Thursday, 16 October 2014

Interview with Martin Davies: Delusions (Part 3)

Martin Davies
This is the third part of an interview with Professor Martin Davies on delusions. (Although this part can be read independently of the previous two, you may want to read also the first and second part of the interview if you haven't done so already!)

LB: In the first stage of our project PERFECT we are going to ask whether delusions can have pragmatic and epistemic benefits. You and your collaborators have noticed how anosognosia (denial of illness), despite initially interfering with rehabilitation, can then lead to lower anxiety and protect from negative emotions (Aimola Davies et al., 2009). Can you think of other examples of delusions having a positive psychological impact? 

MKD: Let me begin by reviewing the findings that you mentioned in your question. Some researchers distinguish denial of illness from anosognosia and use the ‘denial’ terminology for cases with a ‘psychological’ rather than neurological aetiology. In our paper, we referred to a theoretical review by Kortte and Wegener (2004), who found support for both adaptive and maladaptive effects of denial of illness across a range of rehabilitation populations.

They proposed two distinctions to explain these different effects: (i) subtypes of denial and (ii) different time points from symptom identification to hospitalisation and rehabilitation. On (i), they suggested that the effect of avoidance of illness-related information is more likely to be maladaptive while a positive reinterpretation of the illness experience was more likely to be adaptive. On (ii), and focusing now on Kortte and Wegener’s discussion of denial of heart disease, denial at the stage of symptom (self-)identification has obvious negative consequences and long-term denial (particularly, of the avoidance type) after discharge from hospital has been linked with poorer compliance with medication regimes and a failure to heed medical advice about risk factors. However, denial (particularly, of the positive reinterpretation type) during the hospitalisation stage appears to be associated with more positive effects, such as protection from negative emotional states and reduced medical complications.

The first example that comes to mind of a delusion (other than denial of illness or anosognosia) having a positive psychological impact is the case of reverse Othello syndrome (a delusional belief in the fidelity of a romantic partner) reported by Peter Butler (2000). Patient BX suffered a severe head injury in a motor vehicle accident. The relationship between BX and his partner collapsed and she broke off all contact five months after the accident. Seven months later, while he was still paralysed, confined to a wheelchair, unable to eat, and unable to speak (but communicating by using an electronic device), he developed the delusion that he had recently married his former partner. The delusion persisted for several months, until BX began to accept the reality of his situation.

It is interesting to consider how this case of delusion fits into the two-factor framework. Patient BX suffered serious brain injuries but nothing in Butler’s case description suggests a specific neuropsychological deficit producing an anomalous experience from which endorsement or explanation would lead to the delusional belief. The delusion, emerging around the first anniversary of BX’s accident, did not arise as an explanation of his experience, but as a defence against depressive overwhelm. Butler summarises the positive psychological impact of BX’s delusion: ‘BX’s erotic fantasy system seemed to go some way toward reconferring a sense of meaning to his life experience and reintegrating his shattered sense of self. Without it there was only the stark reality of annihilating loss and confrontation with his own emotional devastation’ (2000, p. 89).

Project PERFECT will investigate the pragmatic and epistemic benefits of false beliefs such as BX’s motivated delusion. So perhaps I can briefly indicate how I understand the possibility that you envisage; namely, the possibility that adopting a false belief might have, not only psychological benefits, but also epistemic benefits – that is, benefits in achieving knowledge (propositional knowledge or ‘knowledge that’).

First, we need to set aside one kind of scenario. Starting from a false belief, and engaging in some reasoning, one might validly infer a true belief. This is not a possible epistemic benefit of having the false belief because it would be widely agreed in epistemology (the philosophy of knowledge) that a true belief inferred from a false one does not constitute knowledge. (This is the ‘no false lemmas’ requirement on knowledge.) So epistemic benefits must arise in a more indirect way.

Staying with the example of BX, perhaps the following would be a plausible idea. If BX had been overwhelmed by depression (rather than adopting his motivated delusion) then he would have been less interested in engaging with his situation and the world around him in ways that would yield knowledge. If this idea is correct, then the delusion also allowed BX to function better, not only psychologically, but also epistemically. However, it is not straightforward to point to specific epistemic benefits of the delusion.

Patient BX’s belief that he had recently married his former partner was, of course, false, and was not itself an example of doing well epistemically. The psychological benefits of the delusional belief did allow BX to maintain a degree of epistemic functionality sufficient to engage in cognitive therapy, and he came to accept that he and his former partner were not married and that their separation was permanent. But it is not clear that this knowledge constituted an epistemic benefit of BX’s delusion, by comparison with severe depression. Before the onset of the delusion, BX already showed considerable insight into his physical impairments and his relationship breakdown, and we can suppose that he would have retained that knowledge even if he had been overwhelmed by depression, rather than adopting the delusional belief.

Butler’s report indicates that, by the time of his discharge from hospital, BX had achieved a richer body of knowledge about his situation and his future. We might suppose that BX would not have achieved all of this knowledge if he had been severely depressed. But should this epistemic benefit be attributed to BX’s adoption of the false belief? From the case report, it is not quite clear whether this richer body of knowledge was achieved before or after the delusional belief was rejected. Thus, while the idea of epistemic benefits of a false belief seems clear enough, at least in cases of motivated delusion, perhaps the case of BX does not provide a really convincing example.

You have recently written about epistemic functionality on the Psychiatric Ethics blog and you suggested that ‘challenging a motivated delusion is not always advisable from an epistemic point of view’. On this point, it is noteworthy that members of BX’s treatment team were instructed not to ‘aggressively challenge’ his delusional belief.

LB: Another question we are going to ask as part of the project is whether the person adopting delusions can believe otherwise given perceptual or memory impairments, anomalous experience, reasoning biases or deficits. Do you think it is possible to say, at least in some circumstances, that the delusion is somehow inescapable and that the person could not adopt a non-delusional hypothesis at the time?

Your mention of memory impairments leads me to the case of patient NS, described by Cocchini and colleagues (2002). The patient suffered a severe closed head injury and his left limbs were paralysed. He suffered from unilateral neglect and from anosognosia for his motor impairments. Importantly in the present context, he showed anterograde amnesia for self-related information. Patient NS was able to discover his motor impairments if his paralysed left limbs were moved to the right side of his body and he was asked to move them. But, because of his anterograde amnesia, his anosognosia persisted. He could not retain the new information and he could not update his beliefs about himself. Consequently, he continued to refer to himself ‘through the accrued schema of a healthy person’ (2002, p. 2036). Given NS’s memory impairment, his longstanding, but now false, beliefs about being able to move his left arm and leg were inescapable.

The persistence of delusions is not usually explained by a catastrophic inability to retain new information. But still, one thought would be that any good explanation of a delusion would reveal it to be, in a sense, inescapable. Suppose we were really able to give a good explanation of a delusion – how the delusional idea arose, why the delusional hypothesis was regarded as a live candidate, why it was adopted as a belief, and why the belief was not subsequently rejected. It seems that such an explanation would show that the delusion was – in all the circumstances, given all the patient’s impairments, and given all the conditions to which the explanation appealed – inescapable.

Suppose that we were to focus specifically on the persistence question: Why does the delusional belief, once adopted, persist; why is it not subsequently rejected? And suppose that we had a good answer to that question. Perhaps the answer is, in part, that the task of belief evaluation is demanding of cognitive resources. Specifically, the patient may need to inhibit prepotent doxastic responses to an anomalous and highly salient experience and to adopt an ‘as if’ description of the experience. The patient may also need to generate and consider alternative hypotheses, understand whether they explain the anomalous experience, and evaluate them in the light of available evidence. The difficulty of a cognitive task of this kind will be exacerbated if inhibitory executive processes or working memory are impaired (Aimola Davies and Davies, 2009).

Thus, impaired executive processes or working memory may provide an answer to the persistence question and may seem to make the patient’s delusional belief inescapable. But we should note that one of the background conditions assumed in an explanation of the persistence of a delusion might be that the patient is working alone, trying to understand his or her situation. If that assumption were not to apply – if, for example, cognitive ‘scaffolding’ were provided by a therapeutic intervention – then the delusional belief might not be truly inescapable.

We should also note that any account of delusions as, in some sense, inescapable must be sufficiently nuanced to allow for the fact that delusions sometimes wax and wane. Max Coltheart (2007, pp. 1053–56) provides some good examples of this.


Aimola Davies, A.M., Davies, M., Ogden, J.A., Smithson, M., and White, R.C. 2009: Cognitive and motivational factors in anosognosia. In T. Bayne, and J. Fern├índez (eds.) Delusions and Self-Deception: Affective and Motivational Influences on Belief Formation, pp. 187–225. Hove, East Sussex: Psychology Press.

Kortte, K.B., and Wegener, S.T. 2004:Denial of Illness in Medical Rehabilitation Populations: Theory, Research, and Definition. Rehabilitation Psychology, 49(3), 187-99.

Butler, P.V. 2000: Reverse Othello syndrome subsequent to traumatic brain injury. Psychiatry, 63, 85–92.

Cocchini, G., Beschin, N. and Della Sala, S. 2002: Chronic anosognosia: A case report and theoretical account. Neuropsychologia, 40, 2030–38.

Aimola Davies, A.M. and Davies, M. 2009: Explaining pathologies of belief. In M.R. Broome and L. Bortolotti (eds.), Psychiatry as Cognitive Neuroscience: Philosophical Perspectives, pp. 285–323. Oxford: Oxford University Press.

Coltheart, M. 2007: Cognitive neuropsychiatry and delusional belief. Quarterly Journal of Experimental Psychology, 60, 1041–62.

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