Despite substantial evidence for the effectiveness of Cognitive Behavioural Therapy (CBT), many clinicians fail to implement CBT appropriately. Waller (2009) described therapists’ failure to deliver key elements of CBT protocols as ‘therapist drift’. Such drift often leads to poorer outcomes for patients and might explain, in part, why CBT does not benefit all patients. This thesis aimed to investigate how to tackle therapist drift and involved: (i) a meta-analysis investigating the effects of exposure therapy training, and (ii) an empirical study investigating the effectiveness of asking therapists to form implementation intentions to support them to adhere more closely to CBT protocols for treating adults with eating disorders – more specifically, increasing their weighing behaviour.
The first part of this thesis reports a review of 14 studies that examined the effectiveness of training clinicians in exposure therapy for anxiety. Meta-analyses were conducted to estimate the effect of training on five outcome variables: knowledge, attitudes, intentions, self-efficacy, and behaviour. Training had large-sized positive effects on clinicians’ attitudes and knowledge, medium-sized positive effects on intentions and self-efficacy, but no effect on behaviour. The findings suggest that although clinicians may have the knowledge, confidence and intentions to use exposure therapy, they fail to translate their intentions into action. These findings are in line with research on the intention-behaviour gap, and suggest that future research might consider incorporating volitional interventions (such as implementation intentions) into training to bridge this gap. However, the paucity of available studies and heterogeneity of the effects found among the primary studies indicate that these findings should be interpreted with caution.
The second part of this thesis reports a randomised-controlled trial investigating the possibility that prompting therapists to set goal intentions (to weigh patients with eating disorders) and form implementation intentions (to support these intentions) might help them to increase their weighing behaviour. Eighty-four therapists actively using CBT with adults with eating disorders were randomised to an intervention or a ‘usual practice’ control condition. Therapists in the intervention condition received information about the importance of weighing and a volitional help-sheet to support them to form implementation intentions. Therapists completed the outcome measures at baseline, post-intervention, and follow-up. No significant differences were found in weighing behaviour over time for either condition. However, therapists in the intervention condition weighed significantly more patients than those in the control condition at post-intervention – an effect that approached significance at follow-up. There was no significant impact of anxiety or intentions to weigh on the effect of the intervention. The findings of the study suggest that, although implementation intentions did not increase therapists’ weighing behaviours, they might help to protect against therapist drift.
Taken together, the two studies provide evidence for the use of implementation intentions to support therapeutic practice. Forming implementation intentions might not only be beneficial for people trying to change their own behaviour but might also support therapists supporting others to change their behaviour. Implementation intentions are a relatively quick, easy and cheap intervention. Therefore, even small effects might warrant the investment of time and effort.
