Cognitive biases might also be important for the way in which sensory information from a physical triggering event is weighted during perceptual inference. Patients with somatization disorder have been shown to have cognitive biases towards retaining information relating to illness (Martin et al., 2007) and catastrophic thinking about symptoms (Crombez et al., 1998). The ‘jumping to conclusions’ bias is a well-known tendency of patients with delusions, illustrated by their deciding after fewer draws than most control subjects whether a hidden urn contains a majority of one ball colour or another (Garety and Freeman, 1999). The Bayesian perspective provides a unifying account of these failures to represent uncertainty and the key role of attention—this is because both rest on optimizing the precision in hierarchical models. We have recently demonstrated that the ‘jumping to conclusions’ bias is also present in patients with functional motor symptoms, consistent with a tendency to overweigh evidence; a tendency that could lead to abnormal inferences about sensations during a physical triggering event (Paree´ s et al., 2012a).
This discussion demonstrates the rich and varied potential causative factors behind the development of FMSS, which contrasts with the simplistic concept of them being caused by a single emotional traumatic event (e.g. childhood sexual abuse). Epidemiological studies have not found childhood trauma, or recent emotional life events, to be necessary for FMSS (Roelofs et al., 2002; Sharpe and Faye, 2006; Kranick et al., 2011); indeed, Sharpe and Faye (2006) comment, ‘the association with psychological issues is much less prominent than expected’. The emphasis on emotional triggering events, particularly childhood sexual abuse, is, arguably, based on a specific (and perhaps simplistic) interpretation of the concept of conversion disorder introduced by Breuer and Freud in 1893–95 (Breuer and Freud, 1991) and later extended by Freud alone. In this theory, the role of a psychological conflict is paramount. Freud believed that a psychologically challenging situation, replete with emotional conflicts, could reawaken memories of an earlier (childhood) situation containing similar, unresolved conflicts between biological drives and social demands or childhood experiences. These (unconscious) memories would give rise to unpleasant thoughts or emotions, which were repressed in order to keep them from awareness and hence from causing further distress or conscious recollection. The ‘psychic energy’ of the repressed negative memories had to find another method of discharging itself—so it was converted into a somatic symptom, which generally had some symbolic relation to the memories or wishes being repressed. This protection of consciousness from conflict and distress was the ‘primary gain’ of the production of hysterical symptoms, although Freud noted the patient might then derive a ‘secondary gain’ from their elevated status as an invalid. Although many of the constructs and the symbolism proposed by Freud have been discarded, the idea that FMSS are an unconsciously generated expression of (otherwise uncommunicated) psychological conflict retains considerable popularity. We suggest, however, that this provides a rather one-dimensional approach to causation that may not be appropriate for many patients with FMSS. Indeed, overemphasis of the importance of childhood sexual abuse and other specific life events in causing FMSS by treating physicians may directly harm patients for whom these factors are unimportant.
Psychobabble 2.0. New and improved multi-dimensional psychobabble.