An introduction to Inference-Based Therapy (IBT)

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Inference-Based Therapy is a new treatment for OCD that is based on cognitive-behavioural principles, but puts an emphasis on faulty reasoning systems and doubt. It may be particularly helpful for those with repugnant obsessions (where exposure-based treatment may be challenging) and it is easier to deliver remotely via videoconferencing.


Behavioural treatment for Obsessive Compulsive Disorder (OCD) is traditionally based on an Exposure and Response Prevention (ERP) model; an approach which is evidence-based but often under-used. Since high levels of distress can be experienced during treatment it can be difficult for the patient to fully engage and, in some cases, for the therapist to deliver therapy. The recommended frequency (15-20 sessions), duration (90 minutes), and setting (community rather than office-based) make it challenging for services to deliver optimised treatment.

Inference Based Treatment (IBT) offers an alternative treatment option. In contrast to the cognitive appraisal model which informs ERP, IBT theorises that obsessions arise through a faulty reasoning system which leads to recurrent doubts and faulty inferences. Cognitive interventions in IBT focus on helping patients to identify the reasoning errors that lead to obsessions. IBA is traditionally delivered in a clinic setting, in time limited sessions, and does not generate the levels of anxiety that are a necessary component of ERP.

A comparison of CBT/ERP and IBT

The following table draws some comparisons between 'traditional' CBT/ ERCP and IBT.

Characteristic CBT/ERP IBT
Main theory Learning theory Reasoning theory
Nature of intrusions Extension of normal beliefs Intrusions are not necessarily normal
Underlying error Appraisal (and meaning) is at fault Reasoning is faulty
Focus of treatment Appraisal Doubt
Intervention In vivo exposure and response prevention Imaginal ‘exposure’ and no response prevention. Behavioural experiments are used for ‘reality testing’.