incompatible with demonstration of MI spirit and more favourable treatment outcomes, although limitations appear to be related particularly to manualization (Hettema et al., Reference Hettema, Steele and Miller2005), rather than the use of MI alongside practice frameworks. However, wariness of procedural specification is perhaps understandable, given the need to individualize the emphasis of MI elements, depending on impetus for change, self-efficacy, personal circumstances and client commitment.
Central to competency in MI delivery is demonstration of OARS (Moyers et al., Reference Moyers, Martin, Manuel, Hendrickson and Miller2005). However, recent systematic reviews of MI effectiveness (e.g. Barnett et al., Reference Barnett, Sussman, Smith, Rohrbach and Spruijt-Metz2012; Lundahl et al., Reference Lundahl, Moleni, Burke, Butters, Tollefson, Butler and Rollnick2013) have evaluated the quality of the research study and MI fidelity, but not the quality of MI delivery. In a recent systematic review of school-based MI research, Snape and Atkinson (Reference Snape and Atkinson2016) noted that only one of the eight best-practice studies made reference to OARS.
The Motivational Interviewing Treatment Integrity (MITI) code (Moyers et al., Reference Moyers, Martin, Manuel, Hendrickson and Miller2005, Reference Moyers, Manuel and Ernst2014) was developed by MI proponents as a reliable and valid (Pierson et al., Reference Pierson, Hayes, Gifford, Roget, Padilla and Bissett2007) assessment of core elements of MI, including OARS and the MI spirit, whilst addressing the need for practice flexibility. However, the MITI's complexity, which has training and resources implications, may have practice-based limitations reducing its use to research contexts (Barwick et al., Reference Barwick, Bennett, Johnson, McGowan and Moore2012) and simplification may need to be considered to improve its functionality and access (Frey et al., Reference Frey, Lee, Small, Seeley, Walker and Feil2013).
Training and assessment in MI
Miller and Rose (Reference Miller and Rose2009) suggested that MI is ‘learnable by a broad range of helping professionals’ (p.12); but also reported that following clinicians’ engagement in MI training, tape recorded work indicated only modest practice development and no change to client in-session response. Recent research suggests that acquisition of MI skills may be problematic, particularly for practitioners without a psychological or therapeutic background. Bohman et al. (Reference Bohman, Forsberg, Ghaderi and Rasmussen2013), realising that a one-off workshop format for MI training may have been insufficient, offered enhanced MI training to 36 nurses, which included a 3.5-day workshop, systematic performance feedback and four supervision sessions. The workshop was led by a member of the Motivational Interviewing Network of Trainers (MINT) and practitioner skills were evaluated using the MITI (Moyers et al., Reference Moyers, Martin, Manuel, Hendrickson and Miller2005). Results indicated that despite intensive training, none of the participants reached beginning thresholds on any of the proficiency indicators. Supervision sessions appeared to decrease, rather than increase proficiency in most cases.
Bohman et al. (Reference Bohman, Forsberg, Ghaderi and Rasmussen2013) offered three possible explanations: that the nature of the intervention may have affected the development of proficiencies; that time digressions within the training period affected outcomes; and that the nurses did not have the same level of basic training or were less motivated than participants in other studies. The third explanation should be considered alongside the fact that 64% of the participants had previous MI training and all volunteered to participate. It is also possible that without a practical, conceptual or theoretical framework to support it, MI is not easily learnable because of its ongoing evolution and complexity.
Barwick et al. (Reference Barwick, Bennett, Johnson, McGowan and Moore2012) undertook a systematic review of 22 studies to investigate the effectiveness of MI training in North America and Europe. Whilst seventeen studies reported significant practitioner behaviour change, the authors reported limited baseline skills as a potential barrier to development. Miller and Moyers (Reference Miller and Moyers2006) defined Eight Stages of Learning MI, but noted that methods of assessing MI competence had practice-based limitations in that they required intensive training, were costly to use and were predominantly limited to research contexts. Highlighting their observations on the practice-based applicability of the MITI, Barwick et al. (Reference Barwick, Bennett, Johnson, McGowan and Moore2012) proposed that ‘Research on MI training has yet to develop a product, process, or checklist for practitioners to utilize in the real world. A standard, feasible, and preferred method for establishing MI adherence in practice has not yet been developed’ (p. 1793).
The need for practitioner structure
Miller and Rollnick (Reference Miller and Rollnick2012b) defended the practitioner appeal of MI, which emerged before empirical exploration of its efficacy, claiming, ‘. . . MI disseminated rapidly by word of mouth among clinicians, who are drawn to it not just from the clinical trials but because, for the lack of a better term, they seemed to “recognize” it. It feels intuitively sound based on their own experience’ (para. 3). However, issues relating to training and assessment of MI raise questions about whether this is a sufficiently robust process for practice-based evidence to ensure that therapists deliver MI consistently, potentially casting doubt on the reliability and promise of evidence of MI efficacy emerging from the practitioner community. Claims of therapists not internalizing MI processes on accessing training, despite self-perceptions of practice development (Miller and Rose, Reference Miller and Rose2009) were supported by findings from a systematic literature review by Hall et al. (Reference Hall, Staiger, Simpson, Best and Lubman2016), which examined training outcomes for MI in the field of substance use disorder treatment. The authors set the criterion of: 75% of clinicians undertaking the training achieving beginning proficiency in MI spirit (e.g. Moyers et al., Reference Moyers, Martin, Manuel, Hendrickson and Miller2005), for determining that training had resulted in sustained practice change. However, this figure was achieved in only two of the 11 studies for which proficiency could be established. This led Hall et al. (Reference Hall, Staiger, Simpson, Best and Lubman2016) to conclude that achieving the criterion would be unlikely without competency benchmarking, and ongoing training. Hall et al. (Reference Hall, Staiger, Simpson, Best and Lubman2016) offered evidence for Miller and Rollnick's (Reference Miller and Rollnick2012) claims that MI is ‘simple, but not easy to learn’ (Hall et al., Reference Hall, Staiger, Simpson, Best and Lubman2016, p. 1148), and also suggested that MI's complexity may not just lie in its acquisition of skills, but in its suppression of previous practice. For practitioners who may have limited grounding in psychology or counselling and/or limited opportunities to practise, it could be argued that MI is becoming increasingly inaccessible.
Conclusions
It could be argued that developments between the earlier core texts (Miller and Rollnick, Reference Miller and Rollnick1991, Reference Miller and Rollnick2002) (see Table 1) represent the evaluation and re-evaluation of a therapy in its infancy. However, the MI concept is now more than 30 years old and, given the reported success of previous versions (Miller and Rollnick, Reference Miller and Rollnick1991, Reference Miller and Rollnick2002), radical and repeated changes to the structure should be questioned in the absence of a clear empirical or theoretical rationale. We have argued that the development of a psychological intervention as an evidence-based practice is hampered by the lack of a clear theoretical foundation. The very complexity that practitioners manage and navigate through use of clinical judgement and clinical supervision is only possible through established theoretical coherence (Bickman, Reference Bickman and Bickman1987; Christensen et al., Reference Christensen, Carlson and Valdez2002; Kratochwill and Stoiber, Reference Kratochwill and Stoiber2002). The authors therefore argue against the general credibility of MI at the present time and advocate attention to the general stage of development of MI intervention (cf. Rossi and Freeman, Reference Rossi and Freeman1993). Meanwhile, published studies are still drawing on earlier ‘versions’ of MI. For instance, Anstiss et al. (Reference Anstiss, Polaschek and Wilson2011) used the five principles of MI (Miller and Rollnick, Reference Miller and Rollnick1991) when developing a brief MI intervention for use with prisoners in New Zealand, although notably with positive results. In fact, even some of the most recently public research references previous concepts, such as the principles (Riegel et al., Reference Riegel, Dickson, Garcia, Creber and Streur2016), triadic spirit (Catley et al., Reference Catley, Goggin, Harris, Richter, Williams and Patten2016) and stages of change (Bortolon et al., Reference Bortolon, Moreira, Signor, Guahyba, Figueiró, Ferigolo and Barros2016)
Without a coherent structure, it is difficult to generate an evidence base for MI use, or to reliably train its practitioners. The findings of Burke et al. (Reference Burke, Arkowitz and Menchola2003) suggest that it is difficult to understand the mechanisms behind its efficacy. Additionally, its complexity may limit its accessibility to those only for whom MI represents core practice, while its availability to practitioners using it within other domains remains questionable. The probability is that few practitioners are adhering to a pure model of MI, while many are seeing very real benefits of contemporary approaches using MI principles in non-traditional domains such as prisoner re-offending (Anstiss et al., Reference Anstiss, Polaschek and Wilson2011), educational attainment (Strait et al., Reference Strait, Smith, McQuillin, Terry, Swan and Malone2012), and domestic violence (Zalmanowitz et al., Reference Zalmanowitz, Babins-Wagner, Rodger, Corbett and Leschied2013). Interestingly, all of these interventions employ bespoke adaptations of MI which are manualized and replicable. Kamen (Reference Kamen2009), using the TTM alongside MI with adolescents who were self-harming, acknowledged that the approach used required its own empirical validation and that it may be appropriate for other MI-based interventions to be viewed similarly.
This paper is by no means advocating the manualization of MI, giving full recognition to the role of clinical judgement in the delivery of evidence-based interventions. Nor it is seeking to be critical of a therapeutic approach for which there is strong evidence of efficacy across a multitude of settings and with a great range of behaviours, albeit that the evidence base may actually be referring to different kinds of intervention. Instead, as practitioners wrestling with the theoretical and practice elements, without access to ongoing MI training, practice opportunities and supervision, the authors call for greater clarity with regard to the structure of MI. Developed models consistent with MI principles, such as the Menu of Strategies, could be revised in light of practice developments, although it is acknowledged that these should be offered as a way of providing structure, not replacing core aspects such as the spirit and processes with a set of techniques. Such theoretically informed, transferable frameworks, could then been subjected to rigorous empirical investigation across different settings, allowing examination of the processes for and mechanisms enabling client change. Simplification of the MITI into an accessible practitioner instrument may be one means of ensuring consistency of practice and offering opportunity for self-reflection. Finally, the current evidence for the proponents’ rejection of techniques and frameworks seems insufficient, and more contemporary research investigating the relative benefits of ‘pure’ MI interventions over comparable manualized or framework-referencing approaches would be beneficial.
Acknowledgements
This research received no specific grant from any funding agency, commercial or not-for-profit sectors.
Conflicts of interest: No known conflicts of interest exist.
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