Tuesday, 23 June 2015

Amending the Revisionist Model of the Capgras Delusion

This is the fourth in a series of posts on the papers published in an issue of Avant on Delusions. Here Garry Young summarises his paper 'Amending the Revisionist Model of the Capgras Delusion: A Further Argument for the Role of Patient Experience in Delusional Belief Formation'.

I currently work as a senior lecturer in psychology at Nottingham Trent University, although my postgraduate studies were in philosophy. My research interests cover three distinct areas. First, I am interested in embodied cognition, particularly the relationship between consciousness and procedural knowledge (knowing how to do something, rather than knowledge of facts). I have argued, using cases of visual pathology (e.g. blindsight and visual agnosia), that a form of knowledge-how (knowing how to do something) can occur in the absence of conscious accompaniment. 

I am also interested in the ethics underlying the virtual enactment of real-world taboos, such as murder or physical/sexual assault, particularly in the context of video games. Finally, and more pertinent to what we are discussing here, I am interested in the experiences of patient suffering from specific types of delusion, such as the Cotard and Capgras delusions.

In 'Amending the Revisionist Model of the Capgras Delusion: A Further Argument for the Role of Patient Experience in Delusional Belief Formation', I challenge recent attempts to account for the Capgras delusion (the belief that a wife or husband, some family member or significant other, is an impostor) in the absence of an explanatory role for patient experience. 

In particular, I argue that a recent revisionist model proposed by Max Coltheart and colleagues is partly incorrect and therefore in need revision. I challenge two important (revisionist) claims made by Coltheart and colleagues (2010): (1) that a fully-formed belief enters consciousness (such as 'This person is not my wife, she is an imposter'), and (2) that this is the first conscious delusion-related event.

In keeping with a position I have maintained for a number of years now, in my paper I seek to reinstate the role of patient experience – often referred to as ‘anomalous’ within the literature – in accounting for the disorder. As a consequence, it is my contention that the delusional ‘belief’ is not the first delusion-related event the patient is conscious of. Co-occurring with this ‘belief’ is a sense of estrangement (as I have often described the anomalous experience). 

Moreover, I challenge the view that a fully formed belief co-occurs with the experience. Instead, I argue that the thought that enters consciousness – 'This person is not my wife, she is an impostor' – which occurs alongside the patient’s sense of estrangement, amounts to what Currie and Ravenscroft (2002) refer to as indicative imagining. This is a thought the patient initially entertains as a contender for the truth but which has not yet evolved into a fully-formed / held belief.

The patient’s eventual acceptance of the ‘impostor’ thought as a belief should therefore be understood in terms of the role the newly acquired belief plays in explaining why there is a change in the patient’s experience whenever the patient is presented with his wife (the aforementioned feeling of estrangement). Importantly, the now accepted belief results in the patient’s belief and experience becoming congruent: this is what I should experience when I am in the presence of a stranger and not my wife.

It is my contention, then, that by reinstating a role for patient experience within an explanation of the Capgras delusion, even within Coltheart et al.’s model, one is better able to explain not only why the belief is formed in the first place but, ultimately, why it is maintained, sometimes in the face of overwhelming evidence to the contrary.

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