and Russian philosopher Mikhail Bakhtin. From Vygotsky come concepts such as the zone of proximal development (ZPD) and scaffolding. The ZPD implies that new tasks set for the patient (for example, tolerating anxiety about social situations) should extend what they do beyond their current capabilities, but only by a small and achievable amount. Scaffolding involves the therapist providing support for the patient's efforts to change, but varying this level of support as the patient's needs change. Bakhtin provided concepts such as dialogism from which come techniques such as Dialogical Sequence Analysis. This is a structured attempt to identify and visually display sequences of behaviour, thinking, and emotions so that the patient becomes more aware of these and can start to modify them. In practice The model emphasises collaborative work with the client, and focuses on the understanding of the patterns of maladaptive behaviours. The aim of the therapy is to enable the client to recognise these patterns, understand their origins, and subsequently to learn alternative strategies in order to cope better. The approach is always time-limited, typically taking place over 8–24 weekly sessions (the precise number being agreed at the start of therapy). Sixteen sessions is probably the most common length. In the first quarter of the therapy (the Reformulation phase) the therapist collects all the relevant information, asking the patient about present day problems and also earlier life experiences. At that point the therapist writes a reformulation letter to the client. This letter summarises the therapist's understanding of the client's problems. Particular attention is given to understanding the connection between childhood patterns of behaviour and their impact on adult life. The letter is agreed between patient and therapist and forms the basis for the rest of the work. After the reformulation letter the patient may be asked to complete diaries or rating sheets to record the occurrence of problems and their context. During this period (known as the Recognition phase) patient and therapist construct a diagrammatic formulation to illustrate the unhelpful procedures which maintain problems for the patient. The aim of this phase is to enable the patient to recognise when and how problems occur. In the second half of the therapy work moves into the Revision phase, where patient and therapist identify and practice "exits" from the procedural diagram established in the previous phase. For example, a problematic procedure might move a patient from feeling angry to taking